Drinking water disinfection byproduct iodoacetic acid interacts with catalase and induces cytotoxicity in mouse primary hepatocytes Chemosphere (IF 4.427) Pub Date : 2018-07-18 Jing Wang, Rui Jia, Xiaolin Zheng, Zhiqiang Sun, Rutao Liu, Wansong Zong
Disinfection byproducts (DBPs) are produced during the disinfection of drinking water and pose a hazard to human health. As a typical type of DBPs, iodoacetic acid (IAA) exhibits prominent cytotoxicity in mammalian cell systems which links with oxidative stress. However, little is known about the relationship of catalase (CAT) with the cytotoxicity of IAA and the adverse effects of IAA to CAT. This study investigated the effects of IAA on the cell viability and CAT activity in the mouse primary hepatocytes. It was shown that IAA exposure induced the loss of cell viability and the increase of intracellular CAT activity. Intracellular CAT activity significantly increased due to the stimulation of CAT production under IAA exposure. The molecular CAT activity was inhibited due to the direct interaction of IAA with HIS 74 and TYR 357 around the active sites of CAT. IAA binds to CAT with (4.05 ± 1.98) sites via van der Waals and hydrogen bonding interactions, resulting in the loosening of protein skeletons and the change of protein size.
A Bayesian assessment of polychlorinated biphenyl contamination of fish communities in the Laurentian Great Lakes Chemosphere (IF 4.427) Pub Date : 2018-07-17 Ariola Visha, Nilima Gandhi, Satyendra P. Bhavsar, George B. Arhonditsis
Polychlorinated biphenyl (PCB) contamination has historically posed constraints on recreational and commercial fishing industry in the Great Lakes. Empirical evidence suggests that PCB contamination represents a greater health risk from fish consumption than other legacy contaminants. The present study attempts a rigorous assessment of the spatio-temporal PCB trends in multiple species across the Canadian waters of the Great Lakes. We applied a Bayesian modelling framework, whereby we initially used dynamic linear models to delineate PCB levels and rates of change, while accounting for the role of fish length and lipid content as covariates. We then implemented Bayesian hierarchical modelling to evaluate the temporal PCB trends during the dreissenid pre- and post-invasion periods, as well as the variability among and within the water bodies of the Great Lakes system. Our analysis indicates that Lake Ontario is characterized by the highest PCB levels among nearly all of the fish species examined. Historically contaminated local areas, designated as Areas of Concern, and embayments receiving riverine inputs displayed higher concentrations within each of the water bodies examined. The general temporal trend across the Great Lakes was that the high PCB concentrations during the early 1970s followed a declining trajectory throughout the late 1980s/early 1990s, likely as a result of the reductions in industrial emissions and other management actions. Nonetheless, after the late 1990s/early 2000s, our analysis provided evidence of a decline in the rate at which PCB concentrations in fish were dropping, accompanied by a gradual establishment of species-specific, steady-state concentrations, around which there is considerable year-to-year variability. The overall trends indicate that reduced contaminant emissions have brought about distinct beneficial changes in fish PCB concentrations, but past historical contamination along with other external or internal stressors (e.g., invasive species, climate change) continue to modulate the current levels, thereby posing potential risks to humans through fish consumption.
Novel insights into variation of fluorescent dissolved organic matters during antibiotic wastewater treatment by excitation emission matrix coupled with parallel factor analysis and cosine similarity assessment Chemosphere (IF 4.427) Pub Date : 2018-07-17 Jiukai Tang, Jing Wu, Zhonghua Li, Cheng Cheng, Bo Liu, Yidi Chai, Yongjun Wang
In this work, the variation of fluorescent dissolved organic matters (FDOM) of antibiotic wastewater in a full-scale treatment plant was studied. Fluorescent components of anaerobic, aerobic, Fenton stages were separately figured out by parallel factor analysis (PARAFAC) based on excitation emission matrix (EEM) dataset. Then, these components were pairwise quantitatively compared according to cosine similarity (CS). It was found that, after the anaerobic treatment, the major components showed remarkable similarity (CS > 0.97) to those of raw wastewater, although their maximum fluorescence intensity (Fmax) decreased slightly or moderately (7%～54%). However, the aerobic treatment dramatically changed both the composition and content of fluorescent components, as all the protein-like components completely disappeared and only the humic-like components with much lower intensity were observed. After Fenton oxidation, all these humic-like components were remained (CS > 0.97) with fairly reduced Fmax (51%～61%). For both aerobically treated and Fenton-oxidized wastewater, Fmax correlated well with dissolved organic carbon (DOC). This suggested a dominant proportion of humic-like substances. The combination of PARAFAC based on separate EEM dataset of each treatment stage and CS assessment is a good approach to better understand FDOM variation and can be of much practical significance to monitor wastewater quality.
Black water collected from the septic tank treated with a living machine system: HRT effect and microbial community structure Chemosphere (IF 4.427) Pub Date : 2018-07-17 Zhan Jin, Cunhong Lv, Min Zhao, Yejian Zhang, Xianfeng Huang, Ke Bei, Hainan Kong, Xiangyong Zheng
In this study, the performance of a living machine (LM) system was evaluated for use in the treatment of black water collected from septic tanks with hydraulic retention times (HRTs) of 6, 5, and 4 days. We found that the HRT had little effect on the removal efficiency of chemical oxygen demand (COD). However, the removal rates of total nitrogen (TN) and ammonium nitrogen (NH4+-N) decreased with the reduction of HRT, whereas the removal efficiency of total phosphate (TP) was consistently low because of the long sludge retention time. The working conditions of #1 achieved the highest removal efficiency of COD (85%), NH4+-N (75%), and TN (47%), although the removal efficiency of TP (11%) was slightly lower than that of #2 (12%). The microbial communities in each tank of the LM system were characterized by high-throughput sequencing, which showed that the LM system successfully created more favorable conditions for fermentative bacteria than traditional systems, with relative abundances of 13% (#1), 13% (#2), and 15% (#3) compared to that of the anaerobic/anoxic/oxic (A2O) system (<3%). Smithella was the dominant fermentative bacteria, accounting for 9% (#1), 7% (#2), and 10% (#3) of total bacteria in the LM system. The relative abundances of ammonia oxidizing bacteria (AOB) (12%) and anaerobic ammonium oxidizing bacteria (AnAOB) (7%) in the LM system were much higher than that in the A2O system. Overall, the LM system offered a more sustainable and economical solution for treating black water.
Recent advances in microbial electrochemical system for soil bioremediation Chemosphere (IF 4.427) Pub Date : 2018-07-17 Yichao Wu, Xinxin Jing, Chunhui Gao, Qiaoyun Huang, Peng Cai
Soil contamination poses a serious threat to ecosystem and human well-being. Compared to conventional physical and chemical treatment, the microbial electrochemical system (MES) offers a sustainable and environment-friendly solution for soil bioremediation. In principle, soil microbe degrades organic substrate and releases electron in anode region. The electron flows through electric circuit to the cathode and finally is accepted by oxygen or oxidized metals. With various inherent advantages, MES has been applied in petroleum hydrocarbon, chlorinated organics and heavy metals bioremediation in soils. This paper aims to review the recent advances of MES in soil bioremediation, including main mechanisms of contaminant removal with MES, configurations of soil MES and current development in bioremediation of soil contaminated by organic and inorganic pollutants. Moreover, challenges and future prospects of soil MES are discussed.
Immune and xenobiotic response crosstalk to chemical exposure by PA01 infection in the nematode Caenorhabditis elegans Chemosphere (IF 4.427) Pub Date : 2018-07-17 Youngho Kim, Qaisra Naheed Choudhry, Nivedita Chatterjee, Jinhee Choi
Most organisms simultaneously face various chemical and biological stresses in the environment. Herein, we investigated how pathogen infection modifies an organism's response to chemical exposure. To explore this phenomenon, we conducted a toxicity study combined with pathogen infection by using the nematode Caenorhabditis elegans, the pathogen Pseudomonas aeruginosa, and various environmental chemicals. C. elegans preinfected with PA01, when subsequently exposed to chemicals, became sensitized to the toxicity of nonylphenol (NP) and cadmium (Cd), whereas they became tolerant to the toxicity of silver nanoparticles (AgNPs); this led us to conduct a mechanistic study focusing on AgNP exposure. A gene expression profiling study revealed that most of the immune response genes activated by PA01 infection remained activated after subsequent exposure to AgNPs, thereby suggesting that the acquired tolerance of C. elegans to AgNP exposure may be due to boosted immunity resulting from PA01 preinfection. Further, a functional genetic analysis revealed that the immune response pathway (i.e., PMK-1/p38 MAPK) was involved in defense against AgNP exposure in PA01-preinfected C. elegans, thus suggesting immune and stress response crosstalk to xenobiotic exposure. This study will aid in the elucidation of how pathogen infection impacts the way the defense system responds to subsequent xenobiotic exposure.
Occurrence, distribution, and air-water exchange of organophosphorus flame retardants in a typical coastal area of China Chemosphere (IF 4.427) Pub Date : 2018-07-17 Yan Wang, Xiaowei Wu, Qiaonan Zhang, Hongxia Zhao, Minmin Hou, Qing Xie, Jingwen Chen
Organophosphorus flame retardants (OPFRs) have been detected ubiquitously in the air and water worldwide, but no study has focused on their air-water exchange process. Here, we investigated the concentrations, distributions, and seasonal variations of OPFRs in the coastal air and water of Dalian, China. The total concentrations of 10 OPFRs in the air based on passive air sampling ranged from 0.50 to 20.0 ng/m3, while the concentrations of OPFRs in the water dissolved phase ranged from 48.3 to 681 ng/L. Relatively high concentrations were mainly discovered near the industry areas or river estuaries, suggesting that point sources along the coastline may significantly influence the local OPFR concentrations. Tris(2-chloroisopropyl) phosphate (TCIPP) was the most dominant congener followed by tris(2-chloroethyl) phosphate (TCEP), which was consistent with their high production and persistence. The air-water gaseous exchanges of OPFRs were estimated for the first time according to their concentrations in gaseous and dissolved phases. Generally, the gaseous exchange fluxes varied with sampling site and period. TCIPP showed the highest gaseous deposition flux of −395 ± 1211 ng/(m2 d), while TCEP showed the highest emission flux of 1414 ± 2093 ng/(m2 d). The dry deposition fluxes of OPFRs (0.05–822 ng/(m2 d)) were also calculated based on their particle fractions in the air. The result suggested that both gaseous exchange and particle deposition processes significantly influenced the air-water transport of OPFRs in this area.
Influence of electrode placement for mobilising and removing metals during electrodialytic remediation of metals from shooting range soil Chemosphere (IF 4.427) Pub Date : 2018-07-17 Kristine B. Pedersen, Pernille E. Jensen, Lisbeth M. Ottosen, John Barlindhaug
Electrodialytic remediation was applied to a shooting range soil to investigate the influence of electrode placement on the removal and binding of metals during the treatment. The set-up was based on a 2-compartment cell, in which the cathode was separated from the soil by a cation exchange membrane and the anode was placed directly in the soil, thereby introducing protons and oxygen directly in the soil. Mobilisation of metals from less available fractions (oxidisable and residual) in the soil occurred, due to oxidation/dissolution of insoluble/soluble organic matter and possibly metal oxides in the residual fraction. The transport via electromigration out of the soil and/or re-precipitation in other fractions of the soil (oxidisable, reducible, exchangeable) depended on the metal. More than 30% of the initial content of Mn, Cd, Cu, Pb and Zn and less than 20% of the initial content of Al, Fe, K, Mg, As, Cr and Ni was transported out of the soil. By decreasing the distance between the electrodes from 3.0 to 1.5 cm, the removal of the targeted metal for remediation, Pb, was improved by more than 200%, from 14 to 31%. A similar removal could be achieved in experiments with long distance between electrodes (3.0 cm) by increasing the current intensity from 4 to 10 mA and/or the remediation time from 7 to 35 d. The experiments showed that the design and optimisation of electrodialytic remediation depends on the targeted metal and metal partitioning.
