Application of a microbiotests battery for complete toxicity assessment of rivers

Ecotoxicological assessment of waste foundry sands and the application of different classification systems

The application of a battery of bioassays is widely recognized as a useful tool for assessing environmental hazard samples. However, the integration of different toxicity data is a key aspect of this assessment and remains a challenge. The evaluation of industrial waste leachates did not initially undergo any of the proposed integration procedures. This research addressed this knowledge gap. Twenty-five samples of waste foundry sands were subjected to a leaching test (UNI EN 12457-2) to evaluate waste recovery and landfill disposal. The leachates were evaluated using a battery of standardized toxicity bioassays composed of Aliivibrio fischeri (EN ISO 11348-3), Daphnia magna (UNI EN ISO 6341), and Pseudokirchneriella subcapitata (UNI EN ISO 8692), both undiluted and diluted. Daphnia magna and P. subcapitata were the most affected organisms, with significant effects caused by 68% and 64% of undiluted samples, respectively. The dilution of samples facilitates the calculation of EC50 values, which ranged from greater than the highest concentration tested to 2.5 g/L for P. subcapitata. The data on single-organism toxicity were integrated using three methods: the Toxicity Classification System, the toxicity test battery integrated index, and the EcoScore system. The three classifications were strongly similar. According to all applied systems, three samples were clearly nontoxic (from iron casting plants) and two were highly toxic (from steel casting plants). Moreover, the similar ranking between undiluted and diluted leachates suggests the possibility of using only undiluted leachates for a more cost-effective and time-efficient screening of waste materials. The findings of this study highlight the usefulness of integrating ecotoxicological waste assessment. Integr Environ Assess Manag 2024;00:1-18. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

A critical review on quantitative evaluation of aqueous toxicity in water quality assessment

Conventional chemical techniques have inherent limitations in detecting unknown chemical substances in water. As a result, effect-based methods have emerged as a viable alternative to overcome these limitations. These methods provide more accurate and intuitive evaluations of the toxic effects of water. While numerous studies have been conducted, only a few have been applied to national water quality monitoring. Therefore, it is crucial to develop toxicity evaluation methods and establish thresholds based on quantifying toxicity. This article provides an overview of the development and application of bioanalytical tools, including in vitro and in vivo bioassays. The available methods for quantifying toxicity are then summarized. These methods include aquatic life criteria for assessing the toxicity of a single compound, comprehensive wastewater toxicity testing for all contaminants in a water sample (toxicity units, whole effluent toxicity, the potential ecotoxic effects probe, the potential toxicology method, and the lowest ineffective dilution), methods based on mechanisms and relative toxicity ratios for substances with the same mode of action (the toxicity equivalency factors, toxic equivalents, bioanalytical equivalents), and effect-based trigger values for micropollutants. The article also highlights the advantages and disadvantages of each method. Finally, it proposes potential areas for applying toxicity quantification methods and offers insights into future research directions. This review emphasizes the significance of enhancing the evaluation methods for assessing aqueous toxicity in water quality assessment.

Potential Toxic Effects of Airport Runoff Water Samples on the Environment

Despite the positive aspects of the intensive development of aviation, airports are considered large-scale polluters. Pollution caused by runoff water (stormwater) is one of the major problems related to airport operations. The aim of this study was to characterize the potential toxic impact on aquatic life from runoff water discharges from four international airports in Europe. Samples of stormwater were collected at airports with different capacities of passenger movement in four seasons of the year from 2011 to 2013. Within the ecotoxicological analyses, a battery of biotests incorporating organisms of different trophic levels (Microtox® test, Thamnotoxkit F™) were used. A relatively high number of runoff water samples collected at the investigated airports in Europe was recorded as having very high acute hazard (16.8%), acute hazard (27.7%), and slight acute hazard (18.1%) levels. The results of the research indicate that winter and autumn present a greater toxic threat than the rest of the year. The highest number of toxic samples was observed for samples collected in the de-icing area, the runway and the vicinity of airport terminals. The ecotoxicological assessment applied in this research can be used as a tool for assessing the environmental effect of airports.

Concentration of dioxin and screening level ecotoxicity of pore water from bottom sediments in relation to organic carbon contents

The information about concentrations of dioxin in pore water, ecotoxicity and DOC and TOC content can be key factor for the prediction of the fate of dioxins in the aquatic environment as well as an ecological risk assessment. The aims of the study were to assess the concentration of PCDDs/PCDFs and ecotoxicity of pore water and to compare above results in relation to the dissolved organic carbon (DOC) and total organic carbon (TOC) content. The concentration of dioxins was assessed using an enzyme-linked immunoassay test, while the ecotoxicity of pore water was determined using a crustacean Daphnia magna and bacteria Aliivibrio fischeri. The studies were conducted on two different dammed reservoirs Rożnów (catchment basin of an agricultural character) and Rybnik (catchment basin of an industrial character) located in southern Poland. The concentration of dioxins in pore water was between 8.56 to 90.92 ng EQ/L, with a significantly higher concentration in the pore water from the Rożnów Reservoir than the Rybnik Reservoir. The DOC content in pore water was from 30.29 to 63.02 mg/L (Rożnów Reservoir) and from 35.46 to 60.53 mg/L (Rybnik Reservoir). Higher toxic responses were recorded for A. fischeri than for D. magna. Moreover a significantly higher toxicity for both tested organisms was indicated in pore water from the Rożnów Reservoir. Besides of TOC and DOC, the fine fractions of the sediments were particularly important in the concentration of dioxin in pore water. The other pore water parameters, such as pH and EC can influence the toxicity of water for organisms. The result indicate complex relationships between the PCDD/F, ecotoxicity and DOC, TOC concentration in pore water and confirms that these parameters are important in terms of water environmental contamination.

Bioassay: A useful tool for evaluating reclaimed water safety

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.

