title: Assessing the environmental fate of S-metolachlor, its commercial product Mercantor Gold® and their photoproducts using a water-sediment test and in silico methods.
abstract: Pesticides enter surface and groundwater by several routes in which partition to sediment contributes to their fate by abiotic (e.g. photolysis, hydrolysis) and biotic processes. Yet, little is known about S-metolachlor (SM) transformation in water-sediment systems. Therefore, a newly developed screening water-sediment test (WST) was applied to compare biodegradation and sorption processes between pure SM and Mercantor Gold® (MG), a commercial formulation of SM. Photolysis in water was performed by Xe lamp irradiation. Subsequently, the biodegradability of SM and MG photolysis mixtures was examined in WST. The primary elimination of SM from water phase was monitored and structures of its TPs resulting from biotransformation (bio-TPs) were elucidated by LC-MS/MS. SM was extracted from sediment in order to estimate the role of sorption in WST for its elimination. A set of in silico prediction software tools was applied for toxicity assessment of SM and its bio-TPs. Obtained results suggest that the MG adjuvants do not significantly affect biodegradation, but do influence diffusion of SM into sediment. 50% of SM could not be re-extracted from sediment with 0.01 M CaCl2 aqueous solution recommended in OECD test guideline for adsorption. Neither the parent compound nor the photo-TPs were biodegraded. However, new bio-TPs have been generated from SM and MG photo-TPs due to bacterial activity in the water-sediment interphase. Moreover, according to in silico assessment of the bio-TPs the biotransformation might lead to an increased toxicity to the water organisms compared with the SM. This might raise concerns of bio-TPs presence in the environment.
authors: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE - 21335 Lüneburg, Germany. Electronic address: lukasz.gutowski@leuphana.de.
authors: Lukasz
authors: L
authors: Gutowski
authors: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE - 21335 Lüneburg, Germany. Electronic address: baginska@leuphana.de.
authors: Ewelina
authors: E
authors: Baginska
authors: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE - 21335 Lüneburg, Germany. Electronic address: oliver.olsson@leuphana.de.
authors: Oliver
authors: O
authors: Olsson
authors: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE - 21335 Lüneburg, Germany. Electronic address: cleder@leuphana.de.
authors: Christoph
authors: C
authors: Leder
authors: Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE - 21335 Lüneburg, Germany. Electronic address: Klaus.Kuemmerer@uni.leuphana.de.
authors: Klaus
authors: K
authors: Kümmerer
mesh_terms: D000081:Acetamides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D001711:Biotransformation; D003198:Computer Simulation; D019015:Geologic Sediments / Q000737:chemistry*; D010575:Pesticides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D010782:Photolysis; D053719:Tandem Mass Spectrometry; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism
chemical_list: D000081:Acetamides; D010575:Pesticides; D014874:Water Pollutants, Chemical; D014867:Water; C051786:metolachlor
keywords: Adjuvants; Biodegradation; In silico; QSAR; Transformation; Water–sediment