Bioassay-directed chemical analysis of River Elbe surface water including large volume extractions and high performance fractionation

Comparative evaluation of SPE methods for biotoxicity assessment of water and wastewater: Linkage between chemical extracting efficiency and biotoxicity outcome

Biotoxicity assessment results of environmental waters largely depend on the sample extraction protocols that enrich pollutants to meet the effect-trigger thresholds of bioassays. However, more chemical mixture does not necessarily translate to higher combined biotoxicity. Thus, there is a need to establish the link between chemical extracting efficiency and biotoxicity outcome to standardize extraction methods for biotoxicity assessment of environmental waters. This study compares the performance of five different extraction phases in solid phase extraction (SPE), namely HLB, HLB+Coconut, C18 cartridge, C18 disk and Strata-X, and evaluated their chemical extracting efficiencies and biotoxicity outcomes. We quantitatively assessed cytotoxicity, acute toxicity, genotoxicity, estrogenic activity, and neurotoxicity of the extracts using in vitro bioassays and characterized the chemical extracting efficiencies of the SPE methods through chemical recoveries of 23 model compounds with different polarities and total organic carbon. Using Pareto ranking, we identified HLB+Coconut as the optimal SPE method, which exhibited the highest level of water sample biotoxicity and recovered the most chemicals in water samples. We found that the biotoxicity outcomes of the extracted water samples significantly and positively correlated with the chemical extracting efficiencies of the SPE methods. Moreover, we observed synchronous changing patterns in biotoxicity outcome and chemical extracting efficiencies in response to increasing sample volumes per cartridge (SVPC) during SPE. Our findings underscore that higher chemical extracting efficiency of SPE corresponds to higher biotoxicity outcome of environmental water samples, providing a scientific basis for standardization of SPE methods for adequate assessment of biotoxicities of environmental waters.

Neurotoxicity in complex environmental mixtures-a case-study at River Danube in Novi Sad (Serbia) using zebrafish embryos

Acetylcholinesterase (AChE) inhibitors are an important class of neuroactive chemicals that are often detected in aquatic and terrestrial environments. The correct functionality of the AChE enzyme is linked to many important physiological processes such as locomotion and respiration. Consequently, it is necessary to develop new analytical strategies to identify harmful AChE inhibitors in the environment. It has been shown that mixture effects and oxidative stress may jeopardize the application of in vivo assays for the identification of AChE inhibitors in the environment. To confirm that in vivo AChE assays can be successfully applied when dealing with complex mixtures, an extract from river water impacted by non-treated wastewater was bio-tested using the acute toxicity fish embryo test (FET) and AChE inhibition assay with zebrafish. The zebrafish FET showed high sensitivity for the extract (LC10 = relative extraction factor 2.8) and we observed a significant inhibition of the AChE (40%, p < 0.01) after 4-day exposure. Furthermore, the extract was chromatographically fractionated into a total of 26 fractions to dilute the mixture effect and separate compounds according to their physico-chemical properties. As expected, non-specific acute effects (i.e., mortality) disappeared or evenly spread among the fractions, while AChE inhibition was still detected in five fractions. Chemical analysis did not detect any known AChE inhibitors in these active fractions. These results confirm that the AChE assay with Danio rerio can be applied for the detection of neuroactive effects induced in complex environmental samples, but also, they highlight the need to increase analytical and identification techniques for the detection of neurotoxic substances.

Bioassay guided analysis coupled with non-target chemical screening in polyethylene plastic shopping bag fragments after exposure to simulated gastric juice of Fish

In this study, fragments of polyethylene plastic bags were treated with simulated gastric juice of fish for 16 h. Following solid-phase extraction, methanol eluents caused acute toxicity to embryos and larvae of Japanese medaka. Chromatographic fractions (polar to more non-polar with numbers increasing) of the extract were evaluated for toxicity and estrogenic activity using medaka and an estrogen receptor (ER) cell-line. Fractions 6 and 9 had the highest estrogenic effects with relative hydrophobic chemicals. The vtg expression in fraction 6 was 22-fold higher than control, and the ER cellular response in fraction 9 was 8.5-fold higher than controls. Following non-target screening (NTS), several novel phthalates and phenols were identified in the above two fractions. Fractions 1 and 2 appeared to be primarily responsible for the acute toxicity observed with the whole extract. The hatching rate decreased to 36 % in fraction 2, and was not observed following exposure to fraction 1. NTS of these fractions indicated 635 and 808 entities, respectively, most without toxicity information. These results indicate plastic leachates from gastric juices of fish are complex mixtures of many compounds that can have acute reproductive and sublethal endocrine impacts in fish.

