Tetracycline and sulfamethazine alter dissimilatory nitrate reduction processes and increase N2O release in rice fields Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Jun Shan, Pinpin Yang, M. Mizanur Rahman, Xiaoxia Shang, Xiaoyuan Yan
Effects of antibiotics on transformation of nitrate and the associated N2O release in paddy fields are obscure. Using soil slurry experiments combined with 15N tracer techniques, the influence of tetracycline and sulfamethazine (applied alone and in combination) on the denitrification, anaerobic ammonium oxidation (anammox), dissimilatory nitrate reduction to ammonium (DNRA) and N2O release rates in the paddy soil were investigated, while genes related to nitrate reduction and antibiotic resistance were quantified to explore the microbial mechanisms behind the antibiotics’ effects. The potential rates of denitrification, anammox and DNRA were significantly (p < 0.05) reduced, which were mainly attributed to the inhibitory effects of the antibiotics on nitrate-reducing microbes. However, the N2O release rates were significantly (p < 0.05) stimulated by the antibiotic treatments (0.6–6000 μg kg−1 soil dry weight), which were caused by the different inhibition effects of antibiotics on N2O production and N2O reduction as suggest by the changes in abundance of nirS (nitrite reduction step) and nosZ (N2O reduction to N2 step) genes. Antibiotic resistance gene (tetA, tetG, sulI and sulIII) abundances were significantly (p < 0.05) increased under high antibiotic exposure concentrations (>600 μg kg−1 soil dry weight). Our results suggest that the widespread occurrence of antibiotics in paddy soils may pose significant eco-environmental risks (nitrate accumulation and greenhouse effects) by altering nitrate transformation processes.
Associations between longitudinal serum perfluoroalkyl substance (PFAS) levels and measures of thyroid hormone, kidney function, and body mass index in the Fernald Community Cohort Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Bevin E. Blake, Susan M. Pinney, Erin P. Hines, Suzanne E. Fenton, Kelly K. Ferguson
Perfluoroalkyl substances (PFAS) are a diverse class of manufactured compounds used in a wide range of industrial processes and consumer products and have been detected in human serum worldwide. Previous cross-sectional and cohort studies in humans have suggested exposure to PFAS is associated with a wide array of chronic diseases, including endocrine disruption, developmental health effects, cancer and metabolic changes. We examined the associations between a panel of eight PFAS and indicators of thyroid disruption, kidney function, and body mass index (BMI), all of which were measured at repeated time points (1990–2008) over the course of the study. Participants (N = 210) were selected from the Fernald Community Cohort based on household water supply from a PFAS-contaminated aquifer. In adjusted repeated measures models, we observed several notable associations between serum PFAS and thyroid hormones as well as kidney function as measured by estimated glomerular filtration rate (eGFR). An interquartile (IQR) increase in serum PFOS was associated with a 9.75% (95% CI = 1.72, 18.4) increase in thyroid stimulating hormone. An IQR increase in serum PFNA, PFHxS, and PFDeA was associated with a −1.61% (95% CI = −3.53, −0.59), −2.06% (95% CI = −3.53, −0.59), and −2.20% (95% CI = −4.25, −0.14) change in eGFR, respectively. On the other hand, an IQR increase in serum Me-PFOSA was associated with a 1.53% (95% CI = 0.34, 2.73) increase in eGFR. No significant associations with BMI and serum PFAS were noted. Our findings are in agreement with previous reports that serum PFAS are associated with altered kidney and thyroid function.
Responses and successions of sulfonamides, tetracyclines and fluoroquinolones resistance genes and bacterial community during the short-term storage of biogas residue and organic manure under the incubator and natural conditions Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Chengjun Pu, Liquan Liu, Meng Yao, Hang Liu, Ying Sun
Biogas residue and organic manure are frequently used for crop planting. However, the evaluation of antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs) and bacterial community before their applications to fields is still lacking. This study monitored the variations of bacteria resistant to sulfadiazine, tetracycline and norfloxacin, 57 resistance genes for sulfonamides, tetracyclines and fluoroquinolones as well as the bacterial community during the 28-day aerobic storage of biogas residue and organic manure by using viable plate counts, high-throughput qPCR and Illumina MiSeq sequencing methods. Then two storage conditions, incubator (25 °C) and natural environment, were used to assess the responses of ARB and ARGs to the environmental factors. Results showed that a total of 35 and 21 ARGs were detected in biogas residue and organic manure, respectively. ARB and ARGs were enriched up to 8.01-fold in biogas residue after the 28-day storage, but varied in a narrow range during the storage of organic manure. Compared with the incubator condition, the proliferation of ARB and ARGs in biogas residue under the natural condition was relatively inhibited by the varied and complicated environmental factors. However, we found that there was no significant difference of ARB and ARGs in organic manure between the incubator and natural conditions. Bacterial community was also shifted during the storage of biogas residue, especially Bacteroidetes_VC2.1_Bac22, Aequorivita, Luteimonas and Arenimonas. Network analysis revealed that the relationship in biogas residue was much more complicated than that in organic manure, which ultimately resulted in large successions of ARB and ARGs during the short-term storage of biogas residue. Therefore, we suggest that further measures should be taken before the application of biogas residue to fields.
Characteristics and health effects of formaldehyde and acetaldehyde in an urban area in Iran Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Mahdieh Delikhoon, Mehdi Fazlzadeh, Armin Sorooshian, Abbas Norouzian Baghani, Mohammad Golaki, Qadir Ashournejad, Abdullah Barkhordari
This study reports a spatiotemporal characterization of formaldehyde and acetaldehyde in the summer and winter of 2017 in the urban area of Shiraz, Iran. Sampling was fulfilled according to EPA Method TO-11 A. The inverse distance weighting (IDW) procedure was used for spatial mapping. Monte Carlo simulations were conducted to evaluate carcinogenic and non-cancer risk owing to formaldehyde and acetaldehyde exposure in 11 age groups. The average concentrations of formaldehyde/acetaldehyde in the summer and winter were 15.07/8.40 μg m−3 and 8.57/3.52 μg m−3, respectively. The formaldehyde to acetaldehyde ratios in the summer and winter were 1.80 and 2.43, respectively. The main sources of formaldehyde and acetaldehyde were photochemical generation, vehicular traffic, and biogenic emissions (e.g., coniferous and deciduous trees). The mean inhalation lifetime cancer risk (LTCR) values according to the Integrated Risk Information System (IRIS) for formaldehyde and acetaldehyde in summer and winter ranged between 7.55 × 10−6 and 9.25 × 10−5, which exceed the recommended value by US EPA. The average LTCR according to the Office of Environmental Health Hazard Assessment (OEHHA) for formaldehyde and acetaldehyde in summer and winter were between 4.82 × 10−6 and 2.58 × 10−4, which exceeds recommended values for five different age groups (Birth to <1, 1 to <2, 2 to <3, 3 to <6, and 6 to <11 years). Hazard quotients (HQs) of formaldehyde ranged between 0.04 and 4.18 for both seasons, while the HQs for acetaldehyde were limited between 0.42 and 0.97.
First evidence of association between past environmental exposure to dioxin and DNA methylation of CYP1A1 and IGF2 genes in present day Vietnamese population Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Giuliani Cristina, Biggs David, Nguyen Thanh Tin, Marasco Elena, De Fanti Sara, Garagnani Paolo, Le Phan Minh Triet, Nguyen Viet Nhan, Luiselli Donata, Romeo Giovanni
During the Vietnam War, the United States military sprayed over 74 million litres of Agent Orange (AO) to destroy forest cover as a counterinsurgency tactic in Vietnam, Laos and Cambodia. The main ingredient was contaminated by 2,3,7,8-tetrachlorodibenzo-paradioxin (TCDD). DNA methylation (DNAm) differences are potential biomarker of environmental toxicants exposure. The aim of this study was to perform a preliminary investigation of the DNAm levels from peripheral blood of the present-day Vietnamese population, including individuals whose parents, according to historical data, were exposed to AO/TCDD during the war. 94 individuals from heavily sprayed areas (cases) and 94 individuals from non-sprayed areas (controls) were studied, and historical data on alleged exposure of parents collected. 94 cases were analysed considering those whose father/parents participated in the war (N = 29) and considering the place of residence of both parents (64 living in sprayed areas versus 30 in non-contaminated areas). DNAm levels in CYP1A1 and IGF2 genes were measured (MALDI-TOF technology). The analyses showed that: 1) one CpG site in the CYP1A1 and one in the IGF2 gene showed significant differences in DNAm levels between cases and controls; 2) the CYP1A1 region resulted to be hypomethylated (in 9 out of 16 sites/units; p-val<0.01) in 29 individuals whose father/parents participated in the war in the spray zones; 3) we showed that the place of residence of both parents influenced methylation levels of the CYP1A1 and IGF2 genes (p-val<0.05). In conclusion this study indicates that past environmental exposure to dioxin (AO/TCDD) shapes the DNAm profile of CYP1A1 and that the place of living for parents in former spray zones influences DNAm of CYP1A1 and IGF2 genes. These results open the way to new applications of DNAm as potential biomarker(s) of past human exposure to dioxin.
Remobilization and bioavailability of polycyclic aromatic hydrocarbons from estuarine sediments under the effects of Nereis diversicolor bioturbation Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Nan Sun, Yanli Chen, Shuqin Xu, Ying Zhang, Qiang Fu, Lixin Ma, Qi Wang, Yuqing Chang, Zhe Man
The effects of Nereis diversicolor bioturbation on the remobilization and bioavailability of polycyclic aromatic hydrocarbons from estuarine sediment were determined after 60 d in a laboratory experiment. The release fluxes and mass transfer coefficients showed that bioturbation by N. diversicolor can lead to a significant remobilization of polycyclic aromatic hydrocarbons (PAHs) from estuarine sediments. Bioturbation enhanced the release of PAHs from sediment to water by accelerating the transport of sediment particles to the sediment-water interface followed by PAHs desorption to the water. The bioavailability of PAHs was described by SPMD-sediment accumulation factors (SSAF). The SSAF of low molecular weight PAHs with bioturbation was significantly higher than that of PAHs without bioturbation, and there were no significant variations in high-molecular-weight PAHs. Our results revealed that N. diversicolor bioturbation significantly increased PAH release from sediment to water but only increased the bioavailability of low-molecular-weight PAHs.
Emission factors of particulate and gaseous compounds from a large cargo vessel operated under real-world conditions Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Cheng Huang, Qingyao Hu, Hanyu Wang, Liping Qiao, Sheng'ao Jing, Hongli Wang, Min Zhou, Shuhui Zhu, Yingge Ma, Shengrong Lou, Li Li, Shikang Tao, Yingjie Li, Diming Lou
On-board emissions measurements were performed on a Handysize-class bulk carrier operating under real-world conditions. Emission factors (EFs) were determined for criteria pollutants such as NOx, CO, total hydrocarbons (THC), and PM; PM composition, including organic and elemental carbon (OC and EC), inorganic species, and a variety of organic compounds and VOC species (including alkanes, alkenes, single-ring aromatics, and oxygenated VOCs) were also analyzed. To investigate the impacts of engine type, fuel, and operating conditions on emissions, measurements were conducted on one main and one auxiliary engines using low- and high-sulfur fuels (LSF and HSF) under actual operating conditions, including at-berth, maneuvering, and cruising at different engine loads. OC was the most abundant PM component (contributing 45–65%), followed by sulfate (2–15%) and EC (1–20%). Compounds with 3 or 4 aromatic rings, including phenanthrene, fluoranthene, pyrene, and benzo[b+k]fluoranthene, dominated the particulate polycyclic aromatic hydrocarbons (PAHs) emitted from the ship, accounting for 69–89% of the total PAHs. Single-ring aromatics constituted 50–78% of the emitted VOCs and were dominated by toluene. In this study, switching from HSF (1.12% S) to LSF (0.38% S) reduced emitted PM by 12%, OC by 20%, sulfate by 71%, and particulate PAHs by 94%, but caused an increase in single-ring aromatics. The power-based EFs generally decreased with increasing engine loads. However, decreasing the ship engine load also reduced the vessel speed and, thus, decreased emissions over a given voyage distance. Herein, a Vessel Speed Reduction (VSR) from 11 to 8–9 knots decreased NOx and PM emissions by approximately 33% and 36%, respectively, and OC, EC, sulfate, and particulate PAHs in PM emissions by 34%, 83%, 29%, and 11%. These data can be used to minimize uncertainty in the emission factors used in ship emissions calculations.
