Steroid hormones in the aquatic environment.

Steroid hormones are extremely important natural hormones in all vertebrates. They control a wide range of physiological processes, including osmoregulation, sexual maturity, reproduction and stress responses. In addition, many synthetic steroid hormones are in widespread and general use, both as human and veterinary pharmaceuticals. Recent advances in environmental analytical chemistry have enabled concentrations of steroid hormones in rivers to be determined. Many different steroid hormones, both natural and synthetic, including transformation products, have been identified and quantified, demonstrating that they are widespread aquatic contaminants. Laboratory ecotoxicology experiments, mainly conducted with fish, but also amphibians, have shown that some steroid hormones, both natural and synthetic, can adversely affect reproduction when present in the water at extremely low concentrations: even sub-ng/L. Recent research has demonstrated that mixtures of different steroid hormones can inhibit reproduction even when each individual hormone is present at a concentration below which it would not invoke a measurable effect on its own. Limited field studies have supported the conclusions of the laboratory studies that steroid hormones may be environmental pollutants of significant concern. Further research is required to identify the main sources of steroid hormones entering the aquatic environment, better describe the complex mixtures of steroid hormones now known to be ubiquitously present, and determine the impacts of environmentally-realistic mixtures of steroid hormones on aquatic vertebrates, especially fish. Only once that research is completed can a robust aquatic risk assessment of steroid hormones be concluded.

The effect of wastewater effluent derived ligands on copper and zinc complexation.

The shift toward bioavailability-based standards for metals such as copper and zinc not only improves the ecological relevance of the standard but also introduces significant complexity into assessing compliance. This study examined differences in the copper and zinc complexation characteristics of effluents from a range of different sewage treatment works and in relation to so-called 'natural' samples. This information is essential to determine whether the inclusion of effluent-specific complexation characteristics within the regulatory framework could enhance the environmental relevance of compliance criteria. The data show that for copper, binding affinity was not greater than that measured for materials derived from the receiving water environment, with a mean log K of between 4.4 and 5.15 and mean complexation capacity ranging from 38 to 120 µg/mg dissolved organic carbon (DOC) for effluents compared with a log K of 5.6 and complexation capacity of 37 µg/mg DOC for the Suwannee River fulvic acid. For zinc, however, effluents exhibited a much higher complexation capacity, with effluent means ranging from 3 to 23 µg/mg DOC compared with the Suwannee River fulvic acid, for which the complexation capacity could not be determined. Synthetic ligands in sewage effluent, such as ethylenediaminetetraacetic acid (EDTA), are implicated as contributing to these observed differences. This suggests that the current biotic ligand models for zinc might overstate the risk of harm in effluent-impacted waters. The data also show that the copper and zinc complexation characteristics of effluent samples obtained from the same sewage treatment works were less different from one another than those of effluents from other treatment works and therefore that sewage source has an important influence on complexation characteristics. The findings from this study support the case that the contribution to complexation from effluent-derived ligands could enhance the environmental relevance of bioavailability-based compliance criteria, in particular for zinc, owing to the additional complexation capacity afforded by effluent-derived ligands.

The impact of tertiary wastewater treatment on copper and zinc complexation.

Tightening quality standards for European waters has seen a move towards enhanced wastewater treatment technologies such as granulated organic carbon treatment and ozonation. Although these technologies are likely to be successful in degrading certain micro-organic contaminants, these may also destroy compounds which would otherwise complex and render metals significantly less toxic. This study examined the impact of enhanced tertiary treatment on the capacity of organic compounds within sewage effluents to complex copper and zinc. The data show that granulated organic carbon treatment removes a dissolved organic carbon (DOC) fraction that is unimportant to complexation such that no detrimental impact on complexation or metal bioavailability is likely to occur from this treatment type. High concentrations of ozone (>1 mg O3/mg DOC) are, however, likely to impact the complexation capacity for copper although this is unlikely to be important at the concentrations of copper typically found in effluent discharges or in rivers. Ozone treatment did not affect zinc complexation capacity. The complexation profiles of the sewage effluents show these to contain a category of non-humic ligand that appears unaffected by tertiary treatment and which displays a high affinity for zinc, suggesting these may substantially reduce the bioavailability of zinc in effluent discharges. The implication is that traditional metal bioavailability assessment approaches such as the biotic ligand model may overestimate zinc bioavailability in sewage effluents and effluent-impacted waters.