Factors Affecting Sampling Strategies for Design of an Effects-Directed Analysis for Endocrine-Active Chemicals

Effects-directed analysis (EDA) is an important tool for identifying unknown bioactive components in a complex mixture. Such an analysis of endocrine-active chemicals (EACs) from water sources has promising regulatory implications but also unique logistical challenges. We propose a conceptual EDA (framework) based on a critical review of EDA literature and concentrations of common EACs in waste and surface waters. Required water volumes for identification of EACs under this EDA framework were estimated based on bioassay performance (in vitro and in vivo bioassays), limits of quantification by mass spectrometry (MS), and EAC water concentrations. Sample volumes for EDA across the EACs showed high variation in the bioassay detectors, with genistein, bisphenol A, and androstenedione requiring very high sample volumes and ethinylestradiol and 17β-trenbolone requiring low sample volumes. Sample volume based on the MS detector was far less variable across the EACs. The EDA framework equation was rearranged to calculate detector "thresholds," and these thresholds were compared with the literature EAC water concentrations to evaluate the feasibility of the EDA framework. In the majority of instances, feasibility of the EDA was limited by the bioassay, not MS detection. Mixed model analysis showed that the volumes required for a successful EDA were affected by the potentially responsible EAC, detection methods, and the water source type, with detection method having the greatest effect on the EDA of estrogens and androgens. The EDA framework, equation, and model we present provide a valuable tool for designing a successful EDA. Environ Toxicol Chem 2020;39:1309-1324. © 2020 SETAC.

Solid-phase extraction as sample preparation of water samples for cell-based and other in vitro bioassays

In vitro bioassays are increasingly used for water quality monitoring. Surface water samples often need to be enriched to observe an effect and solid-phase extraction (SPE) is commonly applied for this purpose. The applied methods are typically optimised for the recovery of target chemicals and not for effect recovery for bioassays. A review of the few studies that have evaluated SPE recovery for bioassays showed a lack of experimentally determined recoveries. Therefore, we systematically measured effect recovery of a mixture of 579 organic chemicals covering a wide range of physicochemical properties that were spiked into a pristine water sample and extracted using large volume solid-phase extraction (LVSPE). Assays indicative of activation of xenobiotic metabolism, hormone receptor-mediated effects and adaptive stress responses were applied, with non-specific effects determined through cytotoxicity measurements. Overall, effect recovery was found to be similar to chemical recovery for the majority of bioassays and LVSPE blanks had no effect. Multi-layer SPE exhibited greater recovery of spiked chemicals compared to LVSPE, but the blanks triggered cytotoxicity at high enrichment. Chemical recovery data together with single chemical effect data were used to retrospectively estimate with reverse recovery modelling that there was typically less than 30% effect loss expected due to reduced SPE recovery in published surface water monitoring studies. The combination of targeted experiments and mixture modelling clearly shows the utility of SPE as a sample preparation method for surface water samples, but also emphasizes the need for adequate controls when extraction methods are adapted from chemical analysis workflows.

Assessment of a novel device for onsite integrative large-volume solid phase extraction of water samples to enable a comprehensive chemical and effect-based analysis

