Substances In Aquatic Environment Research Articles

Heavy metals in centralized drinking water sources of the Yangtze River: A comprehensive study from a basin-wide perspective

Water quality in the Yangtze River Basin (YRB) has received considerable attention because it supplies water to 400 million people. However, the trends, sources, and risks associated with heavy metals (HMs) in water of centralized drinking water sources (CDWSs) in the YRB region are not well understood due to the lack of high-frequency, large-scale monitoring data. Moreover, research on the factors affecting the transportation of HMs in natural water are limited, all of which significantly reduce the effectiveness of CDWSs management. Therefore, this study utilized data on 11 HMs and water quality from 114 CDWSs, covering 71 prefecture-level cities (PLC) in 15 provinces (cities), to map unprecedented geospatial distribution of HMs in the YRB region and examine their concentrations in relation to water chemistry parameters. The findings revealed that the frequency of detection (FOD) of 11 HMs ranged from 28.59% (Hg) to 99.64% (Ba). The mean concentrations are ranked as follows: Ba (40.775 μg/L) > B (21.866 μg/L) > Zn (5.133 μg/L) > V (2.668 μg/L) > Cu (2.049 μg/L) > As (1.989 μg/L) > Mo (1.505 μg/L) > Ni (1.108 μg/L) > Sb (0.613 μg/L) > Pb (0.553 μg/L) > Hg (0.002 μg/L). Concentrations of Zn, As, Hg, Pb, Mo, Sb, Ni, and Ba exhibited decreasing trends from 2018 to 2022. Human activities, including industrial and agricultural production, have led to higher pollution levels in the midstream and downstream of the river than in its upstream. Additionally, the high concentrations of Ba and B are influenced by natural geological factors. Anion concentrations and nutrient levels, play a significant role in the transport of HMs in water. Probabilistic health risk assessment indicates that As, Ba, and Sb pose a potential carcinogenic risk. Additionally, non-carcinogenic risk to children under extreme conditions should also be considered.

Aplicabilidad de las determinaciones de absorción en el UV-visible para la caracterización de las sustancias húmicas en ambientes acuáticos

The applicability of UV-visible absorption measurements was analyzed as a rapid and easy way for the determination and characterization of humic substances in aquatic environments taking into account their ecological meaning. Samples for these studies were taken from Río Samborombón, Arroyo Vitel and Laguna de Chascomús (Provincia de Buenos Aires, Argentina). In spite of the different absorption of humic and fulvic acids at the wavelengths employed, the method proved to be useful to account for the relative proportion of them, to make comparisons betwcen different ecosystems and to give the possibility of using it to follow the dinamycs of these substances in a given water body. In an attempt to use absorbance determinations as a measure of soluble organic matter content, correlation between Chemical oxygen demand and absorbance at 250 nm and at 365 nm was analyzed. Good results were obtained for Río Samborombón at both wavelengths, while in the other cases correlation was more significative at 365 nm.

Biochemical and physiological alterations caused by Diuron and Triclosan in mussels (Mytilus galloprovincialis)

The rise in the utilization of pesticides within industrial and agricultural practices has been linked to the occurrence of these substances in aquatic environments. The objective of this work was to evaluate the uptake and adverse impacts of Diuron (Di) and Triclosan (TCS) on the mussel species Mytilus galloprovincialis. To accomplish this, the accumulation and toxicity of these pesticides were gauged following a brief period of exposure spanning 14 days, during which the mussels were subjected to two concentrations (50 and 100 μg/L) of each substance that are ecologically relevant. Chemical analysis of Di and TCS within gills and digestive gland showed that these pesticides could be accumulated in mussel's tissues. In addition, Di and TCS are preferably accumulated in digestive gland.Measured biomarkers included physiological parameters (filtration FC and respiration RC capacity), antioxidant enzyme activities (superoxide dismutase and catalase), oxidative damage indicator (Malondialdheyde concentration) and neurotoxicity level (acetylcholinesterase activity) were evaluated in gills and digestive glands. Both pesticides were capable of altering the physiology of this species by reducing the FC and RC in concentration and chemical dependent manner. Both pesticides induced also an oxidative imbalance causing oxidative stress. The high considered concentration exceeded the antioxidant defense capacity of the mussel and lead to membrane lipid peroxidation that resulted in cell damage. Finally, the two pesticides tested were capable of interacting with the neuromuscular barrier leading to neurotoxicity in mussel's tissues by inhibiting acetylcholinesterase. The ecotoxicological effect depended on the concentration and the chemical nature of the contaminant. Obtained results revealed also that the Di may exert toxic effects on M. galloprovincialis even at relatively low concentrations compared to TCS.In conclusion, this study presents innovative insights into the possible risks posed by Diuron (Di) and Triclosan (TCS) to the marine ecosystem. Moreover, it contributes essential data to the toxicological database necessary for developing proactive environmental protection measures.