Phytotoxicity assays with hydroxyapatite nanoparticles lead the way to recover firing range soils

Shooting activities is an important source of Pb in contaminated soils. Lead accumulates in superficial soil horizons because of its low mobility, favouring its uptake by plants and representing a high transference risk to the trophic chain. A combination of phytoremediation with nanoremediation techniques can be used to recover firing range soils and decrease the mobility, bioavailability and toxicity of Pb. This study examines in depth the changes in Pb behaviour in firing range soils by adding hydroxyapatite nanoparticles (HANPs). These nanoparticles (NPs) may immobilise Pb and improve the quality of these areas. The use of HANPs and the Pb effects were assessed in three different species (Sinapis alba L., Lactuca sativa L. and Festuca ovina L.), focusing on their germination and early growth, through phytotoxicity assays. Single extractions with CaCl₂ (0.01 M) in soils treated with HANPs show that these NPs retained Pb and reduced highly its availability and mobility. HR-TEM and TOF-SIMS were used to determine the interactions between HANPs and Pb, as well as with soil components. According to TOF-SIMS and HR-TEM/EDS analysis, Pb was mainly retained by HANPs but also associated lightly to organic matter, Fe compounds and silicates. Phytotoxicity assays exposed that S. alba, L. sativa and F. ovina were able to germinate and develop in the firing range soils despite the high available Pb contents before adding HANPs. After adding HANPs, Pb retention increased, favouring the germination and the growth of roots in the three species. These results suggest that HANPs can be used to decrease the availability and the toxicity of Pb without negative effects in the species growth. Accordingly, the combination of phytoremediation and nanoremediation techniques can be a great tool to stabilise these soils, avoiding the Pb transfer to nearby areas and its entry in the trophic chain.

Towards a multi-bioassay-based index for toxicity assessment of fluvial waters

Despite their proven reliability for revealing 'acceptable' degrees of toxicity in waste- and reclaimed waters, bioassays are rarely used to assess the toxicity of hazardous contaminants present in natural waters. In this study, we used organisms from different trophic levels to assess the toxicity of water samples collected from four different South Korean rivers. The main objective was to develop a multi-descriptor index of toxicity for undiluted river water. The responses of six test organisms (Aliivibrio fischeri, Pseudokirchneriella subcapitata, Heterocypris incongruens, Moina macrocopa, Danio rerio and Lemna minor) after laboratory exposure to water samples were considered for this index, as well as the frequency of teratologies in diatom assemblages. Each individual test was attributed a toxicity class and score (three levels; no toxicity = 0, low toxicity = 1, confirmed toxicity = 2) based on the organism's response after exposure and a total score was calculated. The proposed index also considers the number of test organisms that received the highest toxicity score (value = 2). An overall toxicity category was then attributed to the water sample based on those two metrics: A = no toxicity, B = slight toxicity, C = moderate toxicity; D = toxicity and E = high toxicity. The susceptibility of the test organisms varied greatly and the sensitivity of their response also differed among bioassays. The combined responses of organisms from different trophic levels and with different life strategies provided multi-level diagnostic information about the intensity and the nature of contamination.

Student-Centered Microbioassay Laboratory Activity Utilizing Bioluminescent Bacteria

Student-centered teaching allows students to be actively engaged in hands-on, minds-on activities that emphasize creativity and collaboration, enabling them to ask questions and design their own investigations to real-world problems. One such problem is water contamination, which causes human health and environmental issues. However, chemical water quality testing for pollutants can be timely and expensive. In addition to chemical testing, researchers have developed assays using unicellular organisms to determine which pollutants are present and in what concentrations. In this three-hour laboratory activity, high school students and undergraduate biology or microbiology students work in pairs to help a fictional company develop a water quality microbioassay. Students design their own laboratory protocols to test the reaction of a bioluminescent bacterial species (i.e., Photobacterium phosphoreum or Aliivibrio fischeri ) to exposure of common aquatic pollutants such as fertilizer, household cleaners, and motor oil. During this laboratory activity, students apply previously learned components of experimental design, including positive and negative controls, constants, and experimental groups. In addition, students gain experience writing a scientific explanation for a recommendation regarding the bioluminescent bacteria's suitability in a bioassay. Pre- and post-evaluation data revealed that students were successful in achieving the activity's objectives as well as in designing their investigations and writing their protocols using scaffolds within the lesson.

Use of Chemical Indicators and Bioassays in Bottom Sediment Ecological Risk Assessment

This study is was designed to assess the ecological risk associated with chemical pollution caused by heavy metals and PAHs on the basis of their ecotoxicological properties in sediments collected from the Rzeszów dam reservoir (Poland). The sediment samples were collected from three sampling stations: S1-inlet, backwater station, S2-middle of reservoir, S3 outlet, near the dam. The sediments' toxicity was evaluated using a battery of bioassays (Phytotoxkit, Phytotestkit, Ostracodtoxkit F, and Microtox). The highest content of metals (120.5 mg Zn; 22.65 mg Pb; 8.20 mg Cd ∙ kg-1 dw) and all PAHs (∑9361 μg ∙ kg-1 dw) in sediments was found at station S1. The lowest content of metals (86.72 mg Zn; 18.07 mg Cu; 17.20 mg Pb; 3.62 mg Cu; 28.78 mg Ni; 30.52 mg Cr ∙ kg-1 dw) and PAHs (∑4390 μg ∙ kg-1 dw) was found in the sediment from station S2. The ecological risk assessment of the six metals and eight PAHs revealed a high potential toxicity in sediments from stations S1 (PECq = 0.69) and S3 (PECq = 0.56) and a low potential toxicity in sediments from station S2 (PECq = 0.38). The studies also showed the actual toxicity of sediments for the test organisms. The sediment pore water was least toxic compared to the whole sediment: solid phases > whole sediment > pore water. The most sensitive organism for metals and PAHs in bottom sediments was Lepidium sativum, and in pore water-Sorghum saccharatum. The concentration of metals and PAHs in bottom sediments generally did not affect the toxicity for other organisms. Clay content and organic C content are likely to be important factors, which control heavy metal and PAH concentrations in the sediments. Data analysis by PCA found the same origin of metals as well as PAHs-mainly anthropogenic sources. The obtained information demonstrated the need to integrate ecotoxicological and chemical methods for an appropriate ecological risk assessment.