The implementation of targeted and nontargeted chemical screening analysis in combination with in vitro and organism-level bioassays is a prerequisite for a more holistic monitoring of water quality in the future. For chemical analysis, little or no sample enrichment is often sufficient, while bioanalysis often requires larger sample volumes at a certain enrichment factor for conducting comprehensive bioassays on different endpoints or further effect-directed analysis (EDA). To avoid logistic and technical issues related to the storage and transport of large volumes of water, sampling would benefit greatly from onsite extraction. This study presents a novel onsite large volume solid phase extraction (LVSPE) device tailored to fulfill the requirements for the successful effect-based and chemical screening of water resources and complies with available international standards for automated sampling devices. Laboratory recovery experiments using 251 organic compounds in the log D range from -3.6 to 9.4 (at pH7.0) spiked into pristine water resulted in acceptable recoveries and from 60 to 123% for 159 out of 251 substances. Within a European-wide demonstration program, the LVSPE was able to enrich compounds in concentration ranges over three orders of magnitude (1ngL^-1 to 2400ngL^-1). It was possible to discriminate responsive samples from samples with no or only low effects in a set of six different bioassays (i.e. acetylcholinesterase and algal growth inhibition, androgenicity, estrogenicity, fish embryo toxicity, glucocorticoid activity). The LVSPE thus proved applicable for onsite extraction of sufficient amounts of water to investigate water quality thoroughly by means of chemical analysis and effect-based tools without the common limitations due to small sample volumes.

Effect-directed analysis supporting monitoring of aquatic environments--An in-depth overview

Aquatic environments are often contaminated with complex mixtures of chemicals that may pose a risk to ecosystems and human health. This contamination cannot be addressed with target analysis alone but tools are required to reduce this complexity and identify those chemicals that might cause adverse effects. Effect-directed analysis (EDA) is designed to meet this challenge and faces increasing interest in water and sediment quality monitoring. Thus, the present paper summarizes current experience with the EDA approach and the tools required, and provides practical advice on their application. The paper highlights the need for proper problem formulation and gives general advice for study design. As the EDA approach is directed by toxicity, basic principles for the selection of bioassays are given as well as a comprehensive compilation of appropriate assays, including their strengths and weaknesses. A specific focus is given to strategies for sampling, extraction and bioassay dosing since they strongly impact prioritization of toxicants in EDA. Reduction of sample complexity mainly relies on fractionation procedures, which are discussed in this paper, including quality assurance and quality control. Automated combinations of fractionation, biotesting and chemical analysis using so-called hyphenated tools can enhance the throughput and might reduce the risk of artifacts in laboratory work. The key to determining the chemical structures causing effects is analytical toxicant identification. The latest approaches, tools, software and databases for target-, suspect and non-target screening as well as unknown identification are discussed together with analytical and toxicological confirmation approaches. A better understanding of optimal use and combination of EDA tools will help to design efficient and successful toxicant identification studies in the context of quality monitoring in multiply stressed environments.

Determination of estrogens and estrogenic activities in water from three rivers in Tianjin, China

Studies on estrogenic disrupting compounds (EDCs) occurrence and identification of main responsible compounds in river water discharged into the sea are of significance. In the present research, we screened estrogenic activities of 10 river water samples from 3 main rivers discharged into Bohai Sea in Tianjin using a recombinant two-hybrid yeast assay and chemical analysis by gas chromatography-mass spectrometry. All sample extracts induced significant estrogenic activity, with 17beta-estradiol equivalents (EEQ) of raw water ranging from 5.72 to 59.06 ng/L. Six most concerned EDCs in the river water samples including estrone, 17beta-estradiol, 17alpha-ethinylestradiol, estriol, diethylstilbestrol and estradiol valerate were determined, with their concentrations up to 50.70, 31.40, 24.40, 37.20, 2.56, and 8.47 ng/L, respectively. Through causality analysis by comparing the EEQ values of yeast assay and chemical analysis, 17alpha-ethinylestradiol and 17beta-estradiol were identified as the main contributors to the estrogenic effects of the river samples, accounting for the whole estrogenic activities (62.99% to 185.66%), and estrogen antagonistic compounds might presented in the heavy polluted water samples. The proposed approach using both chemical analysis and bioassay could be used for identification and evaluation of the estrogenic activity of EDCs in river water.

Characterization of chars produced in the co-pyrolysis of different wastes: decontamination study

The present work is devoted to the study of the decontamination of chars obtained in the co-pyrolysis of plastics, biomass and tyre wastes. The chars were extracted with several organic solvents of different polarities either individually or in sequence. The ability of each selected extractant to remove toxic pollutants was evaluated by comparing the extraction yields and by characterizing the crude extracts with a combination of chemical analysis and toxicity bioassays. Also, the mineral composition of the treated and non-treated chars was assessed. The results obtained in this study indicate that hexane is the more efficient extraction solvent to be used in the organic decontamination of chars obtained in the co-pyrolysis of plastics, tyres and biomass. A sequential extraction with solvents of increasing polarity can provide a better decontamination of the raw pyrolysis char than any individual extraction. The compounds removed from the char during the decontamination process are mainly aliphatic hydrocarbons and aromatic hydrocarbons, therefore a material that may be upgraded to be used as a fuel and/or as raw material for the organic chemical industry.