Meta-Analysis Comparing Nominal and Measured Concentrations of Perfluorooctanoic Acid and Perfluorooctane Sulfonate in Aquatic Toxicity Studies Across Various Experimental Conditions.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are among the most frequently detected chemicals among the per- and polyfluoroalkyl substances in aquatic environments. Because of their high detection frequency, persistence, and potential toxicity, interest in both PFOA and PFOS has increased in recent years. However, a substantial number of PFOA and PFOS toxicity tests only report nominal, or unmeasured, treatment concentrations, which may complicate the determination of protective values. In addition, previous literature has indicated that differences between nominal and measured concentrations of both PFOA and PFOS could be linked to experimental conditions (e.g., feeding regimes for test organisms, test vessel material [glass or plastic], use of solvent, and the presence of substrate). Therefore, this critical review examined whether nominal and measured concentrations were in close agreement with each other among the current PFOA and PFOS aquatic toxicity literature and if experimental conditions were associated with any observed differences. Nominal and measured concentrations in the current PFOA and PFOS aquatic toxicity literature generally displayed a high degree of linear correlation and relatively low median percent differences. Correlations between measured and nominal concentrations were >0.98 for PFOA and >0.95 for PFOS in freshwater tests across experimental conditions. For saltwater tests, correlations of >0.84 were observed for PFOA and PFOS (separate and combined) across experimental conditions. While measured PFOA and PFOS toxicity tests are generally preferred, the present meta-analysis demonstrated that experimental conditions had little influence on observed discrepancies between nominal and measured concentrations, with the exception of PFOS saltwater tests and PFOA and PFOS freshwater studies that contained substrate. Unmeasured tests with these conditions should be considered carefully based on project needs, with the caveat that the data sets for these two experimental conditions were limited. Environ Toxicol Chem 2023;00:1-13. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Distinct chemical adsorption behaviors of sulfanilamide as a model antibiotic onto weathered microplastics in complex systems

Having proved to be harmful to plants, fishes and other species, microplastics as an emerging class of pollutants are raising public concern worldwide. Microplastics that harbor invasive substances in aquatic environment have further attracted scientific attention, due to potential synergistic toxicity greater than that produced individually. This study investigates the fundamental aspect of the adsorption behavior of sulfanilamide, one of the mostly adopted and extensively abused antibiotics, to weathered microplastics via hydrophobic interaction in different contexts. By exerting repeated UV-irradiation/temperature-variation, polyamide (PA), polyvinyl chloride (PVC) and polyethylene terephthalate (PET) microplastics are surface-roughed to display deep furrows depending on composition, while preserving the original chemical groups. Kinetics evaluation reveals an adsorption equilibrium achieved in 2 days. Satisfying fitting with pseudo-second-order model indicates chemical adsorption behavior for sulfanilamide onto all the aged microplastics. Probably due to the distinct surface roughness, a characteristic of Langmuir adsorption for the aged PA and PVC was observed with larger adsorption capacities; While the aged PET microplastics with relatively flat surfaces follow Freundlich adsorption model. We clarified the competition of the antibiotic with other species (e.g., salt, surfactant) and enhanced adsorption by interacting with protein in complex systems. These findings suggest limited adsorption of sulfanilamide antibiotics on microplastics in environment, but incremental toxicity of microplastics to organisms and even human beings that intake antibiotics and microplastics from environment and through food chain.