Biotransformation of disperse dyes using nitroreductase immobilized on magnetic particles modified with tosyl group: Identification of products by LC-MS-MS and theoretical studies conducted with DNA Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Jefferson Honorio Franco, Bianca F. da Silva, Alexandre A. de Castro, Teodorico C. Ramalho, María Isabel Pividori, Maria Valnice Boldrin Zanoni
The present work evaluates the action of nitroreductase enzyme immobilized on Tosylactivated magnetic particles (MP-Tosyl) on three disperse dyes which contain nitro and azo groups. The dyes included Disperse Red 73 (DR 73), Disperse Red 78 (DR 78), and Disperse Red 167 (DR 167). The use of a magnet enabled the rapid and easy removal of the immobilized enzyme after biotransformation; this facilitated the identification of the products generated using high-performance liquid chromatography with diode array detector (HPLC-DAD) and mass spectrometry (LC-MS/MS). The main products formed by the in vitro biotransformation were identified as the product of nitro group reduction to the correspondent amine groups, which were denoted as follows: 50% of 2-(2-(4-((2-cyanoethyl)(ethyl)amino)phenyl)hydrazinyl)-5-nitrobenzonitrile, 98% of 3-((4-((4-amino-2-chlorophenyl) diazenyl)phenyl) (ethyl)amino)propanenitrile and 99% of (3-acetamido-4 - ((4-amino-2-chlorophenyl) diazenyl) phenyl) azanediyl) bis (ethane-2,1-diyl) for DR 73, DR 78 and DR 167, respectively. Based on the docking studies, the dyes investigated were found to be biotransformed by nitroreductase enzyme due to their favorable interaction with the active site of the enzyme. Theoretical results show that DR73 dye exhibits a relatively lower rate of degradation; this is attributed to the cyanide substituent which affects the electron density of the azo group. The docking studies also indicate that all the dyes presented significant reactivity towards DNA. However, Disperse Red 73 was found to exhibit a substantially higher reactivity compared to the other dyes; this implies that the dye possesses a relatively higher mutagenic power. The docking results also show that DR 73, DR 78 and DR 167 may be harmful to both humans and the environment, since the mutagenicity of nitro compounds is associated with the products formed during the reduction of nitro groups. These products can interact with biomolecules, including DNA, causing toxic and mutagenic effects.
Aluminum: A potentially toxic metal with dose-dependent effects on cardiac bioaccumulation, mineral distribution, DNA oxidation and microstructural remodeling Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Rômulo D. Novaes, Viviane G.S. Mouro, Reggiani V. Gonçalves, Andrea A.S. Mendonça, Eliziária C. Santos, Maria C.Q. Fialho, Mariana Machado-Neves
Large amounts of aluminum (Al) are found in wastewater from industrial bauxite mining, which is often responsible for the contamination of drinking water sources in urban and rural communities. Although this metal exhibits broad environmental distribution, its cardiac repercussions are poorly understood, making it difficult to establish diagnostic criteria in cases of Al intoxication. In the absence of clinical data, we used a preclinical model to investigate the impact of Al exposure on heart bioaccumulation, molecular oxidation, micromineral distribution, structural and ultrastructural remodeling of the cardiac tissue. Male Wistar rats were equally randomized into five groups: G1 = distilled water; and G2 to G5 = 0.02, 0.1, 50, and 200 mg/kg aluminum solution, respectively. After 120 days, the hearts were collected and subjected to mineral microanalysis, immunoenzymatic detection of 8-OHdG, as well as bright field, polarizing, scanning and transmission electron microscopy to estimate the extent of the cardiac remodeling and cardiomyocytes ultrastructure. Long-term Al exposure induced dose-dependent bioaccumulation, micromineral imbalance, genomic DNA oxidation, structural and ultrastructural abnormalities of the cardiac tissue, resulting in extensive parenchymal loss, stromal expansion, diffuse inflammatory infiltrate, increased glycoconjugate and collagen deposition, subversion and collapse of the collagen network, reduced myocardial vascularization index, mitochondrial swelling, sarcomere disorganization, myofilament dissociation, and fragmentation in cardiomyocytes. Our findings indicated that the heart was sensitive to Al-mediated toxicity, especially in animals treated with the three highest doses of Al. In response to Al-induced loss of the parenchyma, heart stroma exhibited a reactive and compensatory expansion, which, in combination with the increased distribution of thick myofibrils and degenerated mitochondria in cardiomyocytes, provides morphological evidence that cardiac tissue adaptations are not enough to adjust the relationships between the parenchyma and stroma until a steady state is reached, resulting in continuous pathological remodeling potentially associated with Al-induced proinflammatory and pro-oxidant events.
Thiosulphate-induced phytoextraction of mercury in Brassica juncea: Spectroscopic investigations to define a mechanism for Hg uptake Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Jianxu Wang, Christopher W.N. Anderson, Ying Xing, Yuhong Fan, Jicheng Xia, Sabry M. Shaheen, Jörg Rinklebe, Xinbin Feng
Thiosulphate is extensively used to enhance mercury (Hg) phytoextraction due to its efficient in prompting plant Hg uptake. However, the mechanism by which thiosulphate promotes Hg uptake is poorly understood. We determined the concentrations of Hg and potassium (K), and their spatial distribution, in the tissues of Brassica juncea grown in Hg-contaminated soil treated by thiosulphate and compared this to a non-treated soil (control). The spatial distribution of Hg and K was characterized using micro-X ray fluorescence spectroscopy. The subcellular localization and speciation of Hg in the root of plant treatded by thiosulphate were elucidated using Transmission electron microscope coupled energy-dispersive X-ray (TEM-EDX) spectroscopy. Thiosulphate increased significantly the Hg concentration in the roots (mainly in the epidermis and xylem) and shoots (mainly in the vascular bundles), while Hg was accumulated in the root (mainly in the epidermis) of the control plant. Thiosulphate promoted the movement of Hg from the epidermis to the xylem of roots, with subsequent loading into the stem via vascular bundles. Thiosulphate decreased the K concentration in plant tissues, relative to the control plant, and we propose this is due to leakage of electrolyte from roots via increased plasma membrane permeability as a consequence of physiological damage caused by the added thiosulphate. Mercury was distributed mainly at the extracellular space in the roots and was shown by TEM-EDX to be predominately amorphous nano-clusters of HgS. We conclude that thiosulphate-promoted Hg accumulation in the plant may happen through increased plasma membrane permeability, a changed pathway of Hg movement within plants, and extracellular co-transportation of Hg-S complexes in the roots. Our results may underpin the ongoing development of phytomanagement as an environmental strategy for Hg contaminated soils around the world.
Estimation of the soil hazardous concentration of methylparaben using a species sensitivity approach Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Dokyung Kim, Rongxue Cui, Jongmin Moon, Jin Il Kwak, Shin Woong Kim, Dasom Kim, Youn-Joo An
Methylparaben, which is known to be an endocrine-disrupting chemical, is added to various personal care products, including cosmetics, and is also used as a food preservative and in pharmaceuticals. However, information on the toxicity of methylparaben in soil ecosystems is limited. Furthermore, unlike other substances such as metals and pesticides, there is no regulation of levels or safe concentrations of methylparaben in soil ecosystems. Therefore, the aims of this study were to evaluate the toxicity of methylparaben on soil species and to derive hazardous concentration (HC) values with respect soil ecosystem protection. We conducted acute bioassays on eight species within six taxonomic groups and chronic bioassays on five species within four taxonomic groups. On the basis of the results obtained, we derived an acute HC5 value of 44 mg/kg soil and a corresponding chronic value of 27 mg/kg soil for methylparaben using species sensitivity distribution methodology following Australian and New Zealand guidelines. Given that there has been no proposed standard value for methylparaben in soil in any country, it was not possible to compare the HC values calculated in this study with regulation standard levels. Nevertheless, to our knowledge, this study is first to assess the toxicity of methylparaben against soil-inhabiting species and to estimate acute and chronic HCs for soil fauna and flora. The results of this study will provide valuable fundamental data for the establishment of acceptable levels of methylparaben in soil.
0# Diesel water-accommodated fraction induced lipid homeostasis alteration in zebrafish embryos Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Xiyan Mu, Jia Liu, Ke Yang, Ying Huang, Xuxing Li, Wenbo Yang, Suzhen Qi, Wenqing Tu, Gongming Shen, Yingren Li
To investigate the developmental effects and corresponding molecular mechanism of diesel in freshwater organisms, zebrafish embryos were exposed to 0# diesel water-accommodated fraction (WAF) at different concentrations. Mortality, embryonic morphological endpoints, transcriptional profile and lipid profile were evaluated after exposure. Exposure to 0# diesel WAF had no significant effect on the survival of zebrafish embryos from 1.5 to 96 hpf. However, a significant increase in mortality was observed at 144 and 196 hpf in the groups of 20 and 40 mg/L 0# diesel WAF. RNA-Seq results demonstrated that 0# diesel WAF could induce significant alterations in transcription profile at concentrations of 0.05 mg/L (the limit for petroleum hydrocarbon concentration in surface water in China) and 5 mg/L. Gene Ontology enrichment and similarity analysis indicated that lipid metabolism, lipid synthesis, biological transport, drug metabolism and homeostatic processes were the most altered biological processes after exposure to 0# diesel WAF. Further, transcription levels of genes involved in cholesterol and fatty acid synthesis were significantly inhibited by diesel WAF according to qPCR results. Lipidomics results also indicated that several lipid species (cholesterol ester, fatty acid, diglyceride and triglyceride) decreased after 0# diesel WAF exposure. These results reflect the potential risk of diesel pollution in freshwater ecosystems especially on the alteration of lipid homeostasis and enable a better understanding of the molecular pathways underlying the action of diesel WAF in zebrafish embryos.
Unraveling microbial turnover and non-extractable residues of bromoxynil in soil microcosms with 13C-isotope probing Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Karolina M. Nowak, Markus Telscher, Erika Seidel, Anja Miltner
Bromoxynil is a widely used nitrile herbicide applied to maize and other cereals in many countries. To date, still little is known about bromoxynil turnover and the structural identity of bromoxynil non-extractable residues (NER) which are reported to occur in high amounts. Therefore, we investigated the microbial turnover of 13C-labeled bromoxynil for 32 days. A focus was laid on the estimation of biogenic NER based on the turnover of 13C into amino acids (AA). At the end, 25% of 13C6-bromoxynil equivalents were mineralized, 2% assigned to extractable residues and 72.5% to NER. Based on 12% in the 13C-total AA and an assumed share of AA of 50% in microbial biomass we arrived at 24% of total 13C-biogenic NER. About 33% of the total 13C-NER could thus be explained by 13C-biogenic NER; 67% was unknown and by definition xenobiotic NER with potential for toxicity. The 13C label from 13C6-bromoxynil was mainly detected in the humic acids (28.5%), but significant amounts were also found in non-humics (17.6%), fulvic acids (13.2%) and humins (12.7%). The 13C-total amino acids hydrolyzed from humic acids, humins and fulvic acids amounted to 5.2%, 6.1% and 1.2% of 13C6-bromoxynil equivalents, respectively, corresponding to total 13C-biogenic NER amounts of 10.4%, 12.2% and 2.4%. The humins contained mostly 13C-biogenic NER, whereas the humic and fulvic acids may be dominated by the xenobiotic NER. Due to the high proportion of unknown 13C-NER and particularly in the humic and fulvic acids, future studies should focus on the detailed characterization of these fractions.
Uranium adsorption and subsequent re-oxidation under aerobic conditions by Leifsonia sp. - Coated biochar as green trapping agent Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Lei Ding, Wen-fa Tan, Shui-bo Xie, Kathryn Mumford, Jun-wen Lv, Hong-qiang Wang, Qi Fang, Xiao-wen Zhang, Xiao-yan Wu, Mi Li
It has generally been assumed that the immobilization of U(VI) via polyphosphate accumulating microorganisms may present a sink for uranium, but the potential mechanisms of the process and the stability of precipitated uranium under aerobic conditions remain elusive. This study seeks to explore the mechanism, capacity, and stability of uranium precipitation under aerobic conditions by a purified indigenous bacteria isolated from acidic tailings (pH 6.5) in China. The results show that over the treatment ranges investigated, maximum removal of U(VI) from aqueous solution was 99.82% when the initial concentration of U(VI) was 42 μM, pH was 3.5, and the temperature was with 30 °C much higher than that of other reported microorganisms. The adsorption mechanism was elucidated via the use of SEM-EDS, XPS and FTIR. SEM-EDS showed two peaks of uranium on the surface. A plausible explanation for this, supported by FTIR, is that uranium precipitated on the biosorbent surfaces. XPS measurements indicated that the uranium product is most likely a mixture of 13% U(VI) and 87% U(IV). Notably, the reoxidation experiment found that the uranium precipitates were stable in the presence of Ca2+ and Mg2+, however, U(IV) is oxidized to U(VI) in the presence of NO3− and Na+ ions, resulting in rapid dissolution. It implies that the synthesized Leifsonia sp. coated biochar could be utilized as a green and effective biosorbent. However, it may not a good choice for in-situ remediation due to the subsequent re-oxidation under aerobic conditions. These observations can be of some guiding significance to the application of the bioremediation technology in surface environments.