Bioassays for toxicological risk assessment of landfill leachate: A review

Landfilling is the most common solid waste management practice. However, there exist a potential environmental risk to the surface and ground waters due to the possible leaching of contaminants from the landfill leachates. Current municipal solid waste landfill regulatory approaches consider physicochemical characterization of the leachate and do not assess their potential toxicity. However, assessment of toxic effects of the leachates using rapid, sensitive and cost-effective biological assays is more useful in assessing the risks as they measure the overall toxicity of the chemicals in the leachate. Nevertheless, more research is needed to develop an appropriate matrix of bioassays based on their sensitivity to various toxicants in order to evaluate leachate toxicity. There is a need for a multispecies approach using organisms representing different trophic levels so as to understand the potential impacts of leachate on different trophic organisms. The article reviews different bioassays available for assessing the hazard posed by landfill leachates. From the review it appears that there is a need for a multispecies approach to evaluate leachate toxicity.

General baseline toxicity QSAR for nonpolar, polar and ionisable chemicals and their mixtures in the bioluminescence inhibition assay with Aliivibrio fischeri

The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs. To include all types of environmentally relevant organic pollutants we developed a general baseline toxicity QSAR using liposome-water distribution ratios as descriptors. Previous limitations in availability of experimental liposome-water partition constants were overcome by reliable prediction models based on polyparameter linear free energy relationships for neutral chemicals and the COSMOmic model for charged chemicals. With this QSAR and targeted mixture experiments we could demonstrate that ionisable chemicals fall in the applicability domain. Most investigated water pollutants acted as baseline toxicants in this bioassay, with the few outliers identified as uncouplers or reactive toxicants. The main limitation of the Microtox assay is that chemicals with a high melting point and/or high hydrophobicity were outside of the applicability domain because of their low water solubility. We quantitatively derived a solubility cut-off but also demonstrated with mixture experiments that chemicals inactive on their own can contribute to mixture toxicity, which is highly relevant for complex environmental mixtures, where these chemicals may be present at concentrations below the solubility cut-off.

Spatial distribution of trace elements and ecotoxicity of bottom sediments in Rybnik reservoir, Silesian-Poland

The aim of study was to integrate chemical analyses and toxicity bioassays in order to assess the environmental risk connected with the presence of trace elements in the sediments. This study examined the ecological significance of trace elements in bottom sediments by applying a set of complementary sediment quality assessment methods sediment quality guidelines (SQGs) (mean probable effect concentration quotient (PECQ)), potential ecological risk index (PERI), contamination degree (C d) and two bioassays: the bacterial luminescence inhibition test with Vibrio fischeri on sediment elutriates and the direct contact test with the ostracod crustacean Heterocypris incongruens. The samples were collected from 50 stations of Rybnik reservoir. The reservoir is a region with enormous concentration of industry, mainly hard coal mining, electric power industry, and transportation. Despite the high diversity in metal concentration in the sediments, the spatial distribution of trace elements in the sediments was very similar. Moreover, the strong positive correlations between individual pairs of trace elements indicate that they may derive from a similar source and move together. According to mean PECQs, 68 % of the samples were potentially non-toxic and 32 % of the samples were potentially toxic. PERI values suggested that 70 % of the sediment sampling sites exhibited low ecological risk from metal pollution while 24 % of the samples had severe and serious risk. Based on our combined evaluation, we believe that Cd and Cu in the sediment samples frequently caused adverse biological effects. Higher toxic responses were observed in the Microtox test than in the Ostracodtoxkit test. All the sediment samples were found toxic to V. fischeri, and 96 % of the samples had effect percentages >50 %. For H. incongruens, 12 % of the sediments were not toxic and 44 % had effect percentages >50 %. In order to perform a complex assessment of the environmental impact of metal pollution, both chemical and ecotoxicological analysis should be carried out.

Are combined AOPs effective for toxicity reduction in receiving marine environment? Suitability of battery of bioassays for wastewater treatment plant (WWTP) effluent as an ecotoxicological assessment

Ecotoxicological assessment of three different wastewater treatment plant (WWTP) effluents D1, D2 and D3 was performed before and after tertiary treatment using combination of advanced oxidation processes (AOPs). A multibarrier treatment (MBT) consisting of microfiltration (MF), hydrogen peroxide photolysis (H2O2/UVC) and catalytic wet peroxide oxidation (CWPO) was applied for all effluents. Sparus aurata, Paracentrotus lividus, Isochrysis galbana and Vibrio fischeri, representing different trophic levels, constituted the battery of bioassays. Different acute toxicity effects were observed in each WWTP effluents tested. The percentage of sea urchin larval development and mortality fish larvae were the most sensitive endpoints. Significant reduction (p < 0.05) of effluent's toxicity was observed using a classification pT-method after MBT process. Base on obtained results, tested battery of bioassays in pT-method framework can be recommended for acute toxicity preliminary evaluation of WWTP effluents for the marine environment.