In situ measurement of an emerging persistent, mobile and toxic (PMT) substance - Melamine and related triazines in waters by diffusive gradient in thin-films

Melamine has received increasing public attention as a persistent, mobile and toxic (PMT) substance. To better assess environmental exposure and risks of melamine and related triazines (cyromazine, ammeline, and atrazine), a new passive sampling method based on the diffusive gradients in thin films (DGT) technique has been developed and validated in this study. The studied triazines were adsorbed quickly and strongly by the selected mixed cation exchange (MCX) binding gels. This MCX-DGT can linearly accumulate these chemicals over at least 5 days, with neither significant individual influence from pH (6–8), ionic strength (0.01–0.5 M) or dissolved organic matter (0–10 M), or interaction effects. Field applications in Southern China showed that DGT performed well in both sewage treatment plant (STP) and river samples. Melamine was found to be the dominant triazine with the concentrations at μg·L−1 in the STP and receiving river. Surprisingly, much higher concentration of melanine was found in the STP effluent than influent, and appeared to be some of the highest concentrations reported in STPs worldwide to date. Comparable melamine and atrazine concentraions in the STP effluent and receiving river suggested other sources to the river. The MCX-DGT sampler developed here was demonstrated to be reliable and robust for measuring the triazines in waters, and is promising as an in situ tool in understanding the occurrence, sources, and fate of the emerging PMT substances in aquatic environment.

Veterinary pharmaceuticals in aquaculture wastewater as emerging contaminant substances in aquatic environment and potential treatment methods

Veterinary pharmaceuticals are still unregulated and their residues in the environment have the potential to cause considerable impact on ecosystems. Water pollution due to veterinary pharmaceuticals gained worldwide attention because they deteriorate the water quality and impart a toxic effect on living organisms. Therefore, the effective aquaculture wastewater treatment for veterinary pharmaceuticals removal before releasing into the environment is necessary to prevent the risk of environmental contamination and subsequent negative health and economic impacts on both the human and aquaculture industry. This review provides an overview of currently available methods to remove veterinary pharmaceuticals available in aquaculture wastewater while reviewing some methods already studied for other types of pharmaceuticals but possible to use in aquaculture in the future and the scope of the review has been limited to aquaculture antibiotics used as veterinary medicines. Several water refinement techniques such as conventional mechanical, chemical, biological and physical wastewater treatment methods are practiced but they are not with suitable efficiency. Several studies were published covering small or special sections of water pollution by pharmaceuticals. But most of these studies have been done targeting to remove the antibiotics coming from hospital effluent, livestock or animal farm, and veterinary practices. There are very few research studies done specifically for aquaculture wastewater treatment against veterinary pharmaceuticals. Therefore, more attention and efforts must be given to this topic to be developed and to know all details concerning the toxicity of veterinary pharmaceuticals and how they can be removed from the aquaculture wastewaters.

An all-in-one tool for multipurpose ecological risk assessment and management (MeRAM) of chemical substances in aquatic environment

A quality-assured ecological risk assessment (ERA) requires enormous resources (time and labor) in collection/assessment of hazard data, as well as considerable expertise to interpret the risk. The ERA of chemicals is thereby considered difficult or impossible for those with little assessment experience and cumbersome or complicated for practitioners. To meet the concerns regarding ERA and accelerate the risk assessment and management of chemicals, we developed an all-in-one free tool for multi-purpose ecological risk assessment management (MeRAM) of chemical substances in aquatic environment called the AIST-MeRAM Ver. 2.0.0 (Copyright No: H28PRO-2007). It allows users from beginners to experts to conduct ERA without any preparation because all the necessary ecotoxicity test data and methodologies are available in the system. Approximately 270,000 ecotoxicity test data points for 3900 chemical substances together with the scientific methodologies from traditional simple hazard quotient (HQ) to more ecologically relevant complicated assessments such as species sensitivity distribution (SSD) and population-level assessment are embedded in the AIST-MeRAM. In addition, users can easily understand the Japanese regulatory RA and management of chemical substances due to a special function based on the Japanese Chemical Substance Control Law (CSCL). Here, we demonstrate a tiered ERA using the embedded sample data to evaluate and ensure the functions of AIST-MERAM. We show that the AIST-MeRAM can provide a comprehensive and accurate ERA, suggesting that it is a powerful IT solution for cumbersome ERA.