Dioxin-like PCB 126 increases intestinal inflammation and disrupts gut microbiota and metabolic homeostasis Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Michael C. Petriello, Jessie Hoffman, Olga Vsevolozhskaya, Andrew J. Morris, Bernhard Hennig
The gut microbiome is sensitive to diet and environmental exposures and is involved in the regulation of host metabolism. Additionally, gut inflammation is an independent risk factor for the development of metabolic diseases, specifically atherosclerosis and diabetes. Exposures to dioxin-like pollutants occur primarily via ingestion of contaminated foods and are linked to increased risk of developing cardiometabolic diseases. We aimed to elucidate the detrimental impacts of dioxin-like pollutant exposure on gut microbiota and host gut health and metabolism in a mouse model of cardiometablolic disease. We utilized 16S rRNA sequencing, metabolomics, and regression modeling to examine the impact of PCB 126 on the microbiome and host metabolism and gut health. 16S rRNA sequencing showed that gut microbiota populations shifted at the phylum and genus levels in ways that mimic observations seen in chronic inflammatory diseases. PCB 126 reduced cecum alpha diversity (0.60 fold change; p = 0.001) and significantly increased the Firmicutes to Bacteroidetes ratio (1.63 fold change; p = 0.044). Toxicant exposed mice exhibited quantifiable concentrations of PCB 126 in the colon, upregulation of Cyp1a1 gene expression, and increased markers of intestinal inflammation. Also, a significant correlation between circulating Glucagon-like peptide-1 (GLP-1) and Bifidobacterium was evident and dependent on toxicant exposure. PCB 126 exposure disrupted the gut microbiota and host metabolism and increased intestinal and systemic inflammation. These data imply that the deleterious effects of dioxin-like pollutants may be initiated in the gut, and the modulation of gut microbiota may be a sensitive marker of pollutant exposures.
Stabilizing mixed fatty acid and phthalate ester monolayer on artificial seawater Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Siyang Li, Lin Du, Qingzhu Zhang, Wenxing Wang
Phthalate esters which are widely used as industrial chemicals have become widespread contaminants in the marine environment. However, little information is available on the interfacial behavior of phthalate esters in the seawater, where contaminants generally occur at elevated concentrations and have the potential to transfer into the atmosphere through wave breaking on sea surface. We used artificial seawater coated with fatty acids to simulate sea surface microlayer in a Langmuir trough. The interactions of saturated fatty acids (stearic acid (SA) and palmitic acid (PA)) with one of the most abundant phthalate esters (di-(2-ethylhexyl) phthalate (DEHP)), were investigated under artificial seawater and pure water conditions. Pure DEHP monolayer was not stable, while more stable mixed monolayers were formed by SA and DEHP on the artificial seawater at relatively low surface pressure. Sea salts in the subphase can lower the excess Gibbs free energy to form more stable mixed monolayer. Among the ten components in the sea salts, Ca2+ ions played the major role in condensation of mixed monolayer. The condensed characteristic of the mixed SA (or PA)/DEHP monolayers suggested that the hydrocarbon chains were ordered on artificial seawater. By means of infrared reflection-absorption spectroscopy (IRRAS), we found that multiple sea salt mixtures induced deprotonated forms of fatty acids at the air–water interface. Sea salts can improve the stability and lifetime of mixed fatty acid and phthalate ester monolayer on aqueous droplets in the atmosphere. Interfacial properties of mixed fatty acid and phthalate ester monolayers at the air–ocean interface are important to help understand their behavior and fate in the marine environment.
N2O emission contributions by different pathways and associated microbial community dynamics in a typical calcareous vegetable soil Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Liping Guo, Xuedong Wang, Tiantian Diao, Xiaotang Ju, Xiaoguang Niu, Lei Zheng, Xinyue Zhang, Xue Han
Nitrous oxide, one of the powerful long-lived greenhouse gases, is emitted mainly through biological processes, especially from fertilized soil. It is critical to partition the contribution of different pathways to N2O emissions and the relevant characteristics of microbial communities to identify the key N2O processes. An microcosm was conducted to partition the N2O emissions from different pathways, and the changes in soil mineral nitrogen and various nitrifiers (amoA bacteria and amoA archaea) and denitrifiers (nirS, nirK, and nosZ) were also determined using qPCR and high-throughput sequencing methods. Different gas inhibitor combinations (i.e., 0.06% acetylene, pure oxygen, 0.06% acetylene in pure oxygen, and pure helium) were used to partition the N2O pathways. A 5% oxygen treatment, with and without acetylene, was also included so that the N2O emissions could be measured under lower oxygen partial pressure. Results showed that ammonia-oxidation (AO) and successive nitrifier denitrification (NiD) were the main pathways contributing to N2O emissions at the earlier period after ammonium sulfate application with the cumulative N2O emissions accounting for 30.9% and 59.2% of the total N2O emissions, respectively. The higher NiD N2O contributions occurred when the soil nitrite concentration appeared higher, especially under the lower oxygen conditions. Higher N2O emissions from AO and NiD were associated with the compositional proportion of some dominant AOB species. Denitrification contributed more N2O (63.6%–69.3%) in the later period during incubation, coinciding with the following characteristics for denitrifiers: a) lower nosZ/(nirS + nirK) ratio, b) more diversity in nirS, and c) different proportions of some dominant species in nirK. Our results demonstrated that higher AO and successive NiD were the main N2O emission pathways, suggesting that controlling the ammonium content and weakening the AO are critical in decreasing N2O emissions.
Cadmium detoxification induced by salt stress improves cadmium tolerance of multi-stress-tolerant Pichia kudriavzevii Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Chunsheng Li, Xianqing Yang, Ying Xu, Laihao Li, Yueqi Wang
Heavy metal tolerance of microorganisms is the basis of heavy metal removal by growing cells. In this study, a cross-protection effect generated by salt stress significantly enhanced the cadmium tolerance of multi-stress-tolerant Pichia kudriavzevii. Comparative transcriptome analysis using RNA-Seq linked with physiological and biochemical observation was used to elucidate the underlying mechanisms of the improved cadmium tolerance. The expression of cadmium transport related genes (GSTY2, GLR1, GLO2, YCF1 and YOR1), GSH content and GST activity were elevated by salt stress, suggesting enhanced cadmium conjugation and detoxification in yeast cells. The inhibited cadmium uptake by ZRT1 and enhanced cadmium efflux by YOR1 contributed to the decrease in the intracellular cadmium concentration. The improved expression of antioxidant enzyme genes (SOD1, SOD2, SOD6, CAT1 and PRXIID), along with the enhanced activities of antioxidant enzymes (SOD, CAT and POD) resulted in a decrease in cadmium-induced ROS production, protein carbonylation, lipid peroxidation and cell death. The abundant expression of heat shock protein genes (HSP12, HSP10 and SSC1) and genes related to trehalose synthesis (TPS1 and TSL1) induced by salt stress protected yeast cells against complex stress conditions, contributing to the improved cadmium tolerance. These findings will be useful to develop cadmium-tolerant yeasts for cadmium removal by growing cells.
Optical properties of straw-derived dissolved organic matter and growth inhibition of Microcystis aeruginosa by straw-derived dissolved organic matter via photo-generated hydrogen peroxide Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Hua Ma, Liping Huang, Jie Zhang, Dezhi Shi, Jixiang Yang
Recent advances in research on algae inhibition by using low-cost straw proposed a possible mechanism that reactive oxygen species (ROS) generated by the solar irradiation of straw-derived dissolved organic matter (DOM) might contribute to cyanobacteria inhibition. However, this process is not clearly understood. Here, DOM from three types of straw (barley, rice, and wheat) and natural organic matter (NOM) isolates were investigated in terms of their photochemical properties and ROS generating abilities. Results demonstrated that the DOM derived from the aeration decomposition of barley straw (A-DOMbs) yielded the best formation efficiencies of hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) under solar-simulated irradiation in all organic matter samples. Correlation analysis implies that optical parameters and phenolic hydroxyl group contents can signify ROS generating abilities of different DOM solutions. Bioassay results show that A-DOMbs possesses the highest inhibition performance for M. aeruginosa in all DOM samples, much higher than those of NOM isolates. The addition of catalase greatly relieves the inhibition performance, making the loss of chlorophyll a content decreased from 37.14% to 7.83% in 2 h for A-DOMbs, which implies that for cyanobacteria growth inhibition, photochemically-produced H2O2 from SOM is far more important than singlet oxygen (1O2), •OH, and even SOM itself. Our results show that H2O2 photochemically generated from straw-derived DOM is able to result in rapid inhibition of M. aeruginosa in a relatively short period, furthering the understanding of complicated mechanisms of cyanobacteria inhibition by using low-cost straw in eutrophic waters.
Effects of nitrate on freshwater mussel glochidia attachment and metamorphosis success to the juvenile stage Environ. Pollut. (IF 4.358) Pub Date : 2018-07-17 Adrian P. Moore, Robert B. Bringolf
Water quality and contaminants have been frequently identified as critical stressors for freshwater mussels, many species of which are highly imperiled throughout North America and the world. Nutrient pollution, specifically nitrate, has become one of the most prevalent causes of water quality degradation globally, with increasing anthropogenic input from suburban and agricultural runoff, municipal wastewater, and industrial waste. Nitrate acute toxicity is generally low for aquatic species, but the potential effects of nitrate exposure are largely unknown for freshwater mussels, particularly during the parasitic stage of their complex lifecycle. Therefore, this study was designed to determine the effects of short-term nitrate exposure at environmentally relevant concentrations on juvenile production in two freshwater mussel species. Lampsilis siliquoidea and L. fasciola glochidia were exposed to nitrate (0, 11, or 56 mg NO3-N/L) for 24 h before inoculation on a primary host, Largemouth Bass (Micropterus salmoides). Glochidia attachment, metamorphosis success, and total number of juveniles produced were monitored on individual fish. Exposure of L. siliquoidea glochidia to 56 mg NO3-N/L nitrate resulted in a significant (p = 0.02) 35% reduction of total juveniles produced, a combined result of moderate decreases in both glochidia attachment and metamorphosis success. A similar trend (28% reduction; p = 0.06) was evident with 11 mg NO3-N/L. No effects were apparent for L. fasciola, suggesting species-specific differences in responses even among closely related species. These results are the first to suggest that glochidia exposure to nitrate may adversely affect juvenile recruitment in some species. Findings from these studies are important for improving characterization of the hazards of nitrate pollution to aquatic life and this work will help better define the role of water quality in assessing habitat suitability for mussel conservation efforts.
Schwertmannite transformation via direct or indirect electron transfer by a sulfate reducing enrichment culture Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 Yufei Zeng, Han Wang, Chuling Guo, Jingjing Wan, Cong Fan, John R. Reinfelder, Guining Lu, Fengchang Wu, Weilin Huang, Zhi Dang
Understanding the mechanism of the microbial transformation of Fe(III)-oxyhydroxysulfate minerals is of considerable interest, because this transformation plays an important role in controlling the behaviour of toxic metals from acid mine drainage (AMD). In this study, we examined a sulfate reducing enrichment culture from AMD-contaminated sediments and predicted the possible pathway of electron transfer when incubated with schwertmannite, a common Fe(III)-oxyhydroxysulfate occurring in the AMD environment. Experiments were designed to distinguish the mechanisms by which bacteria facilitate direct (i.e., bacteria allowed to adhere to the mineral) or indirect (i.e., bacteria separated from the mineral by dialysis bag) electron transfer to reduce the mineral. The effects of adding anthraquinone-2,6-disulfonate (AQDS) as an exogenous electron shuttle were also investigated. Vivianite was detected as the main product of schwertmannite transformation. Reduction of sulfate and iron were more pronounced in direct treatments, while more non-reductive dissolution were observed in indirect treatments. The addition of AQDS lead to the production of more dissolved Fe2+ over 20 d than in the absence of AQDS. Microbial community composition differed in direct and indirect treatments, while the addition of AQDS did not significantly affect the community structure in each treatment. After incubation for 20 d, the growth of Desulfovibrio exceeded that of the originally dominant Citrobacter in direct treatments, while an unknown genus most closely related to Citrobacter within Enterobacteriaceae was predominant in indirect treatments. This monodominant community in indirect treatments was assumed not to transfer electron directly to schwertmannite but to rely on shuttling mechanism. PICRUSt results implied that bacteria in indirect treatment have potential to produce shuttling compounds or complexing agents. The absence of dsr genes and the putative fermentative process suggested that the Enterobacteriaceae might indirectly facilitate the dissolution and transformation of schwertmannite.