Depuration time and sublethal effects of microcystins in a freshwater fish from water supply reservoir Chemosphere (IF 4.427) Pub Date : 2018-07-17 Sabrina Loise de Morais Calado, Gustavo Souza Santos, Talitha Pires Borges Leite, Juliana Wojciechowski, Mário Nadaline, Deivyson Cattine Bozza, Valéria Freitas de Magalhães, Marta Margarete Cestari, Viviane Prodocimo, Helena Cristina Silva de Assis
Microcystins (MCs) are hepatotoxins that have been considered to be a worldwide problem due the effects that they can cause to environmental and human health systems. The Iraí Reservoir, located in the South of Brazil, is used as a water supply and MCs concentrations have been reported in this ecosystem. This study aims to determine the MCs concentrations in the Iraí Reservoir and to evaluate the MCs depuration time and the health of Geophagus brasiliensis using biomarkers. Water and fish samples were collected in the Iraí Reservoir from August 2015 to May 2016. Phytoplankton and chemical analyses were conducted using water samples and the fish were divided into two groups; the Immediate Group (IMM) and the Depuration Group (DEP). In the IMM group, the blood, liver, muscle, brain and gills were collected, in order to evaluate the genotoxic, biochemical and chemical biomarkers. The DEP group was used in the depuration experiment for 90 days, and after this period the fish were submitted to the same procedure as the IMM group. Our results suggested that fish accumulated MCs and it may have caused oxidative stress, neurotoxicity and molecular damage. Furthermore, MCs concentrations increased during the depuration time and it resulted in molecular damage over the first 30 days. After 90 days, the recovery of the antioxidant system occurred. The depuration started on the 15th day, however, the toxins were still present in the samples. Therefore, the effects and the persistence of MCs are a risk to environmental systems and human health.
Multi-generational effects of lindane on nematode lipid metabolism with disturbances on insulin-like signal pathway Chemosphere (IF 4.427) Pub Date : 2018-07-17 Rui Chen, Zhenyang Yu, Daqiang Yin
Influences on lipid metabolism and multi-generational obesogenic effects raised new concerns on lipophilic pollutants (e.g., lindane). Yet, the mechanisms remained unanswered. The present study exposed Caenorhabditis elegans to lindane for 4 consecutive generations (F0 to F3) at 1.0 ng/L, and measured effects in the directly exposed generations (F0 to F3), indirectly exposed ones (T1 and T1′) and un-exposed ones (T3 and T3′). Lindane stimulated fat storages in all generations. At the biochemical level, lindane stimulated both acetyl-CoA carboxylase (ACC) and carnitine palmitoyl-transferases (CPT) in F0, T1 and T2, while inhibited them in F3, T1′ and T3′, demonstrating the balance between fatty acid synthesis and its depletion toward fat accumulation over generations. Moreover, lindane caused different effects on insulin among generations. It inhibited insulin in F0 and F3 and exhibited consistent effects on the expression changes of daf-2, sgk-1 and daf-16 genes in insulin-like signal pathway. Lindane also inhibited insulin in T1 and T3 but exhibited consistent effects on the expression changes of daf-2, akt-1 and daf-16. Different roles of sgk-1 and akt-1 indicated the response strategies from tolerance (F0 and F3) to avoidance (T1 and T3). Lindane stimulated insulin in T1′ and T3′ and exhibited consistent effects on expression changes of daf-2, sgk-1 and daf-16 genes that were similar in F0 and F3.
Control strategy for filamentous sludge bulking: Bench-scale test and full-scale application Chemosphere (IF 4.427) Pub Date : 2018-07-17 Niansi Fan, Runfang Wang, Rong Qi, Yingxin Gao, Simona Rossetti, Valter Tandoi, Min Yang
Sludge bulking caused by the overgrowth of filamentous bacteria, especially Microthrix parvicella, has been observed in WWTPs worldwide during low-temperature periods. In this study, the impacts of sludge load on the in situ growth of M. parvicella and sludge settleability were first evaluated at 15 °C over a period of 500 d using a bench-scale anaerobic-anoxic-aerobic reactor fed with raw sewage from a full-scale WWTP. When the reactor was operated at a sludge load of 0.07 ± 0.015 kg COD (kg MLSS·d)−1 for 120 d, the sludge volume index (SVI) increased gradually from 85 mL g−1 to 157 mL g−1, and the abundance of M. parvicella quantified by qPCR and FISH methods also increased from 0.42% to 4.63% and 1.56%–13.59%, respectively. When the sludge load was further reduced to 0.04 ± 0.004 kg COD (kg MLSS·d)−1, the SVI value varied in a narrow range of 135–164 mL g−1 over a duration of 280 d, while the M. parvicella abundance increased to the maximum values of 10.13% (qPCR) and 18.53% (FISH), respectively. When the sludge load was increased to 0.12 ± 0.016 kg COD (kg MLSS·d)−1, filamentous abundance and SVI were reduced to 1.06% (qPCR) and 105 mL g−1 within 100 d, suggesting that it might be possible to control the growth of M. parvicella by keeping the sludge load above 0.1 kg COD (kg MLSS·d)−1. The feasibility of the strategy was further validated in the same WWTP. It was found that the SVI and filamentous abundance in winter were successfully controlled for two successive years at below 120 mL g−1 and 7% (FISH), respectively, when the sludge load was maintained at 0.14 ± 0.04 kg COD (kg MLSS·d)−1 by adjusting sludge discharge, proving that this sludge-load-based strategy could be an efficient approach to control filamentous bulking.
Assessment of the oxidative and genotoxic effects of the glyphosate-based herbicide Roundup on the freshwater shrimp, Macrobrachium nipponensis Chemosphere (IF 4.427) Pub Date : 2018-07-17 Yuhang Hong, Xiaozhen Yang, Yi Huang, Guangwen Yan, Yongxu Cheng
In the present study, an acute toxic test was performed to assess the oxidative stress and genotoxic effects of the herbicide on the freshwater shrimp Macrobrachium nipponensis. The results showed that the 48-h and 96-h LC50 values of Roundup to M. nipponensis were 57.684 mg/L and 11.237 mg/L, respectively. For further investigation, the shrimps were exposed to sublethal concentrations of 0.35, 0.70, 1.40, 2.80 and 5.60 mg/L for 96 h. A significant decrease in total haemocytes count (THC) was observed at concentration of 5.60 mg/L throughout the experiment. The level of superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) in all the treatments decreased in a dose- and time-dependent manner except for the concentration group of 0.35 mg/L. The malondialdehyde (MDA), hydrogen peroxide (H2O2) and protein carbonyl in serum increased significantly at concentrations of 2.80 mg/L and 5.60 mg/L. A significant decrease in acetylcholinesterase (AChE) activity was observed at each concentration (P＜0.05). In addition, the micronucleus (MN) frequency of haemocytes significantly increased (P＜0.05) at concentrations of 1.40, 2.80 and 5.60 mg/L, whereas the comet ratio and %DNA in the tails exhibited a clear time- and dose-dependent response during the exposure. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants, and this dose-dependent relation suggests the sensitivity and availability of all the biomarkers. These results revealed that Roundup had a prominent toxic effect on M. nipponensis based on the antioxidative response inhibition and genotoxicity.
Co3O4 nanocrystals/3D nitrogen-doped graphene aerogel: A synergistic hybrid for peroxymonosulfate activation toward the degradation of organic pollutants Chemosphere (IF 4.427) Pub Date : 2018-07-17 Ruixia Yuan, Lin Hu, Peng Yu, Zhaohui Wang, Huaiyuan Wang, Jingyun Fang
3D porous Co3O4/nitrogen-doped graphene aerogel (NGA) hybrid for heterogeneous activation of peroxymonosulfate (PMS) was prepared by feasible hydrothermal and freeze-drying methods. The morphology, crystal structure and chemical composition of the catalyst were investigated by scanning electron microscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, Raman spectra and Fourier transform infrared spectroscopy. Co3O4/NGA at a high N doping level of 7.6% (in atomic percentage) exhibited excellent catalytic performance for acid orange 7 (AO7) degradation, with almost complete removal within 30 min. Moderate PMS content, higher temperature and lower solution pH conditions would facilitate the decomposition of AO7. The catalyst possesses excellent long-term stability and recycling performance with simple separation and post-treatment approaches. Kinetic models was developed to simulate the transformation of main active radical species and the AO7 oxidation profiles, considering effects of coexisting ions (Cl− and HCO3−). Based on results of electron spin resonance, typical quenching tests and kinetic calculation, sulfate radicals play dominate role in AO7 degradation. Co3O4 nanocrystals and the new active sites created by nitrogen doping into graphene honeycomb network should synergistically contribute to the high degradation efficiency. This work has expanded the possibility of recyclable catalysts design for heterogeneous activation of PMS, with a dual catalytically active center and desirable stability.
The role of the anode material and water matrix in the electrochemical oxidation of norfloxacin Chemosphere (IF 4.427) Pub Date : 2018-07-17 Salatiel W. da Silva, Emma M. Ortega, Marco A.S. Rodrigues, Andréa M. Bernardes, Valentín Pérez-Herranz
The roles of the anode material, boron-doped diamond (BDD), with different boron (B) and substrate Silicon (Si) or Niobium (Nb) content, and one dimensionally stable anode (DSA®), were evaluated in the oxidation of norfloxacin (NOR) by electrochemical advanced oxidation process (EAOP). The effect of other components in real wastewater on the performance of EAOP was also studied. The anode materials were characterized by cyclic voltammetry, regarding diamond quality, electro-generation of oxidants and NOR oxidation mechanism (direct and/or indirect). The results showed that the anode material influences on the NOR oxidation pathway, due to distinct characteristics of the substrate and the coating. Apparently, low difference in diamond-sp³/sp2-carbon ratio (Si/BDD100 × Si/BDD2500) does not leads to significant differences in the EAOP. On the other hand, the variation in the sp³/sp2 ratio seems to be higher when Si/BDD2500 and Nb/BDD2500 are compared, which would explain the best current efficiency result for Si substrate. However, the Nb substrate presented a similar current efficiency and a 60% lower energy consumption. Dissolved organic matter (DOM) present in the real wastewater affect the EAOP-Nb/BDD due to HO and persulfate ions scavenged. However, when supporting electrolyte was added to a real wastewater spiked with NOR, the NOR decay reaches similar values found to the synthetic one. Due to the energy saving and mechanical properties, Nb substrate presents some technological advantages in relation to Si, which can facilitate the application to industrial levels.
Sorption of chlorinated hydrocarbons to biochars in aqueous environment: Effects of the amorphous carbon structure of biochars and the molecular properties of adsorbates Chemosphere (IF 4.427) Pub Date : 2018-07-17 Weifeng Chen, Ran Wei, Jinzhi Ni, Liuming Yang, Wei Qian, Yusheng Yang
Currently, the role of amorphous carbon structure (ACS) in sorption of chlorinated hydrocarbons (CHs) to biochars remains little known. Therefore, three CHs (1,1,2,2-tetrachloroethane, 1,3,5-trichlorobenzene and γ-hexachlorocyclohexane) with different molecular properties were selected as model adsorbates to investigate the effect of ACS on sorption of CHs to biochars produced at seven different pyrolysis temperatures (300–900 °C). There were two main mechanisms for ACS controlling the sorption of CHs. First, the polar sites on ACS are hydrophilic, CHs with greater polarity could strongly compete with the water molecule for the hydrophilic sites. Second, ACS of low temperature (300–400 °C) produced biochars possessing the natural organic matter (NOM)-like structure occupied some hydrophobic sites on condensed graphitic structure (CGS) of biochars. CHs with great hydrophobicity possibly seized the hydrophobic sorption sites on CGS from the NOM-like structure. Therefore, ACS of biochar was more benefit for sorption of strong polar CHs (1,1,2,2-tetrachloroethane: π∗ = 0.95; LogKow = 2.39) or strong hydrophobic CHs (1,3,5-trichlorobenzene: π∗ = 0.70; LogKow = 4.19) than CHs (γ-hexachlorocyclohexane: π∗ = 0.68; LogKow = 3.72) with relatively low polarity and hydrophobicity. The result reflects that the interaction between NOM and natural black carbon/biochars in soil and water environment possibly plays the similar role in controlling the environmental behavior of various polar or hydrophobic organic pollutants. Moreover, with increasing concentration of adsorbate (Ce), the first mechanism enhanced, while the second mechanism weakened. This study gives a deep insight into the roles of ACS of biochars in controlling the fate and availability of CHs with different molecular properties in environment.
