Toxicity Of Water Samples Research Articles

Biotesting for the objectivization of the hygienic evaluation of the surface and underground drinking water sources

Introduction. An algorithm for evaluating the hygienic safety of drinking water sources based on biotesting and studying sanitary and chemical indicators has been developed and tested. Materials and methods. The research methods included sanitary and chemical analysis of water samples, as well as biotesting methods using single-celled green alga Chlorella vulgaris Beijer and bull spermatozoa. Results. For experimental approbation of the developed algorithm for determining the hygienic safety of water based on a two-component system of express biotesting and measurement of sanitary and chemical indicators, 6 underground and 5 surface water sources were evaluated. The response of test objects indicating the presence of acute toxicity in water samples taken from surface and underground in many cases correlates with the excess of MPC for individual indicators identified by sanitary and chemical analysis. For two water samples, differences were found between the results of biotesting and sanitary-chemical analysis, and therefore it is necessary to conduct an extended toxicological and chemical assessment to identify the source of toxic effects. Limitations. The two-component test system cannot be used separately without sanitary and chemical analysis of water media. Conclusion. Biotesting can be an addition to sanitary and chemical analyses, showing the presence of toxic substances that are not in the list of mandatory indicators to be determined (according to MR 2.1.4.0176-20 (in Russian)).

Multi-Level System to Assess Toxicity in Water Distribution Plants.

The toxicity of water samples from water distribution plants needs to be investigated further. Indeed, studies on the pro-oxidant effects driven by tap water are very limited. In this study, the water quality, pro-oxidant effects, and potential health risks driven by exposure to groundwater samples from two water plants (sites A and B) located in Northwestern Italy were investigated in a multi-level system. Physicochemical parameters and the absence of pathogens, cyanotoxins, and endocrine active substances indicated a good water quality for both sites. The 25 metals analyzed were found under the limit of quantification or compliant with the maximum limits set by national legislation. Water samples were concentrated by the solid-phase extraction system in order to assess the aquatic toxicity on Epithelioma papulosum cyprini (EPC) cell line. Levels of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and glutathione reductase were evaluated through the Integrated Biomarkers Response (IBRv2) index. EPC cell line was found a sensible model for assessing the antioxidant responses driven by both water concentrates. A similar antioxidant response was shown by plots and IBRv2 suggesting a muted risk for the two sampling sites.

Removal of trace organic pollutants and generation of halogenated disinfection by-products in membrane UV/chlorine combined process

In this study, the degradation kinetics and degradation mechanism of 23 trace organic pollutants (TrOCs) in the secondary effluent of sewage by the combined membrane-UV/chlorine process were investigated, and the halogenated disinfection by-products (X-DBPs) in the combined process were investigated and its generation potential (X-DBPsFP), and the cytotoxicity and genotoxicity of the treated water samples were also evaluated. The results showed that membrane pretreatment could effectively promote the degradation of TrOCs in UV/chlorine system, and nanofiltration (NF) was more effective than ultrafiltration (UF). Compared with UF, NF intercepts more dissolved organic matter (DOM), thus weakening the light shielding effect, chlorine consumption and radical quenching to a greater extent. It is found that the degradation mechanism of TrOCs can be divided into the following four categories: Ho˙ dominated, RHS dominated, chlorine and RHS jointly dominated and chlorine dominated. Membrane pretreatment can well reduce the formation of X-DBPs, among which UF and NF reduce the formation of haloacetamide (HAMs) and trihalomethanes (THMs) most significantly, while NF reduces the formation of X-DBPs and X-DBPsFP and the toxicity of water samples much stronger than UF. In addition, NF UV/chlorine can significantly remove the precursors of X-DBPs, so as to effectively control the enhancement of cytotoxicity and genotoxicity of water samples in the post chlorination process. The research results promote the development of advanced sewage treatment technology and provide theoretical guidance for related research.