Synthesis of S-ligand tethered cellulose nanofibers for efficient removal of Pb(II) and Cd(II) ions from synthetic and industrial wastewater Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 Emmanuel Abu-Danso, Sirpa Peräniemi, Tiina Leiviskä, Amit Bhatnagar
Cellulose nanofibers (CNFs) tethered with sulphur as anionic ligand were synthesized from medical absorbent cotton by dissolution with NaOH, CO(NH2)₂ followed by mechanical intrusion of sulphur from SC(NH₂)₂ at an elevated temperature. The solid-phase CNFs embedded with sulphur complexes possessed negative sites which were used to remove cationic metals viz., Pb(II) and Cd(II) from synthetic and industrial wastewater. The physicochemical properties of the CNFs were analyzed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), pH point of zero charge (pHpzc) and X-ray photoelectron spectroscopy (XPS). Batch adsorption studies were conducted with synthetic wastewater to optimize the conditions for Pb(II) and Cd(II) removal by CNFs. Different adsorption kinetic models were applied to assess and define the adsorption mechanism. The maximum Langmuir adsorption capacity was found to be 1.16 and 0.82 mmol g-1 for Pb(II) and Cd(II) ions, respectively. Regeneration studies showed that the CNFs can be reused using 0.1 M NaOH as eluent. The percentage removal efficiency of different cationic metals by CNFs from untreated industrial wastewater ranged from ca. 90 to 98%.
The dynamic role of pH in microbial reduction of uranium(VI) in the presence of bicarbonate Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 Jinchuan Xie, Jinlong Wang, Jianfeng Lin, Xiaohua Zhou
The negative effect of carbonate on the rate and extent of bioreduction of aqueous U(VI) has been commonly reported. The solution pH is a key chemical factor controlling U(VI)aq species and the Gibbs free energy of reaction. Therefore, it is interesting to study whether the negative effect can be diminished under specific pH conditions. Experiments were conducted using Shewanella putrefaciens under anaerobic conditions with varying pH values (4–9) and bicarbonate concentrations ([CO32−]T, 0–50 mmol/L). The results showed a clear correlation between the pH-bioreduction edges of U(VI)aq and the [CO32−]T. The specific pH at which the maximum bioreduction occurred (pHmbr) shifted from slightly basic to acidic pH (∼7.5–∼6.0) as the [CO32−]T increased (2–50 mmol/L). At [CO32−]T = 0, however, no pHmbr was observed in terms of increasing bioreduction with pH (∼100%, pH > 7). In the presence of [CO32−]T, significant bioreduction was observed at pHmbr (∼100% at 2–30 mmol/L [CO32−]T, 93.7% at 50 mmol/L [CO32−]T), which is in contrast to the previously reported infeasibility of bioreduction at high [CO32−]T. The pH-bioreduction edges were almost comparable to the pH-biosorption edges of U(VI)aq on heat-killed cells, revealing that biosorption is favorable for bioreduction. The end product of U(VI)aq bioreduction was characterized as insoluble nanobiogenic uraninite by HRTEM. The redox potentials of the master complex species of U(VI)aq, such as (UO2)4(OH)7+, (UO2)2CO3(OH)3−, and UO2(CO3)34−, were calculated to obtain insights into the thermodynamic reduction mechanism. The observed dynamic role of pH in bioreduction suggests the potential for bioremediation of uranium-contaminated groundwater containing high carbonate concentrations.
Validation of mobile in situ measurements of dairy husbandry emissions by fusion of airborne/surface remote sensing with seasonal context from the Chino Dairy Complex Environ. Pollut. (IF 4.358) Pub Date : 2018-07-13 Ira Leifer, Christopher Melton, David M. Tratt, Kerry N. Buckland, Clement S. Chang, Jason Frash, Jeffrey L. Hall, Akihiko Kuze, Brian Leen, Lieven Clarisse, Tryg Lundquist, Martin Van Damme, Sam Vigil, Simon Whitburn, Leonid Yurganov
Mobile in situ concentration and meteorology data were collected for the Chino Dairy Complex in the Los Angeles Basin by AMOG (AutoMObile trace Gas) Surveyor on 25 June 2015 to characterize husbandry emissions in the near and far field in convoy mode with MISTIR (Mobile Infrared Sensor for Tactical Incident Response), a mobile upwards-looking, column remote sensing spectrometer. MISTIR reference flux validated AMOG plume inversions at different information levels including multiple gases, GoogleEarth imagery, and airborne trace gas remote sensing data. Long-term (9-yr.) Infrared Atmospheric Sounding Interferometer satellite data provided spatial and trace gas temporal context.For the Chino dairies, MISTIR-AMOG ammonia (NH3) agreement was within 5% (15.7 versus 14.9 Gg yr−1, respectively) using all information. CH4 emissions were 30 Gg yr−1 for a 45,200 herd size, indicating that Chino emission factors are greater than previously reported.Single dairy inversions were much less successful. AMOG-MISTIR agreement was 57% due to wind heterogeneity from downwind structures in these near-field measurements and emissions unsteadiness. AMOG CH4, NH3, and CO2 emissions were 91, 209, and 8200 Mg yr−1, implying 2480, 1870, and 1720 head using published emission factors. Plumes fingerprinting identified likely sources including manure storage, cowsheds, and a structure with likely natural gas combustion.NH3 downwind of Chino showed a seasonal variation of a factor of ten, three times larger than literature suggests. Chino husbandry practices and trends in herd size and production were reviewed and unlikely to add seasonality. Higher emissions were proposed as legacy soil emissions, the results of a century of husbandry, supported by airborne remote sensing data showing widespread emissions from neighborhoods that were dairies 15 years prior and AMOG and MISTIR observations. Seasonal variations provide insights into the implications of global climate change and must be considered when comparing surveys from different seasons.
Evaluation of PM10, CO2, airborne bacteria, TVOCs, and formaldehyde in facilities for susceptible populations in South Korea Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Sung Ho Hwang, Jaehoon Roh, Wha Me Park
Poor indoor air quality can have adverse effects on human health, especially in susceptible populations; however, few studies have measured multiple pollutants in facilities for susceptible populations at a national scale in South Korea. Therefore, we measured the concentrations of indoor pollutants (fine particulate matter (PM10), CO2, airborne bacteria (AB), total volatile organic compounds (TVOCs), and formaldehyde) to determine their possible relation to other indoor environmental factors and characteristics of facilities with susceptible populations, such as hospitals, geriatric hospitals, elderly care facilities, and postnatal care centers throughout South Korea. Indoor pollutants were sampled at 82 indoor facilities, including 62 facilities for susceptible populations. Spearman's correlation, Kruskal–Wallis, and Mann–Whitney analyses were used to examine the relationship among and differences between pollutants at indoor facilities and indoor/outdoor differences in PM10 concentration. There were significant correlations between indoor temperature and AB concentration (r = 0.37, p < 0.01), TVOCs, and formaldehyde (r = 0.264, p < 0.01). Indoor PM10 concentrations were higher than outdoor concentrations at all facilities for susceptible populations (p < 0.01). CO2 might be a good indicator for predicting indoor pollutants when categorized into two levels (≤750 ppm and >750 ppm). The hazard quotient of formaldehyde was higher than the acceptable level of 1 for children under the age of eight in postnatal care centers, indicative of unsafe levels. Therefore, more depth study for exposure characteristics of formaldehyde and indoor air quality (IAQ) in postnatal care facilities as a national scale is needed for finding the children exposure levels.
Uptake of ozone and modification of lipids in Betula Pendula pollen Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Chao Zhu, Jinane Farah, Marie Choël, Sylvie Gosselin, Moomen Baroudi, Denis Petitprez, Nicolas Visez
Pollen allergy risk is modified by air pollutants, including ozone, but the chemical modifications induced on pollen grains are poorly understood. Pollen lipidic extract has been shown to act as an adjuvant to the allergenic reaction and therefore, the modification of lipids by air pollutants could have health implications. Birch pollen was exposed in vitro to ozone to explore the reactivity of O3 on its surface and on its lipidic fraction. Uptake coefficients of ozone were determined for ozone concentration of 117 ppb on the surface of native birch pollen (8.6 ± 0.8 × 10−6), defatted pollen (9.9 ± 0.9 × 10−6), and for crushed pollen grains (34±3 × 10−6). The mass of ozone uptaken was increased by a factor of four for crushed pollen compared to native pollen showing a higher susceptibility to ozone of cytoplasmic granules and broken pollen grains. The mass of extractible lipids for birch pollen was determined to 27 mg per gram of pollen and a fraction of these lipids was identified and quantified (fatty acids, alkanes, alkenes and aldehydes). The distribution of lipids was modified by ozone exposure of 115 and 1000 ppb for 16 h with the following reactivity: consumption of alkene, formation of aldehydes and formation of nonanoic acid and octadecanoic acid. The quantity of ozone trapped in the lipidic fraction during 15 min at 115 ppb is enough to contribute to the reactivity of one-third of the alkenes demonstrating that pollen could be susceptible to an atmospheric increase of ozone concentration even for a very short duration complicating the understanding of the link between pollen allergy and pollution.
Occurrence of halogenated natural products in highly consumed fish from polluted and unpolluted tropical bays in SE Brazil Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 L.F. Estrella, V.B. Ferreira, C. Gallistl, M.G.R. Alves, W. Vetter, O. Malm, F.D.B. Abadio Finco, J.P.M. Torres
Natural compounds from the metabolism of marine organisms have been detected at high concentrations in environmental samples which are not the producers of these compounds. These natural substances are known as halogenated natural products (HNPs). HNPs are possibly toxic halogenated compounds analogous to POPs that may bioaccumulate and biomagnify along the food web and pose a further risk to human and environmental health. The present study analyzed the occurrence of HNPs in the edible muscle of the three most consumed commercial fish species in the state of Rio de Janeiro: sardine (Sardinella brasiliensis), whitemouth croaker (Micropogonias furnieri) and mullet (Mugil liza) from the highly polluted Guanabara Bay (GB) and the less polluted Ilha Grande Bay (IGB). The analytical steps included Soxhlet extraction, clean-up step and injection in a gas chromatography system coupled to a mass spectrometer operated in the electron-capture negative ion mode (GC/ECNI-MS). The compounds 2,4,6-TBP, 2,4,6-TBA, MHC-1, Q1, 6-MeO-BDE 47 and 2′-MeO-BDE 68 were found in the analyzed fish from both studied areas. Q1, 6-MeO-BDE 47 and 2′-MeO-BDE 68 showed the highest concentrations in samples. Q1 concentrations in the sardines from IGB were higher than the sardines from GB (p < 0.05) and higher than the other IGB species (p < 0.05). The differences found among the species may be related to their characteristic habitat and diet. It is noteworthy that most of these compounds do not have any toxicological reference value. Moreover, the HNPs are being detected in species of low trophic level and since this study has worked only with commercial species, these fish may be considered as a source for human exposure to these natural compounds.
Predicting monthly high-resolution PM2.5 concentrations with random forest model in the North China Plain Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Keyong Huang, Qingyang Xiao, Xia Meng, Guannan Geng, Yujie Wang, Alexei Lyapustin, Dongfeng Gu, Yang Liu
Exposure to fine particulate matter (PM2.5) remains a worldwide public health issue. However, epidemiological studies on the chronic health impacts of PM2.5 in the developing countries are hindered by the lack of monitoring data. Despite the recent development of using satellite remote sensing to predict ground-level PM2.5 concentrations in China, methods for generating reliable historical PM2.5 exposure, especially prior to the construction of PM2.5 monitoring network in 2013, are still very rare. In this study, a high-performance machine-learning model was developed directly at monthly level to estimate PM2.5 levels in North China Plain. We developed a random forest model using the latest Multi-angle implementation of atmospheric correction (MAIAC) aerosol optical depth (AOD), meteorological parameters, land cover and ground PM2.5 measurements from 2013 to 2015. A multiple imputation method was applied to fill the missing values of AOD. We used 10-fold cross-validation (CV) to evaluate model performance and a separate time period, January 2016 to December 2016, was used to validate our model's capability of predicting historical PM2.5 concentrations. The overall model CV R2 and relative prediction error (RPE) were 0.88 and 18.7%, respectively. Validation results beyond the modeling period (2013–2015) shown that this model can accurately predict historical PM2.5 concentrations at the monthly (R2 = 0.74, RPE = 27.6%), seasonal (R2 = 0.78, RPE = 21.2%) and annual (R2 = 0.76, RPE = 16.9%) level. The annual mean predicted PM2.5 concentrations from 2013 to 2016 in our study domain was 67.7 μg/m3 and Southern Hebei, Western Shandong and Northern Henan were the most polluted areas. Using this computationally efficient, monthly and high-resolution model, we can provide reliable historical PM2.5 concentrations for epidemiological studies on PM2.5 health effects in China.
PM2.5 impairs neurobehavior by oxidative stress and myelin sheaths injury of brain in the rat Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Qun Zhang, Qingzhao Li, Jincai Ma, Yaping Zhao
Air particulate matter (PM) is a serious environmental problem that has been found to cause neuropathological disorders. Although the general toxicity of PM2.5 has been intensively studied, its neurobehavior effects are poorly discussed. In this study, we aim to investigate whether different exposure time of PM2.5 influence neurobehavior of rats, induce oxidative stress, histopathologic abnormalities, apoptosis, or changes of mitochondria and myelin. The results reveal that exposure to PM2.5 impaired spatial learning and memory, inquiring ability, as well as sensory function. These alterations were related to ultrastructure changes of mitochondria and myelin sheaths, abnormal expression of apoptosis-related proteins (Caspase-3, Caspase-9). These results provide a basis for a better understanding of myelin abnormality-related neurobehavior impairment in response to PM2.5.
