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This study investigated the degradation of benzophenone-4 (BP-4) in a UV/chlorine disinfection process, with chlorination and UV disinfection as comparisons. With a degradation efficiency of 80% after 10 s, the UV/chlorine process significantly enhanced the degradation of BP-4. However, a rebound of 36% of the initial concentration was observed in the UV/chlorine process ([free active chlorine (FAC)]0:[BP-4]0 = 1:1, pH = 7). The same tendency appeared under the addition of alkalinity, Cl−, and humic acid (HA). This work interpreted this interesting kinetic tendency from the perspective of mechanism. In fact, the transformation between the chlorinated product P1 and BP-4 was reversible under certain conditions. The inhomogeneous charge distribution of the C Cl bond in P1 led to the photolytic dechlorination of P1. This transformation caused an increase in BP-4 concentration. In addition, the increase in the UV light power promoted the photodecomposition of P1 under the experimental condition. In addition, this study evaluated the change in absorbable organic halogens (AOX) and three kinds of toxicity changes in the BP-4 solution after chlorination and the UV/chlorine process, including the acute toxicity of luminescent bacteria, endocrine disrupting effect and cytotoxicity. The UV/chlorine process exhibited lower ecotoxicity than chlorination in water treatment.

Diclofenac was frequently found in various waters, indicating conventional wastewater treatment methods ineffective in its removal. In this study, LaFeO3 (LFO) was synthesized and its catalytic activity of LFO as the activator of different oxidants such as persulfate (PS), hydrogen peroxide and peroxylmonosulfate (PMS) was evaluated in terms of DCF degradation. The influence of calcination temperature was examined on the catalytic activity of LFO. The effects of various parameters including pH levels, PMS concentration, LFO dose and initial DCF concentration were investigated on DCF degradation rate. The marginal effects of PMS concentration and LFO dose were compared. Langmuir-Hinshelwood (LH) model was used to quantitatively describe DCF degradation reaction in LFO/PMS system. The two constants, k (Limiting reaction rate at maximum coverage) and K (Equilibrium adsorption constant), were determined on the basis of LH model. The performance of LFO/PMS process was also estimated in the presence of various inorganic anions. The potential toxicity of LFO and PMS were evaluated using phytoplankton and the toxicity evolution during DCF degradation was also investigated using luminescent bacteria. This contribution provides a basic study regarding the potential application of heterogeneous PMS activation by perovskite LFO for both DCF removal and toxicity elimination.

Due to their widespread use and harmful effects on aquatic environment, sulfonamide antibiotics (SAs) have become an emerging pollutant of great concern around the world. In this study, we investigated the degradation process and mechanism of sulfamerazine (SMR), sulfadiazine (SDZ), and sulfapyridine (SPD) by electron-beam irradiation (EBI). The results showed that the three SAs were well suited to the pseudo-first-order reaction kinetics, and they could be almost completely removed with high efficiency (5 kGy). Among the environmental factors, pH (3.0) and O2 atmosphere can further enhance the removal of the sulfonamides (SAs), while NO2− has the most pronounced degrading inhibitory effects among the many ions, these results illustrate that hydroxyl radicals play a dominant role. Compared with SMR and SDZ, the degree of mineralization of lower molecular weight SPD is obvious (45%). LC-MS and DFT calculations indicate that the concentrations of degradation products of the three SAs show a tendency to increase and then decrease, demonstrating that EBI can achieve efficient removal and further mineralization of SAs. Meanwhile, the results of the common product 4-Aminophenol produced during the degradation process further indicate that HO is the predominant reactive oxygen species (ROS). In addition, acute toxicity experiments with luminescent bacteria and predictions of ECOSAR procedures proved the toxic effects greatly decreased after the degradation. This study provides new ideas for achieving efficient and profound removal of emerging pollutants from the aquatic environment.

Trans-resveratrol becomes more and more popular all over the world as a powerful antioxidant. Since its positive properties, including antioxidant, anti-inflammatory, anti-tumor are indisputable, nowadays trans-resveratrol is used as a component of various products from nutriceutics to body care formulations, where it is supposed to behave as natural antioxidant and anti-aging compound. It is also added to food packaging materials to increase their stability or/and prevent oxidation. Nevertheless, being released to the environment resveratrol easily forms various transformation products with potentially negative environmental and health effects. The present paper deals with transformation of pure resveratrol and its formulation used as UV-protectors in conditions of aquatic chlorination. Over 80 transformation products were tentatively identified using gas chromatography-high resolution mass spectrometry (GC-HRMS) and ultra pressure liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). Chlorinated phenols and biphenyls are the most relevant among them. Estimation of toxicity of resveratrol products was carried out using luminescent bacteria V. fischeri tests.