Electrochemical sensor based on cerium niobium oxide nanoparticles modified electrode for sensing of environmental toxicity in water samples

Water is one of the most necessities for life on the planet. Nowadays, the scarcity of clean water is a major concern, and it is predicted to worsen in the future as a result of industrial globalization and population growth. Among the various procedures being suggested and/or implemented for water analysis that are simple, clean, and inexpensive, semiconductor-mediated electro analytical processing has gotten a lot of attention. On this concern, here we report a facile synthesis, characterization, and electrochemical sensors potential of a rare earth metal of cerium niobium oxide nanoparticles (CNO NPs). The low-temperature hydrothermal method was used to synthesize the catalyst, which was then characterized by XRD, XPS, TEM, and EDS. To explore the electrocatalytic activity of CNO NPs, it was employed as an electrocatalyst to monitor the environmental toxicity 4-Nitrophenol by EIS, CV, and DPV. The effects of different experimental parameters, pH, and scan rate have been optimized for the electrochemical oxidation of 4-Nitrophenol. The linear relationship between the peak current and various concentrations of 4-Nitrophenol was reported to be the over range of 0.01–192.01 µM, with a remarkable detection limit of 0.042 µM. The CNO NPs modified GCE for 4-Nitrophenol sensor exhibits high reproducibility, repeatability, and stability. The results demonstrate the sensing performance and prospective applications of CNO NPs for the electrochemical detection of 4-Nitrophenol in real-time detection is applicable with acceptable recovery results.

The Occurrence of Potential Harmful Cyanobacteria and Cyanotoxins in the Obrzyca River (Poland), a Source of Drinking Water.

Harmful cyanobacteria and their cyanotoxins may contaminate drinking water resources and their effective control remains challenging. The present study reports on cyanobacterial blooms and associated cyanotoxins in the Obrzyca River, a source of drinking water in Poland. The river was examined from July to October 2019 and concentrations of microcystins, anatoxin-a, and cylindrospermopsin were monitored. The toxicity of water samples was also tested using an ecotoxicological assay. All studied cyanotoxins were detected with microcystins revealing the highest levels. Maximal microcystin concentrations (3.97 μg/L) were determined in September at Uście point, exceeding the provisional guideline. Extracts from Uście point, where the dominant species were Dolichospermum flos-aquae (August), Microcystis aeruginosa (September), and Planktothrix agardhii (October), were toxic for Dugesia tigrina Girard. Microcystin concentrations (MC-LR and MC-RR) were positively correlated with cyanobacteria biovolume. Analysis of the chemical indicators of water quality has shown relationships between them and microcystins as well as cyanobacteria abundance.

Poison in paradise: increase of toxic effects in restored sections of two rivers jeopardizes the success of hydromorphological restoration measures

BackgroundTo date, only 8.2% of German surface waters achieve a good ecological status according to the European Water Framework Directive. This is primarily attributed to structural deficits, intensive land use, and chemical contaminations of water bodies. In this context, hydromorphological restoration measures are implemented with the aim to increase habitat and species diversity and thus improve the ecological status of water bodies. Nevertheless, existing studies show that restorations promote the reintroduction of individual species, but only in exceptional cases an improvement in the ecological status is achieved. Therefore, we examined the impact of the prevailing chemical contamination on the restoration success in the catchment of the river Nidda in Hessen (Germany) by comparing restored river sections at the rivers Nidda and Horloff with unrestored sections upstream (space-for-time-substitution) and a transect downstream the restoration measures. For this purpose, we conducted active biomonitoring campaigns with Potamopyrgus antipodarum and Gammarus fossarum and analyzed water and sediment samples with effect-based in vitro bioassays.ResultsAt the river Horloff, mortality of P. antipodarum and toxicity in water samples measured via the microtox assay were highest within the restoration. At the river Nidda, the reproduction of snails and gammarids significantly increased within the restorations, and reproduction of snails correlated positively and significantly with estrogenic activities. The microtox assay also exhibited the highest toxicities in water and sediment samples from the restorations and dioxin-like as well as estrogenic activities significantly increased compared to the unrestored reference site. On the basis of these results, the prevailing chemical contamination has negatively affected snails and gammarids in the active biomonitoring campaigns and consequently is likely to have also a negative impact on the local invertebrate community and thus endangers the restoration success.ConclusionHydromorphological restorations as a stand-alone measure are insufficient to improve the ecological status of a water body as long as the water and sediment quality remain deficient. Therefore, it is necessary to improve water and sediment quality in parallel with hydromorphological restoration measures to achieve the objectives of the EU-WFD.