Lambda-cyhalothrin delays pubertal Leydig cell development in rats Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Huitao Li, Yinghui Fang, Chaobo Ni, Xiuxiu Chen, Jiaying Mo, Yao Lv, Yong Chen, Xianwu Chen, Qingquan Lian, Ren-Shan Ge
Lambda-cyhalothrin (LCT) is a widely used broad-spectrum pyrethroid insecticide and is expected to cause deleterious effects on the male reproductive system. However, the effects of LCT on Leydig cell development during puberty are unclear. The current study addressed these effects. Twenty-eight-day-old male Sprague Dawley rats orally received LCT (0, 0.25, 0.5 or 1 mg/kg body weight/day) for 30 days. The levels of serum testosterone, luteinizing hormone, and follicle-stimulating hormone, Leydig cell number, and its specific gene and protein expression were determined. LCT exposure lowered serum testosterone levels at doses of 0.5 and 1 mg/kg and luteinizing hormone levels at a dose of 1 mg/kg, but increased follicle-stimulating hormone levels at doses of 0.5 and 1 mg/kg. LCT lowered Star and Hsd3b1 mRNA or their protein levels at a dose of 1 mg/kg. Immature Leydig cells were purified from pubertal rats and treated with different concentrations of LCT for 24 h and medium androgen levels, Leydig cell mRNA and protein levels, the mitochondrial membrane potential (△Ψm), and the apoptotic rate of immature Leydig cells were investigated. LCT inhibited androgen production at 5 μM and downregulated Scarb1 at 0.05 μM, Hsd3b1 and Hsd11b1 at 0.5 μM, and Cyp11a1 at 5 μM. LCT also decreased △Ψm at 0.5 and 50 μM. In conclusion, LCT can influence the function of Leydig cells.
Spatiotemporal patterns of PM10 concentrations over China during 2005–2016: A satellite-based estimation using the random forests approach Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Gongbo Chen, Yichao Wang, Shanshan Li, Wei Cao, Hongyan Ren, Luke D. Knibbs, Michael J. Abramson, Yuming Guo
Background Few studies have estimated historical exposures to PM10 at a national scale using satellite-based aerosol optical depth (AOD), and long-term trends have not been investigated. Objectives In this study, daily concentrations of PM10 over China during the past 12 years were estimated with the most recent ground monitoring data and a novel statistical model. Methods Daily measurements of PM10 during 2014–2016 were collected from 1479 sites in China. Two types of Moderate Resolution Imaging Spectroradiometer (MODIS) AOD data were downloaded and merged. A random forest model (non-parametric machine learning algorithms) and two traditional regression models between PM10 and AOD were developed and their predictive abilities compared. The model was applied to estimate daily concentrations of PM10 across China during 2005–2016 at 0.1⁰ (≈10 km). Results Cross-validation showed our random forests model explained 78% of daily variability of PM10 [root mean squared prediction error (RMSE) = 31.5 μg/m3]. When aggregated into monthly and annual averages, the models captured 82% (RMSE = 19.3 μg/m3) and 81% (RMSE = 14.4 μg/m3) of the variability. The random forests model showed much higher predictive ability and lower bias than the two regression models. Based on the predictions, around one-third of China experienced with PM10 pollution exceeding Grade Ⅱ National Ambient Air Quality Standard (>70 μg/m3) in China during the past 12 years. The highest levels of estimated PM10 were present in the Taklamakan Desert of Xinjiang, Beijing-Tianjin metropolitan region, while the lowest were observed in Tibet, Yunnan and Hainan. Overall, the PM10 level in China peaked in 2008 and has declined since 2009. Conclusions This is the first study to estimate the long-term exposure to PM10 pollution historically using satellite-based AOD data in China. The results could be applied to investigate the long-term health effects of PM10 in China.
Endoplasmic reticulum stress mediates 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT)-induced toxicity and liver lipid metabolism changes in Nile tilapia (Oreochromis niloticus) Environ. Pollut. (IF 4.358) Pub Date : 2018-07-11 Yujie Su, Huifeng Li, Chang Xu, Xiaodan Wang, Jia Xie, Jian G. Qin, Liqiao Chen, Erchao Li
DCOIT (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one) is the main active ingredient in an emerging water environment antifoulant, the toxicity and environmental impacts of which need to be further investigated. Thus, this study examined the toxicity of DCOIT on Nile tilapia (Oreochromis niloticus), including its effects on behavior, respiration and energy metabolism as well as the role of endoplasmic reticulum stress (ER stress) in mediating its toxicity and metabolic changes. The changes in fish behavior, respiration, neuronal signal transmission, energy metabolism, ER stress, and liver histology were examined via acute (4 days) and chronic (28 days) exposures to 0, 3, 15, 30 μg/L DCOIT in vivo. Additionally, ER stress levels were measured in 24-h periods of hepatocyte exposure to 0, 3, 15, 30 and 300 μg/L DCOIT in vitro. The hyper-locomotor activities decreased, but the respiration rate increased after a 4-day acute exposure period, indicating that DCOIT exposure altered fish energy metabolism. After acute exposure at a low DCOIT concentration, the activation of ER stress induced triglyceride accumulation in the liver. After chronic exposure for 28 days, the prolonged ER stress induced a series of pathological cellular changes. At the cellular level, exposure to a high DCOIT concentration induced ER stress in the hepatocytes. In addition, as a neurotoxin, DCOIT has the potential to disrupt the neurotransmission of the cholinergic system, resulting in motor behavior disruption. This study demonstrates that DCOIT plays a role in time- and concentration-dependent toxicity and that changes in lipid metabolism are directly related to endoplasmic reticulum function after exposure to an antifouling agent. This work advances the understanding of the toxic mechanism of DCOIT, which is necessary for its evaluation.
Enhancement effect of earthworm (Eisenia fetida) on acetochlor biodegradation in soil and possible mechanisms Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 Yueqi Hao, Lixia Zhao, Yang Sun, Xiaojing Li, Liping Weng, Huijuan Xu, Yongtao Li
Acetochlor is a widely used chloroacetanilide herbicide and has posed environmental risks in soil and water due to its toxicity and high leaching capacity. Earthworm represents the dominant invertebrate in soil and can promote the decomposition of organic pollutants. The effect of earthworm on acetochlor degradation in soil was studied by soil column experiment with or without acetochlor and earthworm in sterile and natural soils. The degradation capacities of drilosphere components to acetochlor were investigated by microcosm experiments. Bacterial and fungal acetochlor degraders stimulated by earthworm were identified by high-throughput sequencing. The degradation kinetics of acetochlor suggested that both indigenous microorganisms and earthworm played important roles in acetochlor degradation. Acetochlor degradation was quicker in soil with earthworms than without earthworms, with the degradation rates increased by 62.3 ± 15.2% and 9.7 ± 1.7% in sterile and natural treatments respectively. The result was related to the neutralized pH, higher enzyme activities and enhanced soil microbial community diversity and richness in the presence of earthworms. Earthworm cast was the degradation hotpot in drilosphere and exhibited better anaerobic degradation capacity in microcosm experiments. The acetochlor degradation rate of cast in anaerobic environment was 12.0 ± 0.1% quicker than that in aerobic environment. Residual acetochlor in soil conferred a long-term impairment on fungal community, and this inhibition could be repaired by earthworm. Earthworm stimulated indigenous degraders like Sphingomonas and Microascales and carried suspected intestinal degraders like Mortierella and Escherichia_coli to degradation process. Cometabolism between nutrition cycle species and degraders in casts also contributed to its faster degradation rates. The study also presented some possible anaerobic degradation species like Rhodococcus, Pseudomonas_fulva and Methylobacillus.
Environmental risk assessment of triclosan and triclocarban from personal care products in South Africa Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 N. Musee
Trends in the widespread use of personal care products (PCPs) containing triclosan (TCS) and triclocarban (TCC) have led to continuous emissions of these chemicals into the environment. Consequently, both chemicals are ubiquitously present at high concentrations in the aquatic systems based on widely reported measured environmental concentration (MECs) data in different environmental systems (e.g. freshwater) worldwide, especially in developed countries. In developing countries, however, lack of MECs data is a major issue, and therefore, inhibits effective risk assessment of these chemicals. Herein, TCS and TCC releases from personal care products (PCPs) were quantified, using a modelling approach to determine predicted environmental concentrations (PECs) in wastewater, freshwater, and soils, and likely risk(s) were estimated by calculating risk quotient (RQs). TCS and TCC in freshwater had RQs >1 based on estimated PECs with wide variations (≈2–232) as performed across the three dilutions factors (1, 3, and 10) considered in this study; an indicator of their likely adverse effect on freshwater organisms. In untreated and treated wastewater, TCS RQs values for bacteria were >1, but <1 for TCC, implying the former may adversely affect the functioning of wastewater treatment plants (WWTPs), and with no plausible impacts from the latter. In terrestrial systems, RQ results for individual chemicals revealed no or limited risks; therefore, additional investigations are required on their toxicity, as effects data was very limited and characterised by wide variations. Future national monitoring programs in developing countries should consider including TCS and TCC as the results suggest both chemicals are of concern to freshwater, and TCS in WWTPs. Potential risks of their metabolites remain unquantified to date.
Concentrations, spatial distributions, and congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans around original plastic solid waste recovery sites in China Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 Liang Ding, Bingjie Cai, Shui Wang, Changsheng Qu
The concentrations, profiles, and spatial distributions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and sediment samples from several typical plastic solid waste (PSW) recovery sites (particularly from areas in which PSW is burned openly) in China were investigated. The results showed that burning PSW directly influenced PCDD/F concentrations immediately around the burning area. All of the samples in which soil contained black burning residue, collected from immediately around burning areas, had PCDD/F concentrations (mean 21708 ng kg−1) and toxic equivalent (TEQ) concentrations (mean 2140 ng I-TEQ kg−1 or 1877 ng WHO2006-TEQ kg−1) more than 100 times higher than the concentrations in samples collected away from burning areas (mean 222 ng kg−1, 8.75 ng I-TEQ kg−1, 7.96 ng WHO2006-TEQ kg−1). Principal component analysis and hierarchical cluster analysis indicated that the PCDD/F concentrations in seven soil samples from near PSW burning areas were influenced by PSW burning but that the PCDD/Fs in these soil samples may have had other or multiple sources. PCDD/F distributions at PSW recovery sites have been investigated in few previous studies. The results presented here indicate that appropriate measures should be taken to decrease the ecological risks posed by PSW recovery and to prevent, control, and remediate PCDD/F and other chemical contamination caused by PSW recovery.
Characterizing benzene series (BTEX) pollutants build-up process on urban roads: Implication for the importance of temperature Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 An Liu, Nian Hong, Panfeng Zhu, Yuntao Guan
Benzene series (BTEX) pollutants which are generated by traffic can deposit (build-up) on urban road surfaces. When they are washed-off by stormwater runoff, BTEX are toxic to ecological and human health if the stormwater is reused. To understand the risk posed by BTEX, it is essential to have an in-depth investigation on BTEX build-up, one of the most important stormwater pollutant processes. This study analysed the relationship between BTEX build-up and BTEX build-up's influential factors. The outcomes confirmed an important role of climatic factors (particularly temperature) on influencing BTEX build-up. This has not been considered in previous stormwater studies although this has been widely focused in atmospheric pollution. BTEX build-up loads were generally higher and the variability was low in dry seasons with low temperature such as winter and spring. Additionally, the influence of temperature on BTEX build-up on urban road surfaces is more important in the case of larger particles (such as >75 μm) than smaller particles. The study also showed that petrol station areas have a potential to export stormwater runoff with high BTEX concentrations, compared to typical urban roads. This is particularly applicable in winter and spring. These outcomes can provide useful guidance to improving stormwater quality modelling approaches, especially relevant to estimation of BTEX concentrations in the stormwater.
Microplastic bacterial communities in the Bay of Brest: Influence of polymer type and size Environ. Pollut. (IF 4.358) Pub Date : 2018-07-12 Laura Frère, Lois Maignien, Morgane Chalopin, Arnaud Huvet, Emmanuel Rinnert, Hilary Morrison, Sandrine Kerninon, Anne-Laure Cassone, Christophe Lambert, Julie Reveillaud, Ika Paul-Pont
Microplastics (<5 mm) exhibit intrinsic features such as density, hydrophobic surface, or high surface/volume ratio, that are known to promote microbial colonization and biofilm formation in marine ecosystems. Yet, a relatively low number of studies have investigated the nature of microplastic associated bacterial communities in coastal ecosystems and the potential factors influencing their composition and structure. Here, we characterized microplastics collected in the Bay of Brest by manual sorting followed by Raman spectroscopy and studied their associated bacterial assemblages using 16S amplicon high-throughput sequencing. Our methodology allowed discriminating polymer type (polyethylene, polypropylene and polystyrene) within small size ranges (0.3–1 vs. 1–2 vs. 2–5 mm) of microplastics collected. Data showed high species richness and diversity on microplastics compared to surrounding seawater samples encompassing both free living and particle attached bacteria. Even though a high proportion of operational taxonomic units (OTU; 94 ± 4%) was shared among all plastic polymers, polystyrene fragments exhibited distinct bacterial assemblages as compared to polyethylene and polypropylene samples. No effect of microplastic size was revealed regardless of polymer type, site and date of collection. The Vibrio genus was commonly detected in the microplastic fraction and specific PCR were performed to determine the presence of potentially pathogenic Vibrio strains (namely V. aestuarianus and the V. splendidus polyphyletic group). V. splendidus related species harboring putative oyster pathogens were detected on most microplastic pools (77%) emphasizing the need of further research to understand the role of microplastics on pathogen population transport and ultimate disease emergence.
