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Batch experiments versus soil pore water extraction--what makes the difference in isoproturon (bio-)availability?

Chemosphere 77, 756-763 (2009)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Two approaches to determine pesticide (bio-)availability in soils (i) batch experiments with "extraction with an excess of water" (EEW) and (ii) the recently introduced "soil pore water (PW) extraction" of pesticide incubated soil samples have been compared with regard to the sorption behavior of the model compound isoproturon in soils. A significant correlation between TOC and adsorbed pesticide amount was found when using the EEW approach. In contrast, there was no correlation between TOC and adsorbed isoproturon when using the in situ PW extraction method. Furthermore, sorption was higher at all concentrations in the EEW method when comparing the distribution coefficients (Kd) for both methods. Over all, sorption in incubated soil samples at an identical water tension (-15 kPa) and soil density (1.3 g cm-3) appears to be controlled by a complex combination of sorption driving soil parameters. Iso-proturon bioavailability was found to be governed in different soils by binding strength and availability of sorption sites as well as water content, whereas the dominance of either one of these factors seems to depend on the individual composition and characteristics of the respective soil sample. Using multiple linear regression analysis we obtained furthermore indications that the soil pore structure is affected by the EEW method due to disaggregation, resulting in a higher availability of pesticide sorption sites than in undisturbed soil samples. Therefore, it can be concluded that isoproturon sorption is overestimated when using the EEW method, which should be taken into account when using data from this approach or similar batch techniques for risk assessment analysis.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords microbial availability; toc; in situ pesticide sorption; saturation of sorption sites; soil pore water; soil extraction; organic-matter; phenylurea herbicides; subcritical water; adsorption; sorption; mineralization; bioavailability; pesticides; desorptio
ISSN (print) / ISBN 0045-6535
e-ISSN 1879-1298
Journal Chemosphere
Quellenangaben Volume: 77, Issue: 6, Pages: 756-763 Article Number: , Supplement: ,
Publisher Elsevier
Publishing Place Kidlington, Oxford
Non-patent literature Publications
Reviewing status Peer reviewed