Photocatalytic performance of multi-walled carbon nanotube/BiVO4 synthesized by electro-spinning process and its degradation mechanisms on oxytetracycline

To enhance the photocatalytic performance of bismuth vanadate (BiVO4) and reveal its catalytic mechanism, a multi-walled carbon nanotube photocatalyst (MWCNT/BiVO4) was prepared by sol-gel preparation and an electro-spinning process. Oxytetracycline was used as the target trace persistent pollutant to research its potential degradation pathways catalyzed by MWCNT/BiVO4. X-ray powder diffraction spectroscopy (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM) and field emission transmission electron microscopy (FE-TEM) were used to observe the crystalline phase, morphological structure of MWCNT/BiVO4. The modification by MWCNTs caused changes of functional groups on the surface and a binding energy shift of Bi4f and V2p, as determined from X-ray photoelectron spectroscopy (XPS). Ultraviolet–visible diffuse reflectometry (UV–Vis DRS) revealed that the band gap became narrower and photoluminescence spectra suggested the recombination of photogenerated electron–hole pairs were inhibited after MWCNT modification. All of the characterizations showed enhancement of catalytic performance of MWCNT/BiVO4. The results from the high-performance liquid chromatography (HPLC) indicated that the degradation rate of oxytetracycline had increased by 42.2% and reached 88.7% within 60 min. Electron paramagnetic resonance (EPR) signals of ·OH and ·O2− were detected and potential photocatalytic mechanisms of the photocatalysts were put forward. Six reaction pathways were proposed based on ultra-performance liquid chromatography triple-quadrupole tandem mass spectrometry (UPLC–MS/MS) results: demethylation (−14 Da), secondary alcohol oxidation (−2 Da), dehydration (−18 Da), hydroxylation (+16 Da), decarbonylation (−28 Da) and deamination (−15 Da). The present study provides a reference for the application of photocatalytic degradation by MWCNT/BiVO4 on hard degradable substances in aquatic environment.

Comparison between humic-like peaks in excitation-emission matrix spectra and resin-fractionated humic substances in aquatic environments

The intensity of the 340/430-nm peak in the three-dimensional excitation-emission matrix spectra of water samples has been used as an index of the concentration of aquatic humic substance (AHS). However, whether this peak corresponds uniquely to AHS has not been definitively verified. Therefore, in this study, our objectives were: (1) to determine whether the 340/430-nm peak in the spectra of lake and river water samples does, in fact, correspond uniquely to AHS; (2) to determine what type of dissolved organic matter (DOM), in terms of hydrophobicity, accounts for the peak; and (3) to determine the advisability of using excitation-emission matrix spectroscopy to rapidly estimate AHS concentrations. We found that the 340/430-nm peak originates not only from the AHS fraction of DOM but also from a portion of the hydrophilic fraction. By analyzing the quantitative relationship between AHS concentration and 340/430-nm peak intensity for DOM samples, we found the intensity can be used to estimate AHS concentration in lake water when the concentration is strongly affected by influent river water or when the ratio of ultraviolet (UV) absorbance to dissolved organic carbon concentration is relatively high.

Acid Blue 161: Decolorization and Toxicity Analysis After Microbiological Treatment

Concern for the incorrect disposal of potentially toxic substances in aquatic environments is growing due to adverse effects caused to the organisms exposed to them. Synthetic azo dyes are part of this group of substances, and increasingly, researchers seek alternatives able to degrade and remove these molecules to prevent their discharge to the environment. Thus, this study sought to examine the dye removal capacity Acid Blue 161 by biosorption and biodegradation from filamentous fungi Aspergillus niger and Aspergillus terreus and perform acute toxicity tests with Lactuca sativa organisms and Artemia salina. The biossorption treatment resulted in 46 % decolorization of the solutions and reducing the toxicity of the means for both organisms tested. While the biodegradation study resulted in 84 % decolorization at the end of treatment. The resulting solution of such treatment did not show toxicity to the larvae of A. salina and the L. sativa seeds were increased by 40 % in the inhibition of root growth of seedlings. FTIR studies indicated the presence of amines in the middle, which justifies the increase in toxicity to seedlings, since these compounds are potentially toxic to a variety of organisms.