The effectiveness of anaerobic digestion in removing estrogens and nonylphenol ethoxylates.

The fate and behaviour of two groups of endocrine disrupting chemicals, steroid estrogens and nonylphenol ethoxylates, have been evaluated during the anaerobic digestion of primary and mixed sewage sludge under mesophilic and thermophilic conditions. Digestion occurred over six retention times, in laboratory scale reactors, treating sludges collected from a sewage treatment works in the United Kingdom. It has been established that sludge concentrations of both groups of compounds demonstrated temporal variations and that concentrations in mixed sludge were influenced by the presence of waste activated sludge as a result of transformations during aerobic treatment. The biodegradation of total steroid estrogens was >50% during primary sludge digestion with lower removals observed for mixed sludge, which reflected bulk organic solids removal efficiencies. The removal of nonylphenol ethoxylates was greater in mixed sludge digestion (>58%) compared with primary sludge digestion and did not reflect bulk organic removal efficiencies. It is apparent that anaerobic digestion reduces the concentrations of these compounds, and would therefore be expected to confer a degree of protection against exposure and transfer of both groups of compounds to the receiving/re-use environment.

The pharmaceutical use of permethrin: sources and behavior during municipal sewage treatment.

Permethrin entered use in the 1970s as an insecticide in a wide range of applications, including agriculture, horticultural, and forestry, and has since been restricted. In the 21st century, the presence of permethrin in the aquatic environment has been attributed to its use as a human and veterinary pharmaceutical, in particular as a pedeculicide, in addition to other uses, such as a moth-proofing agent. However, as a consequence of its toxicity to fish, sources of permethrin and its fate and behavior during wastewater treatment are topics of concern. This study has established that high overall removal of permethrin (approximately 90%) was achieved during wastewater treatment and that this was strongly dependent on the extent of biological degradation in secondary treatment, with more limited subsequent removal in tertiary treatment processes. Sources of permethrin in the catchment matched well with measured values in crude sewage and indicated that domestic use accounted for more than half of the load to the treatment works. However, removal may not be consistent enough to achieve the environmental quality standards now being derived in many countries even where tertiary treatment processes are applied.

The significance of sample mass in the analysis of steroid estrogens in sewage sludges and the derivation of partition coefficients in wastewaters.

Optimization of an analytical method for determination of steroid estrogens, through minimizing sample size, resulted in recoveries >84%, with relative standard deviations <3% and demonstrated the significance of sample size on method performance. Limits of detection were 2.1-5.3 ng/g. Primary sludges had estrogen concentrations of up to one order of magnitude less than those found in biological sludges (up to 994 ng/g). However, partition coefficients were higher in primary sludges (except estriol), with the most hydrophobic compound (ethinylestradiol) exhibiting the highest Kp value, information which may be of value to those involved in modeling removal during wastewater treatment.

Treatment and removal strategies for estrogens from wastewater.

Natural and synthetic steroidal estrogens (estrone, 17beta-estradiol and 17alpha-ethinylestradiol) are endocrine disrupters, that are discharged consistently from the sewage treatment works into surface waters, thereby causing endocrine disrupting effects to aquatic organisms at trace concentrations (nanogram per litre). Several years of research have been focused on their fate, behaviour and removal in the environment but primarily in the sewage treatment works which acts as a sink for these compounds. This review attempts to summarize the factors involved in the removal of these chemicals from the sewage treatment works. Biological processes, and to a limited extent physio-chemical properties, play a vital role in the endocrinal deactivation of these compounds. The efficiency of these processes is highly dependent on operating parameters (such as sludge retention time, redox potential, etc) that govern the secondary treatment process of a functional sewage treatment works. Although advanced treatment technologies are available, cost and operational considerations do not make them a sustainable solution.

Determination of steroid estrogens in wastewater by high performance liquid chromatography-tandem mass spectrometry.

