Guidance document on the impact of water treatment processes on residues of active substances or their metabolites in water abstracted for the production of drinking water.

This guidance document provides a tiered framework for risk assessors and facilitates risk managers in making decisions concerning the approval of active substances (AS) that are chemicals in plant protection products (PPPs) and biocidal products, and authorisation of the products. Based on the approaches presented in this document, a conclusion can be drawn on the impact of water treatment processes on residues of the AS or its metabolites in surface water and/or groundwater abstracted for the production of drinking water, i.e. the formation of transformation products (TPs). This guidance enables the identification of actual public health concerns from exposure to harmful compounds generated during the processing of water for the production of drinking water, and it focuses on water treatment methods commonly used in the European Union (EU). The tiered framework determines whether residues from PPP use or residues from biocidal product use can be present in water at water abstraction locations. Approaches, including experimental methods, are described that can be used to assess whether harmful TPs may form during water treatment and, if so, how to assess the impact of exposure to these water treatment TPs (tTPs) and other residues including environmental TPs (eTPs) on human and domesticated animal health through the consumption of TPs via drinking water. The types of studies or information that would be required are described while avoiding vertebrate testing as much as possible. The framework integrates the use of weight-of-evidence and, when possible alternative (new approach) methods to avoid as far as possible the need for additional testing.

Proposal for regulatory risk mitigation measures for human pharmaceutical residues in the environment.

Environmental risks of human pharmaceutical products should be made transparent and mitigated as far as possible. We propose to apply a risk mitigation scheme to the marketing authorisation of human medicinal products which is pragmatic and tailored, and thus will not increase the burden to regulators and industry too much. This scheme takes into account increasing knowledge and accuracy of the environmental risk estimates, applying preliminary risk mitigation when risks are determined based on model estimates, and definitive, more strict and far-reaching risk mitigation when risks are based on actual measured environmental concentrations. Risk mitigation measures should be designed to be effective, proportional, easy to implement, and in line with current (other) legislation, as well as not being a burden to the patient/health care professionals. Furthermore, individual risk mitigation measures are proposed for products showing environmental risks, while general risk mitigation measures can be applied to all products to reduce the overall burden of pharmaceuticals in the environment. In order to effectively mitigate risk, linking marketing authorisation legislation to environmental legislation is essential.

Improving the regulatory environmental risk assessment of human pharmaceuticals: Required changes in the new legislation.

One of the flagship actions of the Pharmaceutical Strategy for Europe is to address environmental challenges associated with pharmaceutical use. This includes strengthening the Environmental Risk Assessment (ERA) at marketing authorisation (MA) of pharmaceuticals, and revision of the pharmaceutical legislation where needed. The overall aim of an ERA should be to enable comprehensive and effective identification and management of environmental risks of pharmaceuticals without affecting the availability of pharmaceuticals to patients. As experts in the evaluation of ERAs of human medicinal products submitted by pharmaceutical industries (Applicants), we have summarized the current status of the ERA and suggest legislative changes to improve environmental protection without affecting availability. Six regulatory goals were defined and discussed, including possible ways forward: 1) mandatory ERAs in accordance to the EMA guideline at the time of the MA, 2) enforcement of risk mitigation measures including re-evaluation of the ERA, 3) facilitated exchange of environmental data between pharmaceutical and environmental legislations, 4) substance-based assessments, 5) transparency of data, and 6) a catching-up procedure for active pharmaceutical ingredients that lack an ERA. These legislative proposals can be considered as prerequisites for a harmonised assessment and effective management of environmental risks and hazards of human pharmaceuticals.

Effects of biochar on the fate of conazole fungicides in soils and their bioavailability to earthworms and plants.