Microbial communities and functional genes of nitrogen cycling in an electrolysis augmented constructed wetland treating wastewater treatment plant effluent Chemosphere (IF 4.427) Pub Date : 2018-07-17 Pengfei Zhang, Yuke Peng, Junling Lu, Jie Li, Huiping Chen, Lin Xiao
To enhance nitrogen removal efficiency, a new electrolysis augmented constructed wetland (E-CW) was applied for nitrogen removal from waste water treatment plant (WWTP) effluent. This work demonstrated that E-CW could remove NO3− efficiently (45.5%–83.4%) under low CCOD/N ratio (average 2.29 ± 0.45) with little amount of NH4+ and NO2− generation. High throughput 16S rRNA sequence analysis revealed that Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and Verrucomicrobia were the dominant phyla in the E-CW. However, abundance of denitrifiers and denitrification genes decreased along with the operation of E-CW. Four functional gene pairs of anammox-amoA, (narG + napA)-(nirK + nirS), (narG + napA)-nosZ and qnorB-nosZ showed positive correlations with each other. Co-occurrence network analysis results indicated that functional guilds of FeOB and FeRB coupled with denitrifiers and contributed to the process of nitrogen removal in the E-CW. Overall, this work illustrated E-CW was a feasible and effective technology for enhancing nitrogen removal, and provided a theoretical basis for better design and operation of E-CW.
Utilizations of agricultural waste as adsorbent for the removal of contaminants: A review Chemosphere (IF 4.427) Pub Date : 2018-07-17 Yingjie Dai, Qiya Sun, Wensi Wang, Lu Lu, Mei Liu, Jingjing Li, Shengshu Yang, Yue Sun, Kexin Zhang, Jiayi Xu, Wenlei Zheng, Zhaoyue Hu, Yahan Yang, Yuewen Gao, Yanjun Chen, Xu Zhang, Feng Gao, Ying Zhang
In recent years, various industrial activities have caused serious pollution to the environment. Due to the low operating costs and high flexibility, adsorption is considered as one of the most effective technologies for pollutant management. Agricultural waste has loose and porous structures, and contains functional groups such as the carboxyl group and hydroxyl group, so it can be invoked as biological adsorption material. Agricultural waste gets the advantages of a wide range of sources, low cost, and renewable. It has a good prospect for the comprehensive utilization of resources when used for environmental pollution control. This article summarized the current research status of agricultural waste in adsorbing pollutants, which pointed out the influencing factors of adsorption, expounded the adsorption mechanism of biological adsorption and introduced the related parameters of adsorption, proposed the application of adsorbents in engineering including adsorption in liquid and gas phases, at the same time it gave the future development prospect of agricultural waste as adsorbent.
Subchronic, chronic, lethal and sublethal toxicity of insensitive munitions mixture formulations relative to individual constituents in Hyalella azteca Chemosphere (IF 4.427) Pub Date : 2018-07-17 Guilherme R. Lotufo, Jacob K. Stanley, Pornsawan Chappell, Nicolas L. Melby, Mitchell S. Wilbanks, Kurt A. Gust
Insensitive munitions (IMs) are replacing conventional munitions, improving safety from unintended detonation. IMs are deployed in mixture formulations but little is known about their mixture toxicology. We characterized mixture effects of the IM formulations IMX-101 (mixture of 2,4-dinitroanisole [DNAN], 3-nitro-1,2,4-triazol-5-one [NTO], and nitroguanidine [NQ]) and IMX-104 (DNAN, NTO, and hexahydro-1,3,5-trinitro-1,3,5-triazine [RDX]) in subchronic (10 d) and chronic (35 d) water-only tests in Hyalella azteca assessing impacts on survival, growth and reproduction. In 10-d single chemical exposures, DNAN was the most potent constituent, eliciting an LC50 of 16.0 mg/L; the LC50s for NTO and NQ were 891 and 565 mg/L, respectively. RDX did not elicit significant mortality up to 29.5 mg/L, a concentration near its solubility limit. Based on toxic-units (TUs), the toxicity of IMX-101 was driven by the effective concentration of DNAN; however, the presence of NTO, RDX, or both elicited interactive effects causing an approximately 2-fold decrease in lethality for IMX-104. Growth reduction was observed in 10-d exposures to DNAN, IMX-101 and IMX-104, but not for NQ, NTO, or RDX. Longer exposure duration (35 d) to IMX-101, IMX-104, and DNAN resulted in 3–6 times higher sensitivity for lethality and resulted in the most sensitive endpoint for DNAN, RDX, and IMX-101 exposures, decreased reproduction. Slight, but statistically significant, antagonistic responses among IMX-101 constituents were observed for survival and reproduction at 35d. Overall, the results support response-additive summation as a sufficient method to provide conservative hazard assessments of subchronic, chronic, and sublethal IMX-101 and IMX-104 mixture impacts in H. azteca.
Removal effect of the low-low temperature electrostatic precipitator on polycyclic aromatic hydrocarbons Chemosphere (IF 4.427) Pub Date : 2018-07-17 Xiaodong Li, Jingwei Li, Dongli Wu, Shengyong Lu, Chenyang Zhou, Zhifu Qi, Min Li, Jianhua Yan
The low-low temperature electrostatic precipitator (LLT-ESP) is one of the most used devices for pollutant control in ultra-low emission coal-fired power plants. This study investigated the influence of the LLT-ESP on polycyclic aromatic hydrocarbons (PAHs) distributions in flue gas from an ultra-low emission coal-fired power plant. The total gas-phase PAH concentration was reduced from 27.52 μg/m3 to 3.38 μg/m3. The total particulate-phase PAH concentration decreased from 14.36 μg/m3 to 0.34 μg/m3. The removal efficiency of the LLT-ESP for gas-phase and particulate phase carcinogenic higher molecular weight (HMW) PAHs was 85% and 99%, respectively. The total concentration of 16 selected PAHs in feed coal was 98.16 μg/g. The fly ash particle size successively decreased from Electric Field 1 (F1) to Electric Field 4 (F4). The total PAH concentration decreased from F1 to F2 but increased again from F3 to F4. The flue gas cooling process significantly contributed to the elimination of both gas- and particulate-phase PAHs in the flue gas. Presumably, most of the condensed PAHs were adhered to or absorbed in the fly ash and were scavenged in Field 1. Both gas- and particulate-phase 5- and 6-ring PAHs in the flue gas were completely removed in Field 1. The discharge process in the electric fields may promote the formation of several 4- or 5-ring PAHs. In this study, benzo[k]fluoranthene (BKF) and benzo[a]pyrene (BaP) were regenerated in the particles rather than in the flue gas during the discharge process in the electric fields.
Direct identification of Cu(II) species adsorbed on rosin-derived resins using electron paramagnetic resonance (EPR) spectroscopy Chemosphere (IF 4.427) Pub Date : 2018-07-17 Shaogang Liu, Zhangyan Li, Kaisheng Diao, Wanting Huang, Jue Wang, Wen Deng, Fuhou Lei, Bernard A. Goodman
Resins derived from natural rosin have been described recently as environmentally-friendly adsorbents with potential uses in the clean-up of wastewaters and the treatment of drinking waters. However, in order to improve the design of these products it is important to understand the chemical mechanisms through which they act. We now describe the combined use of EPR spectroscopy and Cu(II) to probe directly the metal coordination environment after uptake by various rosin-derived products. Clear distinctions are demonstrated between the copper bonding in different adsorbent preparations. Furthermore, in the case of nitrogen cross-linked products, the spectral parameters also provide information on the number of nitrogen atoms in the immediate atomic environment of the copper atom when covalent bonding is involved. This methodology works well for adsorption from solutions containing multiple components, because only those that are paramagnetic are detected, and different types of paramagnetic metal ion produce distinctly different EPR spectra.
Adsorptive treatment of coking wastewater using raw coal fly ash: Adsorption kinetic, thermodynamics and regeneration by Fenton process Chemosphere (IF 4.427) Pub Date : 2018-07-17 Nannan Wang, Qiang Zhao, Han Xu, Wanyu Niu, Liang Ma, Dongcheng Lan, Linlin Hao
Raw coal fly ash (RCFA) was used directly as adsorbent to treat coking wastewater. The results show that the RCFA can introduce COD (14, 4, and 11 mg L−1 at pH = 1.0, 7.0, and 14.0, respectively) into water due to the dissolution of reductive components from RCFA, this can be avoided by washing (6 times) using distilled water. The concentration of leached metal elements in wastewater is lower than the standard in GB18918-2002, China. The adsorption process accords with the pseudo-second order adsorption kinetic model and Langmuir thermodynamics model better than other ones, and it belongs to a physical and exothermic process. More loading of RCFA (10–60 mg L−1) means less adsorption capacity, and 40 g L−1 is the optimal value. The variation of regeneration rate of SRCFA for the first time (RR1) with regeneration time accords with the behavior of hyperbolic function ( 1 RR 1 = 0.986 + 53.913 t ), and the [H2O2], [Fe2+] and regeneration temperature can affect the RR1 at the manner of exponential function ( RR 1 = e − 1.11 [ H 2 O 2 ] , RR 1 = 1.077 · e − 2.467 [ Fe 2 + ] , and RR 1 = 2.064 · e − 251.048 T ). At the optimal regeneration condition of SRCFA ([H2O2] = 5 mM, [Fe2+] = 8 mM and temperature = 293 K), the RR1 can reach 87.1% after 270 min. The stability of RCFA shows two different stages, i.e., within the first 4 regenerations the RR increases from 87.1% to 89.7% and then decreases gradually and always. This variation trend can be confirmed by the results of SEM and BET tests.
Natural mackinawite catalytic ozonation for N, N-dimethylacetamide (DMAC) degradation in aqueous solution: Kinetic, performance, biotoxicity and mechanism Chemosphere (IF 4.427) Pub Date : 2018-07-17 Jiali Peng, Jianfei Yan, Qixuan Chen, Xia Jiang, Gang Yao, Bo Lai
To enhance the degradation of N, N-dimethylacetamide (DMAC) in aqueous solution, the natural mackinawite (NM) is introduced for catalytic ozonation in this study as it is an environmentally friendly catalyst with low cost and easy availability. The properties of the NM were initially characterized via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Then, impact factors including NM dosage, ozone gas concentration and initial pH were investigated and the optimal conditions (i.e., NM dosage = 3.5 g/L, ozone gas concentration = 300 L/min, initial pH = 6.8) were obtained in NM/O3 process. Besides, the superiority of the NM/O3 process was confirmed by the experiments that the degradation efficiency of DMAC in the NM/O3 process (i.e., 95.4%) was much higher than that in the zero-valent iron (ZVI)/O3 process (i.e., 46.1%) and the synthetic FeS/O3 process (i.e., 68.6%). Furthermore, the intermediate and possible degradation pathway of DMAC were proposed, and the biological toxicity of the intermediate was subsequently evaluated by the activated sludge. Finally, the mechanism of the NM/O3 process was proposed in this study based on control experiment and radical scavenging experiment. The extraordinary efficiency for DMAC degradation was found to be mainly caused by HO• of the reactive oxygen species (ROS) (i.e., HO•, O2•- and H2O2) generated in the NM/O3 process. Therefore, this study confirmed that NM was a high efficient catalyst for degradation the toxic and refractory pollutants in catalytic ozonation system.
