Seagrass systems are integral components of both local and global carbon cycles and can substantially modify seawater biogeochemistry, which has ecological ramifications. However, the influence of seagrass on porewater biogeochemistry has not been fully described, and the exact role of this marine macrophyte and associated microbial communities in the modification of porewater chemistry remains equivocal

Since the seminal work of Milliman and Syvitski (J Geol 100:525–544, 1992), there has been interest in evaluating the significance of small mountainous river (SMRs) systems and their role in the transport of both solutes, and especially sediments, to the world ocean. Although some data exist from portions of the Earth’s mountainous regions, the majority of this work has been focused in the western

Ultra-trace (< 1 ng g−1) rare earth elements and yttrium (REE + Y) and high field strength element (HFSE) geochemistry of freshwater can constrain element sources, aqueous processes in hydrologic catchments, and the signature of dissolved terrestrial fluxes to the oceans. This study details an adapted method capable of quantifying ≥ 38 elements (including all REE + Y, Nb, Ta, Zr, Hf, Mo, W, Th, U)

The octanol–water partition coefficients (Kow) of the aristolochic acids, AA I and AA II, were determined using the traditional shake-flask method as a function of pH and ionic strength. These compounds have been implicated in the etiology of Balkan endemic nephropathy, but evidence of a plausible exposure pathway remains elusive, and research is constrained by the absence of critical physical–chemical

Chemical weathering in the Himalayan river basins is among the highest in the world and has received vast research attention related to past climate change. Many early estimates of chemical weathering are based on a small number of water property data that ignore those spatial and seasonal variations. Therefore, this study analyzed spatial and seasonal variations in chemical weathering in the Mekong

Organic alkalinity is a poorly understood component of total titration alkalinity in aquatic environments. Using a numerical method, the effects of organic acid (HOA) and its conjugate base (OA−) on seawater carbonate chemistry and buffer behaviors, as well as those in a hypothetical estuarine mixing zone, are explored under both closed- and open-system conditions. The simulation results show that

Methane production usually increases from the acidic sphagnum-dominated ombrotrophic peatlands to minerotrophic ones with more neutral pH and higher coverage of vascular plants. Along this ombrotrophic–minerotrophic gradient, pH, microbial communities, and properties of dissolved organic matter in porewater all vary greatly. The hydrographic change resulted from permafrost thaw and projected global

The Marano and Grado Lagoon (northern Adriatic Sea, Italy) is contaminated mainly by mercury (Hg) of mining and industrial origin. This work aims to investigate the sedimentary records of Hg of a tidal flat–saltmarsh (TF–S) system and to understand the role played by tidal fluxes in terms of the transport, accumulation and release of Hg due to the periodic flow of the tide. The complex history of the

This study reports analyses of Ra isotopes in a Mediterranean stream, the Vidourle river, whose upper course drains the granitic and metamorphic basement of the SE part of the French Massif Central (Cévennes) and then flows through the karstified carbonates of Jurassic and Cretaceous ages. In these low-Ra waters (226Ra activities range from 1.5 to 4.9 mBq/L), all four Ra isotopes were successfully

This study presents major element geochemistry, mineral magnetism and textural analysis of lake-bottom sediments collected from the Wular Lake located in the Kashmir Valley (northwest Himalaya). Connected to the Jhelum River, Wular Lake basin occupies ~ 75% watershed area of the valley, covering ~ 10,196 km2, and makes it the major depo-centre for Kashmir Valley. The sediments represent dominant silt

Stream water and associated bottom sediments were sampled within the Lom Basin, and their rare earth element (REE) concentrations have been used to decipher their provenance and environment of deposition. Stream waters in the lower Lom Basin have variable Post Archean Australian Shale-normalized REE concentrations (0.24–4978 ng/l), positive Ce anomalies (Ce/Ce* ranges from 1.08 to 8.03), a general

The Lake Chad Basin (LCB) is one of the main endorheic basins in the world and has undergone large-level and surface variations during the last decades, particularly during the Sahelian dry period in the 1970s and the 1980s. The Chari–Logone River system covers 25% of the LCB but accounts for up to 82% of the Lake Chad water supply. The aim of this study is to investigate the dissolved phase transported

Dissolved organic matter (DOM) strongly participates in a variety of critical environmental and ecological processes and has a large impact on environmental quality. In this study, ultraviolet–visible absorbance spectroscopy and excitation–emission matrices of fluorescence spectroscopy in combination with parallel factor analysis (EEMs–PARAFAC) were applied to characterize a total of 92 DOM samples

The Florida Everglades has one of the most severe methylmercury (MeHg) contamination issues in the USA, resulting from factors including high rates of atmospheric mercury (Hg) deposition and sulfate inputs from agricultural lands. Sulfate loading stimulates microbial sulfate reduction and production of toxic and bioaccumulative MeHg. Controls on regional Hg emissions have been successful in reducing