The study showed novel findings about changes in the fate and bioavailability of conazole fungicides (CFs) after biochar (BC) addition to soil. Two contrasting soils (low- and high-sorbing of CF; L soils, H soils) were amended by three BCs (low-, moderate-, and high-sorbing of CF; L-BC, M-BC, H-BC) at 0.2% and 2% doses. Epoxiconazole (EPC) and tebuconazole (TBC) were then added to the soil-BC mixtures, and their degradation, bioaccumulation in earthworms (Eisenia andrei), and bioconcentration in lettuce (Lactuca sativa) were studied for three months. Also, stir bar sorptive extraction (SBSE) was performed to determine CF (bio)accessibility. The EPC and TBC degradation in the soil-BC mixtures followed usually the first-order decay kinetics. The BC addition prevalently decreased the pesticides degradation in the L soil mixtures but often increased it in the H soil mixtures. In general, EPC degraded less than TBC. BC type and dose roles in the pesticides degradation were unclear. The BC addition significantly reduced pesticide uptake to the earthworms in the L soil mixtures (by 37-96%) and in the H soil mixtures (by 6-89%) with 2% BC. The BC addition reduced pesticide uptake to the lettuce roots and leaves significantly-up to two orders of magnitude, and this reduction was strong in H soil mixtures at 2% of BC. The BC addition reduced the CF (bio)accessibility measured by SBSE in all L soil mixtures and some H soil mixtures with 2% BC. Although not significant, it also seems that the pesticide bioaccumulation, bioconcentration, and (bio)accessibility were decreasing according to the BC type (L-BC > M-BC > H-BC). The pesticide concentrations in the earthworms and lettuce correlated significantly to the SBSE results, which indicates this technique as a possible predictor of biotic uptake. Our results showed that the interactions were hard to predict in the complex soil-BC-pesticide system.

A critical review of the possible adverse effects of biochar in the soil environment.

Biochar has received extensive attention because of its multi-functionality for agricultural and environmental applications. Despite its many benefits, there are concerns related to the long-term safety and implications of its application, mainly because the mechanisms affecting soil and organism health are poorly quantified and understood. This work reviews 259 sources and summarises existing knowledge on biochar's adverse effects on soil from a multiangle perspective, including the physicochemical changes in soil, reduced efficiency of agrochemicals, potentially toxic substances in biochar, and effects on soil biota. Suggestions are made for mitigation measures. Mixed findings are often reported; however, the results suggest that high doses of biochar in clay soils are likely to decrease available water content, and surface application of biochar to sandy soils likely increases erosion and particulate matter emissions. Furthermore, biochar may increase the likelihood of excessive soil salinity and decreased soil fertility because of an increase in the pH of alkaline soils causing nutrient precipitation. Regarding the impact of biochar on (agro)chemicals and the role of biochar-borne toxic substances, these factors cannot be neglected because of their apparent undesirable effects on target and non-target organisms, respectively. Concerning non-target biota, adverse effects on reproduction, growth, and DNA integrity of earthworms have been reported along with effects on soil microbiome such as a shift in the fungi-to-bacteria ratio. Given the diversity of effects that biochar may induce in soil, guidelines for future biochar use should adopt a structured and holistic approach that considers all positive and negative effects of biochar.

Conazole fungicides epoxiconazole and tebuconazole in biochar amended soils: Degradation and bioaccumulation in earthworms.

Biochar usage in agriculture becomes increasingly important for the improvement of soil properties. However, from the perspective of pesticides, biochar can influence exposure to pesticides of both target and non-target organisms and also pesticides' fate in soil. Our study investigated degradation and bioaccumulation (in the Eisenia andrei earthworm) of two conazole fungicides, epoxiconazole and tebuconazole, added to high- and low-sorbing soils (by means of fungicides' sorption measured beforehand) amended with low-, moderate- and high-sorbing biochars at 0.2% and 2% doses. We aimed to investigate the effects of contrasting soil and biochar properties, different doses of biochar in soil-biochar mixtures, and different compounds on the degradation and bioaccumulation. We also wanted to explore if the beforehand determined sorption of fungicides on individual soils and biochars is manifested somehow in their degradation and/or bioaccumulation in soil-biochar mixtures. The biochars' presence in the soils promoted the degradation of fungicides with a clear effect of dose and soil, but less clear effect of biochar or compound. The bioaccumulation factors were higher in low-sorbing soil variants and also decreased with increasing biochar dose. For low-sorbing soil variants, the bioaccumulation was also influenced by the type of biochar corresponding to its sorbing potential and the possible effect on the bioavailability of the fungicides. Our results show that mixing of biochars with soils changes the fate and bioaccumulation of the conazole fungicides. However, the sorption results from original materials are not straightforwardly manifested in the more complex soil-biota system.