Methods for evaluating the pollution impact of urban wet weather discharges on biocenosis: A review

Rainwater becomes loaded with a large number of pollutants when in contact with the atmosphere and urban surfaces. These pollutants (such as metals, pesticides, PAHs, PCBs) reduce the quality of water bodies. As it is now acknowledged that physico-chemical analyses alone are insufficient for identifying an ecological impact, these analyses are frequently completed or replaced by impact studies communities living in freshwater ecosystems (requiring biological indices), ecotoxicological studies, etc. Thus, different monitoring strategies have been developed over recent decades aimed at evaluating the impact of the pollution brought by urban wet weather discharges on the biocenosis of receiving aquatic ecosystems. The purpose of this review is to establish a synthetic and critical view of these different methods used, to define their advantages and disadvantages, and to provide recommendations for futures researches. Although studies on aquatic communities are used efficiently, notably on benthic macroinvertebrates, they are difficult to interpret. In addition, despite the fact that certain bioassays lack representativeness, the literature at present appears meagre regarding ecotoxicological studies conducted in situ. However, new tools for studying urban wet weather discharges have emerged, namely biosensors. The advantages of biosensors are that they allow monitoring the impact of discharges in situ and continuously. However, only one study on this subject has been identified so far, making it necessary to perform further research in this direction.

Assessment of heavy metals mobility and toxicity in contaminated sediments by sequential extraction and a battery of bioassays

The aim of this study was to assess heavy metals mobility and toxicity in sediments collected from a dam reservoir in the conditions of intensive human impact by using chemical fractionation and a battery of bioassays. In the studies, the test organisms were exposed to substances dissolved in water (Microtox, Phytotestkit) as well to substances absorbed on the surface of solid particles (Phytotoxkit, Ostracodtoxkit F). The studies showed that sediments from the Rybnik reservoir are toxic, but the tested organisms showed different sensitivity to heavy metals occurring in the bottom sediments. The sediment samples were classified as toxic and very toxic. Moreover, the studies showed a higher toxicity in solid phases and whole sediment than in pore water. The lowest sensitivity was observed in H. incongruens (solid phases) and V. fischeri (pore water, whole sediment). The studies revealed that the toxicity of the sediments is caused mainly by heavy metal forms associated with the solid phase of the sediments. The studies did not confirm the metals occurring in fraction I (exchangeable) to be bioavailable and toxic to living organisms because most correlations between the metal concentration in fraction I and the response of the organisms were negative. The highest mobility from the bottom sediments was found in zinc, average mobility--in copper, cadmium and nickel, and low mobility--in chromium and lead. Organic matter is likely to be the most important factor controlling metal distribution and mobility in the studied sediments.

High-throughput screening assay for the environmental water samples using cellular response profiles

Chemical and physical analyses are commonly used as screening methods for the environmental water. However, these methods can only look for the targeted substance but may miss unexpected toxicants. Furthermore, the synergistic effects of mixture cannot be detected. In order to set up the assay criteria for determining various biological activities at a cellular level that could potentially lead to toxicity of environmental water samples, a novel test based on cellular response by using Real-Time Cellular Analyzer (RTCA) is proposed in this study. First, the water sample is diluted to a series of strengths (80%, 60%, 40%, 30%, 20% and 10%) to get the multi-concentration cellular response profile. Then, the area under the cellular response profile (AUCRP) is calculated. Comparing to the normal cell growth of negative control, a new biological activity index named Percentage of Effect (PoE) has been presented which reflects the cumulative inhibitory activity of cell growth over the log-phase. Finally, a synthetical index PoE50 is proposed to evaluate the intensity of biological activities in water samples. The biological experiment demonstrates the effectiveness of the proposed method.

The microbiotest battery as an important component in the assessment of snowmelt toxicity in urban watercourses--preliminary studies

The aim of the study was to use a battery of biotests composed of producers (Selenastrum capricornutum, Sorghum saccharatum, Lepidium sativum, and Sinapis alba), consumers (Thamnocephalus platyurus), and decomposers (Tetrahymena thermophila) to evaluate the toxicity of snowmelt and winter storm water samples. The toxicity of the samples collected in the winter period December to February (2010-2011), in one of the largest agglomerations in Poland, the city of Lodz, was compared to that of storm water samples taken under similar conditions in June. The most toxic snowmelt samples were found to be high acute hazard (class IV), while the remaining samples were rated as slight acute hazard (class II). L. sativum (in the Phytotox test) was the most sensitive test organism, giving 27 % of all toxic responses, followed by S. capricornutum with 23 % of all responses. T. thermophila was the least sensitive, with only 2 % of all toxic responses. The greatest range of toxicity was demonstrated by samples from the single family house catchment: no acute hazard (class I) to high acute hazard (class IV).

Chemical pollution and toxicity of water samples from stream receiving leachate from controlled municipal solid waste (MSW) landfill

The present study was aimed to determine the impact of municipal waste landfill on the pollution level of surface waters, and to investigate whether the choice and number of physical and chemical parameters monitored are sufficient for determining the actual risk related to bioavailability and mobility of contaminants. In 2007-2012, water samples were collected from the stream flowing through the site at two sampling locations, i.e. before the stream׳s entry to the landfill, and at the stream outlet from the landfill. The impact of leachate on the quality of stream water was observed in all samples. In 2007-2010, high values of TOC and conductivity in samples collected down the stream from the landfill were observed; the toxicity of these samples was much greater than that of samples collected up the stream from the landfill. In 2010-2012, a significant decrease of conductivity and TOC was observed, which may be related to the modernization of the landfill. Three tests were used to evaluate the toxicity of sampled water. As a novelty the application of Phytotoxkit F™ for determining water toxicity should be considered. Microtox(®) showed the lowest sensitivity of evaluating the toxicity of water samples, while Phytotoxkit F™ showed the highest. High mortality rates of Thamnocephalus platyurus in Thamnotoxkit F™ test can be caused by high conductivity, high concentration of TOC or the presence of compounds which are not accounted for in the water quality monitoring program.