Assessment of source water contamination by estrogenic disrupting compounds in China

Detection of estrogenic disrupting compounds (EDCs) in drinking waters around China has led to rising concerns about health risks associated with these compounds. There is, however, a paucity of studies on the occurrence and identification of the main compounds responsible for this pollution in the source waters. To fill this void, we screened estrogenic activities of 23 source water samples from six main river systems in China, using a recombinant two-hybrid yeast assay. All sample extracts induced significant estrogenic activity, with E2 equivalents (EEQ) of raw water ranging from 0.08 to 2.40 ng/L. Additionally, 16 samples were selected for chemical analysis by gas chromatography-mass spectrometry. The EDCs of most concern, including estrone (E1), 17beta-estradiol (E2), 17alpha-ethinylestradiol (EE2), estriol (E3), diethylstilbestrol (DES), estradiol valerate (EV), 4-t-octylphenol (4-t-OP), 4-nonylphenols (4-NP) and bisphenol A (BPA), were determined at concentrations of up to 2.98, 1.07, 2.67, 4.37, 2.52, 1.96, 89.52, 280.19 and 710.65 ng/L, respectively. Causality analysis, involving comparison of EEQ values from yeast assay and chemical analysis identified E2, EE2 and 4-NP as the main responsible compounds, accounting for the whole estrogenic activities (39.74% to 96.68%). The proposed approach using both chemical analysis and yeast assay could be used for the identification and evaluation of EDCs in source waters of China.

Advances in mass spectrometry-based post-column bioaffinity profiling of mixtures

In the screening of complex mixtures, for example combinatorial libraries, natural extracts, and metabolic incubations, different approaches are used for integrated bioaffinity screening. Four major strategies can be used for screening of bioactive mixtures for protein targets-pre-column and post-column off-line, at-line, and on-line strategies. The focus of this review is on recent developments in post-column on-line screening, and the role of mass spectrometry (MS) in these systems. On-line screening systems integrate separation sciences, mass spectrometry, and biochemical methodology, enabling screening for active compounds in complex mixtures. There are three main variants of on-line MS based bioassays: the mass spectrometer is used for ligand identification only; the mass spectrometer is used for both ligand identification and bioassay readout; or MS detection is conducted in parallel with at-line microfractionation with off-line bioaffinity analysis. On the basis of the different fields of application of on-line screening, the principles are explained and their usefulness in the different fields of drug research is critically evaluated. Furthermore, off-line screening is discussed briefly with the on-line and at-line approaches.

HPLC/APCI-FTICR-MS as a tool for identification of partial polar mutagenic compounds in effect-directed analysis

Identification of unknown compounds remains one of the biggest challenges for the assignment of adverse effects of sediment contamination and other complex environmental mixtures to responsible toxicants by effect-directed analysis (EDA). The identification depends on information gained from biotesting, chromatographic separation, and mass spectrometric detection. Thus, a methodology is provided for non-target identification of partial polar mutagenic polyaromatic compounds in sediment extracts by using polymeric reversed-phase HPLC column, high-resolution mass spectrometry and PubChem database. After visualization and processing the chromatogram constituents by using deconvolution software, the unambiguous elemental compositions generated were used as input in PubChem database to find a possible identity for the suspected species. The retrieved structures from the database search were refined by characterized chromatographic and mass spectrometric classifiers based on 55 model compounds comprising eight different classes representing mutagenic substructures. The applicability of the method was demonstrated by positive and tentative identification of constituents of mutagenic sediment fractions similar to selected model compounds.