Cytogenetic Responses of Plant Root Meristematic Cells to the Arsenic (III) Contaminated Groundwater in Eastern Parts of Burdwan District, W.B., India

Both geogenic and anthropogenic activities have resulted in arsenic pollution of groundwater especially in the Eastern region of Burdwan district in West Bengal. Response of Allium cepa L. genetic material to the presence of potential cytotoxic and genotoxic substances in aquatic environment was used to evaluate the arsenic contaminated groundwater-induced genotoxicity and hormesis. For in situ monitoring of the cytotoxicity level, the inhibition of mitosis in root meristematic cells was assayed. To study genotoxicity, micronucleus assay and DNA purity assay (by A260/280 ratio) were used. Treatment for 4 days of newly developed roots of Allium cepa L. with water samples with arsenic content 50 μg L-1 exhibited stimulation in mitotic activity whereas samples with arsenic 1000 μg L-1 showed inhibition of mitotic activity apparently indicating hormesis. Inhibition of mitosis was compared with the concentration dependent increase in generation of reactive oxygen species (ROS), cell death, decrease in activity of antioxidative enzymes (catalase, superoxide dismutase), the absorbance ratio (A260/280) of DNA, or micronuclei in root cells. These findings indicated that contaminated groundwater depending on the magnitude of the arsenic concentration, might either be mitogenic or mitostatic/toxic, which in turn has obvious implications in agriculture and human health.

Adverse effects induced by ecgonine methyl ester to the zebra mussel: A comparison with the benzoylecgonine

Cocaine and its metabolites are the prevalent psychotropic substances in aquatic environment. However, to date the knowledge on their adverse effects to non-target organisms is inadequate. The aims of this study were to investigate sub-lethal effects induced by the ecgonine methyl ester (EME) to the freshwater bivalve Dreissena polymorpha and to compare its toxicity to that by benzoylecgonine (BE), the other main cocaine metabolite. EME sub-lethal effects were investigated by 14 days in-vivo exposures and a multi-biomarker approach. Slight variations in biomarker responses were found at 0.15 μg/L treatment. 0.5 μg/L EME treatment induced destabilization of lysosome membranes, an overall inactivation of defense enzymes, increases in lipid peroxidation, protein carbonylation and DNA fragmentation, but no variations in fixed genetic damage. The use of a biomarker response index (BRI) showed that at 0.5 μg/L both cocaine metabolites had the same toxicity to zebra mussels specimens.

Occurrence of antibiotics as emerging contaminant substances in aquatic environment

The occurrence of pharmaceutical residues in the environment has become a subject of growing concern. Due to the constant input of the emerging contaminants in the surface water via wastewater which leads to the long-term adverse effects on the aquatic and terrestrial organisms, special attention is being paid to their presence in the aquatic environment. Most of the emerging substances, especially pharmaceuticals, could not be completely removed using the wastewater treatment. Pharmaceuticals are usually water soluble and poorly degradable. They can pass through all natural filtrations and then reach the groundwater and, finally, the drinking water. The trace levels of antibiotics could have a negative impact on the environment and public health because of their inherent bioactivity. This article is an overview of the presence of the antibiotic residual concentrations, methods and levels of detection and possible risks to both health and environment.

Spectral Characterization of Fungal Metabolites in Aqueous Medium with Humus Substances

The work is targeted to confirm participation of microscopic fungi in transformation of humus substances in aquatic environments. The research is focused on the spectroscopic study of the collection of fungal strains with different pigmentation of mycelium. Spectral properties of fungal metabolites were measured and compared to that of natural aquatic nonliving organic matter and commercial humus substances in aqueous solutions. The experiments revealed that the effect of microscopic fungi growing in the culture medium with added humate appeared as changes in the humic-type fluorescence: its characteristics became more similar to that of nonliving organic matter in natural waters than to original humate preparation. The experiments demonstrated degradation of coal-originated humate due to microbial activity into compounds of smaller molecular size and increased heterogeneity. We resume that transformation of humus substances by fungal cultures can be monitored and characterized using spectral measurements.