Effect of activated carbon on removal of four phenolic endocrine-disrupting compounds, bisphenol A, bisphenol F, bisphenol S, and 4-tert-butylphenol in constructed wetlands Chemosphere (IF 4.427) Pub Date : 2018-07-17 Riry Wirasnita, Kazuhiro Mori, Tadashi Toyama
We investigated the effects of activated carbon, used as constructed wetlands (CWs) medium, on its ability to remove four emerging endocrine-disrupting chemicals (EDCs): bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS) and 4-tert-butylphenol (4-tert-BP). Two types of CWs planted with common reed were constructed, one with pumice rock called normal CW and the other was amended with activated carbon (AC) called AC-CW. EDCs contaminated synthetic wastewater (5 mg/L of each) was treated by CWs for 8 weeks. AC-CW completely and sustainably removed all four EDCs (98–100%) starting immediately and continuing throughout the experiment. Removal performances of all EDCs by AC-CW were significantly higher than those by normal CW. After experiment, no BPA and BPF and very small amounts of BPS and 4-tert-BP were detected in AC. In AC-CW, final elimination step of EDCs might be biodegradation. In addition, bacterial populations on AC component of AC-CW were one–two orders higher than those on the pumice rock of normal CW. Therefore, in AC-CW, EDCs were initially adsorbed onto AC, where they could be effectively degraded by high bacterial population.
Implementation of martite nanoparticles prepared through planetary ball milling as a heterogeneous activator of oxone for degradation of tetracycline antibiotic: Ultrasound and peroxy-enhancement Chemosphere (IF 4.427) Pub Date : 2018-07-17 Reza Darvishi Cheshmeh Soltani, Masumeh Mashayekhi, Sahand Jorfi, Alireza Khataee, Mohammad-Javad Ghanadzadeh, Mika Sillanpää
The aim of the present study was to employ martite nanoparticles synthesized through planetary ball milling instead of conventional sources of iron for the activation of Oxone in order to decompose tetracycline (TC) antibiotic in the aquatic phase. Accordingly, martite nanoparticles-activated Oxone exhibited a remarkable improvement in degrading TC molecules up to 87%. The results indicated an increased decomposition rate of TC with increasing Oxone concentration, martite nanoparticles dosage, and initial pH. In the absence of ultrasound, the decomposition rate of TC was 0.0481 min−1 within 30 min, while the implementation of ultrasound at 320 W and addition of hydrogen peroxide at 40 mM led to increase in the decomposition rate up to 0.0770 and 0.0907 min−1, respectively. The presence of carbonate and even persulfate ions suppressed the decomposition rate. Inversely, the addition of chloride and carbon tetrachloride enhanced the reactor performance in terms of TC degradation. Within four consecutive experimental runs, only 10.8% was dropped in the decomposition rate, indicating the appropriate reusability potential of martite nanoparticles. The results confirmed the appropriate ability of the treatment process in degrading and mineralizing the target pollutant but a longer exposure time is required for an efficient mineralization.
Modulations of TCDD-mediated induction of zebrafish cyp1a1 and the AHR pathway by administering Cd2+in vivo Chemosphere (IF 4.427) Pub Date : 2018-07-12 Ying Ying Chen, King Ming Chan
Trace metal ions such as cadmium (Cd2+) and trace organics typified by 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) are common co-contaminants in the environment and cause toxic effects in aquatic organisms that pose serious health risks. We studied the effects of Cd2+ on the regulation of cytochrome P450 1A1 (cyp1a1) gene-induction by TCDD using zebrafish embryos and larvae and adult zebrafish tissues. Our results showed that TCDD induced the cyp1a1 gene in all developmental stages and tissues of zebrafish, and the induction was higher in females than males. However, for the upstream genes (ahr2 and arnt2b) that mediate cyp1a1 gene induction in the zebrafish liver cell line was not induced by TCDD similar to the pattern of cyp1a1 in all investigated groups. After co-treatment with Cd2+, induction of the aryl hydrocarbon receptor pathway by TCDD was inhibited in the zebrafish larvae and the livers, intestines, kidneys and gills of adult zebrafish, but not in the embryos or brains of adult zebrafish, indicating that the toxicological effects of Cd2+ on TCDD are dependent on the developmental stages and tissue types. The present study confirms that Cd2+ blocks the TCDD-induced cyp1a1 gene in vivo but emphasizes that the effects are specific to the developmental stage, type of tissue and sex. The combined effects of Cd2+ and TCDD must be taken into consideration together with these parameters to accurately predict and assess cadmium and TCDD-induced toxicity in fish and carcinogenesis in animals in general.
Remediation of hexavalent chromium in contaminated soil by Fe(II)-Al layered double hydroxide Chemosphere (IF 4.427) Pub Date : 2018-07-12 Xin He, Pei Zhong, Xinhong Qiu
In this study, high-efficiency and low-cost Fe(II) and Al(III) layered double hydroxide (Fe-Al-LDH) was synthesized and used for the remediation of Cr(VI) contaminated soil. The Fe-Al-LDH characteristics were analyzed with different techniques. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses revealed its highly crystalline structure with sheet morphology, and a Brunauer–Emmett–Teller (BET) surface area of 46.85 m2/g. In addition, the remediation tests indicated that adding 1 g/L of Fe-Al-LDH to a solution of Cr(VI)-contaminated soil, at a soil to solution ratio of 1 g: 5 mL, completely immobilized the pre-adsorbed Cr(VI) in the soil (2079.84 mg/kg). Additionally, the Fe-Al-LDH could be used in a wide range of pH conditions and no Cr(VI) was detected in the leaching solution. Based on the characterization of X-Ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), and X-ray photoelectron spectroscopy (XPS) analysis, it is proposed that adsorption and reduction may be involved in the mechanism of Cr(VI) immobilization by Fe-Al-LDH. At the beginning of the reaction, Cr(VI) entered the layer structure of the LDH or was adsorbed on the surface of the LDH. Then, Fe(II) was involved in reducing the Cr(VI) to Cr(III) and was oxidized to Fe(III). Part of the Cr(VI) and Cr(III) were co-precipitated with Fe(III) and Al (III) during the formation of iron oxide or hydroxide.
Silicone–water partition coefficients determined by cosolvent method for chlorinated pesticides, musks, organo phosphates, phthalates and more Chemosphere (IF 4.427) Pub Date : 2018-07-12 Foppe Smedes
To further support implementation of monitoring by passive sampling, robust sampler–water partition coefficients (Kpw) are required to transfer data from passive sampler into aqueous phase concentrations. In this work silicone–water partition coefficients were determined for ∼80 hydrophobic organic contaminants using the cosolvent method. Partition coefficients (Kpm) were measured in pure water and water-methanol mixtures up to a methanol mole fraction of 0.3 (50% v/v). Subsequently, logKpw in pure water was determined as the intercept of linear regression of the logKpm with the corresponding methanol mole fractions. LogKpw were determined for phthalates, musks, organo phosphorus flame-retardants, chlorobenzenes, pesticides, some PCBs and a number of miscellaneous compounds. LogKpw Within compounds The median standard error and 95% confidence interval of the measured logKpw was 0.06 and 0.13, respectively. The overall relationship between Kpw and Kow seems insufficient to predict Kpw for unknown compounds. Prediction may work within a group of compounds with similar nature, e.g. homologues but HCH isomers having the same Kow exhibit Kpw ranging over an order of magnitude. Long alkyl-chain phthalates and tris(2-ethylhexyl) phosphate; all having a molecular volume >400 Å3, deviated the most from the Kpw–Kow relationship.
Comparison of organic matter removals in single-component and bi-component systems using enhanced coagulation and magnetic ion exchange (MIEX) adsorption Chemosphere (IF 4.427) Pub Date : 2018-07-12 Yingying Chen, Weiying Xu, Hongjian Zhu, Dong Wei, Ning Wang, Mengting Li
Natural organic matter (NOM) in aquatic environments have a significant impact on NOM-organic compound interactions, which could strongly affect the distribution and transformation of organic compounds during water treatment. This study focused on the removals of NOM (humic acid, HA) and synthetic organic matter (ibuprofen, IBP) through enhanced coagulation and magnetic ion exchange (MIEX) resin adsorption in single and bi-component systems. Two coagulants, traditional aluminum sulfate (AS) and lab-prepared polyaluminum chloride (PACl), were employed. The charge properties, particle size distribution, and fractal dimension (Df) during organic matter removal were studied in both the single and bi-component systems to explore the purification behaviors and mechanistic effects of interactions between coagulants, MIEX, and organic matters. The experimental results indicated that the Al-based coagulants could remove over 80% of HA in both the single and IBP-HA combined systems, while the presence of HA could considerably improve the IBP removal rate. The aggregates formed during single-component coagulation were larger, but weaker and more loosely structured than those formed in the bi-component system under the same coagulation conditions. In the single-component system, the maximum removal efficiencies of IBP and HA by MIEX adsorption were 65% and 72%, respectively, at a resin dosage of 20.0 mL/L and mixing time of 60 min. Under the same conditions, the removals of these components in the bi-component system were improved to 68% and 98%, respectively. The reaction rate between IBP and MIEX resin was found faster than that between HA and MIEX resin.
Electrochemical activation of sulfate by BDD anode in basic medium for efficient removal of organic pollutants Chemosphere (IF 4.427) Pub Date : 2018-07-12 Luchuan Chen, Chaojun Lei, Zhongjian Li, Bin Yang, Xingwang Zhang, Lecheng Lei
Electrochemical advanced oxidation processes (EAOPs) based on hydroxyl radicals (OH) have some limitations when they are applied to real wastewater treatment, such like strict requirements on pH (acidic electrolyte) and high energy consumption. Compared to OH, Sulfate radicals (SO4–) have high redox potential in wider range of pH (2–9). In this study, SO4– were efficiently produced by electrochemical activation of SO42− at boron doped diamond (BDD) anode. The degradation rate of 2,4-DCP (k = 0.828 ± 0.05 h−1) in the presence of Na2SO4 was approximately 4 times than that without Na2SO4 (k = 0.219 ± 0.01 h−1), indicating that SO4– exhibited higher reactivity than OH at initial pH = 9. Moreover, the amount of O2 decreased by 65% after 100 min during electro-oxidation of 2,4-DCP and the specific energy consumption per unit TOC (ECTOC) was reduced by 70% when the concentration of Na2SO4 increased from 0.01 to 0.1 M. The impact of sulfate ions in the electrochemical advanced oxidation were investigated. Electron spin resonance (ESR) measurements were conducted to identify the formation of SO4–. Electrolysis of 2,4-DCP with specific radical scavengers (ethanol and tert-Butanol) were conducted and the results revealed that SO4– were mainly produced by one-electron loss of sulfate at basic condition. Electro-generation persulfate was measured and participation of non-radical activation of persulfate was investigated. O2 production was quantified and we found electrochemical activation of sulfate could inhibit water dissociation. Taken all findings, a mechanism of electrochemical activation of sulfate at BDD anode was summarized. This technology eliminates the requirement for pH adjustment for wastewater treatment and makes EAOPs more effective and economic as well.
Screening of biological sulfate reduction conditions for sulfidogenesis promotion using a methanogenic granular sludge Chemosphere (IF 4.427) Pub Date : 2018-07-12 M. Mora, J. Lafuente, D. Gabriel
Effluents containing great amounts of oxidized sulfur compounds, such as sulfate or sulfite, can be valorized as elemental sulfur from a sequential reduction-oxidation biological process. However, the most important, challenging step to be optimized is the reduction of sulfate. The present study aimed at seeking out the optimal conditions to promote sulfidogenesis instead of methanogenesis using waste carbon sources and a methanogenic granular sludge. Crude glycerol showed better results in terms of the consumed COD/S-Sulfate ratio compared with acetate, cheese whey, pig slurry, and vinasse. Then, the screening of several conditions (T, pH, and COD/S-Sulfate ratio) and the effects of air presence and dissolved sulfide inhibition on sulfate reduction was carried out. Sulfidogenesis was promoted at 35 °C, pH = 8.5, COD/S-Sulfate ratio above 7.0 g O2 g−1 S, microaerophilic conditions, and dissolved sulfide concentrations below 250 mg S2− L−1. These conditions were tested for nearly 3 months in the startup and operation of a 2 L UASB reactor. An inlet sulfate concentration of 220 mg S L−1 and an HRT of 2 h were set. Removal efficiencies of approximately 90% were obtained with less than 20% of organic matter destined for biogas production.