Pesticide Mixture Toxicity in Surface Water Extracts in Snails (Lymnaea stagnalis) by an in Vitro Acetylcholinesterase Inhibition Assay and Metabolomics.

Many chemicals in use end up in the aquatic environment. The toxicity of water samples can be tested with bioassays, but a metabolomic approach has the advantage that multiple end points can be measured simultaneously and the affected metabolic pathways can be revealed. A current challenge in metabolomics is the study of mixture effects. This study aims at investigating the toxicity of an environmental extract and its most abundant chemicals identified by target chemical analysis of >100 organic micropollutants and effect-directed analysis (EDA) using the acetylcholinesterase (AChE) bioassay and metabolomics. Surface water from an agricultural area was sampled with a large volume solid phase extraction (LVSPE) device using three cartridges containing neutral, anionic, and cationic sorbents able to trap several pollutants classes like pharmaceuticals, pesticides, PAHs, PCBs, and perfluorinated surfactants. Targeted chemical analysis and AChE bioassay were performed on the cartridge extracts. The extract of the neutral sorbent cartridge contained most of the targeted chemicals, mainly imidacloprid, thiacloprid, and pirimicarb, and was the most potent AChE inhibitor. Using an EDA approach, other AChE inhibiting candidates were identified in the neutral extract, such as carbendazim and esprocarb. Additionally, a metabolomics experiment on the central nervous system (CNS) of the freshwater snail Lymnaea stagnalis was conducted. The snails were exposed to the extract, the three most abundant chemicals individually, and a mixture of these. The extract disturbed more metabolic pathways than the three most abundant chemicals individually, indicating the contribution of other chemicals. Most pathways perturbed by the extract exposure overlapped with those related to exposure to neonicotinoids, like the polyamine metabolism involved in CNS injuries. Metabolomics for the straightforward comparison between a complex mixture and single compound toxicity is still challenging but, compared to traditional biotesting, is a promising tool due to its increased sensitivity.

Combining physico-chemical analysis with a Daphnia magna bioassay to evaluate a recycling technology for drinking water treatment plant waste residuals

Recycling water treatment plant (WTP) waste residuals is considered to be a feasible method to enhance the efficiency of pollutant removal. This study also evaluated the safety and water quality of a pilot-DWTP waste residuals recycling technology by combining physical-chemistry analysis with a Daphnia magna assay. The water samples taken from each treatment step were extracted and concentrated by XAD-2 resin and were then analyzed for immobilization and enzyme activity with D. magna. The measured parameters, such as the dissolve organic carbon (DOC), UV254 and THM formation potential (THMFPs) of the recycling process, did not obviously increase over 15 days of continuous operation and were even lower than typical values from a conventional process. The extract concentration ranged from 0 to 2Leq/ml as measured on the 7th and 15th days and the immobilization of D. magna exposed to water treated by the recycling process was nearly equivalent to that of the conventional process. Both the superoxide dismutase (SOD) and the catalase (CAT) activity assay indicated that a lower dose of water extract (0.5, 1, 1.5Leq/ml) could stimulate the enzyme activity of D. magna, whereas a higher dose (2Leq/ml at the sampling point C3, R3, R4 ) inhibits the activity. Moreover, the SOD and CAT activity of D. magna with DOC and UV254 showed a strong concentration–effect relationship, where the concentration range of DOC and UV254 were 4.1–16.2mg/L and 0.071–4.382cm−1, respectively. The results showed that there was no statistically significant difference (p>0.05) between the conventional and recycling treatment processes and the toxicity of water samples in the recycling process did not increase during the 15-day continuous recycling trial.