A review on the stereospecific fate and effects of chiral conazole fungicides.

The production and use of chiral pesticides are triggered by the need for more complex molecules capable of effectively combating a greater spectrum of pests and crop diseases, while sustaining high production yields. Currently, chiral pesticides comprise about 30% of all pesticides in use; however, some pesticide groups such as conazole fungicides (CFs) consist almost exclusively of chiral compounds. CFs are produced and field-applied as racemic (1:1) mixtures of two enantiomers (one chiral center in the molecule) or four diastereoisomers, i.e., two pairs of enantiomers (two chiral centers in the molecule). Research on the stereoselective environmental behavior and effects of chiral pesticides such as CFs has become increasingly important within the fields of environmental chemistry and ecotoxicology. This is motivated by the fact that currently, the fate and effects of chiral pesticides such as CFs that arise due to their stereoselectivity are not fully understood and integrated into risk assessment and regulatory decisions. In order to fill this gap, a summary of the state-of-the-art literature related to the stereospecific fate and effects of CFs is needed. This will also benefit the agrochemistry industry as they enhance their understanding of the environmental implications of CFs which will aid future research and development of chiral products. This review provides a collection of >80 stereoselective studies for CFs related to chiral analytical methods, fungicidal activity, non-target toxicity, and behavior of this broadly used pesticide class in the soil environment. In addition, the review sheds more light on mechanisms behind stereoselectivity, considers possible agricultural and environmental implications, and suggests future directions for the safe use of chiral CFs and the reduction of their environmental footprint.

Adsorption of epoxiconazole and tebuconazole in twenty different agricultural soils in relation to their properties.

Conazole fungicides are currently used pesticides with considerable chronic toxicity and ecotoxicity that are also on EU list for substitution. They enter the soil forming short- or long-term residues. In this study two of their representatives, epoxiconazole (EPC) and tebuconazole (TBC), have been tested with 20 soils from the Czech Republic for their adsorption. Adsorption, by means of Kd coefficients, was compared to "basic" (TOC, pH, clay …) and "advanced" (surface area, minerals ..) soil properties. After doing multivariate analysis of the variables it was apparent that adsorption of both pesticides was highly associated with pH (negatively correlated), and less associated with soil organo-mineral complex (TOC, clay and surface area) and C and N in soil organic matter (OM). Particle sizes or cation exchange capacity (CEC) did not show correlation with adsorption, but showed an association in multidimensional space in factor analysis (FA). Some correlations were revealed between EPC adsorption and soil organic matter parameters. Recalculating Kd to Koc and to Gibb's free energy (ΔG) and its values indicated that the adsorption of EPC and TBC is mainly weak physical adsorption - partitioning. Also, ΔG values gave better correlation with pH(H2O) than Kd. Surface area impacted EPC adsorption. From the several soil minerals, kaolinite showed EPC and TBC adsorption. EPC adsorption was not highly influenced with pH changes compared to TBC. The number and types of H-bonds with molecular geometry govern the sorption, which might crucially affect leachibility in soil, and this may indicate that TBC is more leachable than EPC for the same soil.

Chiral conazole fungicides - (Enantioselective) terrestrial bioaccumulation and aquatic toxicity.