Comparison of performance between boron-doped diamond and copper electrodes for selective nitrogen gas formation by the electrochemical reduction of nitrate Chemosphere (IF 4.427) Pub Date : 2018-07-11 Peijing Kuang, Keisuke Natsui, Yasuaki Einaga
The electrochemical nitrate reduction by using boron-doped diamond (BDD) and copper (Cu) electrodes was investigated at various potentials. Product selectivity of nitrate reduction was strongly dependent on the applied potential for both electrodes. The highest selectivity of nitrogen gas production was obtained at −2.0 V (vs. Ag/AgCl) by using a BDD electrode with a faradaic efficiency as high as 45.2%. Compared with Cu electrode, nitrate reduction on BDD electrode occurred at more positive potential, and the production of nitrogen gas was larger. The transformation of surface-adsorbed nitrate into molecular nitrogen would be accelerated on BDD electrode with hindering nitrite production. In addition, low concentration of surface-adsorbed hydrogen on the BDD would also retard the ammonia generation, leading to increase in the selectivity of nitrogen gas formation. Meanwhile, BDD electrode could hinder the hydrogen evolution reaction, which enhanced the efficiency for nitrate reduction and decreased energy consumption. BDD electrode has excellent stability to remain better performance for reducing nitrate during electrolysis without any variation of surface morphology or chemical components.
Efficient prevention of nanomaterials transport in the porous media by treatment with polyelectrolytes Chemosphere (IF 4.427) Pub Date : 2018-07-11 Tirto Soenaryo, Shizuaki Murata, Anatoly Zinchenko
Contamination of soil by engineered nanomaterials (ENM) is an emergent environmental problem that urges the development of robust treatment protocols to prevent ENM transport through soil. We developed a method for efficient entrapment and retention of ENM in solid porous media of quartz sand with grain size of 300–500 μm used as a simple model of soil and studied the transport of multi-walled carbon nanotubes, fullerenes, silica and gold nanoparticles through the sand-packed column by UV–vis and fluorescent spectroscopy. The treatment of ENM-contaminated porous media with a mixture of oppositely charged polyelectrolytes, cationic poly(diallyldimethylammonium chloride) and anionic poly(acrylic acid) sodium salt, dissolved in NaCl solution followed by dilution in the column results in strong electrostatic interaction between the polyelectrolytes and a formation of inter-polyelectrolyte complexes (IPEC) that induce flocculation of ENM and adsorption to the surface of sand. The method demonstrates excellent ENM entrapment efficiency (>90%) and high capacity of several grams of ENM per 1 g of polyelectrolytes. The IPEC network formed after the treatment also serves as an efficient protection barrier for newly added ENM contaminants. The method is universal for various types of ENM (carbon ENM, metal and oxide nanoparticles) and equally efficient for distilled water, tap water, or lake water eluents.
Trace element biomonitoring in the Peruvian andes metropolitan region using Flavoparmelia caperata lichen Chemosphere (IF 4.427) Pub Date : 2018-07-11 Alex Rubén Huamán De La Cruz, Jusber Kevin Huamán De La Cruz, Daniel Alvarez Tolentino, Adriana Gioda
In the present study, in situ lichens (Flavoparmelia caperata) were used to assess the deposition of atmospheric trace elements in the metropolitan area of Huancayo (Junín, Peru). In total, ten sampling sites were chosen and categorized as urban, peri-urban (rural-urban) and rural areas according to land use. In addition, samples were also collected from a non-contaminated area categorized as a control site. The concentrations of 16 trace elements were measured using an inductively coupled plasma mass spectrometer (ICP-MS) and examined by enrichment factor (EF), hierarchical cluster analysis (HCA), and principal component analysis (PCA). Twelve of the 16 trace elements in urban and peri-urban sites present concentration higher than those at the rural and control sites (p < 0.05). The EF results revealed significant enrichment (at least twice that of the control site) of Ba, Cr, Cd, Pb, Sb, V, and Zn at most sites. PCA and HCA showed that more elements were derived from vehicular sources and fewer from agricultural and natural sources.
What is driving the NF-κB response in environmental water extracts? Chemosphere (IF 4.427) Pub Date : 2018-07-11 Peta A. Neale, Frederic D.L. Leusch, Beate I. Escher
In vitro bioassays are increasingly applied for water quality monitoring, with assays indicative of adaptive stress responses commonly included in test batteries. The NF-κB assay is responsive to surface water and wastewater extracts, but the causative compounds are unknown and micropollutants typically found in water do not activate the NF-κB assay. The current study aimed to investigate if co-extracted organic matter and/or endotoxins could cause the NF-κB response in surface water extracts. The effect of model bacterial lipopolysaccharides (LPS) and dissolved organic carbon (DOC) was evaluated in the NF-κB assay both before and after solid-phase extraction (SPE), with 7% effect recovery for LPS and between 7 and 52% effect recovery for DOC observed. The NF-κB response, endotoxin activity, micropollutant concentration and total organic carbon concentration was measured in four surface water extracts. All water extracts showed a response in the NF-κB assay, but the detected micropollutants could not explain the effect. Comparison of predicted bioanalytical equivalent concentrations based on micropollutant, DOC and endotoxin concentrations in surface water with experimental bioanalytical equivalent concentrations suggest that co-extracted endotoxins are the most important drivers of the observed effect, with DOC only having a minor contribution. While in vitro bioassays typically detect mixtures of organic micropollutants, the current study shows that the NF-κB assay can integrate the effects of co-extracted endotoxins. Given that endotoxins can pose a risk for human health, the NF-κB assay is a valuable inclusion in bioanalytical test batteries used for water quality monitoring.
Monitoring the stress resistance of Pennisetum purpureum in Pb (II) contaminated soil bioaugmented with Enterobacter cloacae as defence strategy Chemosphere (IF 4.427) Pub Date : 2018-07-11 Anamika Das, Jabez W. Osborne
Lead (Pb) is reported to have negative effects on the biogeochemical behaviour of the plant growth. In recent years, the significance of rhizoremediation of heavy metals has been of great focus aiding in the development rates of plants under stressed conditions. The present study evaluated the physio-biochemical response of Pennisetum purpureum to different concentrations of Pb (II) viz., 0, 50, 100 and 150 mg kg−1 in the form of lead (II) nitrate. The pre-characterized PGPR strain, Enterobacter cloacae - KU598849 was used to augment the plants. After Pb exposure for 45 d, parameters such as plant growth, lead accumulation, H2O2 content, MDA content, protein, proline content and antioxidant enzymatic activities were quantified. Results illustrated that increasing Pb concentration reduced the early growth, metal accumulation, protein content and affected physio-biochemical changes by causing oxidative damage in plants. Upon augmentation of the bacterial inoculum, the plants significantly resisted the toxic effects of Pb. Increased Pb bioaccumulation pattern was recorded in roots than shoots, were highest uptake was found to be 72 mg kg−1 dry weight when exposed to 150 mg kg−1 Pb concentration. Lead supplementation increased the activities of malonylaldehyde (MDA), superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX) and catalase (CAT) in P. purpureum. Bacterial bioaugmentation resulted in the reduction of the oxidative stress aided with reduced antioxidant enzyme activities indicating the minimization of the damages under stress.
Assessment of the committed effective dose due to the 210Po intake from fish consumption for the Arabian Gulf population Chemosphere (IF 4.427) Pub Date : 2018-07-11 Zaid Q. Ababneh, Anas. M. Ababneh, Fahad I. Almasoud, Sultan Alsagabi, Yousef J. Alanazi, Ahmad A. Aljulaymi, Khaled M. Aljarrah
This study aims to assess the committed effective dose due to the intake of 210Po from the consumption of fish in Arabian Gulf countries. Twenty different kinds of fish, which represent the most common fish species consumed in the Arabian Gulf countries, were analyzed using alpha spectrometer technique. 210Po activity concentrations in fish samples were found to vary over a wide range from 0.1 to 14.7 Bq kg-1 fresh weight. This variation of 210Po concentrations between various type of fish samples might be attributed to the feeding type pattern and the size of fish. The annual committed effective dose due to ingestion of 210Po in fish species for adults in the Arabian Gulf countries was estimated and found to vary from 38 µSv in Bahrain to 85 µSv in Oman with an average value of 59 µSv. These values are considered relatively high compared to those reported in some other regions. However, it is still much lower than the world average ingestion dose due to natural radiation sources.
Degradation of norfloxacin in aqueous solution by atmospheric-pressure non-thermal plasma: Mechanism and degradation pathways Chemosphere (IF 4.427) Pub Date : 2018-07-11 Qifu Zhang, Hong Zhang, Qunxia Zhang, Qing Huang
Norfloxacin is a synthetic antibiotics drug which is widely used in the treatment of infectious diseases and also often carelessly released into natural environment resulting in antibiotics-contaminated wastewater. In this work, we employed atmospheric-pressure non-thermal dielectric barrier discharge (DBD) to treat norfloxacin-contaminated water and investigated the degradation efficiency and mechanism for the plasma treatments under different conditions with varied working gas atmospheres. Our results showed that the DBD efficiency for norfloxacin degradation depended on reactive oxygen/nitrogen species (RONS) produced in the plasma treatment, while the plasma-induced hydroxyl radical played a critical role in the norfloxacin degradation. For O2-DBD, except for the contribution from reactive oxygen species (ROS), ozone could also play an important role. For N2-DBD, reactive nitrogen species (RNS) could work synergistically with H2O2 to enhance the degradation effect. We also checked the plasma activated liquid (PAL) effect and analyzed the degradation products so that the degradation mechanism and pathways could be elucidated. This work may therefore provide the guidance for effective and feasible application of low-temperature plasma technology in treatment of antibiotics-contaminated wastewater.
Featured structure-activity relationships for some tri- and tetrachlorobiphenyls in human CYP2E1-activated mutagenicity — impact of the extent of ortho-chlorination Chemosphere (IF 4.427) Pub Date : 2018-07-11 Yuting Chen, Na Zhu, Yuyi Luo, Keqi Hu, Yungang Liu
Polychlorinated biphenyls (PCBs) as a group of persistent organic pollutants are confirmed human carcinogens; however, their mutagenicity remains mostly unknown. We have reported the mutagenicity of some PCBs with one to four chlorines in mammalian cells expressing human CYP2E1. To further explore the structural requirements for the mutagenicity of PCBs, eight tri- and tetrachlorobiphenyls untested before were investigated for the induction of gene mutations and micronuclei in a V79-derived cell line expressing both human CYP2E1 and sulfotransferase (SULT) 1A1 (V79-hCYP2E1-hSULT1A1), with SULT1A1 activity inhibited by pentachlorophenol, a potent SULT1 inhibitor. 2,2',6-Tri-, 2,3',6-tri, 2,4',6-tri-, and 2,2’,5-trichlorobiphenyls (PCBs 19, 27, 32, and 18, respectively) induced micronuclei and gene mutations in V79-hCYP2E1-hSULT1A1 cells, at potencies slightly higher than 2,6-dichlorobiphenyl, but one order of magnitude below that by 2,3,3’- and 2,3,4’-trichlorobiphenyls as reported recently; in the parental V79-Mz cells, they were nonmutagenic and weak in micronuclei induction. Among the four tetrachlorobiphenyls with varying number of ortho chlorines, 2,3,3',4'-tetrachlorobiphenyl (PCB 56) induced both micronuclei and gene mutations in V79-hCYP2E1-hSULT1A1 cells with a potency greater than the above compounds; however, 2,2',3,3'-tetrachlorobiphenyl was equivocal and 2,2',3,6'-tetra- and 2,2',6,6'-tetrachlorobiphenyls inactive in V79-hCYP2E1-hSULT1A1 cells. Immunofluorescent staining of micronuclei formed by PCBs 32 and 56 in V79-hCYP2E1-hSULT1A1 cells with centromere protein B antibodies indicated that they were predominantly whole chromosomes, implying aneugenic potentials. This study suggests that tri- and tetrachlorobiphenyls with a single ortho chlorine can be most mutagenic under activation by human CYP2E1, and greater numbers of ortho chlorines may cause a drastic decline in the activity, especially for tetrachlorobiphenyls.