In this study, the applicability of UV absorbance at 254 nm (UV254) and volatile fatty acids (VFAs) to serve as reliable surrogates to predict acute toxicity of traditional Chinese medicine (TCM) wastewater was investigated. The medicine residues and VFAs were identified as main components of the TCM wastewater, and their individual and joint toxicity assays were operated with luminescent bacteria. The median effective concentration (EC50) values of medicine residues and VFAs were in the range of 26.46-165.55 mg/L and 11.45-20.58 g/L, respectively. The joint toxicity action modes of medicine residues, VFAs and medicine residues-VFAs were identified as additive, additive and synergistic respectively. UV254 and VFAs showed better correlations with acute toxicity according to the correlation analysis, compared with other conventional parameters. The regression model was a good fit for toxic unit (TU50) as a function of UV254 and VFAs according to the stepwise regression method (adjusted R2 = 0.836). Validation of the model to the pilot-scale samples provided satisfactory prediction results in the influent and hydrolysis acidification effluent samples tests, but for EGSB effluent and final effluent samples, the model needed further optimization. Surrogates prediction using UV254 and VFAs provided a valuable and cost-saving tool for rapid or on-line monitoring of acute toxicity of TCM wastewater.

Advanced oxidation processes (AOPs) can degrade heavy metal complexes in wastewater to improve the removal efficiency of metals. However, the influences of AOP treatments on toxicity induced by metal complexes are not well understood. This study compared the toxicity induced by EDTA-copper (Cu) after UV/persulfate (PS) and UV/H2O2 treatments on luminescent bacteria and human HepG2 cells. The results showed that EDTA-Cu complexes decreased Cu toxicity in luminescent bacteria but increased the cytotoxicity in HepG2 cells, indicating species-specific toxicity. The UV/PS and UV/H2O2 treatments under most pH values and [oxidant]/[EDTA-Cu] conditions decreased the toxicity of EDTA-Cu in HepG2 cells but increased the toxicity in luminescent bacteria. When the ratio of [oxidant] to [EDTA-Cu] was 10, low toxicity in treated solutions was observed in both UV treatment processes. The alkaline precipitation treatment had a significant influence on toxicity reduction after UV/PS treatment; however, it had minimal influence on the UV/H2O2 treatment system. The Cu and total organic carbon (TOC) removal efficiency cannot completely explain the results of toxicity assays. EDTA-Cu intermediates might play important roles in changing the toxicity of EDTA-Cu after both UV treatments. This study provides insights into evaluating the treatment efficiency of UV/PS and UV/H2O2 on EDTA-Cu decomplexation.

The environmental compatibility of reactive fire-retardant coatings (intumescent paints) was investigated by a combination of leaching and ecotoxicological tests. Three representative fire-retardant coating systems were tested using two leaching procedures: “Horizontal Dynamic Surface Leaching Test” (DSLT) and the “Intermittent Immersion Test” (IIT). All eluate fractions (8 for DSLT and 9 for IIT) were analyzed for pH, conductivity, concentration of total organic carbon and selected anions und cations. Additionally, a GC-MS screening of selected fractions was conducted for identification of organic compounds. Eluate fractions 1 + 2 and fraction 7 of the DSLT were analyzed in four ecotoxicological tests (algae, daphnia, fish egg, luminescent bacteria) and in one genotoxicity test (umu). Concentration of most analytes was rather low or below limit of detection for many eluates. Analytes detected in eluates of all three products are Zn, Ba, SO42− and PO43−. Release patterns do not indicate a general trend: some compounds show maximum release in the first fractions while for others the maximum was observed in later test stages. Ecotoxic effects in eluates were found, which were higher in the eluate fraction 7 (maximum lowest ineffective dilution for luminescent bacteria (LIDL) 256) than in the eluate fraction 1 + 2 (maximum LIDL = 24). The sensitivity of the test systems was very different with highest effects for luminescent bacteria, followed by algae and daphnia and without effects in the fish egg test and umu test. A biotest battery for the comprehensive assessment is therefore advisable.

Chlorination is essential to provide safe drinking water. However, this process leads to the formation of disinfection byproducts (DBPs). In this study, tryptophan (Trp) has been selected as a precursor to conduct the chlorine disinfection. Moreover, the factors that affect the formation of trihalomethanes (THMs) and iodinated trihalomethanes (I-THMs) are investigated. The formation pathway of Trp chlorination is proposed based on the intermediate products identified. According to the experimental results, the formation of THMs and I-THMs during Trp chlorination fitted a new first-order kinetic model. The dosage of chlorine, temperature, pH and the ratio of bromide and iodide had major influence on the formation of THMs and I-THMs during chlorination. In addition, the inhibition of luminescent bacteria Vibrio fischeri in the water sample increased during Trp chlorination.