Five conazole fungicides (CFs) (epoxiconazole, tebuconazole, myclobutanil, uniconazole (P), rac-uniconazole, and diniconazole) were tested in order to provide additional information on i) the effects of CFs on the nematode Caenorhabditis elegans and on the aquatic insect Chironomus riparius under acute exposure scenarios and in multi-generation exposure studies, taking advantage of the short life cycle of nematodes and ii) on the bioaccumulation (earthworm Eisenia andrei) profiles of CFs including also the enantiomer-specific assessment of degradation in soils and uptake/elimination by earthworms. Acute toxicity was considered low following the exposure of up to 2.5 mg of CFs per liter of the test medium. In a multigeneration study on nematodes, all five generations exposed to epoxiconazole were significantly negatively affected in terms of reproductive efficiency, and the severity of effects increased from F0 to F1 generation and was sustained thereafter. Adverse effects were also observed in the case of uniconazole (P) and diniconazole, and similarly to epoxiconazole, the effects occurred within the active life of the pesticides and were assumed to be based on their half-lives in soil (e.g., 53.3 to 691 days for uniconazole and diniconazole in our study) and in sediment/water. Bioaccumulation of diniconazole and uniconazole by earthworms varied between soils (Lufa 2.1 ≥ Lufa 2.4 > sandy soil > Lufa 2.2) and compounds (diniconazole > uniconazole) and was enantioselective. Earthworms preferentially accumulated R-uniconazole as a result of faster elimination of the S-form, which was evidenced from the enantiomer-specific uptake/elimination rate constants derived from the bioaccumulation profiles. Our results suggest that multigeneration exposure studies can advantageously be used for assessing the long-term and trans-general effects of pesticides. Also, the enantioselectivity in bioaccumulation observed for both uniconazole and diniconazole suggests that enantioselectivity in the fate and effects should be considered when exploring ways for safer and sustainable use of chiral pesticides.

Uptake kinetics of four hydrophobic organic pollutants in the earthworm Eisenia andrei in aged laboratory-contaminated natural soils.

Laboratory studies of pollutant uptake kinetics commonly start shortly after experimental soil contamination when it is not clear if the processes between soil and chemicals are equilibrated and stabilized. For instance, when the concentration in soil quickly decreases due to initial biodegradation, bioaccumulation may show a peak-shape accumulation curve instead of conventional first order kinetics with a plateau at the end. The results of such experiments with soil freshly contaminated in the laboratory are then hardly comparable to bioaccumulation observed in soils from historically contaminated sites. Therefore, our study focused on the uptake kinetics of four hydrophobic organic compounds (pyrene, lindane, p,p'-DDT and PCB 153) in two laboratory-contaminated natural soils with different soil properties (e.g. total organic carbon content of 1.6 and 9.3%) aged for 203 days to mimic long-term contamination. For pyrene, the results surprisingly showed peak-shape accumulation curves despite long aging. It seems compound biodegradation might be significant in aged soils when the conditions change (e.g. by distribution to the experimental vessels) and this should be also considered when testing historically contaminated soils. For lindane, longer aging seems to guarantee stability of the soil-compound-earthworm system and the steady state was reached after 5 days of exposure. Furthermore, although concentrations of p,p'-DDT and PCB 153 in earthworms after 11-15-day exposure did not statistically differ, which is a commonly-used indicator that a steady state was reached, they continuously increased until the end of the exposure. Therefore, despite the aging, longer exposure was probably needed to reach the true equilibrium between concentrations in earthworms and soil. In summary, aging does not warranty the conventional first order kinetic curve with the equilibrium at the end of the exposure but may have diverse effects for compounds with different environmental properties and should be taken into account in the bioaccumulation factor calculation and the risk assessment.

Can polyethylene passive samplers predict polychlorinated biphenyls (PCBs) uptake by earthworms and turnips in a biochar amended soil?

A pot experiment was carried out in which aged polychlorinated biphenyls (PCBs) contaminated soil was amended with biochar, and three phases: earthworms, turnips and polyethylene (PE) passive samplers, were added simultaneously in order to investigate changes in bioavailability of PCB following biochar amendment. Two biochars were used: one made from rice husk in Indonesia using local techniques and the other made from mixed wood shavings using more advanced technology. The biochars were amended at 1 and 4% doses. The overall accumulation of PCBs to the phases followed the order: earthworm lipid > PE > turnip. The rice husk biochar reduced PCB accumulation to a greater degree than the mixed wood biochar for all phases, however there was no effect of dose for either biochar. Earthworm uptake was reduced between 52% and 91% for rice husk biochar and by 19% to 63% for mix wood biochar. Turnip uptake was not significantly reduced by biochar amendment. Phase to soil accumulation factors (PSAF) were around 0.5 for turnips, approximately 5 for PE and exceeded 100 for earthworms. This study demonstrates that both biochars can be a sustainable alternative for in situ soil remediation and that PE can be used as tool to simulate the uptake in earthworms and thus remediation effectiveness.

Monitoring wastewater discharge from the oil and gas industry using passive sampling and Danio rerio bioassay as complimentary tools.