Chemical properties and toxicity of soils contaminated by mining activity

This research is aimed at assessing the total content and soluble forms of metals (zinc, lead and cadmium) and toxicity of soils subjected to strong human pressure associated with mining of zinc and lead ores. The research area lay in the neighbourhood of the Bolesław Mine and Metallurgical Plant in Bukowno (Poland). The study obtained total cadmium concentration between 0.29 and 51.91 mg, zinc between 7.90 and 3,614 mg, and that of lead between 28.4 and 6844 mg kg(-1) of soil d.m. The solubility of the heavy metals in 1 mol dm(-3) NH4NO3 was 1-49% for zinc, 5-45% for cadmium, and <1-10% for lead. In 1 mol HCl dm(-3), the solubility of the studied metals was much higher and obtained values depending on the collection site, from 45 to 92% for zinc, from 74 to 99%, and from 79 to 99% for lead. The lower solubility of the heavy metals in 1 mol dm(-3) NH4NO3 than 1 mol HCl dm(-3) is connected with that, the ammonium nitrate has low extraction power, and it is used in determining the bioavailable (active) form of heavy metals. Toxicity assessment of the soil samples was performed using two tests, Phytotoxkit and Microtox(®). Germination index values were between 22 and 75% for Sinapis alba, between 28 and 100% for Lepidium sativum, and between 10 and 28% for Sorghum saccharatum. Depending on the studied soil sample, Vibrio fischeri luminescence inhibition was 20-96%. The sensitivity of the test organisms formed the following series: S. saccharatum > S. alba = V. fischeri > L. sativum. Significant positive correlations (p ≤ 0.05) of the total and soluble contents of the metals with luminescence inhibition in V. fischeri and root growth inhibition in S. saccharatum were found. The general trend observed was an increase in metal toxicity measured by the biotest with increasing available metal contents in soils. All the soil samples were classified into toxicity class III, which means that they are toxic and present severe danger. Biotest are a good complement to chemical analyses in the assessment of quality of soils as well as in properly managing them.

Phytotoxkit/Phytotestkit and Microtox® as tools for toxicity assessment of sediments

The aim of the study was to use bioassays to evaluate the toxicity of pore water, sediments and sediments elutriates. Furthermore, a possible relationship between observed toxicity and results of chemical analysis was examined. Sediment (0-10 cm) samples were collected from 21 locations in Zeslawice reservoir, Southern Poland using an Ekman sampler. Toxicity assessment of the sediment and pore water samples was performed using direct-contact tests Phytotoxkit/Phytotestkit and Microtox®. Inhibition of seed germination in the test plants was from -25 to 38 percent for sediment and from 0 to 50 percent for pore water, whereas inhibition of root growth was within a range from -42 to 37 percent for sediment and from -49 to 37 percent for pore water. Depending on the sediments, Vibrio fischeri luminescence inhibition was from -18 to 40 percent for sediments elutriates and from -12 to 28 percent for pore water. The toxicity tests showed a positive correlation between metals and the root growth inhibition in Lepidium sativum and Sinapis alba as well as the luminescence inhibition in V. fischeri. No significant correlations were found between the inhibition of luminescence and the phytotoxicity assays, so these analyses do not show a similar sensitivity to toxicants in the sediments. While estimating the sensitivity of the performed biotests, the highest number of toxic responses was recorded in the Microtox® test towards V. fischeri. Among the plant species, Sorghum saccharatum appears to be the most sensitive plant species. Most of the examined sediment samples (67 percent) were classified as class II (low-toxic samples, low acute hazard) and 33 percent of the examined samples were class I (no essential toxic effect, non-toxic sample, no acute hazard) in terms of toxicity. Most of the pore water samples (71 percent) were also classified as class II.

Hazard assessment of sediments from a wetland system for treatment of landfill leachate using bioassays

Four bioassays were used in this study for the hazard assessment of sediments from sediment traps and several ponds in a treatment wetland for landfill leachate at Atleverket, Sweden. In the 6-day solid phase microbiotest with the sediment-dwelling crustacean Heterocypris incongruens both acute and chronic effects were observed with a gradual decrease and loss of toxicity with treatment in the wetland system. Some samples showed a low toxicity in porewater and only one sample was weakly toxic in the whole sediment test when assessed with Aliivibrio fischeri (Vibro fischeri). No genotoxicity was detected in the umu test. The toxicity response in the H4IIE- luc test evaluating the presence of dioxin-like compounds was considerably higher in the samples from the sediment traps. The hazard of the sediment therefore appears to be highest in the sediment traps and pond 1 with the methods employed. The result indicates that the wetland system has a design supporting the concentration and sequestration of toxic substances in the first part of the wetland. Based upon the results we suggest that hazard assessment of sediments from other treatment wetlands for landfill leachate should be conducted.

The toxicity of selected trace metals to Lecane inermis rotifers isolated from activated sludge

The aim of the study was to assess the toxicity of a range of trace metals to the rotifer Lecane inermis, a species tested as a potential biological tool to control activated sludge bulking caused by overgrowth of filamentous bacteria in wastewater treatment plants. LC50 values (concentration lethal to 50 % of individuals, mg dm(-3)) were ranked in the following order: Cu < Al < Fe < Zn < Sn < Mn. L. inermis apparently is more sensitive to metals than other aquatic species widely used as model organisms in ecotoxicological testing, making it potentially useful for quick ecotoxicological tests.