In this study, peroxydisulfate (PDS) was successfully activated by nanoscale zero-valent iron (nZVI) for the degradation of sulfamethoxazole (SMX, antibiotic frequently detected in the environment) in agricultural soils. The results indicated that the degradation of SMX was affected by the nZVI dose, the ratio of SMX/PDS, the ratio of soil/water and reaction temperature, and in cinnamon soils 87.6% of SMX degradation can be achieved within 4 h at 30 °C when the initial nZVI dose was 0.03 g g−1 soil, the molar ratio of SMX/PDS = 1/75 and the soil/water = 1/1. The results of radical scavenger experiments and electron spin resonance (ESR) tests showed that hydroxyl radical ( OH) was the dominant reactive species in this system. The ecotoxicity tests of the soil by germination test, luminescent bacteria experiment and enzyme activity test indicated that the ecotoxicity of soil after treatment was obviously lower than the contaminated soil. In addition, there was almost no effect on plant growth when compared with original soil. Furthermore, this system exhibited a great degradation capacity for SMX in different types of agricultural soils, and the degradation efficiencies of SMX in other four soils were 90.6% (yellow brown earths), 80.8% (brown earths), 86.5% (black soils) and 96.1% (red earths), respectively. This work provides an optional method for agricultural soil pollution control.

Acute toxicities of anaerobic ammonia oxidation (ANAMMOX) substrates and four antibiotics from pharmaceutical wastewaters on ANAMMOX process were reported. Individual and joint acute toxicity assays were performed using 50% inhibitory concentration (IC50). Results showed that IC50 values and their 95% confidence interval of ammonium chloride (A), sodium nitrite (B), penicillin G-Na (C), polymyxin B sulfate (D), chloramphenicol (E) and kanamycin sulfate (F) were 2708.9 (2247.9–3169.9), 1475.4 (1269.9–1680.9), 5114.4 (4946.4–5282.4), 10.2 (1.8–18.6), 409.9 (333.7–486.1) and 5254.1 (3934.4–6573.8) mg L−1 respectively, suggesting toxicities were in the order of D > E > B > A > C > F. Joint acute toxicities of bicomponent mixtures A and B, C and D, C and F, D and F were independent; D and E, E and F were additive while C and E were synergistic. Joint acute toxicities of multicomponent mixtures were synergistic or additive. Luminescent bacteria test is an easy and robust method for forecasting the feasibility of ANAMMOX process for pharmaceutical wastewater treatment.

Since aminophosphonate-based herbicides like glyphosate are currently one of the most popular and widely applied active agent in agrochemistry, there is an urgent need for searching new compounds among this family with potential herbicidal activity, but exhibiting low toxicity against surrounding environment. Six new (5-nitrofurfuryl)-derived aminophosphonates were synthesized for the first time and apart from the only one example of N-benzylamino(5-nitrofuryl)-methylphosphonic acid, it was the first time in the history, when this class of compounds was prepared. Their prospective and real biological properties have been followed up by evaluation of their preliminary ecotoxicology. They have been then investigated in aspect of their phytotoxicity against oat (A. sativa) and common radish (R. sativus) exhibiting moderate-to-severe toxicity for these plants. The significant selectivity towards radish (up to 3 times greater toxicity against radish) was observed in some cases. Title compounds were also tested in terms of their toxicity for freshwater crustaceans H. incongruens (ostracods) and marine luminescent bacteria A. fischeri. Although their harmful action on ostracods was not too much elevated, they were found to be highly toxic for bacteria. Various aspects of their ecotoxicity are discussed in this paper.

A photodegradation technology based on the combination of ultraviolet radiation with H2O2 (UV/H2O2) for degrading tri(chloroisopropyl) phosphate (TCPP) was developed. In ultrapure water, a pseudo-first order reaction was observed, and the degradation rate constant reached 0.0035 min−1 (R2 = 0.9871) for 5 mg L−1 TCPP using 250 W UV light irradiation with 50 mg L−1 H2O2. In detail, the yield rates of Cl− and PO43− reached 0.19 mg L−1 and 0.58 mg L−1, respectively. The total organic carbon (TOC) removal rate was 43.02%. The pH value of the TCPP solution after the reaction was 3.46. The mass spectrometric detection data showed a partial transformation of TCPP into a series of hydroxylated and dechlorinated products. Based on the luminescent bacteria experimental data, the toxicity of TCPP products increased obviously as the reaction proceeded. In conclusion, degradation of high concentration TCPP in UV/H2O2 systems may result in more toxic substances, but its potential application for real wastewater is promising in the future after appropriate optimization, domestication and evaluation.