Spatial variability of on-bicycle black carbon concentrations in the megacity of São Paulo: A pilot study Environ. Pollut. (IF 4.358) Pub Date : 2018-07-05 Admir Créso Targino, Patricia Krecl, João Edson Danziger Filho, Julián Felipe Segura, Mark David Gibson
In 2015, a controversial bicycle lane was installed on Paulista Avenue –a thoroughfare in the heart of the megacity of São Paulo with a high rate of motorised vehicles. For the first time, on-bicycle air pollution concentrations were assessed along this lane using black carbon (BC) as an indicator of fossil fuel combustion. We measured BC concentrations with a hand-held AE51 microaethalometer at a high temporal resolution, enabling the capture of fine spatial gradients along the route. Although this new link expanded the city’s cycling network, our pioneering study showed that BC concentrations were large (mean 8.5 μg m-3) with extreme values reaching 24.0 μg m-3, comparable to concentrations found in many megacities. In agreement with other studies, we observed that concentrations decreased about 1.6 times on a section of the bicycle lane running through a calmer neighbourhood, which could indicate the potential to safeguard the health of cyclists by installing lanes with greater separation from main roads, such as Paulista Avenue. This pilot work paves the way to more detailed studies aiming to map out the spatial distribution of other traffic-related pollutants across the city’s 458-km long bicycle network.
Denitrifier communities impacted by heavy metal contamination in freshwater sediment Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Qingwei Guo, Ningning Li, Yongxin Bing, Sili Chen, Zhengke Zhang, Sha Chang, Yao Chen, Shuguang Xie
Heavy metals are widely detected in natural environments, however their impacts on denitrifier community in freshwater ecosystem remain unclear. The present study investigated the changes of denitrifier communities (based on nosZ (nitrous oxide reductase) gene) in a freshwater reservoir contaminated by a severe accidental spill of heavy metals. The abundance of nosZ-denitrifiers drastically decreased, and their community richness, diversity and structure also showed considerable variations. The mainly detected denitrifying bacteria included Pseudogulbenkiania, Pseudomonas and two unknown groups. These major nosZ-denitrifier groups responded in different ways to heavy metal pollution. Metal contamination could exert a profound influence on denitrifier community in freshwater sediment. This work could provide some new insights to the impact of metal pollution on nitrogen cycling.
Assessing the influence of the genetically modified factor on mixture toxicological interactions in Caenorhabditis elegans: Comparison between wild type and a SOD mutant Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Kai Li, Ya-Qian Xu, Li Feng, Shu-Shen Liu
How to evaluate the ecological risk of transgenic technology is a focus of scientists because of the safety concerns raised by genetically modified (GM) organisms. Nevertheless, most studies are based on individual chemicals and always analyze the GM organism as a type of toxicant. In this study, we changed the approach and used GM organisms as the test objects with normal chemical exposure. Three types of chemicals (two substituted phenols, 4-chlorophenol and 4-nitrophenol; two ionic liquids, 1-butylpyridinium chloride and 1-butylpyridinium bromide; two pesticides, dichlorvos and glyphosate) were used to construct a six-component mixture system. The lethality to wild-type (N2) and mutant sod-3::GFP (SOD-3) Caenorhabditis elegans was determined when they were exposed to the same mixture system after 12 and 24 h. The results showed that the pEC50 values of all of the single chemicals on SOD-3 were greater than those on N2 at 24 h. The toxicities of the single chemicals and nine mixture rays on the two strains increased with time. Notably, we discovered a significant difference between the two strains; time-dependent synergism occurred in mixtures on N2, but time-dependent antagonism occurred in mixtures on SOD-3. Finally, the strength of the synergism or antagonism turned to additive action on the two strains as the exposure time increased. These findings illustrated that the GM factor of the mutant influenced the mixture toxicological interaction at some exposure times. Compared with N2, mutant C. elegans were more sensitive to stress or toxic reactions. Therefore, the influence of the GM factor on mixture toxicological interactions in environmental risk assessment must be considered.
How important are maritime emissions for the air quality: At European and national scale Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 A. Monteiro, M. Russo, C. Gama, C. Borrego
Due to its dependence on fossil fuel combustion, emissions from the marine transport sector can significantly contribute to air pollution. This work aims to evaluate the impact of maritime transport emissions on air quality in Portugal using a numerical air quality modelling approach, with high-resolution emission data. Emissions from the European TNO inventory were compiled and pre-processed at hourly and high spatial (∼3 × 3 km2) resolutions. Scenarios with and without these maritime emissions were then simulated with the WRF-CHIMERE modelling system, extensively tested and validated for Portugal domain, in order to evaluate their impact on air quality. A simulation was performed for one year (2016) and the resulting differences were analysed in terms of spatial distribution, time series and deltas. The main deltas for NO2 and PM10 are located over international shipping routes and major ports, while O3 concentrations are impacted in a larger area. The modelling results also indicate that shipping emissions are responsible for deltas in the concentration of NO2 higher than 20% over specific urban areas located in the west coast of Portugal, and less than 5% for PM10. For O3 the relative contribution is low (around 2%) but this contribution is also observed at locations more than 50 km from the coast.
Microplastics in seawater and zooplankton from the Yellow Sea Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Xiaoxia Sun, Junhua Liang, Mingliang Zhu, Yongfang Zhao, Bo Zhang
Marine plastic pollution is a worldwide problem. Microplastics (MPs) are the predominant form of marine plastic debris, a form small enough to be ingested by and potentially harm marine organisms. It is urgent to develop ecologically relevant metrics for the risk assessment of MPs based on in situ data, especially for coastal areas. For the first time, we performed a comprehensive study of the characteristics of MPs in seawater and zooplankton in the Yellow Sea. For MPs in seawater, the average concentration is 0.13 ± 0.20 pieces/m3, dominated by fragments (42%). The average size is 3.72 ± 4.70 mm, with the most frequent size appearing at 1200 μm. The major polymer types are polypropylene and polyethylene, accounting for 88.13% in total. The distribution of MPs in seawater is patchy, with high MP concentrations close to the coastal cities. The average concentration of MPs in 11 total zooplankton groups is 12.24 ± 25.70 pieces/m3. The average size is 154.62 ± 152.90 μm, with 90% being <500 μm. Fiber is the dominant shape of MPs found in zooplankton, accounting for 46%, but the composition of the polymer type is diverse. The retention of MPs in zooplankton depends on the taxa and their abundance in the Yellow Sea. Siphonophorea, Copepoda, Euphausiacea and Amphipoda are the main repositories compared to other groups, achieving 3.57, 2.44, 1.41 and 1.36 pieces/m3, respectively. The high concentration area of MPs in zooplankton appeared near the adjacent waters of the Yangtze estuary. These results prove that zooplankton act as a repository for MPs in coastal waters. The retention of MPs in zooplankton is recommended as a key index for further ecological risk assessment of MPs.
Re-emission of legacy mercury from soil adjacent to closed point sources of Hg emission Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Wei Zhu, Zhonggen Li, Ping Li, Ben Yu, Che-Jen Lin, Jonas Sommar, Xinbin Feng
Mercury (Hg) emissions from point sources to air may disperse over long distance depending on Hg speciation in the plume. A significant fraction of Hg, particularly in its divalent forms, deposits locally and causes pollution to surrounding biomes. The objective of this study was to investigate (1) the historic Hg deposition to the immediate vicinity of an industrial complex that had intentional use of Hg (i.e., chlor-alkali and polyvinyl chloride production) for 5 decades until 2011, and (2) the Hg0 re-emission from soil to air soon after the closure of the facility. The spatial distribution of near-ground Hg0 vapor in air, soil Hg concentration and stable isotope ratio, air-soil Hg0 flux and Hg0 concentration in soil pore-gas were measured. It was found that the surrounding soils are severely contaminated with Hg due to the Hg release of the industrial complex, displaying soil Hg content up to 4.8 μg g−1. A spatial trend of Hg mass dependent isotope fractionation signature (δ202Hg = −2.11‰–0.72‰) with respect to the distance from the closed facility was identified, representing a mixing between regional background and industrial Hg sources. Hg release from the industrial operation enhanced surface soil Hg content within a 6.5-km radius from the facility. Inside the facility, residual Hg wastes (i.e., electrolysis sludge and consumed HgCl2 catalyst) represent a strong localized emission source of atmospheric Hg0. Near-ground atmospheric Hg0 concentration and soil Hg0 efflux progressively elevated toward the facility with an increase by 2–3 orders of magnitude compared to the values observed in the off-site background. These results suggest that the natural soil surfaces surrounding the closed industrial facility act as a large nonpoint source emitting legacy deposited Hg as much as the release from naturally enriched mines.
Leaf magnetic properties as a method for predicting heavy metal concentrations in PM2.5 using support vector machine: A case study in Nanjing, China Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Xiang'zi Leng, Xin Qian, Meng Yang, Cheng Wang, Huiming Li, Jinhua Wang
The aim of this study was to establish a method for predicting heavy metal concentrations in PM2.5 (particulate matter with a diameter of less than 2.5 μm) using support vector machine (SVM) models combined with magnetic properties of leaves. In this study, PM2.5 samples and the leaves of three common evergreen tree species were collected simultaneously during four different seasons in Nanjing, China. A SVM algorithm was used to establish models for the prediction of airborne heavy metal concentrations based on leaf magnetic properties, with or without meteorological factors and pollutant concentrations as input variables. Results showed that the annual average PM2.5 concentration was 58.47 μg/m3. PM2.5 concentrations, leaf magnetic properties, and nearly all airborne heavy metals had higher concentrations in winter than in spring, summer, or fall. Ferrimagnetic minerals preponderant in dust-loaded leaves were sampled from the three tree species. Models using magnetic properties of leaves from Ligustrum lucidum Ait and Osmanthus fragrans Lour yielded better prediction effects than those based on the leaves of Cedar deodara G. Don, showing relatively higher correlation coefficient (R) values and lower errors in both training and test stages. Fe and Pb concentrations were well-simulated by the prediction models, with R values > 0.7 in both training and test stages. By contrast, the concentrations of V, Co, Sb, Tl, and Zn were relatively poor-simulated, with most R values < 0.7 in both training and test stages. Predictions for the main urban areas of Nanjing showed that the highest heavy metal concentrations occurred near industrial and traffic pollution sources. Our results provide a cost-effective approach for the prediction of airborne heavy metal concentrations based on the biomagnetic monitoring of tree leaves.
Thermal and non-thermal health effects of low intensity non-ionizing radiation: An international perspective Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Dominique Belpomme, Lennart Hardell, Igor Belyaev, Ernesto Burgio, David O. Carpenter
Exposure to low frequency and radiofrequency electromagnetic fields at low intensities poses a significant health hazard that has not been adequately addressed by national and international organizations such as the World Health Organization. There is strong evidence that excessive exposure to mobile phone-frequencies over long periods of time increases the risk of brain cancer both in humans and animals. The mechanism(s) responsible include induction of reactive oxygen species, gene expression alteration and DNA damage through both epigenetic and genetic processes. In vivo and in vitro studies demonstrate adverse effects on male and female reproduction, almost certainly due to generation of reactive oxygen species. There is increasing evidence the exposures can result in neurobehavioral decrements and that some individuals develop a syndrome of “electro-hypersensitivity” or “microwave illness”, which is one of several syndromes commonly categorized as “idiopathic environmental intolerance”. While the symptoms are non-specific, new biochemical indicators and imaging techniques allow diagnosis that excludes the symptoms as being only psychosomatic. Unfortunately standards set by most national and international bodies are not protective of human health. This is a particular concern in children, given the rapid expansion of use of wireless technologies, the greater susceptibility of the developing nervous system, the hyperconductivity of their brain tissue, the greater penetration of radiofrequency radiation relative to head size and their potential for a longer lifetime exposure.