Identification of estrogen-like effects and biologically active compounds in river water using bioassays and chemical analysis

The Nackdong River is the longest river in South Korea and passes through major cities that have several industrial complexes, including chemical, electric, and petrochemical complexes, and municipal characteristics such as apartment complexes. Along the river, the Gumi region has an electric industrial complex and an apartment complex that may be possible point sources of xenoestrogens such as phenolic compounds. To identify the causative chemicals for estrogenic activity in the river water of this region, bioassay-directed chemical analysis was performed. All samples from six sampling sites (an upstream point: S1; hot spot points: S2-1, S2-2, and S2-3; and downstream points: S3, and S4) showed estrogenic activity in the E-screen assay, with bio-EEQs (17beta-E(2)-equivalent quantities) ranging from 25.35-677.15 pg/L. Samples from S2-2, the sampling point downstream of the junction of stream water, and domestic and industrial wastewater, contained the highest estrogenic activity. Since the bio-EEQ of the organic acid fraction (F2) of the S2-2 sample had the highest activity (823.25 pg-EEQ/L) and F2 may contain phenolic compounds, GC-MS analyses for phenolic xenoestrogens were conducted with the organic acid fractions of the river water samples. Six estrogenic phenolic chemicals, 4-NP, BPA, 4-t-OP, 4-t-BP, 4-n-OP, and 4-n-HTP, were detected, with the highest concentrations (I-EEQ) found in S2-2 (231.80 pg/L). Among these phenolic chemicals, 4-NP was the most potent estrogen (bio-EEF; 8.12 x1 0(-5)) and acted as a full agonist. Furthermore, 4-NP was present at levels (2.0 microg/L in S2-2) that can induce VTG induction in fish (>1 microg/L). In addition, we confirmed that river water (S2-2) significantly increased serum VTG levels in crucian carp (Carassius auratus) in a fish exposure experiment under laboratory conditions. Therefore, phenolic xenoestrogens, especially 4-NP, may be the main causative compounds responsible for the estrogenic effect on the Nackdong River.

Substance-related environmental monitoring: Work group 'Environmental Monitoring'-Position paper

BACKGROUND

Due to the requirements of the EU Water Framework Directive and other legal regulations (e.g., national laws like the German Federal Soil Protection Act), but also due to the implementation of the new EU chemicals management system REACH, environmental monitoring will gain increasing importance for the surveillance of environmental quality as well as for the assessment of chemicals. Against this background, the Work Group on 'Environmental Monitoring' of the Division of 'Environmental Chemistry and Ecotoxicology' within the German Chemical Society has compiled a position paper on substance-related environmental monitoring.

SCOPE

Core elements of this position paper are the definitions of important terms like monitoring, exposure monitoring, effect monitoring, and integrated monitoring. Moreover, temporal and spatial aspects (monitoring of spatial distributions, trend monitoring, and retrospective monitoring) and their applications are discussed. The main focus of this position paper is the coverage of aspects which have to be observed for the preparation and implementation of a monitoring program. Essential is the clear specification of the targets of the monitoring which determine the development of the monitoring concept and its realization, e.g., if environmental media (compartments) or organisms are most appropriate as samples for the aim of the study. Of course, also the properties of the target substances are important (e.g., lipophilicity/bioaccumulation as pre-requisite for an exposure monitoring with organisms). Finally, the monitoring phases of sample planning, sampling, storage and transport of samples, selection of analytical methods, quality assurance measures as well as reporting are discussed.

PERSPECTIVES

An important issue for the future is to link the quantification of chemicals in environmental compartments (exposure and pollution monitoring) more closely to the study of biological effects (effect monitoring) than has been the case up to now. Furthermore, by inclusion of a spatial differentiation, a comprehensive evaluation of the state of an ecosystem can be obtained and the relevance of the results improved. Practical examples of monitoring studies which illustrate various aspects covered in this position paper will be presented in a series of publications by members of the Work Group in the following issues of this journal.