The reported partition coefficients of REE with calcite are reviewed and critically discussed. In some of the reported experimental sets, REE concentrations are found to be supersaturated with respect to individual REE2(CO3)3 but never to REE(OH)3. Although the solutions are unsaturated with respect to individual REY carbonates, REY including Y are incorporated in calcite surfaces, where they are overgrown

The aim of this research was to investigate the competition between methanogens and sulfate-reducing bacteria in hypersaline environments. Samples of photosynthetic microbial mats, both soft mats (salinities of 55–126 ppt) and gypsum-hosted endoevaporite mats (salinities of 77–320 ppt), were obtained from hypersaline environments in California, USA, Mexico and Chile. Methane production was determined

We have studied iron (Fe)-isotope signals in particles (> 0.22 µm) and the dissolved phase (< 0.22 µm) in two subarctic, boreal rivers, their estuaries and the adjacent sea in northern Sweden. Both rivers, the Råne and the Kalix, are enriched in Fe and organic carbon (up to 29 µmol/L and up to 730 µmol/L, respectively). Observed changes in the particulate and dissolved phase during spring flood in

Large volumes of seawater were sampled in the Gulf of Trieste (northern Adriatic Sea) in order to study the interactions between colloidal organic matter (COM) and metal(loid)s (Me) in coastal waters. COM (> 5 kDa) was isolated by ultrafiltration and characterized using 1H NMR spectroscopy and elemental Corg. and Ntot. analyses. COM in the gulf represents about one quarter of the dissolved organic

Reactions between cyanide and compounds, which contain S–S bonds, in aqueous media result in formation of thiocyanate. In this work, we studied the kinetics of reactions of thiosulfate with free cyanide and its complexes under environmental conditions. Rates of reactions between cyanide species and thiosulfate decrease in the following order: CN− > HCN > [Fe(CN)6]3− > [Fe(CN)6]4−. However, at neutral

The nature of groundwater recharge along the mountain front (MF) and riparian zone (RZ) was discerned by multiple tools involving rain/water level relationship, geophysical of subsurface, seasonal hydrochemistry and environmental isotopic signatures. The proposed study has been carried out in Courtallam Hills, the north-western part of Tirunelveli District, South India. The study area is a hilly terrain

The Manuguru geothermal area, located in the Khammam district of Telangana state, India, is one of the least explored medium-enthalpy geothermal systems in India. In this study, subsurface reservoir temperature was estimated by applying various methodologies such as chemical geothermometry, multicomponent geothermometry and mixing models. Chemical geothermometers provided wide range in temperature

Seagrass ecosystems have a potential role in climate change mitigation due to their ability to store high amount of carbon, particularly in the sediment. Studying the factors and mechanisms responsible for this storing capacity is essential to understand seagrass carbon sink function. Therefore, in this study, we identified the sources of organic carbon (Corg) in seagrass sediments and the implication

Sweet Springs Creek, located in the Valley and Ridge Province of the Appalachian Mountains in southeastern West Virginia and southwestern Virginia, USA, contains major fluvial tufa formations at the sites of localized fractures and faults. Sweet Springs Creek receives input from higher-temperature thermal springs of lower pH and higher sulfate concentration that differ significantly in chemical composition

Abstract The Manuguru geothermal area, situated in the Telangana state, is one of the least explored geothermal fields in India. In this study, the chemical characteristics of the groundwater (thermal and non-thermal waters) are investigated to elucidate the source of the solutes dissolved in the water and to determine the approximate residence time of the thermal waters. The major hydrogeochemical

Abstract Several rivers of Chile from the latitude 30°–38° have been sampled during a stable anticyclonic period (October 2008). Firstly, our aim was to evaluate the dissolved chemical composition (major and trace elements) of poorly known central Chilean rivers. Secondly, we used a co-inertia analysis (see Dolédec and Chessel in Freshw Biol 31:277–294, 1994) to explore the possible relationships between

Abstract The reduced sulfur species, sulfide, elemental and thiosulfate were considered in the thermal waters of Jiangxi Province for the first time. It is shown that the sulfur speciation content significantly varies and depends on the pH values. The major part of reduced sulfur refers to sulfide species in the nitric thermal waters, to elemental—in the carbon dioxide thermal waters. The presence

A 1-D biogeochemical reactive transport model with a full set of equilibrium and kinetic biogeochemical reactions was developed to simulate the fate and transport of arsenic and mercury in subaqueous sediment caps. Model simulations (50 years) were performed for freshwater and estuarine scenarios with an anaerobic porewater and either a diffusion-only or a diffusion plus 0.1-m/year upward advective