Toxicity of Vertimec® 18 EC (active ingredient abamectin) to the neotropical cladoceran Ceriodaphnia silvestrii

The aim of the present study was to evaluate the toxicity of abamectin to the neotropical cladoceran Ceriodaphnia silvestrii. To this end, acute and chronic bioassays were conducted with the commercial formulation Vertimec® 18 EC. In addition, the toxicity of water samples taken from a microcosm experiment evaluating the effects of a single application (144μga.i./L) and two applications (2×36μga.i./L) of Vertimec® 18 EC, in the presence or absence of a tadpole species (Lithobates catesbeianus), was also assessed. The acute LC50-48h for immobilization was 1.47μga.i./L and chronic NOEC-8d for survival and fertility (number of neonates per female) were 169 and 84nga.i./L, respectively. Irrespective of the presence of tadpoles, water samples from the microcosms applied with the single concentration of 144μga.i./L remained toxic until the end of the experiment, even when samples were diluted 32 times with culture medium. Water in the repeated pesticide treatment showed a similar toxic response after both applications. Toxicity of water samples from the microcosms was lower than that expected based on the generated LC50 values, which is explained by a potential reduced bioavailability of the test compound resulting from absorbance to organic material. Potential side-effects on C. silvestrii related with the use of Vertimec® 18 EC in Brazil and the suitability of this species for tropical toxicity testing are discussed.

Toxicological monitoring of a watersupply reservoir by acute assays with Daphnia pulex

Daphnia pulex assays (48 hours) were performed to determine acute toxicity of water samples from La Fe reservoir, Antioquia, Colombia. Eight sampling campaigns were done between March 2010 and June 2012, a period that included rainfall episodes. Samples were taken from the water column at three depths and from lotic areas. Physicochemical properties such as pH, electrical conductivity, temperature and dissolved oxygen were measured both in field and laboratory, and concentrations of dissolved iron (Fe), manganese (Mn), aluminium (Al), lead (Pb), cadmium (Cd) and chromium (Cr) were assessed. The overall results for the physicochemical properties remained at expected levels for natural waters with slightly higher conductivities in samples collected from bottom and some tributaries. The results of the toxicity tests showed significant mortalities in only 28% of assays. A higher mortality of Daphnia pulex was detected for tests performed during periods of higher precipitation (August 2010, February and July 2011) mainly for samples taken near the confluence of natural tributaries. No significant relationships between physicochemical variables and mortality of Daphnia pulex were found. DOI: http://dx.doi.org/10.5755/j01.erem.71.1.9788

Risk assessment of an abandoned pyrite mine in Spain based on direct toxicity assays

This research reports the risk assessment of an abandoned pyrite mine using direct toxicity assays of soil and groundwater samples taken at the site. The toxicity of As and heavy metals from mining soils to soil and aquatic organisms was studied using the Multispecies Soil System (MS-3) in soil columns. Ecotoxicological assessment was performed with soil samples diluted with a control soil at concentrations of 12.5, 25, 50 and 100% test soil/soil (w/w). In this way, changes in the mobility and bioavailability of soil contaminants due to changes in geochemical soil properties via soil dilution were studied. The toxicity of water samples was tested on algae and Daphnia magna. The assessment of the mining area indicated that the current presence of As and heavy metals at the site may cause injuries to soil and aquatic organisms in the entire research area. Moreover, this investigation demonstrated that changes in geochemical conditions can increase the availability of arsenic and, consequently, the environmental risk of these soils. A good correlation was not found between toxicity parameters and the concentrations of soil contaminants based on total and extracted element concentrations. This finding reinforces the usefulness of direct toxicity assays for evaluating environmental risk.

