Wastewater, 5. Physical Treatment

Mann, Theo; Koglin, Bernd; Kienle, Hartmut von; Wegmann, Uwe; Weisbrodt, Walter

doi:10.1002/14356007.o28_o11

Cited by 1 publication

(1 citation statement)

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“…From eq , a correction of the DOC term is not required to interpret CSIA data for pesticides with log K oc between 1 and 6 and realistic DOC surface water concentrations between 5 and 20 mg L –1 . However, a correction of the DOC term is needed for the same range of log K oc and DOC concentrations higher than 300 mg L –1 , which can be reached in the activated sludge of wastewater treatment plants …”

Section: Resultsmentioning

confidence: 99%

Phase Transfer and Biodegradation of Pesticides in Water–Sediment Systems Explored by Compound-Specific Isotope Analysis and Conceptual Modeling

Droz

Drouin

Maurer

et al. 2021

Environ. Sci. Technol.

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Current approaches are often limited to evaluating the contribution of pesticide dissipation processes in water–sediment systems as both degradation and phase transfer, that is, sorption–desorption, contribute to the apparent decrease of pesticide concentration. Here, the dissipation of widely used herbicides acetochlor and S-metolachlor was examined in laboratory by water–sediment microcosm experiments under oxic and anoxic conditions. Compound-specific isotope analysis (CSIA) emphasized insignificant carbon isotope fractionation in the sediment, indicating prevailing pesticide degradation in the water phase. Conceptual modeling accounting for phase transfer and biodegradation indicated that biodegradation may be underestimated when phase transfer is not included. Phase transfer does not affect carbon isotope fractionation for a wide spectrum of molecules and environmental conditions, underscoring the potential of pesticide CSIA as a robust approach to evaluate degradation in water–sediment systems. CSIA coupled with the identification of transformation products by high-resolution tandem mass spectrometry suggests the degradation of acetochlor and S-metolachlor to occur via nucleophilic substitution and the predominance of oxalinic acids as transformation products under both anoxic and oxic conditions. Altogether, combining the pesticide CSIA, the identification of transformation products, and the use of conceptual phase-transfer models improves the interpretation of pesticide dissipation in water–sediment systems.

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Section: Resultsmentioning

confidence: 99%