Assessing acute toxicity of effluent from a textile industry and nearby river waters using sulfur‐oxidizing bacteria in continuous mode

Bioassays are becoming an important tool for assessing the toxicity of complex mixtures of substances in aquatic environments in which Daphnia magna is routinely used as a test organism. Bioassays outweigh physicochemical analyses and are valuable in the decision‐making process pertaining to the final discharge of effluents from wastewater treatment plants as they measure the total effect of the discharge which is ecologically relevant. In this study, the aquatic toxicity of a textile plant effluent and river water downstream from the plant were evaluated with sulfur‐oxidizing bacterial biosensors in continuous mode. Collected samples were analysed for different physicochemical parameters and 1,4‐dioxane was detected in the effluent. The effluent contained a relatively high chemical oxygen demand of 60 mg L−1, which exceeded the limit set by the Korean government for industrial effluent discharges. Results showed that both the effluent and river waters were toxic to sulfur‐oxidizing bacteria. These results show the importance of incorporating bioassays to detect toxicity in wastewater effluents for the sustainable management of water resources.

Substrate Utilization Profiles of Bacterial Strains in Plankton from the River Warnow, a Humic and Eutrophic River in North Germany

Bacteria are very important degraders of organic substances in aquatic environments. Despite their influential role in the carbon (and many other element) cycle(s), the specific genetic identity of active bacteria is mostly unknown, although contributing phylogenetic groups had been investigated. Moreover, the degree to which phenotypic potential (i. e., utilization of environmentally relevant carbon substrates) is related to the genomic identity of bacteria or bacterial groups is unclear. The present study compared the genomic fingerprints of 27 bacterial isolates from the humic River Warnow with their ability to utilize 14 environmentally relevant substrates. Acetate was the only substrate utilized by all bacterial strains. Only 60% of the strains respired glucose, but this substrate always stimulated the highest bacterial activity (respiration and growth). Two isolates, both closely related to the same Pseudomonas sp., also had very similar substrate utilization patterns. However, similar substrate utilization profiles commonly belonged to genetically different strains (e.g., the substrate profile of Janthinobacterium lividum OW6/RT-3 and Flavobacterium sp. OW3/15-5 differed by only three substrates). Substrate consumption was sometimes totally different for genetically related isolates. Thus, the genomic profiles of bacterial strains were not congruent with their different substrate utilization profiles. Additionally, changes in pre-incubation conditions strongly influenced substrate utilization. Therefore, it is problematic to infer substrate utilization and especially microbial dissolved organic matter transformation in aquatic systems from bacterial molecular taxonomy.

Gas–liquid chromatography–tandem mass spectrometry methodology for the quantitation of estrogenic contaminants in bile of fish exposed to wastewater treatment works effluents and from wild populations

Fish can be exposed to a complex mixture of chemical contaminants arising from the exposure to wastewater treatment works (WwTWs) effluents. Some of these contaminants are estrogenic and have been associated with feminisation of male fish and the presence of populations containing intersex individuals. However the detection of trace levels (ng/L) of estrogenic chemicals surface waters can be difficult and does not give information on the exposure of aquatic organisms to these contaminants. In this study we assessed whether the analysis of estrogenic substances that bioconcentrate in fish bile can be used to detect the exposure of fish to feminising contaminants in receiving waters and effluents, and thus facilitate their monitoring of these substances in aquatic environments. Estrogenic metabolites in bile were deconjugated using enzymatic hydrolysis and partially purified by solid phase extraction. Steroidal and xenoestrogens were derivatized to their trimethylsilyl ethers and quantified by gas–liquid chromatography–mass spectrometry (GC–MS/MS) using multiple reaction monitoring. The method was validated using spiked bile samples from immature female rainbow trout ( Oncorhynchus mykiss) as well as bile from sexually mature roach ( Rutilus rutilus) that had been exposed to either tap water or an undiluted estrogenic effluent for 10 days or captured from a river site downstream of a WwTWs effluent discharge. The mean recovery of target analytes from spiked bile was between 86 and 99% and the limit of detection was between 0.1 and 0.7 ng/mL bile for bisphenol A (BPA), 17β-estradiol (E2), estrone (E1) and 17α-ethinylestradiol (EE2), and 11, 60 and 327 ng/mL bile for branched nonyl chain isomeric mixtures of 4-nonylphenolethoxylate (NP1EO), 4-nonylphenol (NP) and 4-nonylphenoldiethoxylate (NP2EO), respectively. All target analytes were detected in bile from roach exposed directly to a WwTWs effluent, with concentrations between 6–13 μg/mL bile for NP, 18–21 μg/mL for NP1EO, 75–135 μg/mL for NP2EO, 0.7–2.5 μg/mL for BPA, E2 and E1 and 17–29 ng/mL for EE2. With the exception of NP2EO, all analytes were detected in at least 2 out of the 5 fish sampled from the River Thames. BPA and NP1EO were detected in all three reference fish held in tap water indicating possible contamination from laboratory plastics. The work shows that analysis of 20–100 μL quantities of bile could be a useful approach in detecting exposure to mixtures of estrogenic contaminants taken up by fish from WwTW effluents and has the potential for monitoring the efficacy of remediation strategies that may be adopted for reduction of these endocrine disrupting chemicals in the aquatic environment.