Triclosan, one of the most widely used disinfectants, has been found to be toxic to animals and human beings. In this paper, triclosan was degraded on TiO 2 nanotube arrays, using a photoelectrocatalytic (PEC) process under UV illumination, with Na 2 SO 4 as the supporting electrolyte. The effect of bias potential was investigated and the results showed that 0 V was the most appropriate potential for the degradation of triclosan. In 30 min, 78.7% of triclosan had degraded during the PEC process. Intermediate analysis showed that 2,7-dichlorodibenzodioxin (DCDD) had formed during the degradation. The toxicity change during the PEC process was investigated using a luminescent bacteria test, with the results demonstrating that the toxicity of the reaction liquid decreased at the beginning and subsequently increased to a stable level. The indications were that some intermediates such as 2,7-dichlorodibenzodioxin was more toxic and stable than triclosan in the solution.

Fenamic acids, one important type of non-steroidal anti-inflammatory drugs, are ubiquitous in environmental matrices. Thus it is of high significance to know the fate of them during chlorination disinfection considering their potential toxicity to the environment and humans. In the present study, the chlorination kinetics of three fenamic acids, i.e. mefenamic acid (MEF), tolfenamic acid (TOL) and clofenamic acid (CLO), were examined at different pHs, which followed second-order reaction under studied conditions. The studied fenamic acids degraded fast, with the largest apparent second-order rate coefficient ( k app ) values of 446.7 M −1 s −1 (pH 7), 393.3 M −1 s −1 (pH 8) and 360.0 M −1 s −1 (pH 6) for MEF, TOL and CLO, respectively. The transformation products (TPs) were identified by solid-phase extraction-liquid chromatography-mass spectrometer and ion-pair liquid-liquid extraction and injection port derivatization-gas chromatography-mass spectrometer. Despite different numbers of TPs were detected for each studied fenamic acid through these two analytical methods, the types of TPs were almost the same; chlorine substitution, oxidation and the joint oxidation with chlorine substitution are transformation reactions involved in chlorination. Moreover, the total toxicity of the TPs was assayed based on luminescent bacteria. Under different pHs, the different types of TPs might form, resulting in the varied total toxicity. The toxicity of all three fenamic acids chlorinated at pH of 8 was greater than those at pHs of 6 and 7. This study provided the information about the kinetics, transformation and toxicity of three fenamic acids during water chlorination, which is important to the drinking water safety.

The European Construction Products Regulation allows Member States to adopt rules for evaluating the environmental impact of their buildings. The aim of the project was to develop recommendations for a test battery for the ecotoxicological assessment of the environmental impact of construction products for outdoor use and contribute to the European harmonization of test methods. From a shortlist of 39 products 20 products were included in the ecotoxicological testing program. Monolithic and plate-like construction products were eluted in the Dynamic Surface Leaching test (DSLT) in accordance with CEN/TS 16637-2, granular products were eluted in a one stage batch test in accordance with DIN EN 12457-1. The eluates were examined in four aquatic toxicity tests (algae, daphnia, luminescent bacteria, fish eggs), a genotoxicity test (umu test) and in the respirometer test (OECD 301 F). Here, low to very high ecotoxicity was observed (up to a dilution factor of 1536). Six out of 8 eluates, whose TOC exceeded 10 mg L −1 showed a good biodegradability above 75%. The intra-laboratory repeatability of the Lowest Ineffective Dilution (LID) usually was within ±1 dilution steps (ecotoxicity tests) and ±2 dilution steps (leaching and ecotoxicity tests). This is acceptable, when considering that the overall variability of sample preparation, leaching test, and bioassays add up. The conclusions lead to practical recommendations for a suitable combination of leaching and ecotoxicity tests.

The aim of the work was to study the biodegradation process of biocomposites prepared from renewable resources and the ecotoxicological assessment of their biodegradation products. Biocomposites from modified starch reinforced with various cellulose fibers were prepared by the extrusion process. Biodegradation studies were carried out according to the ISO respirometic method. Ecotoxicity of biodegradation products was assessed by the luminescent bacteria test. It was found that biodegradation of biocomposites was above 60% within 24 days according to the results of respirometric test. Increase in the amount of natural fiber reinforcement, as well as smaller fiber size increased the biodegradability of biocomposites. On the basis of the preliminary results of the ecotoxicological test using luminescent bacteria it seems that the biodegradation products of the biocomposites studied are ecologically safe.