Oxidation of benzo[a]pyrene by laccase in soil enhances bound residue formation and reduces disturbance to soil bacterial community composition Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Jun Zeng, Qinghe Zhu, Yucheng Wu, Jun Shan, Rong Ji, Xiangui Lin
Laccases are capable of rapidly oxidizing benzo[a]pyrene. It is thought that the metabolites with an increase in water solubility caused by the oxidation of benzo[a]pyrene may stimulate the subsequent mineralization. However, to date, there has been no experimental evidence to support this. In this study, the fate of benzo[a]pyrene in soil affected by laccase amendment and the resulting soil bacterial responses were investigated. Laccase amendment promoted benzo[a]pyrene dissipation (15.6%) from soil, accompanied by trace mineralization (<0.58 ± 0.02%) and substantial bound residue formation (∼80%). An increase of ∼15% in the bound residue fraction was observed by laccase amendment, which mainly resulted from covalent binding of the residues to humin fraction. During the incubation, the abundance of bacterial 16S rRNA and polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase genes did not change markedly. In contrast, benzo[a]pyrene treated with laccase resulted in a smaller shift in the bacterial community composition, indicating a reduced disturbance to the soil microbial communities. These results here suggest that benzo[a]pyrene contaminated soil can be detoxified by laccase amendment mainly due to the enhanced bound residue formation to soil organic matter via covalent binding.
Case study of spring haze in Beijing: Characteristics, formation processes, secondary transition, and regional transportation Environ. Pollut. (IF 4.358) Pub Date : 2018-07-06 Hui Li, Fengkui Duan, Yongliang Ma, Kebin He, Lidan Zhu, Tao Ma, Siqi Ye, Shuo Yang, Tao Huang, Takashi Kimoto
Continuous haze monitoring was conducted from 12:00 3 April to 12:00 8 April 2016 in Beijing, China to develop a more detailed understanding of spring haze characteristics. The PM2.5 concentration ranged from 6.30 to 165 μg m−3 with an average of 63.8 μg m−3. Nitrate was the most abundant species, accounting for 36.4% of PM2.5, followed by organic carbon (21.5%), NH4+ (19.3%), SO42− (18.8%), and elemental carbon (4.10%), indicating the key role of nitrate in this haze event. Species contribution varied based on the phase of the haze event. For example, sulfate concentration was high during the haze formation phase, nitrate was high during the haze, and secondary organic carbon (SOC) had the highest contribution during the scavenging phase. The secondary transition of sulfate was influenced by SO2, followed by relative humidity (RH) and Ox (O3+NO2). Nitrate formation occurred in two stages: through NO2 oxidation, which was vulnerable to Ox; and by the partitioning of N (+5) which was susceptible to RH and temperature. SOC tended to form when Ox and RH were balanced. According to hourly species behavior, sulfate and nitrate were enriched during haze formation when the mixed layer height decreased. However, SOC accumulated prior to the haze event and during formation, which demonstrated the strong contribution of secondary inorganic aerosols, and the limiting contribution of SOC to this haze case. Investigating backward trajectories showed that high speed northwestern air masses following a straight path corresponded to the clear periods, while southwesterly air masses which traversed heavily polluted regions brought abundant pollutants to Beijing and stimulated the occurrence of haze pollution. Results indicate that the control of NO2 needs to be addressed to reduce spring haze. Finally, the correlation between air mass trajectories and pollution conditions in Beijing reinforce the necessity of inter-regional cooperation and control.
Indirect N2O emissions with seasonal variations from an agricultural drainage ditch mainly receiving interflow water Environ. Pollut. (IF 4.358) Pub Date : 2018-07-07 Linlin Tian, Hiroko Akiyama, Bo Zhu, Xi Shen
Nitrogen (N)-enriched leaching water may act as a source of indirect N2O emission when it is discharged to agricultural drainage ditches. In this study, indirect N2O emissions from an agricultural drainage ditch mainly receiving interflow water were measured using the static chamber-gas chromatography technique during 2012–2015 in the central Sichuan Basin in southwestern China. We found the drainage ditch was a source of indirect N2O emissions contributing an inter-annual mean flux of 6.56 ± 1.12 μg N m−2 h−1 and a mean indirect N2O emission factor (EF5g) value of 0.03 ± 0.003%. The mean EF5g value from literature review was 0.51%, which was higher than the default EF5g value (0.25%) proposed by the Intergovernmental Panel on Climate Change (IPCC) in 2006. Our study demonstrated that, more in situ observations of N2O emissions as regards N leaching are required, to account for the large variation in EF5g values and to improve the accuracy and confidence of the default EF5g value. Indirect N2O emissions varied with season, higher emissions occurred in summer and autumn. These seasonal variations were related to drainage water NO3−-N concentration, temperature, and precipitation. Our results showed that intensive precipitation increased NO3−-N concentrations and N2O emissions, and when combined with warmer water temperatures, these may have increased the denitrification rate that led to the higher summer and autumn N2O emissions in the studied agricultural drainage ditch.
Effects of mercury addition on microbial community composition and nitrate removal inside permeable reactive barriers Environ. Pollut. (IF 4.358) Pub Date : 2018-07-07 Kenly Hiller-Bittrolff, Kenneth Foreman, Ashley N. Bulseco-McKim, Janina Benoit, Jennifer L. Bowen
Permeable reactive barriers (PRBs) remove nitrogen from groundwater by enhancing microbial denitrification. The PRBs consist of woodchips that provide carbon for denitrifiers, but these woodchips also support other anaerobic microbes, including sulfate-reducing bacteria. Some of these anaerobes have the ability to methylate inorganic mercury present in groundwater. Methylmercury is hazardous to human health, so it is essential to understand whether PRBs promote mercury methylation. We examined microbial communities and geochemistry in fresh water and sulfate-enriched PRB flow-through columns by spiking replicates of both treatments with mercuric chloride. We hypothesized that mercury addition could alter bacterial community composition to favor higher abundances of genera containing known methylating taxa and that the sulfate-rich columns would produce more methylmercury after Hg addition, due mainly to an increase in abundance of sulfate reducing bacteria (SRB). However, methylmercury output at the end of the experiment was not different from output at the beginning, due in part to coupled Hg methylation and demethylation. There was a transient reduction in nitrate removal after mercury addition in the sulfate enriched columns, but nitrate removal returned to initial rates after two weeks, demonstrating resilience of the denitrifying community. Since methylmercury output did not increase and nitrate removal was not permanently affected, PRBs could be a low cost approach to combat eutrophication.
Biomarker responses in fish exposed to polycyclic aromatic hydrocarbons (PAHs): Systematic review and meta-analysis Environ. Pollut. (IF 4.358) Pub Date : 2018-07-04 Manuela S. Santana, Leonardo Sandrini-Neto, Francisco Filipak Neto, Ciro A. Oliveira Ribeiro, Maikon Di Domenico, Maritana M. Prodocimo
Biomarkers of antioxidant and biotransformation systems are commonly used to assess polycyclic aromatic hydrocarbons (PAHs) pollution in fish. Despite their extensive application of biomarkers, contradictory results are vastly reported in the literature, even for the same species in similar contamination scenarios. This study aims to verify response patterns of biomarkers in fish exposed to PAHs. Through systematic reviews and meta-analyses, we were able to evaluate: (i) overall magnitude of PAHs effects on biotransformation and oxidative stress biomarkers; (ii) patterns of response among experimental approaches (laboratory, field and active biomonitoring), environment (marine and freshwater) and fish habitat (pelagic, demersal, etc.); (iii) effects of exposure route, time and concentration of PAHs; and (iv) which biomarkers respond best to PAHs exposure. Overall, biomarker responses were significantly affected by PAHs exposure. The activities of ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GPx) and levels of oxidized glutathione (GSSG) and lipid peroxide (LPO) significantly increased in fish exposed to PAHs, whereas catalase (CAT) and glutathione reductase (GR) activities and levels of reduced glutathione (GSH) were not affected. Amongst responsive biomarkers, EROD and GST activities significantly differed among approaches and between marine and freshwater environments, but were not affected by fish habitat. GSSG levels were higher in fish from laboratory bioassays compared to the field, but did not differ between environments nor habitats. Exposure route played a major role only for GST and GPx responses. Finally, increasing PAHs concentration and exposure time had a significant effect on all assessed biomarkers, except for CAT. We conclude that EROD and GST are robust biomarkers to assess PAHs effects in fish. Contrarily, CAT is an inadequate biomarker of PAHs exposure since no significant response was observed. Our study also highlighted some research gaps in PAHs contamination studies, such as a clear lack of active biomonitoring experiments.
Biodegradation of microcystin-LR using acclimatized bacteria isolated from different units of the drinking water treatment plant Environ. Pollut. (IF 4.358) Pub Date : 2018-07-04 Pratik Kumar, Krishnamoorthy Hegde, Satinder Kaur Brar, Maximiliano Cledon, Azadeh Kermanshahi-pour, Audrey Roy-Lachapelle, Rosa Galvez-Cloutier
Bacterial community isolated from different units of a Drinking Water Treatment Plant (DWTP) including pre-ozonation unit (POU), the effluent-sludge mixture of the sedimentation unit (ESSU) and top-sand layer water sample from the filtration unit (TSFU) were acclimatized separately in the microcystin-leucine arginine (MC-LR)-rich environment to evaluate MC-LR biodegradation. Maximum biodegradation efficiency of 97.2 ± 8.7% was achieved by the acclimatized-TSFU bacterial community followed by 72.1 ± 6.4% and 86.2 ± 7.3% by acclimatized-POU and acclimatized-ESSU bacterial community, respectively. Likewise, the non-acclimatized bacterial community showed similar biodegradation efficiency of 71.1 ± 7.37%, 86.7 ± 3.19% and 94.35 ± 10.63% for TSFU, ESSU and POU, respectively, when compared to the acclimatized ones. However, the biodegradation rate increased 1.5-folds for acclimatized versus non-acclimatized conditions. The mass spectrometry studies on MC-LR degradation depicted hydrolytic linearization of cyclic MC-LR along with the formation of small peptide fragments including Adda molecule that is linked to the reduced toxicity (qualitative toxicity analysis). This was further confirmed quantitatively by using Rhizobium meliloti as a bioindicator. The acclimatized-TSFU bacterial community comprised of novel MC-LR degrading strains, Chryseobacterium sp. and Pseudomonas fragi as confirmed by 16S rRNA sequencing.
Do progestins contribute to (anti-)androgenic activities in aquatic environments? Environ. Pollut. (IF 4.358) Pub Date : 2018-07-04 Pavel Šauer, Adam Bořík, Oksana Golovko, Roman Grabic, Andrea Vojs Staňová, Olga Valentová, Alžběta Stará, Marie Šandová, Hana Kocour Kroupová
Unknown compounds with (anti-)androgenic activities enter the aquatic environment via municipal wastewater treatment plants (WWTPs). Progestins are well-known environmental contaminants capable of interfering with androgen receptor (AR) signaling pathway. The aim of the present study was to determine if 15 selected progestins have potential to contribute to (anti-)androgenic activities in municipal wastewaters and the respective recipient surface waters. AR-specific Chemically Activated LUciferase gene eXpression bioassay in agonistic (AR-CALUX) and antagonistic (anti-AR-CALUX) modes and liquid chromatography tandem atmospheric pressure chemical ionization/atmospheric photoionization with hybrid quadrupole/orbital trap mass spectrometry operated in high resolution product scan mode (LC-APCI/APPI-HRPS) methods were used to assess (anti-)androgenic activity and to detect the target compounds, respectively. The contribution of progestins to (anti-)androgenic activities was evaluated by means of a biologically and chemically derived toxicity equivalent approach. Androgenic (0.08–59 ng/L dihydrotestosterone equivalents – DHT EQs) and anti-androgenic (2.4–26 μg/L flutamide equivalents – FLU EQs) activities and progestins (0.19–75 ng/L) were detected in selected aquatic environments. Progestins displayed androgenic potencies (0.01–0.22 fold of dihydrotestosterone) and strong anti-androgenic potencies (9–62 fold of flutamide). Although they accounted to some extent for androgenic (0.3–29%) and anti-androgenic (4.6–27%) activities in influents, the progestins’ contribution to (anti-)androgenic activities was negligible (≤2.1%) in effluents and surface waters. We also tested joint effect of equimolar mixtures of target compounds and the results indicate that compounds interact in an additive manner. Even if progestins possess relatively strong (anti-)androgenic activities, when considering their low concentrations (sub-ng/L to ng/L) it seems unlikely that they would be the drivers of (anti-)androgenic effects in Czech aquatic environments.