Biomonitoring of detoxifying activity as measured by CYP1A1 induction in Yangtze and Jialing Rivers in Chongqing City in China

In order to determine the potential toxicities of organic pollutants in the river water of Chongqing City (China), chemicals were extracted from surface water of the Yangtze River and Jialing River between August 2004 and January 2005. Gas chromatography/mass spectrometry (GC/MS) analysis showed that the main compounds detected were polycyclic aromatic hydrocarbons (PAH) and phthalate acid esters (PAE). The ethoxyresorufin O-deethylase (EROD) test showed that the toxic equivalency (TEQ) values of the samples ranged from 0.9 to 13.3 x 10(-4) pg 2,3,7,8-TCDD/L river water. Incubation of H4IIE cells with organic extracts produced a time-dependent induction of cytochrome P-450 1A1 (CYP1A1) mRNA expression as determined by (1) reverse-transcription polymerase chain reaction (RT-PCR), (2) positive binding to aryl hydrocarbon receptor (AhR), and (3) activation of xenobiotic response element (XRE) by electrophoretic mobility shift assay (EMSA). Data indicated that organic extracts from the river water of Chongqing City induced CYP1A1 activity in hepatocytes in vitro. A possible mechanism underlying toxicity might involve the AhR signal pathway, but further studies are necessary.

Bioassay-directed identification of toxic organic compounds in creosote-contaminated groundwater

Despite the fact that creosote mainly consists of polycyclic aromatic hydrocarbons (PAHs), more polar compounds like phenolics, benzenes and N-, S-, O-heterocyclics dominate the groundwater downstream from creosote-contaminated sites. In this study, bioassay-directed fractionation, combined with fullscan GC-MS, identified organic toxicants in creosote-contaminated groundwater. An organic extract of creosote-contaminated groundwater was fractionated on a polar silica column using high performance liquid chromatography (HPLC), and the toxicity of the fractions was measured by the Microtox-bioassay. PAHs, which comprise up to 85% of pure creosote, accounted for only about 13% of total toxicity in the creosote-contaminated groundwater, while methylated benzenes, phenolics and N-heterocyclics accounted for ca. 80% of the measured toxicity. The fraction containing alkylated quinolines was the most toxic single fraction, accounting for 26% of the total measured toxicity. The results imply that focus on PAHs may underestimate risks associated with creosote-contaminated groundwater, and that environmental risk assessment should focus to a higher degree on substituted PAHs and phenolics because they are more toxic than the unsubstituted ones. Additionally, benzenes and N-heterocyclics (e.g., alkylated quinolines) should be assessed.

Brominated indoles and phenols in marine sediment and water extracts from the north and baltic seas-concentrations and effects

This work presents results from analytical as well as ecotoxicologic investigations of sediment and water samples from the North and Baltic Seas. A bioassay-directed procedure was used to investigate cause-effect relationships between observed effects in acute laboratory bioassays (luminescent bacteria assay with Vibrio fischeri and embryo test with Danio rerio) and analyte concentrations in extracted samples. Brominated phenols and indoles-including 4-bromophenol; 2,4-dibromophenol; 4- and 6-bromoindole; 3,4-, 4,6-, and 3,6-dibromoindole; and tribrominated compounds-were identified in partly remarkable concentrations (up to 40,000 ng g(-1) total organic carbon TOC for 4-bromophenol) in North Sea sediment samples and water samples (913 ng L(-1) 3,6-dibromoindole) from the German Bight. The toxicity of some of the identified brominated substances was low, with median effect concentration levels (EC(50)) ranging from 0.08 to 21.7 mg/L for V. fischeri and 4.3 to 46.3 mg/L for D. rerio. Comparison of the concentrations of analytes with ECs showed a toxicity contribution of brominated phenols and indoles to overall toxicity of the fraction. In the case of one water sample from the German Bight, brominated phenols and indoles accounted for the observed toxicity. Brominated phenols and indoles, which are assumed to be of biogenic origin, have rarely been discussed so far in the context of ecotoxicologic effects in marine ecosystems.

Identification of toxicants from marine sediment using effect-directed analysis

Effect-directed analysis (EDA) has been reported to be a powerful tool for the identification of the responsible toxicants in contaminated, hazardous environmental samples. The aim of this study was to investigate whether it also is possible to use currently available EDA methodology to identify potentially relevant toxicants in samples that do not pose obvious problems. For this purpose, compounds extracted from a marine sediment sample from the west coast of Sweden were separated into distinct fractions, using two preparative chromatographic techniques. One algal bioassay using Scenedesmus vacuolatus and two bacterial bioassays using Vibrio fischeri were applied as detectors of toxicity, representing acute and chronic end points. Chronic algal toxicity was a powerful tool for discriminating between toxic and nontoxic fractions, whereas acute and chronic bacterial toxicity failed to identify toxic fractions. Eight compounds were identified as potentially relevant toxicants by chemical analysis of toxic fractions: anthracene, fluoranthene, pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[a]pyrene, benzo[k]fluoranthene, and indeno[1,2,3-cd]pyrene.