This paper discusses the requirement for, and presents an analytical procedure for, the determination of four steroid hormones and a conjugated steroid (estrone-3-sulfate) in wastewaters. The method utilizes LC/MS/MS following solid phase extraction and a two stage clean-up procedure, achieving limits of detection of 0.2 ng l(-1) for estriol, 17beta-estradiol and 17 alpha-ethinylestradiol, and 0.1 ng l(-1) for estrone and the conjugate. The approach demonstrates that using appropriate clean-up and deuterated internal standards, the impact of matrix effects on ionization can be overcome to reliably determine estrogens at environmentally relevant concentrations. The robustness of the method was demonstrated by achieving recoveries of >83% for all steroids in settled sewage and final effluent samples with relative standard deviations of 0.5-12%.

Butyltin compounds in a sediment core from the old Tilbury basin, London, UK.

Sections from a sediment core taken from the River Thames were analysed for butyltin species using gas chromatography with species-specific isotope dilution mass spectrometry. Results demonstrated that in most samples tributyltin concentrations of 20-60 ng/g accounted for <10% of the total butyltin species present, which is in agreement with data from other sediment samples which were historically contaminated with tributyltin. Vertical distribution of the organotin residues with depth throughout the core, with data on organochlorine compounds and heavy metals allowed for the construction of a consistent hypothesis on historical deposition of contaminated sediments. From this it was possible to infer that the concentrations of tributyltin in sediments deposited during the early 1960s were in the order of 400-600 microg/g by using degradation rate constants derived by other workers. Such values fall well within the range quoted for harbour sediments in the literature.

Removal of struvite to prevent problems associated with its accumulation in wastewater treatment works.

Deposition of struvite within the infrastructure of wastewater treatment works can cause significant operating difficulties. A laboratory-scale, two-stage, continuously stirred tank reactor was developed to remove struvite to prevent problems associated with its deposition. Before any experimental work was conducted, the mixing regime within the system was determined using a pH-tracer response method. Perfect mixing conditions were achieved once the stirring speed reached 500 rpm. Experiments were conducted examining the effects of various process parameters such as retention time, pH, recycling rate, and ammonium concentration. By increasing the hydraulic retention time, the residual magnesium concentration decreased, with the optimum conditions occurring at 125 minutes.

Analytical methods for the determination of alkylphenolic surfactants and polybrominated diphenyl ethers in wastewaters and sewage sludges. II method development.

Analytical methods for the determination of two groups of compounds, the non-polar alkyl phenols along with their more polar ethoxylates, and the hydrophobic polybrominated flame retardants in wastewater samples have been developed. The methods allow for determination of the analytes in both the aqueous and solid phases, which were separated by centrifugation and filtration. Extraction from the aqueous phase involved the use of SPE for the surfactants, however, liquid-liquid extraction was found to be more efficient for the PBDE. Alkyl phenols and their ethoxylates were extracted from the solid phase by shaking with solvent and Soxhlet was used for extraction of PBDE. Sample cleanup was based on alumina columns for the PBDE and surfactants when extracted form solids. Quantification of surfactants utilised LC-MS with ESI in both positive and negative ionisation mode, and GC-MS (NCI) was used to determine the PBDE, with the exception of the deca congener, where a 10 m column installed on GC-ECD resulted in short run times and reduced thermal decomposition. Method recoveries for the surfactants were above 80%, and for PBDE 92.5% from the solid phase and 95+/-5% from the liquid phase.

Analytical methods for the determination of alkylphenolic surfactants and polybrominated diphenyl ethers in wastewaters and sewage sludges. I a review of methodologies.

Alkylphenolic surfactants (alkylphenol polyethoxylates) and the polybrominated diphenyl ether flame retardants are important environmental contaminants and have been implicated as endocrine disrupters. Both groups of compounds have come under increasing scrutiny from legislators and there are proposals to curb their use. However, these compounds continue to enter the environment and there is a need to determine their occurrence, fate and behaviour throughout the hydrosphere and in wastewater treatment processes to determine mass fluxes and sources. This paper reviews analytical methods for their determination in the aqueous and solid (sediment / sludge) phase. Extraction, cleanup and quantification by gas and liquid chromatographic (GC and LC) techniques linked to mass spectrometric (MS) detectors are considered. The literature indicates that for the alkylphenols research papers favour the use of LC/MS which is more amenable to determination of more highly ethoxylated oligomers, however, standard methods focus on GC/MS and the less ethoxylated oligomers and parent alkylphenols. The use of GC with negative chemical ionisation MS techniques predominates for the analysis of polybrominated diphenyl ethers.