Produced water (PW) represents the largest volume waste stream in oil and gas production operations from most offshore platforms. PW is difficult to monitor as releases are rapidly diluted and concentrations can reach trace levels. The use of passive samplers can over come this. Here polyethylene (PE) was calibrated for a diverse range of PW pollutants. Zebrafish were exposed to dilutions of PW and passive sampler extracts in order to investigate the relationship between freely dissolved chemical concentrations and acute toxic effects. The raw PW had an LC50 of 13% (percentage of PW in the standardized zebrafish medium). Observed non-viable deformations to embryos (at 5 hpf) included heart and yolk edema, head, spine and tail deformations. The dose-response relationship of lethal effects showed that if 0.0041 g of PE is exposed to this PW, then extracted, 50% of exposed D. rerio will suffer lethal effects. The sum of tested freely dissolved concentrations that led to 50% lethal effects (mortality and non-viable deformations) was 2.32 × 10-4 mg/L for PW and 7.92 × 10-2 mg/L for PE. This implies that exposure to raw PW was more toxic than exposure to PE extracts. This toxicity was attributed both to the presence of contaminants as well as PW salinity. Passive samplers are able to detect very low freely dissolved pollutant concentrations which is important for assessing the spatial dilution of PW releases. Bioassays provide complimentary information as they account for all toxic compounds including those that are not taken up by passive samplers.

What are the effects of soil treatment procedures (sterilization by γ-irradiation and solvent-assisted spiking) on DDE bioaccumulation by earthworms?

Ionizing γ-irradiation and solvent-assisted spiking are frequently applied to eliminate microbial activity and to induce hydrophobic organic compounds (HOCs) into soil, respectively, when studying the accumulation of chemicals in terrestrial organisms. However, the side-effects that may arise from these treatments on soil-HOC interaction and, subsequently, the kinetics and extents of bioaccumulation are not thoroughly understood. To this end, the accumulation of 1,1-dichloro-2,2-bis(p-chlorophenyl)etylene (p,p'-DDE) by Eisenia andrei was studied in sterilized or unsterilized and freshly spiked (FS) or historically contaminated (HC) soils in parallel with an analysis of aliphatic and hydrophilic soil organic matter (SOM) moieties using mid-infrared diffuse reflectance spectroscopy (DRIFT-S). Irradiation did not impart significant changes on spectral SOM descriptors. In contrast, earthworm inhabitation increased the relative presence of aliphatic moieties to a greater extent than hydrophilic ones, reaching or exceeding pre-treatment levels. Overall, effects on SOM chemistry can be ranked as earthworms > spiking > irradiation. Corresponding changes at the bioaccumulation level were observed for the FS soil (i.e., a 27% reduction in bioaccumulation upon sterilization) but not for the HC soil. This implies that in contrast to the interactions between aged p,p'-DDE and sterilized HC soil, the interactions established between freshly added p,p'-DDE and sterilized FS soil were altered by γ-irradiation-induced secondary effects alone or in combination with earthworm inhabitation. Thus, although the soil treatment processes studied here should not drastically impact compound bioaccumulation, they should be considered in mechanistic studies where the qualitative and quantitative aspects of compound-soil (organic matter)-earthworm interactions are at the centre of attention.

Sorption to soil, biochar and compost: is prediction to multicomponent mixtures possible based on single sorbent measurements?

Amendment with biochar and/or compost has been proposed as a strategy to remediate soil contaminated with low levels of polycyclic aromatic hydrocarbons. The strong sorption potential of biochar can help sequestering contaminants while the compost may promote their degradation. An improved understanding of how sorption evolves upon soil amendment is an essential step towards the implementation of the approach. The present study reports on the sorption of pyrene to two soils, four biochars and one compost. Detailed isotherm analyzes across a wide range of concentration confirmed that soil amendments can significantly increase the sorption of pyrene. Comparisons of data obtained by a classical batch and a passive sampling method suggest that dissolved organic matter did not play a significant role on the sorption of pyrene. The addition of 10% compost to soil led to a moderate increase in sorption (<2-fold), which could be well predicted based on measurements of sorption to the individual components. Hence, our result suggest that the sorption of pyrene to soil and compost can be relatively well approximated by an additive process. The addition of 5% biochar to soil (with or without compost) led to a major increase in the sorption of pyrene (2.5-4.7-fold), which was, however, much smaller than that suggested based on the sorption measured on the three individual components. Results suggest that the strong sorption to the biochar was attenuated by up to 80% in the presence of soil and compost, much likely due to surface and pore blockage. Results were very similar in the two soils considered, and collectively suggest that combined amendments with compost and biochar may be a useful approach to remediate soils with low levels of contamination. Further studies carried out in more realistic settings and over longer periods of time are the next step to evaluate the long term viability of remediation approaches based on biochar amendments.