The use of conventional plastic microplates for a miniaturised luminescent bacteria test may result in an underestimation of the toxicity for poorly water soluble highly adsorbing toxicants such as PAHs. In this study, the suitability of microplates for testing elutriates of PAH-contaminated soils was investigated. The LUMIStox® test was performed as the standard test in the miniaturised format using contaminated soil elutriates and aqueous solutions of four selected PAHs (viz. naphthalene (NAP), acenaphthene (ACE), fluorene (FLU), and phenanthrene (PHE)). For the aqueous PAH-solutions, we observed reduced light inhibition values for the miniaturised bioassay when using black microplates made of polypropylene (PP) and polystyrene (PS) compared to the standard LUMIStox® test. This phenomenon was most likely due to adsorption of toxicants to the microplate surfaces with PAHs of lower water solubility being significantly more affected; however, after minimizing the exposure of samples to plastic surfaces, polystyrene microplates revealed equivalent performance (>80% ‘relative’ light inhibition) to the standard glass cuvette test system. For soil elutriates, black microplates again exhibited slightly lower light inhibition values while white plates made of PS and Barex® resulted in a pronounced overestimation of toxicity for a coloured soil elutriate. In general, microplates were applicable for testing elutriates of PAH-contaminated soils. In cases where samples are coloured or turbid, the application of black microplates is recommended.

A closed-system algal toxicity test with no headspace was applied to evaluate the toxicity of chlorophenols to Pseudokirchneriella subcapitata. The dissolved oxygen production and the growth rate based on cell density were the response endpoints. Phenol and seven chlorophenols were tested using the above test technique. Median effective concentrations (EC50) range from 0.004 to 25.93 mg/l (based on DO production) and 0.0134 to 20.90 mg/l (based on growth rate). No-observed-effect concentration (NOEC) is within the range of 0.001-8.19 mg/l. In general, growth rate is a more sensitive response endpoint than the oxygen production, except for the case of pentachlorophenol. However, the differences in sensitivity between the two parameters were marginal. Furthermore, quantitative structure-activity relationships (QSAR's) based on the n-octanol/water partition coefficient (log P) and the acid dissociation constant (pK(a)) values were established with R(2) ranged from 0.90 to 0.96. From literature data also based on P. subcapitata, the new test method is 1.65-108 times more sensitive than the conventional algal batch tests. A completely different relative-sensitivity relationship among various aquatic organisms was thus observed. The results of this study indicate that the toxicity data of volatile organic chemicals derived by conventional algal toxicity tests may severely underestimate the impact of these toxicants. Our results show that alga is very sensitive to chlorophenols compared to other aquatic organisms such as the luminescent bacteria (the Microtox test), Daphnia magna, and rainbow trout.

Results from two mathematical approaches to predict the toxicity of all the possible binary equitoxic mixtures of Co, Cd, Cu, Zn and Pb were compared to the observed toxicity of these mixtures to Vibrio fischeri bacteria. Combined effect of the metals was found to be antagonistic for Co-Cd, Cd-Zn, Cd-Pb and Cu-Pb, synergistic for Co-Cu and Zn-Pb and merely additive in other cases, revealing a complex pattern of possible interactions. Besides, Cd appears much less toxic to the bacterial model than to animal cells. The synergistic effect of the Co-Cu combination and the strong lowering of Pb toxicity in the presence of Cd deserve much attention when establishing environmental safety regulations.

Reducing bioassay variability by identifying sources of variation and controlling important parameters in assay protocol was demonstrated in this study. The variability of a bioassay based on a luminescent bacterium was examined as an example. This assay involved the growth of cells, storage at a low temperature, activation, and exposure to a test sample, and the assay response was bioluminescence inhibition. After determining that measurement error was small and negligible, the total assay variability was decomposed in an initial variance components study into between-batch, between-vial, and between-tube variations. Results indicated that between-vial variations accounted for the majority of the total observed variability and that reducing this type of variation would be beneficial. Five parameters in the assay protocol were determined as factors that potentially affected assay variability significantly. A split-plot design was employed to investigate the effects of these factors and some of their interactions on the assay response. One of the five factors, i.e., activation temperature, turned out to have a significant effect. The variance components study was repeated with better control of activation temperature as well as other parameters. Results indicated that the total variability of the bioassay was reduced by approximately 85%.

A bioassay-directed fractionation and identification (toxicity identification evaluation procedure) was performed on extracts of 10 l River Elbe water samples. The experimental method included a SDB-1 solid phase extraction followed by RP-HPLC fractionation and subfractionation. Chemical analysis by GC–MS as well as acute toxicity testing using a luminescent bacteria assay were conducted in the respective fractions. Many substances were identified, among which were pesticides and pharmaceuticals, but many compounds remained unknown.