In vitro bioassay for reactive toxicity towards proteins implemented for water quality monitoring

Reactive organic chemicals comprise a large number of compounds with a variety of reactive moieties. While most assays for reactive toxicity focus on DNA damage, reactivity towards proteins can also lead to irreparable damage, but reactivity towards proteins is typically not included in any test battery for water quality assessment. Glutathione (GSH) is a small tripeptide whose cysteine moiety can serve as a model for nucleophilic sites on proteins. GSH is also an important indicator of detoxification processes and the redox status of cells and due to its protective role, depletion of GSH ultimately leads to adverse effects. A bioassay based on genetically modified Escherichia coli strains was used to quantify the specific reactivity towards the protein-like biological nucelophile GSH. The significance of GSH for detoxification was assessed by comparing the growth inhibition induced by reference chemicals or water samples in a GSH-deficient strain to its fully functional parent strain. The GSH deficient strain showed the same sensitivity as the GSH proficient strain to non-reactive and DNA damaging chemicals, but was more sensitive to chemicals that attack cysteine in proteins. The difference in effect concentrations for 50% inhibition of growth assessed as biomass increase (EC(50)) between the two strains indicates the relevance of GSH conjugation as a detoxification step as well as direct reactivity with cysteine-containing proteins. Seven reference compounds serving as positive and negative controls were investigated. The E. coli strain that lacks GSH was four times more sensitive towards the positive control Sea-Nine, while negative controls benzo[a]pyrene, 2-aminoanthracene, phenol, t-butylhydroquinone, methyl methane sulfonate and 4-nitroquinoline oxide showed equal effect concentrations in both strains. Water samples collected across an indirect potable reuse scheme representing the complete water cycle from sewage to drinking water in South East Queensland, Australia were used to evaluate the applicability of the E. coli assay for reactive toxicity in water samples. While the EC(50) values of the GSH+ strain showed similar trends as in other biological endpoints over the various treatment chains, the specific response indicative of protein damage was only observed in samples that had undergone chlorination as a disinfection process. High natural organic matter or other matrix components disturbed the bioassay so much that we recommend it for future routine testing only in tertiary treated water or drinking water.

Bioanalytical tools for the evaluation of organic micropollutants during sewage treatment, water recycling and drinking water generation

A bioanalytical test battery was used for monitoring organic micropollutants across an indirect potable reuse scheme testing sites across the complete water cycle from sewage to drinking water to assess the efficacy of different treatment barriers. The indirect potable reuse scheme consists of seven treatment barriers: (1) source control, (2) wastewater treatment plant, (3) microfiltration, (4) reverse osmosis, (5) advanced oxidation, (6) natural environment in a reservoir and (7) drinking water treatment plant. Bioanalytical results provide complementary information to chemical analysis on the sum of micropollutants acting together in mixtures. Six endpoints targeting the groups of chemicals with modes of toxic action of particular relevance for human and environmental health were included in the evaluation: genotoxicity, estrogenicity (endocrine disruption), neurotoxicity, phytotoxicity, dioxin-like activity and non-specific cell toxicity. The toxicity of water samples was expressed as toxic equivalent concentrations (TEQ), a measure that translates the effect of the mixtures of unknown and potentially unidentified chemicals in a water sample to the effect that a known reference compound would cause. For each bioassay a different representative reference compound was selected. In this study, the TEQ concept was applied for the first time to the umuC test indicative of genotoxicity using 4-nitroquinoline as the reference compound for direct genotoxicity and benzo[a]pyrene for genotoxicity after metabolic activation. The TEQ were observed to decrease across the seven treatment barriers in all six selected bioassays. Each bioassay showed a differentiated picture representative for a different group of chemicals and their mixture effect. The TEQ of the samples across the seven barriers were in the same order of magnitude as seen during previous individual studies in wastewater and advanced water treatment plants and reservoirs. For the first time a benchmarking was performed that allows direct comparison of different treatment technologies and covers several orders of magnitude of TEQ from highly contaminated sewage to drinking water with TEQ close or below the limit of detection. Detection limits of the bioassays were decreased in comparison to earlier studies by optimizing sample preparation and test protocols, and were comparable to or lower than the quantification limits of the routine chemical analysis, which allowed monitoring of the presence and removal of micropollutants post Barrier 2 and in drinking water. The results obtained by bioanalytical tools were reproducible, robust and consistent with previous studies assessing the effectiveness of the wastewater and advanced water treatment plants. The results of this study indicate that bioanalytical results expressed as TEQ are useful to assess removal efficiency of micropollutants throughout all treatment steps of water recycling.