Do biofilms affect the measurement of mercury by the DGT technique? Microcosm and field tests to prevent biofilm growth Chemosphere (IF 4.427) Pub Date : 2018-07-11 Sergi Díez, Riccardo Giaggio
The diffusive gradients in thin films (DGT) technique has been used routinely for monitoring the dissolved, bioavailable fraction of trace metals in freshwater during field campaigns. Nevertheless, for long deployment times, the biofilm formed on the filter of the DGT devices restricts trace metal uptake and hence interferes with the DGT measurements. In this work, we design different experiments to evaluate the potential of silver nanoparticles (AgNPs) in preventing the formation of biofilms on in-house manufactured mercury-specific DGTs. Laboratory tests were carried out by a microcosm system in independent glass containers, where biofilms obtained from field inocula were grown for weeks. Afterward, several experiments were performed with Hg-spiked river water, biofilms and DGTs treated and untreated with AgNPs to better understand biofilm colonization, inhibition and Hg uptake. The results showed that the treatment is very useful, since the mass of the biofilm accumulated at the surface of the treated DGT is significantly (p < 0.05) lower than in control (untreated) devices. Tests in colonized environments and Hg-spiked river water showed that the Hg uptake by the treated DGT matched the theoretical values and prevented biofilm formation up to 24 days post-deployment. Conversely, in deployments longer than two weeks using the untreated DGT, measurements could be underestimated by 35%. The results in the field reveal that in sampling stations with high levels of suspended matter, the filter becomes clogged despite there being no biofilm, thereby explaining its low efficiency for the uptake of Hg. In summary, the use of AgNPs inhibits biofilm formation and their use is especially recommended in eutrophic freshwaters with low amounts of suspended particulate matter.
Eichhornia crassipes mediated copper phytoremediation and its success using catfish bioassay Chemosphere (IF 4.427) Pub Date : 2018-07-11 Sunayana Goswami, Suchismita Das
Copper (Cu) pollution in aquaculture ponds poses substantial ecological threats. Most phytoremediation studies deal with the efforts of removing Cu from water, but seldom, such endeavors are validated by suitable bioassays. The present study undertook a two-pronged effort to remediate Cu by phytoextraction with an aquatic macrophyte, Eichhornia crassipes, and establish the efficacy of such endeavors by Clarias batrachus bioassay. For phytoextraction trials, E. crassipes was exposed to Cu concentration 0, 5, 10, 15 and 20 mg L-1 in Hoagland solution for 21 days. The highest uptake of 2168 µg g-1 dw was at 10 mg L-1 Cu exposure, and efficient root to leaf translocation was seen for 5-10 mg Cu L-1. For these doses, there was 55-57% decline in Cu from test waters. We evaluated morphological, physiological and biochemical response of plants towards Cu stress to gauge its phytomediation capacity. For bioassays, fish were reared for 7 days in phytoremediated Cu doses of 5 and 10 mg L-1. The accumulation of Cu followed the pattern: kidney>liver>gill>muscle. Fish muscle accumulated 21.8-27.0 µg Cu g-1 dw after 7d, however, for E. crassipes remediated doses, muscle accumulated 8.2-10.9 µg Cu g-1 dw, which was within the safe levels of Cu in edible tissues. Metal doses declined protein contents and augmented malondialdehyde, superoxide dismutase, catalase and peroxidase concentrations in tissues. Although their concentrations in remediated groups failed to reach the levels of control fish, significant recovery in these parameters were observed. The results pointed towards the efficacy of Cu phytoextration by E. crassipes.
Bi2Zr2O7 nanoparticles synthesized by soft-templated sol-gel methods for visible–light–driven catalytic degradation of tetracycline Chemosphere (IF 4.427) Pub Date : 2018-07-11 Xiaowei Liu, Lihui Huang, Xueyuan Wu, Zexiang Wang, Guihua Dong, Chuang Wang, Yangyang Liu, Lisha Wang
Tetracycline (TC), an antibiotic, is persistent in nature and frequently detected in water and sediments. Visible-light-driven photocatalyst for TC degradation is a promising environmental-friendly technology. Bi2Zr2O7, an effective photocatalyst, but no studies on its photodegradation of TC could be found in literature. In this study, Bi2Zr2O7 was synthesized by three soft templated sol-gel methods. Three synthesized Bi2Zr2O7 catalysts have different structures, morphologies and band gaps. The Bi2Zr2O7 nanoparticles synthesized with citric acid as the template (BZO-3) had a larger specific surface area (30.7 m2/g) and a narrower band gap (2.39 eV), and exhibited a better performance for TC degradation under visible light with an efficiency of up to 81.3%. They also exhibited good stability and reusability in recycled experiments. A reaction mechanism of TC degradation by these photocatalyst was proposed. The enhanced photocatalytic performance was mainly due to photogenerated holes of reactive species and TC was mainly degraded on the surface of the photocatalyst. Pathways of TC photodegradation were derived from the result of analyses of the reaction intermediates. In conclusion, Bi2Zr2O7 nanoparticles were found effective as photocatalyst for TC photodegradation by visible light.
Chromium uptake by lettuce as affected by the application of organic matter and Cr(VI)-irrigation water: Implications to the land use and water management Chemosphere (IF 4.427) Pub Date : 2018-07-11 Stavros Raptis, Dionisios Gasparatos, Maria Economou-Eliopoulos, Anastasios Petridis
Toxic chromium [(Cr(VI)] in food chain has created an alarming situation for human life and ecosystems. The present study through a greenhouse pot experiment aims to (a) investigate the ability of organic matter in reducing Cr uptake by lettuce (Lactuca sativa L.) from a sandy loam soil irrigating with Cr(VI)-water, (b) to provide a way for the restriction of Cr transfer from contaminated soils and irrigation water to plants/crops and (c) to contribute to the better management of soil (land) and water use, without reduction of the agricultural production. Since soil and groundwater contamination by Cr is a potential risk in a worldwide scale, due to industrial activities and/or natural processes, organic carbon may play a key role in the mobility of added Cr(VI) to soil via irrigation water, in a significant way. The cultivation of lettuce, using organic matter in the form of leonardite (10 and 30 wt%) and Cr(VI)-irrigation water (100, 200 and 300 mgL−1), showed that the uptake of Cr in both shoots and roots increased with increasing concentration of Cr in the irrigation water. The highest Cr values in shoots (average = 10 mg/kg) and in roots (average = 28 mg/kg) were recorded in those plants cultivated in soil after the addition of Cr(VI)- water without organic matter, whereas the lowest Cr values in shoots (average = 0.44 mg/kg) and in roots (average = 0.7 mg/kg) were recorded in those plants cultivated in soil with addition of 30 wt% organic matter. The used leonardite as organic matter that is an oxidized form of lignite, due to its high content of humic acid is considered to be a useful organic fertilizer that provides possibilities for combining food production with soil protection. Therefore, the application of the natural organic material leonardite, as a land management technique, seems to be a cost-effective method consistent to related protocols for the protection of the soil quality.
The combined toxicity of UV/chlorinated products from binary ibuprofen (IBP) and tyrosine (Tyr) on Escherichia coli: Emphasis on their occurrence and underlying mechanism Chemosphere (IF 4.427) Pub Date : 2018-07-11 Han Chen, Tao Lin, Wei Chen
In this study, the combined toxicity of UV/chlorinated products on Escherichia coli (E. coli) was investigated when ibuprofen (IBP) and tyrosine (Tyr) were used as two precursors. The median-effect equation and combined index (CI)-isobologram equation were used to evaluate the combined toxicity of UV/chlorinated products. Results revealed that the UV/chlorinated products originated from binary Tyr and IBP showed a synergism in toxicity on Escherichia coli at low concentration level while it turned into a clear antagonism effect above a fa value of 0.2 in the toxicity trial. The combined toxic effects on E. coli were determined by both the potential toxicity mode of specific disinfection byproducts (DBPs) and the complicated interaction caused by Tyr and IBP. The addition of IBP decreased the yield of N-DBPs generated from Tyr, which dominated the effect of combined toxicity. Even though the antagonism predominated in toxicity effect on E. coli, the synergistic toxicity at low dose levels should be getting attention, which was more close to the natural concentration of N-DBPs in waters.
The influence of selected bivalent metal ions on the photolysis of diethylenetriamine penta(methylenephosphonic acid) Chemosphere (IF 4.427) Pub Date : 2018-07-11 Ramona Kuhn, Robert Jensch, Isaac Mbir Bryant, Thomas Fischer, Stephan Liebsch, Marion Martienssen
DTPMP is predominantly utilized as scale inhibitor. We investigated the reaction rates and degradation mechanism of DTPMP with and without addition of Fe2+, Mg2+ and Ca2+ by performing LC/MS and 31P NMR analyses. DTPMP undergoes conversion with and without addition of bivalent metal ions. The initial cleavage of DTPMP is initiated at the CN bond leading to release of IDMP as its major breakdown product. The release of smaller quantities of EABMP and AMPA confirmed the nucleophilic attack on the DTPMP amines. Oxidation of Fe2+ to Fe3+ during the initial 30 min indicated an intramolecular electron transfer changing the electron density distribution at the nitrogen centre, which increased the radical attack during UV irradiation. Independent of the fact that Fe2+ acted as catalyst and Mg2+ and Ca2+ acted as reactants, we found no significant differences in their degradation mechanisms. However, the reaction rates were strongly affected by the addition of the bivalent metal ions as Fe2+ accelerated most DTPMP degradation followed by Mg2+ and Ca2+. The UV treatment without metal ion addition was four times slower compared with Fe2+ addition. We conclude that in environments rich in ferrous iron and/or at reduced redox potential, photolysis of DTPMP will be catalysed by iron and will lead to accumulation of IDMP, EABMP and AMPA and several other none-quantifiable breakdown products.
Lethal and sublethal toxicity of abamectin and difenoconazole (individually and in mixture) to early life stages of zebrafish Chemosphere (IF 4.427) Pub Date : 2018-07-11 Ana Letícia Madeira Sanches, Michiel Adriaan Daam, Emanuela Cristina Freitas, Aline Andrade Godoy, Gabriela Meireles, Ana Rita Almeida, Inês Domingues, Evaldo Luiz Gaeta Espíndola
In recent years, the need for the development of alternative test methods for the conventional acute fish toxicity test (AFT) with adult fish has often been discussed. In addition, concerns have been raised on the potential risks related with environmentally realistic pesticide mixtures since risk evaluations have traditionally been based on individual pesticides. The insecticide/acaricide abamectin and the fungicide difenoconazole are the main pesticides that are intensively used in Brazilian strawberry crop and are hence likely to occur simultaneously in edge-of-field waterbodies. The aim of the present study was therefore to evaluate the lethal and sublethal toxicity of single and mixture exposures of these pesticides to zebrafish early life stages (embryos and juveniles). By comparing the derived toxicity data of the individual compounds with that previously determined for zebrafish adults, the order of life stage sensitivity was juvenile > adult > embryo. The pesticide mixture revealed a dose-level dependent deviation of the independent action model, with antagonism at low dose levels and synergism at high dose levels. Sublethal parameters (especially those related with locomotion) were considerably more sensitive than lethality. Subsequently, the inclusion of sublethal parameters may greatly improve the sensitivity of FET tests and hence its suitability as a substitution of adult fish testing in risk assessment evaluations.