The acute toxicities of 19 substituted benzene compounds and intermediates of pesticides to Photobacterium phosphoreum in β -CD aqueous solution (5 g/L) were studied and compared with those in water through luminescent bacteria toxicity test, and 15min-EC50 values were obtained. The presence of β -CD significantly reduce biotoxicities of the low-polarity compounds, while for the higher-polarity compounds, such effect was slight. The differences of biotoxicities were correlated with Log10Kow (octanol / water partition coefficients). A significant linear relationship was obtained with some abnormal data picked out. Some explanations concerning molecular structure of chemicals as well asβ -CD were given for the relationship.

Twenty-two landfill leachates were tested on a battery of aquatic organisms (microalgae, daphnids, rotifers, crustaceans, protozoans, luminescent bacteria) and analysed for various physico-chemical parameters (pH, conductivity, alkalinity, chemical oxygen demand, dissolved organic carbon, organic nitrogen, total ammonia, K+, Na+, Cl−, SO42−, Ca2+, Mg2+, Fe, Zn, Cu). Principal Components Analyses (PCA) and regression analyses were performed on both types of variables in order to find possible explanations for the observed toxicity. The results of multivariate analyses showed a general relationship between both data sets, namely the most (or least) contaminated samples were also generally the most (or least) toxic. These analyses also suggested that ammonia, alkalinity, and chemical oxygen demand (COD) were associated with increasing toxicity. Simple and multiple regression analyses allowed to confirm the importance of ammonia and alkalinity for causing toxicity to most organisms. Luminescent bacteria, however, were found to be more sensitive to the organic load of the leachates. The results are discussed in the context of risk assessment of various types of landfills.

The aquatic toxicity and biodegradability of the new chelating agent beta-alaninediacetic acid (beta-ADA) were investigated. There is no inhibition effect of beta-ADA in the daphnia magna 24 h test up to a concentration of 1000 mg/L. The algal growth inhibition test resulted in an EC 50 of 19.7 mg/L. An EC 20 of 740 mg/L was determined in the luminescent bacteria test. An EC 50 was not obtained in this test up to a concentration of 2000 mg/L beta-ADA. The degree of biodegradation of beta-ADA was determined in a static and a continuous test. The beta-ADA removal reached 98% at the end of the test after eight weeks in the continuous test which was carried out with laboratory activated sludge units simulating a waste water treatment plant. Further, biodegradation and toxicity tests were coupled, i.e. the effluents of the laboratory activated sludge units were applied in the toxicity tests. A higher toxicity of the effluents of the test units in comparison with the control unit was not observed.

Twenty-seven landfill leachates were tested on a battery of conventional toxicity tests (microalgae, daphnids, duckweeds) and new microbiotests (rotifers, crustaceans, protozoans, luminescent bacteria). The toxicity varied substantially from one test species to the other, from one site to the other, as well as from one type of landfill to the other. Leachates of domestic wastes were significantly more toxic than those of pure industrial wastes; the most toxic leachates were found for landfills receiving hazardous industrial wastes mixed with domestic wastes. The highest sensitivity was found for the protozoan assay, followed by the crustacean microbiotests. All other types of bioassays appeared to be substantially less sensitive to the toxicants present in the landfill leachates. The results of a Principal Component Analysis suggest that in approximately 90% of the cases the toxicity of landfill leachates can be assessed by applying a test battery composed of a bacterial assay, a protozoan test and an assay with micro-algae, jointly with one of the following bioassays: higher plants, rotifers or crustaceans. The application of a factor 100 to to the highest toxicity figure for each landfill leachate to extrapolate a Predicted No-Effect Concentration (PNEC) revealed that in quite a number of cases, the leachates need to be diluted by more than 10.000 times to make them innocuous for environmental biota.

Four different biological test systems were used for monitoring the biological activity of a laboratory-scale wastewater treatment plant which was operated with municipal wastewater. The heterotrophic respiration activity test (HRA), dehydrogenase activity test (DHA) and nitrification activity test were used for monitoring the biological activity of the activated sludge, and the luminescent bacteria test was used for screening the effluent of the treatment plant. In shock loading experiments with 2.3-dichlorophenol and 3.5-dichlorophenol it was shown that both the nitrification and heterotrophic respiration activities and the TOC degradation in the treatment plant were significantly reduced, whereas no clear effect on dehydrogenase activity was found. Screening of the effluent revealed a clear increase in luminescent bacteria inhibition during the shock loading experiments.