The effects of insecticides on butterflies – A review Environ. Pollut. (IF 4.358) Pub Date : 2018-07-04 Nora Braak, Rebecca Neve, Andrew K. Jones, Melanie Gibbs, Casper J. Breuker
Pesticides, in particular insecticides, can be very beneficial but have also been found to have harmful side effects on non-target insects. Butterflies play an important role in ecosystems, are well monitored and are recognised as good indicators of environmental health. The amount of information already known about butterfly ecology and the increased availability of genomes make them a very valuable model for the study of non-target effects of pesticide usage. The effects of pesticides are not simply linear, but complex through their interactions with a large variety of biotic and abiotic factors. Furthermore, these effects manifest themselves at a variety of levels, from the molecular to metapopulation level. Research should therefore aim to dissect these complex effects at a number of levels, but as we discuss in this review, this is seldom if ever done in butterflies. We suggest that in order dissect the complex effects of pesticides on butterflies we need to integrate detailed molecular studies, including characterising sequence variability of relevant target genes, with more classical evolutionary ecology; from direct toxicity tests on individual larvae in the laboratory to field studies that consider the potentiation of pesticides by ecologically relevant environmental biotic and abiotic stressors. Such integration would better inform population-level responses across broad geographical scales and provide more in-depth information about the non-target impacts of pesticides.
Household biomass fuel use, blood pressure and carotid intima media thickness; a cross sectional study of rural dwelling women in Southern Nigeria Environ. Pollut. (IF 4.358) Pub Date : 2018-07-04 Sandra N. Ofori, Julius N. Fobil, Osaretin J. Odia
BackgroundRising prevalence of cardiovascular disease requires in-depth understanding of predisposing factors. Studies show an association between air pollution and CVD but this association is not well documented in southern Nigeria where the use of biomass fuels (BMF) for domestic purposes is prevalent.PurposeThis study aimed to explore the association between household BMF use and blood pressure (BP) and carotid intima media thickness (CIMT) among rural-dwelling women.MethodsA cross-sectional study of 389 women aged 18 years and older. Questionnaires were used to obtain data on predominant fuel used and a brief medical history. Wood, charcoal and agricultural waste were classified as BMF while kerosene, bottled gas and electricity were classified as non-BMF. Blood pressure and CIMT were measured using standard protocols. Regression analysis was used to assess the relationship between fuel type and BP, CIMT, pre-hypertension and hypertension after adjusting for confounders.ResultsThere was a significant difference in the mean (standard deviation) systolic BP (135.3, 26.7 mmHg vs 123.8, 22.6 mmHg; p < 0.01), diastolic BP (83.7, 18.5 mmHg vs 80.1, 13.8 mmHg; p = 0.043) and CIMT (0.63, 0.16 mm vs 0.56, 0.14 mm; p = 0.004) among BMF users compared to non-BMF users. In regression analysis, the use of BMF was significantly associated with 2.7 mmHg higher systolic BP (p = 0.040), 0.04 mm higher CIMT (p = 0.048) in addition to increased odds of pre-hypertension (OR 1.67 95% CI 1.56, 4.99, P = 0.035) but not hypertension (OR 1.23 95% CI 0.73, 2.07, P = 0.440).ConclusionIn this population, there was a significant association between BMF use and increased SBP, CIMT and pre-hypertension. This requires further exploration with a large-scale longitudinal study design because there are policy implications for countries like Nigeria where a large proportion of the population still rely on BMF for domestic energy.
Lake sediment records of persistent organic pollutants and polycyclic aromatic hydrocarbons in southern Siberia mirror the changing fortunes of the Russian economy over the past 70 years Environ. Pollut. (IF 4.358) Pub Date : 2018-07-03 Jennifer K. Adams, César C. Martins, Neil L. Rose, Alexander A. Shchetnikov, Anson W. Mackay
Persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) have previously been detected in the surface sediments, water, and endemic organisms of Lake Baikal, a UNESCO World Heritage Site. The Selenga River is the primary source of freshwater to Lake Baikal, and transports pollutants accumulating in the Selenga River basin to the lake. Sources of POPs and PAHs in the Selenga River basin grew through the 20th century. In the present study, temporal changes in the concentrations of PAHs and POPs were reconstructed from two lakes in the Selenga River basin over the past 150 years using paleolimnological techniques. Increased concentrations in PAHs and PCBs were recorded initially in the 1930s. The 1940s–1980s was the period of greatest exposure to organic contamination, and concentrations of dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs) and many PAHs peaked between the 1960s and 1980s in the two lakes. Declines in concentrations and fluxes were recorded for most PAHs and POPs in the 1980s and 1990s. Temporal trends in concentrations of total and individual compounds/congeners of PAH, PCBs, and polybrominated diphenyl ethers (PBDEs) indicate the contribution of both local and regional sources of contamination in the 20th and 21st centuries. Temporal variations in contaminants can be linked to economic and industrial growth in the former USSR after World War II and the economic decline of Russia in the late-1980s and early-1990s, as well as global trends in industrialization and development during the mid-20th century.
Polycyclic aromatic hydrocarbons in surface sediments of the mid-Adriatic and along the Croatian coast: Levels, distributions and sources Environ. Pollut. (IF 4.358) Pub Date : 2018-07-03 Jelena Mandić, Jacek Tronczyński, Grozdan Kušpilić
This study provides contamination levels, distributions and source apportionment of PAHs in surface sediments in the mid-Adriatic and along the Croatian coast. Median summed concentrations of parent and alkyl-PAHs are circa 10 times lower in the off-shore transect stations of the mid-Adriatic (22.3 and 18.2 μg.kg−1 d.w.) than the ranges determined at the coastal stations, including those of Kaštela bay (227–331 and 11.7–197 μg.kg−1 d.w., respectively). The highest levels, circa 20 times higher, were found in Šibenik bay (median 6603 and 3051 μg.kg−1). The overall range of PAH concentrations spans more than 2000 times between the lowest and the highest contamination level. The geographical distributions reflect the presence of strong gradients at local and regional scales. A major factor influencing sedimentary PAH distributions at local scale appears to be the distance from their known continental and coastal upstream emission sites (urban, industrial, harbour …), whereas at regional scale, this distribution depends more on the routes of entry of PAHs into the study area. Two combustion and one petroleum model source profiles of PAHs were determined by alternative least square analysis. Benzo[b+j]fluoranthenes and fluoranthene/pyrene are compounds characterizing two pyrogenic sources respectively, while signatures of alkyl-substituted homologues (phenanthrenes/anthracenes, fluranthenes/pyrenes, chrysenes and dibenzothiophenes) delineate a petrogenic source profile. The quantitative apportionment of source contributions shows significant geographical differences, with a dominant petrogenic source found along the mid-Adriatic transect (approximately 74%) and in Kaštela bay (61%). In the coastal sediments about a fifty-fifty contamination mix is assigned to a petrogenic/pyrogenic source of PAHs (47% and 53% respectively), whereas in Šibenik bay a strong predominance is apportioned to the combustion compounds (81%).
Multiple trace element accumulation in the mussel Septifer virgatus: Counteracting effects of salinity on uptake and elimination Environ. Pollut. (IF 4.358) Pub Date : 2018-07-03 Qijun Yin, Wen-Xiong Wang
Salinity effects on the bioaccumulation and biokinetic processes of eight trace elements (Cu, Cr, Pb, Ni, Zn, Cd, Se, and As) in the black mussel Septifer virgatus were explored in the present study. A 6-week laboratory waterborne exposure first showed that salinity (15, 20, 25, and 30) had relatively weak or even no significant influence on trace element accumulation in the black mussels. Biokinetics including uptake and efflux was then quantified in the mussels at different salinities. Uptake rates of Ni and Zn were negatively correlated with the salinity, while the uptake of Cd was not significantly influenced by salinity. The efflux rates of Ni and Zn also exhibited an inverse relationship with salinity, whereas the case of Cd was on the contrary. Biokinetic modeling showed that the salinity effects on uptake and elimination of Ni and Zn counteracted with each other, thus weakening the combined effects on accumulation. Overall, the response of uptake to salinity could weakened, removed, or even overturned by elimination, depending on the relative magnitude of the change of the two processes. The combined effects of uptake and elimination further led to negative, no, or positive relationship between trace element accumulation and salinity.
Systematic characterization and proposed pathway of tetracycline degradation in solid waste treatment by Hermetia illucens with intestinal microbiota Environ. Pollut. (IF 4.358) Pub Date : 2018-07-03 Minmin Cai, Shiteng Ma, Ruiqi Hu, Jeffery K. Tomberlin, Chan Yu, Yongping Huang, Shuai Zhan, Wu Li, Longyu Zheng, Ziniu Yu, Jibin Zhang
Antibiotics can effectively protect livestock from pathogen infection, but residual antibiotics in manure bring risks to ecosystems and public health. Here, we demonstrated that black soldier fly larvae (BSFL) could provide an environmentally friendly manure treatment based on their ability to effectively and rapidly degrade tetracycline (TC). Investigation of the biological mechanisms and degradation pathways of TC by BSFL indicated that nearly 97% of TC was degraded within 12 days in a non-sterile BSFL treatment system, which is up to 1.6-fold faster than that achieved by normal composting. Our results showed that rapid TC-degradation was largely carried out by the intestinal microbiota of the larvae, which doubled the TC-degradation rates compared to those achieved in sterile BSFL systems. This conclusion was further supported by highly-efficient TC-biodegradation both in vivo and in vitro by four larval intestinal isolates. Moreover, detailed microbiome analysis indicated that intestinal bacterial and fungal communities were modified along with significantly increased tet gene copy number in the gut, providing the means to tolerate and degrade TC. Through analysis of TC degradation in vitro, four possible biodegradation products, two hydrolysis products and three conceivable inactivation products were identified, which suggested TC degradation reactions including hydrolysis, oxygenation, deamination, demethylation, ring-cleavage, modification, etc. In conclusion, our studies suggested an estimation of the fate of TC antibiotics in manure treatment by BSFL colonized by gut microbes. These results may provide a strategy for accelerating the degradation of antibiotics by adjusting the intestinal microbiota of BSFL.
Influence of microplastic addition on glyphosate decay and soil microbial activities in Chinese loess soil Environ. Pollut. (IF 4.358) Pub Date : 2018-07-03 Xiaomei Yang, Célia P.M. Bento, Hao Chen, Hongming Zhang, Sha Xue, Esperanza Huerta Lwanga, Paul Zomer, Coen J. Ritsema, Violette Geissen
The intensive use of pesticide and plastic mulches has considerably enhanced crop growth and yield. Pesticide residues and plastic debris, however, have caused serious environmental problems. This study investigated the effects of the commonly used herbicide glyphosate and micrometre-sized plastic debris, referred as microplastics, on glyphosate decay and soil microbial activities in Chinese loess soil by a microcosm experiment over 30 days incubation. Results showed that glyphosate decay was gradual and followed a single first-order decay kinetics model. In different treatments (with/without microplastic addition), glyphosate showed similar half-lives (32.8 days). The soil content of aminomethylphosphonic acid (AMPA), the main metabolite of glyphosate, steadily increased without reaching plateau and declining phases throughout the experiment. Soil microbial respiration significantly changed throughout the entirety of the experiment, particularly in the treatments with higher microplastic addition. The dynamics of soil β-glucosidase, urease and phosphatase varied, especially in the treatments with high microplastic addition. Particles that were considerably smaller than the initially added microplastic particles were observed after 30 days incubation. This result thus implied that microplastic would hardly affect glyphosate decay but smaller plastic particles accumulated in soils which potentially threaten soil quality would be further concerned especially in the regions with intensive plastic mulching application.
Effect of erythromycin and modulating effect of CeO2 NPs on the toxicity exerted by the antibiotic on the microalgae Chlamydomonas reinhardtii and Phaeodactylum tricornutum Environ. Pollut. (IF 4.358) Pub Date : 2018-07-03 Marta Sendra, Ignacio Moreno-Garrido, Julián Blasco, Cristiano V.M. Araújo
Erythromycin is an antibiotic employed in the treatment of infections caused by Gram positive microorganisms and the increasing use has made it a contaminant of emerging concern in aqueous ecosystems. Cerium oxide nanoparticles (CeO2 NPs), which are known to have catalytic and antioxidant properties, have also become contaminants of emerging concern. Due to the high reactivity of CeO2 NPs, they can interact with erythromycin magnifying their effects or on the other hand, considering the redox potential of CeO2 NPs, it can alleviate the toxicity of erythromycin. The present study was carried out to assess the toxicity of both single compounds as well as mixed on Chlamydomonas reinhardtii and Phaeodactylum tricornutum (freshwater and marine microalgae respectively) employed as target species in ecotoxicological tests. Mechanisms of oxidative damage and those harmful to the photosynthetic apparatus were studied in order to know the toxic mechanisms of erythromycin and the joint effects with CeO2 NPs. Results showed that erythromycin inhibited the microalgae population growth and effective quantum yield of PSII (E.Q.Y.) in both microalgae. However, the freshwater microalgae Chlamydomonas reinhardtii was more sensitive than the marine diatom Phaeodactylum tricornutum. Responses related to the photosynthetic apparatus such as E.Q.Y. was affected by the exposure to erythromycin of both microalgae, as chloroplasts are target organelle for this antibiotic. Mixed experiments (CeO2 NPs + erythromycin) showed the protective role of CeO2 NPs in both microalgae preventing erythromycin toxicity in toxicological responses such as the growth of the microalgae population and E.Q.Y.
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