Effect of high salinity in wastewater on surface properties of anammox granular sludge Chemosphere (IF 4.427) Pub Date : 2018-07-11 Fang Fang, Ming-Ming Yang, Han Wang, Peng Yan, You-Peng Chen, Jin-Song Guo
Bacterial surface properties fundamentally affect the stability and aggregation of anammox granular sludge. The variation in the surface properties of the granular sludge at different salinities were investigated to further clarify the effect of salinity on the aggregation of anammox granular sludge in this study. High anammox activity was obtained at a salinity of 30 g/L NaCl, and the average removal efficiency of NH4+N, NO2−-N and TN reached 91.9% ± 1.4%, 97.3% ± 0.4% and 86.3% ± 0.9%, respectively. The sludge particle size in Reactor 1 (with 0 g/L NaCl as control) and Reactor 2 (with 0, 15 and 30 g/L NaCl) increased from 1.62 ± 0.16 mm and 1.59 ± 0.12 mm to 2.71 ± 0.23 mm and 2.44 ± 0.19 mm, respectively, during total operation. PN gradually decreased from 30.58 ± 2.5 mg/g to 18.11 ± 2.1 mg/g, and PS sharply increased from 1.48 ± 0.09 mg/g to 10.52 ± 0.50 mg/g with the increase in salinity. The PS/PN ratio of extracellular polymeric substances (EPS) rapidly increased from 0.05 to 0.58 with an increase of salinity. Fourier transform infra-red spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results showed that salinity inhibited the expression of anammox sludge hydrophobicity by changing surface groups. Binding between multivalent metal ions and EPS was significantly hindered by the high Na+ concentration. The results of this study provided a better understanding of the effect of salinity on the stability and aggregation of anammox granular sludge in saline wastewater treatment.
Effectiveness of a neutral electrolysed oxidising water (NEOW) device in reducing Legionella pneumophila in a water distribution system: A comparison between culture, qPCR and PMA-qPCR detection methods Chemosphere (IF 4.427) Pub Date : 2018-07-11 Sara Bonetta, Cristina Pignata, Silvia Bonetta, Lorenza Meucci, Donatella Giacosa, Elena Marino, Ilaria Gorrasi, Giorgio Gilli, Elisabetta Carraro
Disinfection of hot water systems is critical for reducing Legionnaires’ disease in high-risk buildings. The use of neutral electrolysed oxidising water (NEOW) is a promising method for the control of microorganisms in hot water systems. However, full-scale evaluations of the efficacy of NEOW devices to control Legionella pneumophila are currently lacking. The aim of this study was to assess the effectiveness of a NEOW device in reducing L. pneumophila in a hotel water network. Water samples (n = 67) were collected from different sites of a hotel distribution system before and after the installation of the NEOW device at the 1st, 4th, 8th and 12th week. Detection of L. pneumophila was performed comparing culture, qPCR and PMA-qPCR methods. Total bacterial counts (22 °C and 37 °C), Pseudomonas spp. and physico-chemical parameters were also monitored. The NEOW treatment resulted in a reduction of the amount of L. pneumophila positive samples (−32%) and of the number of heavily contaminated points (>104 CFU/L and >103 CFU/L) (−100% and −96%, respectively). Treatment maintained L. pneumophila at low levels (<102 CFU/L), which do not require specific intervention measures. The effectiveness of the disinfection system was also confirmed by PMA-qPCR (p < 0.001). The use of PMA resulted in a signal decrease in almost all samples upon the disinfection treatment. The NEOW disinfection device appears to be a promising approach to reduce the colonisation of hot water systems by L. pneumophila; however, further investigations are needed to ascertain its efficiency over longer time periods.
Removal of contaminants of emerging concern (CECs) and antibiotic resistant bacteria in urban wastewater using UVA/TiO2/H2O2 photocatalysis Chemosphere (IF 4.427) Pub Date : 2018-07-11 Margarita Jiménez-Tototzintle, Izabel Jales Ferreira, Sheila da Silva Duque, Paulo Rubens Guimarães Barrocas, Enrico Mendes Saggioro
The dispersion of pollutants and proliferation of antibiotic resistant bacteria in the aquatic environment are an emerging health concern worldwide. In this sense, it is essential to develop new technologies to increase the quality of wastewater treatment, which is spread throughout the environment. The present study has demonstrated evidence of the existence of antibiotic and mercury-resistant bacteria in the aquatic environment. The application of heterogeneous photocatalysis with UVA/TiO2 P25 slurry (200 mg L−1), UVA/TiO2-immobilized, and UVA/TiO2-immobilized/H2O2 were evaluated for the simultaneous elimination of a mixture of contaminants of emerging concern (acetamiprid (ACP), imazalil (IMZ) and bisphenol A (BPA)) and inactivation of antibiotic- and mercury-resistant bacteria (Pseudomonas aeruginosa and Bacillus subtilis). UVA/TiO2-immobilized/H2O2 increased the inactivation and elimination of the contaminants. After the combined treatment, the mixture of BPA, IMZ and ACP decreased 62%, 21% and <5%, respectively, after 300 min at 13.10 kJ L−1 of accumulated UV energy. The Pseudomonas aeruginosa strain was inactivated after 120 min using 5.24 kJ L−1 of accumulated UV energy, whereas the Bacillus subtilis strain was shown to be extremely resistant, with a capacity to develop mechanisms to avoid the oxidation process.
Arsenic accumulation in paddy plants at different phases of pre-monsoon cultivation Chemosphere (IF 4.427) Pub Date : 2018-07-12 Nilanjana Roy Chowdhury, Reshmi Das, Madhurima Joardar, Soma Ghosh, Subhojit Bhowmick, Tarit Roychowdhury
Geogenic arsenic (As) contamination in Bengal Delta Plain is a growing environmental and research concern. Cultivation of staple crops like paddy on these contaminated fields is one of the major routes for human dietary exposure. The present study investigates changes of arsenic concentrations in paddy plant parts, root soil and surface soil throughout the various phases of pre-monsoon (boro) cultivation. Arsenic uptake property of paddy plants collected from 10 fields was found to be dependent on the variety of paddy plant (like Minikit, Jaya) other than arsenic levels in groundwater (0.074–0.301 mg/l) or soil (25.3–60 mg/kg). Arsenic is translocated from root to aerial parts in descending order. Leaf, stem, root, root soil and surface soil showed a similar trend in their change of arsenic concentration throughout the cultivation period. Arsenic concentration was highest in vegetative phase; sharply declined in reproductive phase; followed by moderate increase in ripening phase. The young root tissues in vegetative (primary) phase could uptake arsenic at a much faster rate than the older tissues in later phases. With the growth of the plant, higher concentrations of iron in root soil in the reproductive phase confirmed the formation of iron plaques on the surface of the root, which sequester arsenic and prevented its uptake by plants. Finally, co-precipitation of arsenic with iron released from crystallized iron plaques results in loosening of the iron plaques from root surface. Thus, soil arsenic concentration increases in the final phase of cultivation which in turn contributes to increased concentration in plant parts.
Fluazinam impairs oxidative phosphorylation and induces hyper/hypo-activity in a dose specific manner in zebrafish larvae Chemosphere (IF 4.427) Pub Date : 2018-07-12 Xiao H. Wang, Shan S. Zheng, Tao Huang, Li M. Su, Yuan H. Zhao, Christopher L. Souders, Christopher J. Martyniuk
Fluazinam is a pyridinamine fungicide that induces oxidative stress and mitochondrial damage in cells, and it has been reported to exhibit neurotoxicity. To characterize the biological effects of fluazinam, we assessed mitochondrial bioenergetics, dopamine system expression, and behavior of early life staged zebrafish (0.01 μM–0.5 μM). Fluazinam at environmentally-relevant levels did not induce sub-lethal effects in larvae, but at the LC50 (0.5 μM), fluazinam decreased basal and ATP-linked respiration significantly in embryos. As mitochondria are directly related to redox homeostasis and apoptosis, the expression of genes related to oxidative stress and apoptosis were measured. Superoxide dismutase 2 (sod2), heat stock protein 70 (hsp70), bcl2-associated X protein (bax), and caspase 9 (casp9) mRNA levels were up-regulated by 0.5 μM fluazinam. Taken together, there is evidence for mitochondrial dysfunction and oxidative damage, only at the highest concentration of fluazinam (0.5 μM). As there are reports for fluazinam-induced neurotoxicity in dopamine synthesizing cells, transcriptional targets in the dopamine system were assessed in the zebrafish. Tyrosine hydroxylase 1 (th1) and dopamine receptor 2a (drd2a) were suppressed by 0.5 μM fluazinam, suggesting that this fungicide may affect the dopaminergic system. To further assess the potential for fluazinam-mediated neuromodulation, the dark photokinesis response was assessed in larvae following exposure. Larvae exposed to 0.1 μM fluazinam showed hyperactivity, while larvae exposed to 0.2 and 0.3 μM showed hypo-activity. This study demonstrates that fluazinam disrupts mitochondrial bioenergetics in zebrafish, potentially leading to an oxidative stress response, and aberrant behaviors in larvae that are dose dependent.
Single or mixture halogenated chemicals? Risk assessment and developmental toxicity prediction on zebrafish embryos based on weighted descriptors approach Chemosphere (IF 4.427) Pub Date : 2018-07-12 Supratik Kar, Shinjita Ghosh, Jerzy Leszczynski
Halogenated chemicals including perfluoroalkyl substances (PFASs) represent an emerging class of endocrine-disrupting pollutants for human populations across the globe. Distress related to their environmental fate and toxicity has initiated several research projects, but the amount of experimental data available for these pollutants is limited. The objective of this study is to assess the toxicity of potentially “safer” alternatives, in relation to their existing counterparts. Developmental toxicity data on zebrafish (Danio rerio) embryos of single and tertiary halogenated mixtures were modeled employing quantitative structure-toxicity relationship (QSTR) tool. The computed models are then employed for toxicity prediction of theoretically generated binary and tertiary mixtures (which have no experimental data) to check their possible threshold and mode of toxicity for future risk assessment. Further, for toxicity screening, we have prepared a huge external dataset consists of single (24), binary (276) and tertiary (2024) mixtures of PFASs. It was accomplished by combination method and predicted through developed models for interpretation of toxicity threats for individuals and mixtures along with identification of diverse range and combination of toxicity thresholds. We found that chemicals in mixtures displayed concentration addition of individual chemical suggesting a similar mode of toxic action and non-interaction of chemicals. Not only that, mixtures of halogenated compounds including PFASs showed less toxicity than their single counterparts and the obtained toxicity trend is: Single chemical > Binary mixture > Tertiary mixture.
Towards sustainable removal of methylthioninium chloride by using adsorption-electroradical regeneration Chemosphere (IF 4.427) Pub Date : 2018-07-09 Imen Ouiriemmi, Emilio Rosales, Marta Pazos, Abdellatif Gadri, Salah Ammar, María Angeles Sanromán
The current need for effective regeneration processes to be used in valorization of spent adsorbent demands the research of novel alternative techniques such as application of Advances Oxidation Processes. In this sense, the recent application of electroradical (ER) processes turned out to be very promising in terms of the drugs degradation from different environments. Thus, in this study, harnessing of a low cost natural adsorbent, Tunisian bentonite (BE), was evaluated for the removal of a model drug such as methylthioninium chloride (MC), and then its regeneration by ER processes was demonstrated. Initially, the BE was characterized and the adsorption of the MC was studied. This process followed a pseudo-first order kinetic and Langmuir isotherm fitted well to data reaching uptake values around 145–155 mg g−1. After that, BE regeneration by an ER process such as electro-Fenton process was ascertained. Due to the high buffering capacity of the BE, the addition of citric acid (1 mM) was necessary in order to assure the acidic medium to favor the oxidation reaction. By operating under optimized experimental conditions (current intensity 300 mA, pH 3, Fe2+ (1 mM) and citric acid (1 mM)) near complete adsorbent regeneration was achieved after 300 min of treatment and the pseudo-first-order model fitted well the degradation data. Furthermore, the adsorbent was efficiently used in successive cycles of adsorption-regeneration without operational problems that proved the efficiency of this technology. From the obtained results, a side-by-side configuration was designed and simulated, confirming the viability of the design at large scale.