Landfill leachates were evaluated using assays with plants and luminescent bacteria as indicators of toxicity. Four tests were conducted with several dilutions of untreated leachate samples from two landfills (Braunschweig and Hannover), and untreated and treated samples from a third landfill (Schwicheldt). The experimental variables were growth rate of the aquatic plant Lemna minor , root lengths of the terrestrial plants Brassica rapa and Lepidium sativum after a 72 hour germination period, root elongation of Lepidium sativum over 8 days, and light emission by Photobacterium phosphoreum . Chemical analyses of the leachates were also made. At concentrations of 100 ml/L and higher, all untreated leachate samples exhibited severe toxicity, resulting in plant death or substantially poorer root growth compared to controls. EC 50 values obtained from the bacterial toxicity test were 350 and 180 ml/L for the Braunschweig and Hannover samples respectively. Plants grown in treated samples from the Schwicheldt landfill demonstrated negative responses only with undiluted leachate, indicating that this sample was less toxic than the untreated one. Chemical analysis showed substantial differences between untreated and treated samples, which may explain the decreased toxicity observed in biological tests with the treated sample. Results of the different tests were similar for all the leachates evaluated, increasing the reliability of these assays. Analytical techniques can elucidate the chemical characteristics of an environmental sample, but give little information regarding its potential ecological effects. In contrast, the bacterial and phytotoxicity assays used in this study provided inexpensive and consistent, ecologically relevant information on the toxicity of landfill leachates.

EC 50 values of different nitroparaffins were determined by a photobacterium phosphoreum toxicity test. Octanol/water partition coefficients were determined by a reversed phase HPLC method. From these experimental data quantitative structure activity relationships were deduced which point to a dependence of toxicity on a “form factor” that includes the number of methyl and methylene groups in a molecule. The hypothesis will be formulated that the specific effects depend on the number of methylgroups and an equation for specific effects is given.

The extensive utilization of antibiotics in the pharmaceutical therapies and agricultural husbandry has led to the worldwide pollution in environments. In this study the photolysis behaviors of tetracycline (TC) and toxicity of its degradation products were investigated. The results showed that TC photolysis followed first-order kinetics. The photolysis rate was found to be dependent on the initial TC concentration and increasing TC concentration from 10 to 40mgl(-1) led to the decrease of the photolysis rate constant from 0.0045min(-1) to 0.0014min(-1). TC photolysis was highly pH-dependent and strongly enhanced at high pH value. Markedly elevated TC photolysis was also observed in the presence of nitrate and dissolved organic matter. Upon irradiation for 300min, only 15% reduction of total organic carbon (TOC) occurred in spite of quick conversion of 73% of TC, suggesting that a majority of TC transformed into intermediate products without complete mineralization. The intermediate products from TC photolysis were analyzed using high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS) and the main photolysis products of TC were proposed. The toxicity of the photolysis compounds was evaluated using luminescent bacterium, and the results revealed that the toxicity increased with irradiation, indicative of a higher adversity risk of the degradation products of TC on bacteria upon photolysis.

The toxicity of mononitrophenols and dinitrophenols (DNP) to luminescent bacteria Vibrio fischeri (Microtox® test) and ciliated protozoan Spirostomum ambiguum (Spirotox test) was evaluated. Spirotox was more sensitive to the tested nitrophenols (NPs) than the Microtox® test. 2,5-DNP was the most toxic and 2-NP was the least toxic to the both bioindicators. The toxicity depended greatly on the pH of the medium. The highest changes were observed for DNPs, where the toxicity decreased more than 20-times when the pH increased from 6 to 8. No significant decrease of the toxicity was found for NPs, when the pH increased from 6 to 7. Greater increase of the pH to 8 caused from 1.5 to 4-fold decrease of the toxicity.

In situ bioremediation is increasingly being discussed as a useful strategy for cleaning up contaminated soils. Compared to established ex situ procedures, meaningful and reliable approaches for monitoring the remediation processes and their efficiency are of special importance. The subject of this study was the significance of two bioassays for monitoring purposes. The work was performed within the scope of a research project on the in situ bioremediation of topsoil contaminated with 2,4,6-trinitrotoluene (TNT). To evaluate changes within different experimental fields during a 17-month remediation period, the results of soil microbial assays and luminescent bacteria assays were compared with chemical monitoring data. The luminescent bacteria assays showed a significant reduction of the water-soluble soil toxicants in the treated fields. This bioassay proved to be a sensitive screening indicator of toxicity and may effectively aid the ecotoxicological interpretation of chemical monitoring data. Microbial biomass ( C mic ), the metabolic quotient (qCO 2 ), and the ratio of microbial to organic carbon ( C mic / C org ) showed a highly significant correlation with total concentrations of TNT in the soil. But, in contrast to luminescent bacteria assays, this approach did not reveal any recovery of the soil at the end of the remediation period. There is clear evidence for persistent adverse effects of chronic TNT contamination on the site-specific microbial community and the local carbon cycle in the soil. The study clearly exhibits the differences between, as well as the complementary value of both bioassay approaches for monitoring short-term and long-term effects of soil contamination and the efficiency of remediation.