Validation of interlaboratory studies on toxicity in water samples

Toxicity tests are important for assessing the impact of chemicals on aquatic ecosystems because they indicate toxic effects of complex chemical mixtures. Several methods have been developed for rapid assessment of the dangerous biological effects of samples. These methods can be important improvements for comprehensive environmental monitoring and complementary tools for implementing the new environmental directives and regulations in Europe. However, toxicity tests using different species have shown different sensitivities and endpoints, and only a limited number of tests have been standardized and validated. In order to verify the quality of biological measurements, to estimate the analytical precision of different participating laboratories using the same test, and to determine if statistically significant differences exist between results of participating laboratories, different interlaboratory exercises have been carried out. In this overview article, we present and discuss the most advanced aspects of current aquatic toxicity methodologies, as well results of different round-robin exercises.

Detection and monitoring toxigenicity of cyanobacteria by application of molecular methods

The aim of this study was early genetic identification of microcystin-producing cyanobacteria and monitoring their toxigenicity by determining toxin concentrations in three Polish lakes throughout the summer of 2004. The assessment of cyanobacterial blooms was carried out in shallow, eutrophic water bodies: Lake Jeziorak, Lake Bninskie, and Sulejow Reservoir. Samples for DNA, phycological, and toxin analyses were collected from July till October. Molecular analysis of the 16S rRNA region was used to detect cyanobacteria in water samples. The microscopic analysis was performed to investigate seasonal variation of phytoplankton. Cyanobacteria, with domination by Microcystis, Planktothrix, and Planktolyngbya were detected during the whole monitoring period in Sulejow Reservoir, Lake Bninskie, and Lake Jeziorak, respectively. The presence and identification of toxic strains in water bodies was studied by PCR amplification of mcy genes in the microcystis synthesis pathway. The presence of the mcyA, mcyB, mcyD, and mcyE genes in water samples indicated the genetic potential to produce microcystins. Toxicity of water samples and microcystin concentrations were established by PPIA and HPLC, respectively. The maximum concentration of microcystins was 11.13 microg/L and 4.67 microg/L in samples dominated by P. agardhii and M. aeruginosa, respectively. Molecular analysis showed that toxigenic strains of cyanobacteria occurred in the three lakes throughout the summer season.

Selection of a battery of rapid toxicity sensors for drinking water evaluation

Comprehensive identification of chemical contaminants in Army field water supplies can be a lengthy process, but rapid analytical methods suitable for field use are limited. A complementary approach is to directly measure toxicity instead of individual chemical constituents. Ten toxicity sensors utilizing enzymes, bacteria, or vertebrate cells were tested to determine the minimum number of sensors that could rapidly identify toxicity in water samples containing one of 12 industrial chemicals. The ideal sensor would respond at a concentration just exceeding the Military Exposure Guideline (MEG) level for the chemical (an estimated threshold for adverse effects) but below the human lethal concentration. Chemical solutions were provided to testing laboratories as blind samples. No sensors responded to deionized water blanks, and only one sensor responded to a hard water blank. No single toxicity sensor responded to more than six chemicals in the desired response range, and one chemical (nicotine) was not detected by any sensor with the desired sensitivity. A combination of three sensors (Microtox, the Electric Cell Substrate Impedance Sensing (ECIS) test, and the Hepatocyte low density lipoprotein (LDL) uptake test) responded appropriately to nine of twelve chemicals. Adding a fourth sensor (neuronal microelectrode array) to the test battery allowed detection of two additional chemicals (aldicarb and methamidophos), but the neuronal microelectrode array was overly sensitive to paraquat. Evaluating sensor performance using a standard set of chemicals and a desired sensitivity range provides a basis both for selecting among available toxicity sensors and for evaluating emerging sensor technologies. Recommendations for future toxicity sensor evaluations are discussed.