Assessing the toxicity of chemical compounds associated with land-based marine fish farms: the sea urchin embryo bioassay with Paracentrotus lividus and Arbacia lixula

In aquaculture, disinfection of facilities, prevention of fish diseases, and stimulation of fish growth are priority goals and the most important sources of toxic substances to the environment, together with excretory products from fish. In the present study, embryos of two species of sea urchin (Paracentrotus lividus and Arbacia lixula) were exposed to serial dilutions of six antibiotics (amoxicillin (AMOX), ampicillin, flumequine (FLU), oxytetracycline (OTC), streptomycin (ST), and sulfadiazine [SFD]) and two disinfectants (sodium hypochlorite (NaClO) and formaldehyde [CH(2)O]). Alterations in larval development were studied, and the effective concentrations (ECs) were calculated to evaluate the toxicity of the substances. Both species showed similar sensitivities to all substances tested. Disinfectants (EC(50) = 1.78 and 1.79 mg/l for CH(2)O; EC(50) = 10.15 and 11.1 mg/l for NaClO) were found to be more toxic than antibiotics. AMOX, OTC, and ST caused <20 % of alterations, even at the highest concentrations tested. FLU was the most toxic to P. lividus (EC(50) = 31.0 mg/l) and SFD to A. lixula (EC(50) = 12.7 mg/l). The sea urchin bioassay should be considered within toxicity assessment-monitoring plans because of the sensitivity of larvae to disinfectants.

Ecotoxicological characterisation of sedimentation in the Kis-Balaton Water Protection System

The main function of the Kis-Balaton Water Protection System is to retain nutrients and total suspended solids, thus protecting the water quality of Lake Balaton. In this paper, the toxic nature of the sediment in the 2nd reservoir of the KBWPS has been characterised, using a battery of tests: Vibrio fischeri acute bioassay on whole sediment samples, and V. fischeri bioassay on pore water and elutriate samples. The latest version of the V. fischeri bioluminescence inhibition was applied, the Flash assay which uses a kinetic mode and is able to detect the toxicity of solid, turbid/coloured samples. Whole sediment toxicity showed a clear spatial distribution of toxicity, in parallel with elutriate toxicity. However, no pore water toxicity was detected, leading to the conclusion that contaminants are not water soluble.

Implementation of a minimal set of biological tests to assess the ecotoxic effects of effluents from land-based marine fish farms

Environmental monitoring plans (EMP) that include chemical analysis of water, a battery of bioassays and the study of local hydrodynamic conditions are required for land-based marine aquaculture. In this study, the following standardized toxicity tests were performed to assess the toxicity of effluents from eight land-base marine fish farms (LBMFFs) located on the northwest coast of Spain: bacterial bioluminescence (with Vibrio fischeri at 15 and 30 min), microalgal growth (with Phaeodactyllum tricornutum and Isochrysis galbana) and sea urchin larval development (with Paracentrotus lividus and Arbacia lixula). These bioassays were evaluated for inclusion in routine fish farm monitoring. Effective concentrations (EC(5), EC(10), EC(20), EC(50)) for each bioassay were calculated from dose-response curves, obtained by fitting the bioassay results to the best parametric model. Moreover, a graphical method of integrating the results from the battery of bioassays and classifying the toxicity was proposed, and the potential ecotoxic effects probe (PEEP) index was calculated. The bacterial bioluminiscence test at 30min, growth of I. galbana and larval development of A. lixula were found to be the most sensitive and useful tests. Graphical integration of these test results enabled definition of the ecotoxicological profiles of the different farms. The PEEP index, considering EC(20), efficiently reflected the toxic loading potential of LBMFF effluents. In conclusion, a battery of bioassays with species from different low trophic levels is recommended as a rapid and cost-effective methodology for assessing LBMFF discharges. The graphical integration method and the PEEP index are proposed for consideration in EMPs for such farms.

Groundwater quality assessment of one former industrial site in Belgium using a TRIAD-like approach

Contaminated industrial sites are important sources of pollution and may result in ecotoxicological effects on terrestrial, aquatic and groundwater ecosystems. An effect-based approach to evaluate and assess pollution-induced degradation due to contaminated groundwater was carried out in this study. The new concept, referred to as "Groundwater Quality TRIAD-like" (GwQT) approach, is adapted from classical TRIAD approaches. GwQT is based on measurements of chemical concentrations, laboratory toxicity tests and physico-chemical analyses. These components are combined in the GwQT using qualitative and quantitative (using zero to one subindices) integration approaches. The TRIAD approach is applied for the first time on groundwater from one former industrial site located in Belgium. This approach will allow the classification of sites into categories according to the degree of contaminant-induced degradation. This new concept is a starting point for groundwater characterization and is open for improvement and adjustment.

Assessment of wastewater effluent quality in Thessaly region, Greece, for determining its irrigation reuse potential

The objective of the present study is to assess wastewater effluent quality in Thessaly region, Greece, in relation to its physicochemical and microbiological burden as well as its toxic potential on a number of organisms. Wastewater may be used for agricultural as well as for landscape irrigation purposes; therefore, its toxicity potential is quite important. Thessaly region has been chosen since this region suffers from a distinct water shortage in summer period necessitating alternative water resources. During our research, treated effluents from four wastewater treatment plants operating in the region (Larissa, Volos, Karditsa, and Tirnavos) were tested for specific physicochemical and microbiological parameters [biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity, selected metals presence (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As), and fecal coliforms' (FC) number]. The effluents were also tested for their toxicity using two different bioassays (Daphnia magna immobilization test and Phytotoxkit microbiotest). The findings were compared to relative regulations and guidelines regarding wastewater reuse for irrigation. The results overall show that secondary effluents in Thessaly region are generally acceptable for reuse for irrigation purposes according to limits set by legislation, if effective advanced treatment methods are applied prior to reuse. However, their potential toxicity should be closely monitored, since it was found that it may vary significantly in relation to season and location, when indicator plant and zooplankton organisms are used.