Concentration/time-dependent dissipation, partitioning and plant accumulation of hazardous current-used pesticides and 2-hydroxyatrazine in sand and soil.

The dissipation, partitioning dynamics and biouptake was measured for selected hazardous current-used pesticides (conazole fungicides: epoxiconazole, flusilazole, tebuconazole; prochloraz, chlorpyrifos, pendimethalin) and for a transformation product (2-hydroxyatrazine) in agricultural soil and quartz sand as representatives of a real and a worst-case scenario. Dissipation, uptake to Lactuca sativa and the freely dissolved concentration along with the organic carbon-normalized sorption coefficients (Koc) were determined on days 12, 40, and 90 following the application of compounds at three fortification levels (0.1-1.0-10 mg/kg). Conazole fungicides showed similar dissipation patterns and were more persistent in soil than prochloraz, chlorpyrifos and pendimethalin. 2-Hydroxyatrazine showed a concentration-depended decrease in persistency in soil. Lettuce roots were shown to accumulate higher amounts than shoots where the extent of root uptake was driven by compound partitioning. This was evidenced by the ability of freely dissolved concentration (Cfree) to reliably (r2 = 0.94) predict root uptake. Concentration in leaves did not exceed the maximum residue levels (MRLs) for lettuce, which was likely given by the low root-to-shoot translocation factors (TFs) of the tested compounds varying between 0.007 and 0.14. Koc values were in the range of literature values. Sorption to soil was higher than to sand for all compounds, yet following the Koc dynamics compounds did not appear to be sequestered in soil with increasing residence time. From these results, it follows that the tested compounds may persist in soil but since they did not accumulate in lettuce above MRLs, contamination of the food web is unlikely.

Influence of soil γ-irradiation and spiking on sorption of p,p'-DDE and soil organic matter chemistry.

The fate of organic chemicals and their metabolites in soils is often investigated in model matrices having undergone various pre-treatment steps that may qualitatively or quantitatively interfere with the results. Presently, effects associated with soil sterilization by γ-irradiation and soil spiking using an organic solvent were studied in one freshly spiked soil (sterilization prior to contamination) and its field-contaminated (sterilization after contamination) counterpart for the model organic compound 1,1-Dichloro-2,2-bis(4-chlorophenyl)ethene (p,p'-DDE). Changes in the sorption and potential bioavailability of spiked and native p,p'-DDE were measured by supercritical fluid extraction (SFE), XAD-assisted extraction (XAD), and solid-phase microextraction (SPME) and linked to qualitative changes in soil organic matter (SOM) chemistry measured by diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy. Reduced sorption of p,p´-DDE detected with XAD and SPME was associated more clearly with spiking than with sterilization, but SFE showed a negligible impact. Spiking resulted in an increase of the DRIFT-derived hydrophobicity index, but irradiation did not. Spectral peak height ratio descriptors indicated increasing hydrophobicity and hydrophilicity in pristine soil following sterilization, and a greater reduction of hydrophobic over hydrophilic groups as a consequence of spiking. In parallel, reduced sorption of p,p´-DDE upon spiking was observed. Based on the present samples, γ-irradiation appears to alter soil sorptive properties to a lesser extent when compared to common laboratory processes such as spiking with organic solvents.

Currently and recently used pesticides in Central European arable soils.