Ecotoxicological assessment for receiving waters with the premetamorphic tadpoles acute assay

The toxicity of receiving waters was evaluated by means of the young tadpoles assays. The sentinel organism was Bufo arenarum, an indigenous anuran species. The assayed water samples were taken from a highly polluted urban watercourse (Reconquista River, Buenos Aires, Argentina), characterized by high concentration of nitrites, phosphates and heavy metals. The toxicity of water samples was assessed performing the pass–fail test and by means of the NOEC and LC 50; TUs (toxic units) were also calculated. The effect of the addition of a positive control (Cd) on the toxicity of the river water samples was also examined. Water samples of three sites, characterised by their different degree of pollution, were assayed. The lethal response had a clear cut correspondence with the water quality of the sample evaluated by means of physicochemical parameters. In most cases, the dilution of the samples resulted in a significant reduction of their toxicity to TU values compatible to those stated by the USEPA for industrial effluents. It was concluded that (a) the used Bufo arenarum bioassay was an adequate method for assessing the toxicity of natural polluted water samples and (b) the three considered endpoints showed no important differences after 48 or 96 h of exposure, therefore we concluded that it may not be necessary to extend the assay for a longer period than 48 h.

The mineralisation of methamidophos using ionised AN air water treatment pilot system and ultraviolet irradiation

The degradation of methamidophos in pure bi-distilled water (with initial concentration 5 mg L −1, pH=7 at the beginning) was studied. For the first time, 2 ionised air water treatment pilot systems (IAPS-1, -2, no additives) were set up ( Figs. 1 and 2). The degradation of methamidophos was carried out with only the IAPS-2 and with two different ultraviolet (UV) lamps: high- and low-pressure mercury lamps (HP and LP, with or without H 2O 2). The kinetics of these oxidative processes was investigated. The highest rate constant was reached by the LP, 0.2% H 2O 2 ( k=0.7524 min −1, t 1/2=0.9 min), followed closely by both treatments with the HP, 0.2% H 2O 2 ( k=0.6328 min −1, t 1/2=1.1 min) and LP, 0% H 2O 2 ( k=0.4749 min −1, t 1/2=1.5 min). The lowest rate constants were achieved from the HP, 0% H 2O 2 process ( k=0.0303 min −1, t 1/2=22.9 min) and from the IAPS-2 ( k=0.0117 min −1, t 1/2=59.2 min). The mineralisation of methamidophos was confirmed by the determination of the anions produced including NO 3 −, PO 4 3− and SO 4 2− during and at the end of each experiment. The toxicity of water samples before, during and after the experiments was tested with Daphnia test.

Use of microbiotests to compare the toxicity of water samples fortified with active ingredients and formulated pesticides

Use of microbiotests to compare the toxicity of water samples fortified with active ingredients and formulated pesticides

Effects of protracted cadmium exposure on gametes of the purple sea urchin, Arbacia punctulata.

Gametes and larvae of sea urchins and more specifically Arbacia punctulata have been used extensively in embryological studies and toxicity bioassay testing. Most of the experiments and bioassays have used the fertilized eggs of different sea urchin species and measured abnormal growth, malformations, or changes in the rates of growth as a function of contaminant exposure. Guida demonstrated that cupric ion activities of <10{sup -10.5} M caused reductions in the rates of growth of Arbacia Punctulata larvae and caused incomplete or malformed pluteal skeletons. These effects occurred at cupric ion concentrations that were in the same ranges as some measured in the more contaminated estuaries in the northeastern U.S. Sunda and coworkers also used sea urchin embryonic development to test potential trace metal toxicity in water samples collected from those same estuaries, and demonstrated toxicity potentially attributable to dissolved trace metals in the water column. The purpose of these experiments was to determine if protracted sublethal exposure of sexually mature sea urchins to dissolved cadmium in sea water would affect the viability of eggs and sperm, and whether it would affect fertilization and embryonic development and ultimately the larvae. The results of the experiments support the hypothesis that spermatogenesis andmore » oogenesis were affected by cadmium exposure.« less