title: (Bio)degradation of glyphosate in water-sediment microcosms - A stable isotope co-labeling approach.
abstract: Glyphosate and its metabolite aminomethylphosphonic acid (AMPA) are frequently detected in water and sediments. Up to date, there are no comprehensive studies on the fate of glyphosate in water-sediment microcosms according to OECD 308 guideline. Stable isotope co-labeled (13)C3(15)N-glyphosate was used to determine the turnover mass balance, formation of metabolites, and formation of residues over a period of 80 days. In the water-sediment system, 56% of the initial (13)C3-glyphosate equivalents was ultimately mineralized, whereas the mineralization in the water system (without sediment) was low, reaching only 2% of (13)C-glyphosate equivalents. This finding demonstrates the key role of sediments in its degradation. Glyphosate was detected below detection limit in the water compartment on day 40, but could still be detected in the sediments, ultimately reaching 5% of (13)C3(15)N-glyphosate equivalents. A rapid increase in (13)C(15)N-AMPA was noted after 10 days, and these transformation products ultimately constituted 26% of the (13)C3-glyphosate equivalents and 79% of the (15)N-glyphosate equivalents. In total, 10% of the (13)C label and 12% of the (15)N label were incorporated into amino acids, indicating no risk bearing biogenic residue formation from (13)C3(15)N-glyphosate. Initially, glyphosate was biodegraded via the sarcosine pathway related to microbial growth, as shown by co-labeled (13)C(15)N-glycine and biogenic residue formation. Later, degradation via AMPA dominated under starvation conditions, as shown by the contents of (13)C-glycine. The presented data provide the first evidence of the speciation of the non-extractable residues as well as the utilization of glyphosate as a carbon and nitrogen source in the water-sediment system. This study also highlights the contribution of both the sarcosine and the AMPA degradation pathways under these conditions.
authors.affiliation: School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China; Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Shizong
authors.initials: S
authors.lastname: Wang
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Analytical Chemistry, Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Seiwert
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kästner
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Miltner
authors.affiliation: RWTH Aachen University, Institute for Environmental Research, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäffer
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Analytical Chemistry, Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Reemtsma
authors.affiliation: School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstrasse 15, 04318 Leipzig, Germany; RWTH Aachen University, Institute for Environmental Research, Worringerweg 1, 52074 Aachen, Germany. Electronic address: karolina.nowak@ufz.de.
authors.forename: Karolina M
authors.initials: KM
authors.lastname: Nowak
mesh_terms: D004784:Environmental Monitoring; D005998:Glycine / Q000031:analogs & derivatives; D006540:Herbicides / Q000737:chemistry*; D007553:Isotope Labeling; D007554:Isotopes; D014867:Water
chemical_list: D006540:Herbicides; D007554:Isotopes; D014867:Water; D005998:Glycine
keywords: (13)C(3)(15)N-Glyphosate; AMPA; Amino acids; Biogenic residues; Sarcosine