Evaluation of the toxicity of river and creek sediments in Hungary with two different methods

The aim of this study is to compare the responses of two different ecotoxicological methods for the determination of the toxic hazard of river or creek sediments in Hungary. Since water quality is intrinsically linked to sediment quality, the ecotoxicological control of sediments is also very important in the water quality policy. The 2000/60 EC Water Framework Directive aims at achieving a good qualitative and quantitative status of all water bodies by 2015. Fifteen sediments and four sludges were collected at different sites in Hungary, which are contaminated by industrial sewage. The first assay is the acute toxicity test with the crustacean Daphnia magna Straus (OECD 202) using larvae less than 1 day old, and an exposure time of 2 days. The second assay is the Ostracodtoxkit F with freshly hatched larvae of the crustacean Heterocypris incongruens and an exposure time of 6 days. The Ostracodtoxkit F test is a "direct sediment contact" bioassay, in which the test organisms are in continuous contact with the sediments. The Daphnia tests were applied on water extracts of the sediment without any contact of the test organisms with the contaminated sediment. The same 1:4 water/sediment ratio has been applied to both tests. The results showed higher toxic effects of the sediments to H. incongruens than to D. magna confirming the need to complement "water only" tests with "solid phase" assays for a meaningful evaluation of the toxic hazard of aquatic environments. The sensitivity of H. incongruens is similar to that of the other test species which are currently used for solid-phase assays. The growth inhibition of H. incongruens is a very sensitive endpoint for sediment toxicity testing. The sediment toxicity tested by ostracods showed strong correlation with concentration of total chromium, lead, and cadmium together.

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Alqueva Reservoir (Portugal)

BACKGROUND, AIM, AND SCOPE

Freshwater reservoirs can be impacted by several hazardous substances through inputs from agricultural activity, sewage discharges, and groundwater leaching and runoff. The water quality assessment is very important for implementation of the monitoring and remediation programs to minimize the risk promoted by hazardous substances in aquatic ecosystems. Evaluation of the degree of contamination of aquatic environments must not take in account only its chemical characterization but it must be complemented with biological assays, which determine potential toxic effects and allows an integrated evaluation of its effects in populations and aquatic ecosystem communities. The application of this type of strategy has clear advantages allowing a general evaluation of the effects from all the water components, including those due to unknown substances and synergic, antagonistic, or additive effects. There are only a few studies that reported ecotoxicological acute end points, for the assessment of surface water quality, and the relationship among toxicity results and the anthropogenic pollution sources and the seasonal period. The aim of this study was to assess the ecotoxicological characterization of the surface water from Alqueva reservoir (South of Portugal) and to evaluate the influence of anthropogenic sources of pollution and their seasonal variation in its toxicity. The construction of Alqueva reservoir was recently finished (2002) and, to our knowledge, an ecotoxicological assessment of its surface water has not been performed. Because of that, no information is available on the possible impact of pollutants on the biota. The surface water toxicity was assessed using acute and chronic bioassays. The results are to be used for developing a monitoring program, including biological methods.

MATERIALS AND METHODS

Water samples were collected during 2006-2007, at each of the nine sampling sites selected in Alqueva reservoir. These sampling points allow an assessment at the upstream (Sra. Ajuda, Alcarrache, Alamos-Captação), at the middle (Alqueva-Montante, Alqueva-Mourão, Lucefecit), and at the downstream of the water line (Alqueva-Jusante; Ardila-confluência; Moinho das Barcas). The campaigns occurred in February, March, May, July, September, and November of 2006 and February, March, and May of 2007. The rainy season comprised November, February, and March, and the dry season included May, July, and September. A total of 81 samples were collected during the study period. The physical-chemical parameters were analyzed following standard and recommended methods of analysis (APHA et al. 1998). The pesticide analyses were performed using gas chromatography according to DIN EN ISO 6468 (1996). Surface water ecotoxicity was evaluated using the following bioassays: Vibrio fischeri luminescence inhibition, Thamnocephalus platyurus mortality, and Daphnia magna immobilization and reproduction assay. The Spearman rank correlation coefficients were used to evaluate the associations between the water sample physicochemical properties (from each sampling station in each season) and the acute and chronic toxicological effects, with a level of significance p < 0.05.

RESULTS

In the acute toxicity study, the species that was found to be the most sensitive was T. platyurus. T. platyurus detected a higher number of toxic water samples during the dry season. Concerning the luminescent inhibition of V. fischeri, the results showed that this organism detected a great number of toxic water samples in rainy seasons. The water samples, which promoted higher toxic effects towards this species, were from the north and from the middle of the reservoir. The correlation analysis showed that V. fischeri luminescent inhibition (%) was positively correlated with total phosphorus, chlorpyrifos, iron, and arsenic. T. platyurus mortality (%) was positively correlated with the water pH, 5-day biochemical oxygen demand (BOD(5)), chlorides, atrazine, simazine, terbuthylazine, and endosulfan sulfate contents. Although the surface waters did not promote acute toxicity to the crustacean D. magna, in the chronic exposure, a significant decrease in the number of juveniles per female was observed, mainly at the dry period. The number of juveniles per female, in the reproduction test of D. magna, was negatively correlated with pH, temperature, BOD(5), chloride, atrazine, simazine, terbuthylazine, and endosulfan sulfate. The water toxicity of the Alqueva water might be due principally to the intensive agriculture activities surrounding the reservoir and to the municipal wastewater discharges.

DISCUSSION

The physicochemical parameters and the pesticide concentrations indicated that the water quality was worse in the north part of the reservoir system. These results are characteristic of the majority of reservoirs, once the construction of the dam promoted, by itself, the impounding of water flow and the increase of compound residence time. The toxicity tests corroborate with the chemical characterization. Acute toxicity of Alqueva water may be a result of the effect promoted by chlorpyrifos, endosulfan sulfate, phosphorus, and iron. Chronic toxicity may be a result of the effect of herbicides, arsenic, organic matter, endosulfan sulfate in mixture. Hence, the water toxicity of the Alqueva might be due principally to the intensive agriculture activities surrounding the reservoir and to the municipal wastewater discharges.