The toxicity of 17 selected process effluents, 11 reactive dyestuffs and 8 auxiliaries from a textile dyeing and finishing mill in Ayazaga, Istanbul, Turkey was evaluated by bioluminescence test using bacteria Vibrio fischeri in LUMIStox 300. The EC20 and EC50 for auxiliaries, the EC20 for dyestuffs were determined. For selected process effluents GL-values, the dilution level at which a wastewater sample causes less than 20% inhibition, were examined. Our results demonstrate that the toxicity assessment with luminescent bacteria is effective and of practical use for chemicals applied in textile finishing industry with the limitation of the deep dark-colored dye bath samples and for the related effluents. Inhibition effects of numerous dyestuffs as well as auxiliaries to luminescent bacteria differed considerably with a range 5-600 mg 1(-1) for EC20 and 9-6930 mg 1(-1) for EC50, respectively. Among 17 effluents, 1 sample exhibited high toxicity (GL = 100), 7 showed moderate toxicity (GL = 12 32), and 9 had a GL-value

Industrial and municipal wastewaters constitute major sources of contamination of the aquatic compartment and represent a threat to aquatic life. Artificial neural networks based on three different learning paradigms were studied as a means of predicting acute toxicity to trout (5 days exposure to wastewaters) using input data from two simple microbiotests requiring only 5 or 15 min of incubation. These microbiotests were 1) the chemoluminescent peroxidase (Cl-Per) assay, which can detect radical scavengers and enzyme-inhibiting substances, and 2) the luminescent bacteria toxicity test (Microtox), in which reduction of light emission by bacteria during exposure is taken as a measure of toxicity. The responses obtained with the trout bioassay, the Cl-Per and the Microtox test were analyzed through statistical correlation (Pearson product-moment correlation), unsupervised learning by a self-organizing network, and assisted learning by the backpropagation and the Boltzmann machine (probabilistic) paradigms. No significant correlation (p0.05) was found between the responses obtained with either the Cl-Per assay (p = 0.121) or the Microtox (p = 0.061) microbiotest and those resulting from the trout bioassay. The self-organizing network was able to identify by itself a maximum of five classes that were more or less relevant for predicting toxicity to fish: class 1 contained 2 samples that were toxic to fish, class 2 contained 2/3 samples that were toxic, class 3 showed 6/8 samples that were non toxic, class 4 contained 5/6 samples that were non-toxic and class 5 comprised one sample that was toxic. Supervised learning with backpropagation analysis yielded two kinds of networks that hold potential. The first one was able to predict the actual toxic wastewater concentration with an overall performance of 65% when fed fresh data, while the second one, which was designed to differentiate between toxic and non-toxic effluents, exhibited a much better performance (90%). However, the probabilistic network also proved to be a very good predictive model for toxicity to fish, with an overall performance of 90%. Although more data are needed, the network based on the backpropagation paradigm seems to be a better predictor or classifier of trout toxicity when used with the Cl-Per and the Microtox microbiotests.

Binary mixtures of copper-pesticide (zineb, maneb, carbaryl) were tested on bacteria, Photobacterium phosphoreum (Microtox test), and on protozoa, Colpidium campylum . Factorial experiments were used, and results treated with multiple regression analysis. The toxic concentrations chosen were comprised between the NOEL (No Effect Level) and the IC50, when considering the inhibition of the bacterial luminescence and the growth rate of protozoa, induced by each toxicant tested alone. Interactions of copper with zineb or maneb resulted in dramatic synergistic effects in the two species: a total inhibition of the bacterial luminescence or of the growth of colpidium cultures occured at concentrations considered as non toxic when each compound was tested alone. A synergism could be observed on the luminescent bacteria with concentrations as low as 20 ug/l Cu++ and 9 ug/l zineb or 9 ug/l maneb. On the colpidium cultures, these threshold concentrations were 63 ug/l Cu++, 50 ug/l zineb, 400 ug/l maneb. Carbaryl differed from the two dithiocarbamates since only a slight interaction was registered with copper on the protozoa at high concentrations (0.2 mg/l Cu++, 8 mg/l carbaryl).