volV) (0123456789().,-volV) can move into the groundwater specified in the exposure assessment option as well as the magnitude of residues in groundwater. The objective may also include determining degradation rates in soil as a function of depth, persistence and movement of residues in groundwater, efficacy of mitigation measures, or confirmation of more detailed studies on a wider range of sites. Sampling schedules should consider the expected time required for an active substance to move through the soil into groundwater, as well as expected persistence in both soil and groundwater. Movement and persistence can be affected by both site characteristics and properties of the active substance and its metabolites. The need to tailor study designs to objectives, exposure assessment options, compound properties and site characteristics complicates the development of standardised study designs. Therefore, this report includes a number of example designs.Other key points that must be addressed by study designs are the vulnerability of the chosen sites compared to the vulnerability of all use areas supported by the study, the product use before and during the study, and the connectivity of the sampled groundwater to treated fields. Demonstrating connectivity (a quality criterion in the EU assessment of monitoring sites to exclude false negative measurements) is more challenging for catchment or aquifer monitoring compared to shallow wells installed as part of in-field or edge-of-field studies. This report includes an extensive discussion on assessing vulnerability of monitoring sites. This includes information on different approaches to vulnerability assessment and mapping as well as for setting monitoring sites into context. Lists of available methods and data sources available at the European level are also included. In addition to information on study design and estimating vulnerability, this report includes information on a number of other topics: avoiding contamination during sampling and/or analysis, avoiding influencing residue movement as a result of purging during sampling, and proper study documentation (Good Laboratory Practices and/or quality criteria). Procedures that are discussed include site selection (new or existing wells), installation of monitoring wells, sample collection, and analysis of samples. The report also provides information on causes of outliers (abnormally high concentrations not the result of normal leaching through soil), the use of public monitoring data, information on further hydrological characterisation (such as use of tracers, groundwater age dating, and geophysical methods), and information that should be included in reports providing results of groundwater studies. AbstractGroundwater monitoring is recommended as a higher-tier option in the regulatory groundwater assessment of crop protection products in the European Union. However, to date little guidance has been provided on the study designs. The SETAC EMAG-Pest GW group (a mixture of regulatory, academic, and industry scien...
Atrazine's bound residues (BR), in the range of 10-40% of the applied atrazine,were obtained by laboratory incubation (56 d) of four soils having different capacities to degrade atrazine in relation to the presence or absence of a microflora able to mineralize the triazinic ring. Soil size fractionation followed by alkaline extraction, before and after HF treatment, and then acid hydrolysis with 2 M HCl in reflux conditions was applied to the soils containing BR. Most of the BR were in the finest fraction (<20 microm) that contained the humified organic matter (from 61 to 77% of the total BR), and between 78 and 89% was made soluble during the different steps of the chemical fractionation procedure. From 20 to 50% of the BR of the fraction <20 microm was identified as the intact atrazine and its main derivatives, indicating that this proportion of the BR was probably formed by entrapment in voids of the soil organic matter. Between 13 and 30% of the BR was associated to humic acids (HA); they were not dialyzable and were released by acid hydrolysis with HCl, indicating that these BR were chemically bound to HA by an heteroatomic bond after the substitution of the chlorine atom of atrazine. Comparison of the results obtained for the four soils indicated that (i) an important activity of microorganisms able to mineralize the triazinic ring favors the formation of highly degraded products that can form BR; (ii) a soil pH <6 favors the formation and stabilization of hydroxylated derivatives of atrazine, and (iii) a high content of humic acids favors the formation of chemically bound residues.
NaOH extraction, HF treatment, and HCl hydrolysis applied on the humified fraction of two soils incubated with 14 C-atrazine allowed to release between 77 and 89% of the total non-extractable (bound) residues of atrazine. Between 40 and 58% of the released 14 C-bound residues were identified as the parent compound or degradation products (mainly hydroxy-atrazine). Humin seemed to be the most quantitative compartment responsible for the accumulation of the bound residues. A large part of bound residues was associated with the fulvic organic matter (only in the most acidic soil). In spite of the artefacts in relation to the transformation of extracted residues by the reagents used, important information is acquired about the identity of the bound residues and its association to the soil constituents. atrazine / bound residue / alkaline extraction / acid hydrolysis / HF treatment Résumé -Libération de résidus non-extractibles (liés) d'atrazine de deux sols par l'utilisation de techniquesdégradatives. Des extractions alcalines (NaOH), un traitement HF, et une hydrolyse HCl de l'humine, appliquées aux fractions contenant la matière organique humifiée de deux sols, ont permis de libérer de 77 à 89 % des résidus non-extractibles (liés) totaux d'atrazine. De 40 à 58 % des 14 C-résidus libérés ont été identifiés en tant que molécule mère et/ou produits de dégradation (principalement sous forme d'hydroxy-atrazine). L'humine semble être le principal compartiment où s'accumule les résidus liés. Une grande partie des résidus liés est associée à la matière organique fulvique dans le sol le plus acide. Malgré les artéfacts dus aux réactifs utilisés sur les résidus libérés, des informations ont été acquises quant à l'identité des résidus liés et leurs associations avec les constituants du sol. atrazine / résidu lié / extraction alcaline / hydrolyse acide / traitement HF Agronomie 20 (2000) 513-524 513
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