Removal of organotins during sewage treatment: a case study.

Discharge consents for tributyltin (TBT) from wastewater treatment works in the UK are set by the Environment Agency. These values are normally derived from the Environmental Quality Standards for concentrations of TBT in the receiving water, based on the volume of effluent discharged and subsequent dilution within the environment. In this study, a sampling program was designed to monitor concentrations of TBT (and other organotins) in the influent and effluent at each stage of treatment. Sampling was undertaken at 3 hourly intervals, over 24 hours, at 8 locations throughout the works for five days. Organotin concentrations were determined using capillary gas chromatography with flame photometric detection. The results demonstrated that TBT was consistently present in the influent at concentrations of approximately 0.1 microg l(-1). However, a "pulse" of TBT and monobutyltin (MBT) was observed on the third day when the concentration of TBT and MBT in the influent increased to 14 microg l(-1). This "pulse" of TBT and MBT was also observed as the wastewater passed through the unit treatment processes. Concentrations of both compounds were much reduced in the final effluent (TBT 2.5 microg l(-1) and MBT 6.9 microg l(-1)). Over the entire period, the average removal of TBT during primary treatment was 81%, and during secondary biological treatment was 71%. The overall removal efficiency of the plant, taking into account the recycling of returned liquors was 86% between influent and effluent for TBT. Removal efficiency of TBT was correlated to that of suspended solids, and it was demonstrated that on days when suspended solids removal was low, TBT removal was also reduced. The mass flow of organotins through the plant indicated that the majority of TBT was concentrated into the sewage sludge. Concentrations of TBT in sludge at the plant were approximately 18 microg kg(-1) (dry weight).

Quantifying uncertainties in the assessment of sediment quality: statistical criteria and guidelines for sediment quality assessments.

Current sediment quality guidelines generally adopt a tiered approach in order to assess sediment quality more cost-effectively. The uncertainties involved in the tiered approach of an integrative assessment, however have not been quantified resulting in a risk of committing type I error or type II error at the final confirmatory stage. This study develops statistical criteria and guidelines for the sediment chemistry component of an integrative assessment of sediment quality. At the tier 1 screening stage, historical data or an initial survey is required to determine the minimum sample numbers that will be required to be representative of the study site. Understanding the guiding principles which have underpinned the setting of sediment quality criteria for contaminant is an important factor in tier 1 evaluations. To reduce cost and uncertainty in data, sampling should include the least number of samples necessary to minimise uncertainties by estimating the probability distribution function (which represents the variability of the natural environment at the location of concern), with subsequent application of kriging and sequential simulation methods on data obtained. Implementation of statistical criteria and guidelines in sediment quality assessments can provide a foundation for a further quantitative cost/benefit analysis and decrease the risk of committing type I and type II statistical errors at later classification stages.

Public perceptions and attitudes towards an established managed realignment scheme: Orplands, Essex, UK.

Where appropriate, managed realignment is the preferred policy option for sustainable coastal defences in the UK, since it provides both economic and ecological advantages. Until recently however, research has failed to address the social implications of this policy option having only acknowledged that communities in general, show reluctance in conceding land to the sea. Orplands managed realignment scheme is the third in a series of case studies to address a variety of social issues, but with a particular focus on the public acceptance of schemes and public confidence in the Environment Agency. It is hypothesised that local residents will be more accepting of a realignment scheme the longer it is in the public domain, rather than at its inception or construction. This paper presents findings from the Orplands scheme and demonstrates that overall scheme acceptance was greater at this site in comparison to previous case studies. Despite this, respondents did not show any more confidence in the Environment Agency and this has been attributed to their general scepticism towards a statutory body and the lack of recent contact between the various stakeholders. It is suggested that the development of criteria for consultation and public participation would facilitate public acceptance of managed realignment schemes.

Prediction of the bioaccumulation factors and body burden of natural and synthetic estrogens in aquatic organisms in the river systems.