Although large amounts of pesticides are used annually and a majority enters the soil to form short- or long-term residues, extensive soil surveys for currently used pesticides (CUPs) are scarce. To determine the status of CUPs' occurrence in arable land in Central Europe, 51 CUPs and 9 transformation products (TPs) were analysed in 75 arable soils in the Czech Republic (CR) several months after the last pesticide application. Moreover, two banned triazines (simazine and atrazine) and their TPs were analysed because of their frequent detection in CR waters. Multi-residue pesticide analysis on LC-MS/MS after soil QuEChERS extraction was used. The soils contained multiple pesticide residues frequently (e.g. 51% soils with ≥5 pesticides). The levels were also noticeable (e.g. 36% soils with ≥3 pesticides exceeding the threshold of 0.01mg/kg). After triazine herbicides (89% soils), conazole fungicides showed the second most frequent occurrence (73% soils) and also high levels (53% soils with total conazoles above 0.01mg/kg). Frequent occurrence was found also for chloroacetanilide TPs (25% of soils), fenpropidin (20%) and diflufenican (17%). With the exception of triazines' negative correlation to soil pH, no clear relationships were found between pesticide occurrence and soil properties. Association of simazine TPs with terbuthylazine and its target crops proved the frequent residues of this banned compound originate from terbuthylazine impurities. In contrast, frequent atrazine-2-hydroxy residue is probably a legacy of high atrazine usage in the past. The occurrence and levels of compounds were closely associated with their solubility, hydrophobicity and half-life. The results showed links to CR water-monitoring findings. This study represents the first extensive survey of multiple pesticide residues in Central European arable soils, including an insight into their relationships to site and pesticide properties.

Sorption, bioavailability and ecotoxic effects of hydrophobic organic compounds in biochar amended soils.

This work addresses the effect of biochar amendment to soil on contaminant sorption, bioavailability, and ecotoxicity. A distinction between positive primary amendment effects caused by reduced toxicity resulting from contaminant sorption, and negative secondary amendment effects of the biochars themselves was seen. Two biochars (one from high technology and one from low technology production processes) representing real world biochars were tested for the adsorption of pyrene, polychlorinated biphenyl (PCB) 52), and dichlorodiphenyldichloroethylene (p,p'-DDE). Sorption by both biochars was similar, both for compounds in single and mixed isotherms, in the presence and absence of soil. p,p'-DDE natively contaminated and spiked soils were amended with biochar (0, 1, 5, and 10%) and bioavailability, operationally defined bioaccessibility and ecotoxicity were assessed using polyethylene (PE), polymeric resin (XAD) and Folsomia candida, respectively. At the highest biochar dose (10%), bioavailability and bioaccessibility decreased by >37% and >41%, respectively, compared to unamended soils. Mortality of F. candida was not observed at any biochar dose, while reproductive effects were dose dependent. F. candida benefited from the reduction of p,p'-DDE bioavailability upon 1% and 5% biochar addition to contaminated soils while at 10% dose, these positive effects were nullified by biochar-induced toxicity. p,p'-DDE toxicity corrected for such secondary effects was predicted well by both PE uptake and XAD extraction.

Bioavailability and toxicity of pyrene in soils upon biochar and compost addition.

The study investigates the role of biochar and/or compost in mitigating the toxic effects of pyrene in soils using reproduction of nematodes and porewater concentration as measures of pyrene toxicity and bioavailability, respectively. Two soils were spiked with increasing levels of pyrene to achieve a concentration-response relationship for the reproduction of Caenorhabditis elegans. The observed EC50 values (pyrene concentration causing 50% inhibition of reproduction) were 14mg/kg and 31mg/kg (dry mass) for these soils, corresponding to equilibrium porewater concentrations of 37µg/L and 47µg/L, respectively. Differences in organic carbon content were not sufficient to explain the variability in toxicity between the different soils. Soils causing a significant inhibition of reproduction were further amended with 10%-compost, 5%-biochar, or both, and the effects on reproduction and porewater concentration determined. Combined addition of compost and biochar was identified as the most effective strategy in reducing pyrene concentration in soil porewater, which was also partly reflected in soil toxicity. However, porewater concentrations predicted only 52% of pyrene toxicity to nematodes, pointing to particle-bound or dietary exposure pathways. Capsule: Amending pyrene-spiked soil with biochar and compost effectively reduced pyrene porewater concentrations and toxicity to nematodes, which were significantly related.