CONCLUSIONS

This study has shown that a large number of samples from different sites of the Alqueva reservoir contained potentially toxic contaminants. The sites with impaired water quality were those located at the north of the reservoir and in the surrounding areas of intensive agricultural activity. The results demonstrated that the use of a screening of acute and chronic toxicity tests with organisms from different trophic levels and with distinct sensibilities allowed the detections of several patterns of toxicity from spatial and temporal variability promoted by natural or anthropogenic sources. The chronic responses showed, especially in the dry season, that some of the species belonging to this aquatic ecosystem might be at risk.

RECOMMENDATIONS AND PERSPECTIVES

The V. fischeri and T. platyurus are two species that should be used in the acute bioassays for the ecotoxicological monitoring programs of this reservoir. It is recommended that other species, such as a productive organism (algae), be included in the next study, once the water reservoir had high levels of herbicides. Ecotoxicological assessment of surface water must integrate initial screening based on acute tests followed always by chronic bioassays. The results implicitly suggest that the implementation of processes of remediation by reducing pollutant input into the reservoir and by the implementation of water treatment processes is important and necessary.

Toxicity of fungicides to natural bacterial communities in wetland water and sediment measured using leucine incorporation and potential denitrification

We assessed potential toxicity of fungicides to natural bacterial communities from a constructed wetland, located in southern Sweden, and compared the sensitivity of two endpoints indicating bacterial activity, leucine incorporation, and potential denitrification, in detecting toxicity. The effects of eight fungicides (benomyl, carbendazim, carboxin, captan, cycloheximide, fenpropimorph, propiconazole, and thiram), two bactericides (bronopol and chlortetracycline) as controls, and one reference compound (3,5-dichlorophenol), were tested in a water-sediment microcosm set-up. Leucine incorporation was measured in both the water and sediment column, while potential denitrification was measured for the entire microcosm. The bactericides and the reference compound gave sigmoid concentration-response curves for both endpoints in all but one case. The fungicides thiram, captan, and benomyl, and to a lesser extent fenpropimorph and propiconazole had quantifiable toxic effects on leucine incorporation, with EC(50) values ranging from 3 to 70 mg l(-1), while carbendazim, carboxin, and cycloheximide had little effect at the investigated concentrations. Only thiram and captan inhibited potential denitrification; the other fungicides showed no quantifiable effect. A greater toxic effect on leucine incorporation was recorded for bacterial communities associated with the water column, compared to the sediment column, for all tested compounds. Leucine incorporation was the more sensitive method for toxicity assessment of bacterial communities, and also allowed for a rapid and simple way of comparing exposure in the sediment and water column, making it an attractive standard method for community based toxicological assays in aquatic environments.

Effect of lixiviated sediments affected with treated water on Selenastrum capricornutum, Printz and Origanum vulgare L

Xochimilco is an area of Mexico City fulfilling important ecological functions. However, the water of the canal network in the lacustrine zone of Xochimilco is supplied by the water treatment plants of the city, implying a risk of accumulated contaminants in the sediments. This study reports the effect of lixiviates obtained from sediments collected in the canals of Xochimilco on the growth of the alga Selenastrum capricornutum and the angiosperm Origanum vulgare. Three factors were tested: (a) water source in terms of the effluent from the two water treatment plants (urban waste-water, located at Cerro de la Estrella (CE) and urban-rural waters at San Luis Tlaxialtemalco (SLT); (b) sampling season (January, dry season; May and September, rainy season; and (c) distances from the water discharge point in the Xochimilco's main canal (5200 and 1000 m for CE, and 0, 200 m for SLT). The chemical water properties analyzed were: pH, electrical conductivity, N-NO(3), N-NH(3), N(Total), P-PO(4) and P(Total). The alga was more sensitive to the contaminants than O. vulgare, showing growth inhibition of 93-100%. The effect of sampling season on the inhibition of algal growth was ordered as follows: September > May > January. Lixiviates obtained from sediment samples 200 and 1000 m from the main point of water discharge caused a higher algal growth inhibition than the samples obtained at the source point. Lixiviate promoted the growth of seedlings of O. vulgare.

Evaluation of toxic and interactive toxic effects of three agrochemicals and copper using a battery of microbiotests

Three commonly used test organisms of different trophic levels (Vibrio fischeri, Pseudokirchneriella subcapitata and Daphnia magna) were exposed to selected agrochemicals (fosthiazate, metalaxyl-M, imidacloprid) and copper, in single doses or in binary mixtures. The toxicity of each single compound varied up to two orders of magnitude, depending on the test species examined. V. fischeri was the most sensitive test organism regarding fosthiazate and metalaxyl-M, indicating an IC(50) value of 0.20 mg/L (0.17-0.25 mg/L) and 0.88 mg/L (0.35-1.57 mg/L), respectively. Imidacloprid was the least toxic compound, indicating an EC(50) value on D. magna of 64.6 mg/L (43.3-122.5 mg/L) and an IC(50) value on V. fischeri of 226 mg/L (159-322 mg/L), while for imidacloprid at a concentration of 1000 mg/L the effect on P. subcapitata was lower than 50%. Copper was the most toxic compound towards all test organisms exhibiting the highest toxic effect on P. subcapitata, with an IC(50) value of 0.05 mg/L (0.003-0.008 mg/L). The toxic effects of the binary mixtures have been compared to the theoretically expected effect, resulting from a simple mathematical model based on the theory of probabilities. The independent action model was used in order to predict the theoretically expected effect. The interactive effects were mostly antagonistic or additive, while in few cases (interactive effects of metalaxyl-M and copper on V. fischeri) a synergistic mode of action was observed for some concentration combinations. Experiments showed that interactive effects of chemicals may vary depending on the test species used as well as on the chemicals and their respective concentrations. Although most of the concentrations of chemicals tested in this study are higher than the ones usually found in natural environment, the evaluation of their interactive toxic effects using a battery of bioassays may comprise a useful tool for the estimation of the environmental hazard of chemicals.