This study undertakes an initial prediction of the bioaccumulation factors and body burden of the steroid estrogens, estrone, estradiol, estriol and ethinylestradiol in a range of aquatic organisms (plankton, benthic and free-living invertebrates and fish) in river systems using a food-web model. These data are compared to that derived from less complex predictions based on octanol-water partition coefficient and molecular connectivity index. The model predicted that bioaccumulation of steroid estrogens occurred in all organisms, however, the values were small, and the maximum and minimum bioaccumulation factors in this study were found in the fish at the lowest trophic level with ethinylestradiol (332) and the fish at the highest trophic level with estriol (1.8), respectively. Moreover, the bioaccumulation factors were sensitive to the metabolic rates of the estrogens in the free living organisms, while the concentration of estrogens in sediment was a significant factor in determining these values in benthic invertebrates. Biomagnification contributed little to the overall bioaccumulation, but the importance increased in fish exposed to ethinylestradiol. The predicted bioaccumulation factors from the food web model were generally smaller than the calculated bioconcentration factors from the simpler octanol-water partition coefficient/molecular connectivity index based estimates. Compared to literature measured data, the predicted values for fish were approximately 1000 times less than the values observed in laboratory tests, while for invertebrates, the modeled values were less than two orders of magnitude below laboratory results. However, the model predicted a similar bioconcentration factor for plankton in relation to experimental data for Chlorella vulgaris for estrone and estriol.

The effects of natural and synthetic steroid estrogens in relation to their environmental occurrence.

Laboratory-based acute toxicity data and physiological studies relating to natural and synthetic steroid estrogens in a range of animals and plants are reviewed. Steroid estrogens may induce adverse effects in animals that do or do not express the estrogen receptor, and in plants, and they may mimic other hormones or induce nonestrogenic effects. Although the findings of such studies should be treated with caution when extrapolated to possible environmental effects, the available data indicate that a wide range of effects may be manifested in a diversity of species. The environmental occurrence of the compounds and possible environmental exposure routes are also reviewed and discussed in relation to the laboratory-based acute toxicity data. While there are likely to be difficulties in relating some of the observed laboratory data to possible environmental effects, studies undertaken on fish are directly relevant because exposure pathways and concentrations were related to those occurring in the environment. Effects that may occur in the environment are discussed in relation to their significance to the individual and at the species level.

Biotransformation and bioconcentration of steroid estrogens by Chlorella vulgaris.

The biotransformation and bioconcentration of natural and synthetic steroid estrogens by Chlorella vulgaris were investigated by using batch-shaking experiments with incubation for 48 h in the light or dark. Estradiol and estrone were interconvertible in both light and dark conditions; however, this biotransformation showed a preference for estrone. In the light, 50% estradiol was further metabolized to an unknown product. Apart from biotransformation, estrone, as well as hydroxyestrone, estriol, and ethinylestradiol, was relatively stable in the algal culture, whereas estradiol valerate was hydrolyzed to estradiol and then to estrone within 3 h of incubation. All of the tested estrogens exhibited a degree of partitioning to C. vulgaris; however, the concentrations of estriol, hydroxyestrone, ethinylestradiol, and estradiol valerate were always below the quantification limits. For estradiol and estrone, the partitioning of these estrogens in the algal extracts to the filtrates was <6% of the total amount present. The average concentration factor for estrone was ca. 27; however, the concentration factor for estradiol was not reported since no equilibrium was reached between the aqueous solution and that within the cells due to continuing biotransformation.

Partitioning of selected antifouling biocides in the aquatic environment.

Following a ban on the use of tributyltin in antifouling products on small boats, a number of organic booster biocides have been utilised in conjunction with copper in antifouling paints as alternative treatments. The fate of organic compounds in the aquatic environment is closely linked to their partitioning between aqueous media and sediment. In this study, experiments were designed to investigate the partitioning and sorptive behaviour of Irgarol 1051, chlorothalonil, dichlofluanid and diuron in the aquatic environment. Factorial experiments were undertaken to determine the importance of pH, particulate matter concentration and salinity to their sorption. A Mackay fugacity model was also applied. Results demonstrated that dichlofluanid had the stronger adsorption characteristics and was predicted to bind more strongly to sediments than Irgarol or chlorothalonil. Diuron exhibited the least preference for sorptive behaviour. Sorption appeared to be enhanced by increased suspended matter, whilst salinity does not seem to play a significant role in the partitioning behaviour of these biocides.