Comparison of TCPP concentrations in sludge and wastewater in a typical German sewage treatment plant—comparison of sewage sludge from 20 plants

Tris(chloro-isopropyl)phosphate (TCPP) was identified by GC-MS by comparing mass spectra and retention times to original standards. The concentrations in wastewater of a sewage treatment plant's influent and effluent were analysed (520 ng l(-1) and 380 ng l(-1), respectively (mean values). The concentrations of TCPP in the wastewater inflow exhibited a high variability. The elimination of this compound in the sewage treatment plant also exhibits a high variability but is low. Additionally the concentrations in sewage sludge of the same plant were determined (mean value 5100 ng g(-1) dry weight; 1700 ng g(-1) wet weight, respectively). For a comparison sludge samples from twenty other plants were analysed. In these samples concentrations ranging from 1000-20000 ng g(-1)(dry weight) were determined. Thus sorption to sludge does occur to some extent.

Evaluation of wastewater effluents by small-scale biotests and a fractionation procedure

Municipal and industrial effluents were screened with a battery of biotests and with a modified toxicity identification evaluation Phase I procedure. The acute toxicities of the effluent samples were low and the submitochondrial reverse electron-transport (RET) test was the most sensitive toxicity test. Estrogenic effects were found in almost all effluent samples, and genotoxicity was detected in one concentrated effluent sample. The fractionation methods we used proved to be especially effective at tracking toxicity caused by metals and organic contaminants, with the RET test being particularly suited to evaluating pH-dependent toxicity. The used solid-phase extraction columns with both hydrophilic and hydrophobic binding properties turned out to be suitable for removing or reducing organic toxicity-causing substances from the effluent samples. The results of this study show that the use of only conventional acute toxicity tests for effluent assessment will not be sufficient-the genotoxic, hormonal, and even bioaccumulative potential of the effluents and effluent fractions should be evaluated as well.

Screening organic micropollutants in surface waters by SPE extraction and ecotoxicological testing

Complex mixtures of toxic substances occurring in surface waters are difficult to characterise by chemical analyses because each compound occurs at a very low concentration and requires a specific analytical method to be identified. Ecotoxicological tests on water extracts can be used as a screening tool to evaluate quickly and simply the overall quality of a water body with regard to micropollutant contamination. In this work, a pre-concentration procedure based on solid-phase extraction (SPE), suitable for both biological testing and analytical determination, is proposed. The extraction procedure is an improved version of a methodology used to evaluate the toxicity of organic micropollutants occurring in surface waters. It offers the advantage of using disposable commercial cartridges, which are easier to manage than the columns prepared with macromolecular resins. Water extracts from two representative Italian rivers, characterised by a different gradient of potential contamination and prepared according to the new concentration techniques, are used. The acute toxicity of the water extracts is tested on Daphnia magna and the bioluminescence inhibition in Vibrio fischeri. Criteria based on the concentration factor (CF) are proposed for assessing the hazard to aquatic life due to the exposure to toxic substances in surface waters. The aim of hazard ranking is to focus analytical efforts towards those samples that show the highest toxic potential.

Development of new toxicity identification evaluation by assessing toxicity reduction on adsorption and ion-exchange treatments

A new toxicity identification evaluation method for water exhibiting toxicity has been suggested by evaluating toxicity reduction resulting from adsorption and ion-exchange treatments. Adsorption using various adsorbents such as activated carbon, chitosan and zeolite, and ion-exchange using cationic and anionic ion-exchange resins were performed. In addition, toxicity was evaluated by a cell survival test using human liver cancer origin cells (HepG2), and the dose response data was applied to treatment characteristics. The amount of toxicity adsorbed by the various adsorbents was defined based on adsorption isotherm. Parameters of the toxicity adsorption isotherm provided information that allowed us to identify the toxicity-controlling chemicals in environmental water containing various chemicals. The method is promising for water quality management because it can be used to identify toxicity-controlling chemicals among various environmental pollutants.