(Bio)degradation of glyphosate in water-sediment microcosms - A stable isotope co-labeling approach.
(Bio)degradation of glyphosate in water-sediment microcosms - A stable isotope co-labeling approach.
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DOI：
10.1016/j.watres.2016.04.041
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发表时间：
2016-08
期刊：
影响因子：
12.8
通讯作者：
Shizong Wang;B. Seiwert;M. Kästner;A. Miltner;A. Schäffer;T. Reemtsma;Qi Yang;K. Nowak
中科院分区：
文献类型：
--
作者：
Shizong Wang;B. Seiwert;M. Kästner;A. Miltner;A. Schäffer;T. Reemtsma;Qi Yang;K. Nowak
在水和沉积物中经常检测到草甘膦及其代谢物氨基甲基膦酸(AMPA)。到目前为止，还没有根据OECD 308指南对草甘膦在水-沉积物微宇宙中的去向进行全面的研究。稳定同位素共标记13C315N-草甘膦被用来测定在80天内的周转质量平衡、代谢物的形成和残留物的形成。在水-沉积物系统中，最初的13C3-草甘膦当量中56%最终被矿化，而在水系统(没有沉积物)中矿化程度较低，仅达到13C-草甘膦当量的2%。这一发现表明了沉积物在其降解过程中的关键作用。在第40天，在水箱中检测到的草甘膦低于检测限，但在沉积物中仍然可以检测到，最终达到13C315N-草甘膦当量的5%。10天后，13C15N-AMPA迅速增加，这些转化产物最终占13C3-草甘膦当量的26%和15N-草甘膦当量的79%。总体而言，10%的13C标记和12%的15N标记被结合到氨基酸中，这表明13C315N-草甘膦没有形成生物残基的风险。最初，草甘膦是通过与微生物生长相关的肌氨酸途径生物降解的，如共标记的13C15N-甘氨酸和生物残基的形成所示。随后，在饥饿条件下，13C-甘氨酸的含量表明，AMPA降解占主导地位。所提供的数据首次证明了不可提取残留物的形态以及草甘膦在水-沉积物系统中作为碳和氮源的利用。这项研究还强调了肌氨酸和AMPA降解途径在这些条件下的贡献。
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-labeled13C315N-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 initial13C3-glyphosate equivalents was ultimately mineralized, whereas the mineralization in the water system (without sediment) was low, reaching only 2% of13C-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% of13C315N-glyphosate equivalents. A rapid increase in13C15N-AMPA was noted after 10 days, and these transformation products ultimately constituted 26% of the13C3-glyphosate equivalents and 79% of the15N-glyphosate equivalents. In total, 10% of the13C label and 12% of the15N label were incorporated into amino acids, indicating no risk bearing biogenic residue formation from13C315N-glyphosate. Initially, glyphosate was biodegraded via the sarcosine pathway related to microbial growth, as shown by co-labeled13C15N-glycine and biogenic residue formation. Later, degradation via AMPA dominated under starvation conditions, as shown by the contents of13C-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.