Understanding and optimization of the flocculation process in biological wastewater treatment processes: A review Chemosphere (IF 4.427) Pub Date : 2018-07-05 Akshaykumar Suresh, Ewa Grygolowicz-Pawlak, Santosh Pathak, Leong Soon Poh, Maszenan bin Abdul Majid, Dominik Dominiak, Thomas Vistisen Bugge, Xin Gao, Wun Jern Ng
In the operation of biological wastewater treatment processes, fast sludge settling during liquid-solids disengagement is preferred as it affects effluent quality, treatment efficiency and plant operation economy. An important property of fast settling biological sludge is the ability to spontaneously form big and dense flocs (flocculation) that readily separates from water. Therefore, there had been much research to study the conditions that promote biological sludge flocculation. However, reported findings have often been inconsistent and this has possibly been due to the complex nature of the biological flocculation process. Thus, it has been challenging for wastewater treatment plant operators to extract practical information from the literature. The aim of this review is to summarize the current state of understanding of the factors that affect sludge flocculation so that evaluation of such information can be facilitated and strategize for intervention in the sludge flocculation and deflocculation process.
Revisiting elimination half live as an indicator for bioaccumulation in fish and terrestrial mammals Chemosphere (IF 4.427) Pub Date : 2018-07-05 Kai-Uwe Goss, Lukas Linden, Nadin Ulrich, Christian Schlechtriem
Current bioaccumulation regulation is focused on bioconcentration in fish. An extension to terrestrial mammals, e.g. rat, is urgently needed but will have to use a different metric, most likely the BMF. While both metrics are thermodynamically not equivalent the regulative testing requirements for both might be reduced to the investigation of the respective elimination rate constants k2 for fish or rat. These k2 values could be derived from animal tests or from in vitro - in vivo extrapolation and could be combined with estimated uptake rate constants to yield either a BCF or a BMF value. The possibility to use in vitro methods for k2 has the advantage that animal tests can be avoided and it bears the chance to experimentally cover species differences which are currently ignored in bioaccumulation regulation. Existing data for BCF and the respective k2 values for fish - either from feeding studies or from BCF studies themselves-indicate that this approach works. For terrestrial bioaccumulation this approach still needs further experimental support.
Considerations on the use of equilibrium models for the characterisation of HOC-microplastic interactions in vector studies Chemosphere (IF 4.427) Pub Date : 2018-07-05 Jorge F.M. Velez, Yvonne Shashoua, Kristian Syberg, Farhan R. Khan
The association of hydrophobic organic contaminants (HOCs) to microplastics (MPs) in the aquatic environment and the possible perturbation of how biota and HOCs interact (i.e. ‘MP vector effect’) is a much researched topic in the emergent field of aquatic MP pollution. Consensus on whether the vector-effect is relevant can in part be ascertained using laboratory experimentation. Such studies, of which there are now many examples, have as a mandatory component a characterization of the HOC-MP interaction. However, important considerations must be made when planning and executing such laboratory experiments, and subsequently when choosing equilibria models to fit sorption curves, as it is necessary to recognize that simplified conceptual models (i.e. Freundlich or Langmuir models) do not fit all HOC-MP interactions under all circumstances. The sorption equilibrium of HOCs to most plastic particles occurs as a combination of surface adsorption in the crystalline regions of the polymer (typically characterized by Langmuir models) and internal partition into amorphous regions (modelled with Freundlich relations), but this is rarely recognized. In this discussion we highlight some considerations needed when both characterizing the interactions between MPs and HOCs and improving the environmental realism of vector studies through the use of, for instance, weathered particles, adequate time for HOC-MP equilibria to be reached and working at lower concentrations. Increasing environmental realism of vector studies corresponds to a greater complexity in the equilibria model, but ultimately allows better understanding of any potential HOC-MP vector effect in nature.
PAHs and heavy metals in the surrounding soil of a cement plant Co-Processing hazardous waste Chemosphere (IF 4.427) Pub Date : 2018-07-05 Chen Wang, Zhenzhou Yang, Yanhao Zhang, Zuotai Zhang, Zongwei Cai
The Chinese government is encouraging domestic cement producers to move from traditional coal power sources to the co-processing of waste as the primary energy source for the industry. In this study, 32 samples collected from the soil surrounding a cement plant in Beijing were analyzed for the presence of 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) and 12 heavy metals. Ten samples were selected for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) analysis. The pollution distribution patterns, sources, and potential risks to human health and the environment were investigated and evaluated. The highest concentrations of PCDD/Fs occurred 1200 m downwind from the cement plant. The levels of ∑16 PAHs ranged from 130.6 to 1134.3 μg kg−1 in the sampled soils. Source identification analysis suggested that the cement plant was the most likely source of PAH contamination. The concentrations of most of the heavy metals detected in the sampled soils were close to background levels, except for the levels of cadmium (Cd) and mercury (Hg), which were, on average, two times and six times higher than background values, respectively. The co-incineration of sludge, coal, and hazardous waste in the cement plant is a major contributing cause for the high levels of Hg in the surrounding soil. Risk assessment models, both the incremental lifetime cancer risks (ILCRs) for PAHs and the potential ecological risk index (RI) for heavy metals, indicate potential risks to the population and the environment surrounding the cement plant.
A combination of ternary classification models and reporter gene assays for the comprehensive thyroid hormone disruption profiles of 209 polychlorinated biphenyls Chemosphere (IF 4.427) Pub Date : 2018-07-06 Xiaoxia Bai, Lu Yan, Chenyang Ji, Quan Zhang, Xiaowu Dong, An Chen, Meirong Zhao
Computational toxicology is widely applied to screen tens and thousands of potential environmental endocrine disruptors (EDCs) for its great efficiency and rapid evaluation in recent years. Polychlorinated biphenyls (PCBs) with 209 congeners have not been comprehensively tested for their ability to interact with the thyroid receptor (TR), which is one of the most extensively studied targets related to the effects of EDCs. In this study, we aimed to determine the thyroid-disrupting mechanisms of 209 PCBs through the combination of a novel computational ternary classification model and luciferase reporter gene assay. The reporter gene assay was performed to examine the hormone activities of 22 PCBs via TR to classify their profiles as agonistic, antagonistic or inactive. Thus, six agonists, eleven antagonists and seven inactive chemicals against TR were identified in in vitro assays. Then, six relevant variables, including molecular structural descriptors and molecular docking scores, were selected for describing compounds. Machine learning methods (i.e., linear discriminant analysis (LDA) and support vector machines (SVM)) were used to build classification models. The optimal model was obtained by using SVM, with an accuracy of 88.24% in the training set, 80.0% in the test set and 75.0% in 10-fold cross-validation. The remaining 187 PCB congeners' hormone activities were predicted using the obtained models. Out of these PCBs, the SVM model predicted 38 agonists and 81 antagonists. The findings revealed that higher chlorinated PCBs tended to have TR-antagonistic activities, whereas lower chlorinated PCBs were agonists. This study provided a reference for further exploring PCBs' thyroid effect.
Assessment of the effects of graphene exposure in Danio rerio: A molecular, biochemical and histological approach to investigating mechanisms of toxicity Chemosphere (IF 4.427) Pub Date : 2018-07-06 Amanda Lucena Fernandes, Jefferson Patrício Nascimento, Adelina Pinheiro Santos, Clascídia Aparecida Furtado, Luis Alberto Romano, Carlos Eduardo da Rosa, José Maria Monserrat, Juliane Ventura-Lima
Graphene has been shown to induce toxicity in mammals and marine crustaceans; however, information regarding oxidative stress in fish is scarce. The aim of this study was to evaluate the mechanism of graphene toxicity in different tissues of Danio rerio, considering different parameters of stress. Animals were injected intraperitoneally (i.p.) with 10 μL of suspensions containing different graphene concentrations (5 and 50 mg/L); the gills, intestine, muscle and brain were analysed 48 h later. There was no significant difference in the expression of the gclc (glutamate cysteine ligase catalytic subunit) and nrf2 (nuclear factor (erythroid-derived 2)-like 2) genes after exposure. In contrast, glutamate cysteine ligase (GCL) and glutathione-S-transferase (GST) activities were modulated and the glutathione (GSH) concentration was reduced in different tissues and at different concentrations. Lipid damage was observed in the gills. Histological analyses were performed to observe if the exposure could induce pathological damage in these tissues. The results showed pathological effects in all tissues, excluding the intestine, after exposure to both concentrations. Overall, these results indicate that graphene induces different grades of toxicological effects that are dependent on the analysed organ, with distinct pathological effects on some and oxidative effects on others. However, the brain and gills seem to be the primary target organs for graphene toxicity.
A disadvantageous effect of adsorption of barium by melanin on transforming activity Chemosphere (IF 4.427) Pub Date : 2018-07-06 Yasuhiro Omata, Masafumi Yoshinaga, Ichiro Yajima, Nobutaka Ohgami, Kazunori Hashimoto, Kaho Higashimura, Akira Tazaki, Masashi Kato
At present, beneficial effects of melanin and harmful effects of barium have been reported. However, little is known about the adsorption of barium, and even less is known about the biological significance of adsorption of barium by melanin. In this study, we showed that there was a strong correlation between the digitalized level of skin pigmentation and barium level in murine skin compared to the correlations between skin pigmentation level and levels of homologous elements of barium (magnesium, calcium and strontium). The concentration of subcutaneously injected barium in skin with a high level of pigmentation was higher than that in skin with a low level of pigmentation. Our cell-free experiment using the Langmuir isotherm for adsorption of barium in synthetic melanin also provided direct evidence of adsorption of barium by melanin. We then investigated the biological significance of melanin-mediated barium adsorption. We found barium-mediated increase in transforming activity in pigmented melanocytes (melan-a) but not in unpigmented melanocytes (melan-c) after confirming that the barium level in melan-a melanocytes was 3.4-fold higher than that in melan-c melanocytes after culture of 5 μM barium for 24 h. Taken together, our results not only indicate adsorption of barium by melanin in mice, cells and cell-free systems but also suggest a disadvantageous effect of adsorption of barium by melanin on transforming activity in cultured cells.
Toxicity of biomining effluents to Daphnia magna: Acute toxicity and transcriptomic biomarkers Chemosphere (IF 4.427) Pub Date : 2018-07-06 Leena Sivula, Eeva-Riikka Vehniäinen, Anna K. Karjalainen, Jussi V.K. Kukkonen
Increasing metal consumption is driving the introduction of new techniques such as biomining to exploit low grade ores. The biomining impacts notably aquatic ecosystems, yet, the applicability of ecotoxicological tests to study the complex mixture effects of mining waters is insufficiently understood. The aim of the present work was to test if transcriptomic biomarkers are suitable and sensitive for the ecotoxicity assessment of biomining affected waters. The study site had been affected by a multimetal biomine, and the studied water samples formed a concentration gradient of contamination downstream from the biomining site. Cadmium and nickel were used as positive controls in the toxicity tests. Selected transcriptomic biomarkers, previously shown to be differentially regulated by metals, were used to evaluate the ecotoxicity of the water samples. Parallel samples were used to compare the transcriptomic biomarkers with the conventional acute D. magna toxicity test. In the acute test, one sample was acutely toxic to D. magna, when pH was adjusted according to the standard, whereas, in the native pH, three samples caused total immobility. Monooxygenase was up-regulated by the highest concentration of Cd in control samples and three of the water samples. Vtg-SOD was up-regulated by one of the water samples, and catalase by the second highest concentration of Cd. The results show that transcriptomic biomarkers in D. magna can be used as sensitive bioindicators for metal mixture toxicity assessment in complex environmental water samples.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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