Distribution of antifouling substances in aquatic environment

The temporal trend of antifouling substances in aquatic environment has been clarified by measurement of the organotin compounds in water, sediment, and biological samples. The concentrations of tributyltin (TBT) compounds in water and mussels decreased dramatically after regulation, and no changes of TBT concentrations were then observed. TBTs in fish also decreased moderately, Whereas no changes of TBTs were observed in sediment. Although triphenyltin (TPT) compounds in water, sediment, and biological samples decreased after regulation, TPTs were still detected in fish. The partition coefficients of organotin compounds for water and sediment or biological samples ranged from 103 to 105. The concentrations of Sea-Nine 211, Diuron, Irgarol 1051, pyrithions, and M1 were measured in an aquatic environment for 2 years. Higher concentrations of Diuron and Irgarol 1051 occurred in the summer season. The concentrations of Sea-Nine 211, Diuron, and Irgarol 1051 in sediment increased during the observation period. The partition coefficients of Sea-Nine 211, Diuron and Irgarol 1051 for water and sediment ranged of 102-103.

Suspended Particles: Their Role in Estuarine Biogeochemical Cycles

Suspended particles are instrumental in controlling the reactivity, transport and biological impacts of substances in aquatic environments, and provide a crucial link for chemical constituents between the water column, bed sediment and food chain. This article reviews the role of suspended particles in the chemical and biological cycling of trace constituents (trace metals, organo-metallic compounds and hydrophobic organic micropollutants; HOMs) in estuaries, with particular emphasis on the effects of and changes to particle reactivity and composition.The partitioning (or distribution coefficient,KD ) and bioavailability of chemical constituents, and assimilation efficiency (AE) of such by bivalve suspension feeders, are identified as key parameters requiring definition for accurate biogeochemical modelling, and the discussion centres around the determination of and controls on these parameters. Particle-water interactions encompass a variety of physical, biological, electrostatic and hydrophobic effects, and are largely dependent on the character and concentration of suspended particles and salinity. The salinity-dependence results from the competing and complexing effects of seawater ions for trace metals, and the compression of water in the presence of dissolved seawater ions and consequent salting out of neutral solute (HOMs, organo-metallic compounds and some trace metal complexes). The extent of biological solubilization of chemical constituents from suspended particles is dependent on the nature of chemical components of the gastro-intestinal environment and their interactions with ingested particles, and the physiological (e.g. gut passage time) and chemical (e.g. redox conditions and pH) constraints imposed on these interactions. Generally, chemicals that associate with fine, organic-rich particles (or, for some HOMs, fine inorganic particles), and desorb at pH 5–6 and/or complex with digestive enzymes or surfactants are most readily solubilized in the gut. The extent of assimilation of solubilized chemical is then determined by its ability to pass the gut lining and partition into cytosolic material.In practice, KD and AE are determined experimentally by means of radiotracers added to contained suspensions or mesocosms, while operational measurement of bioavailability relies on in vitro chemical or biological (enzymatic) extraction of particles. What is lacking, however, and is identified as an ultimate goal of future research, is the ability to predict these parameters from theoretical principles and thermodynamic constants. Since many of the inherent interactions and mechanisms are controlled by particle composition and reactivity, a more immediate objective would be better characterization of the biogeochemical properties of suspended particles themselves. This includes chemical resolution of the bulk organic matter, definition of the abundance and synergistic effects of component sorbent phases, and determination of the effects of particle-seawater ion interactions on the reactivity of the particle surface.