Schnurer Ylva, Persson Per, Nilsson Mats, Nordgren Anders, Giesler Reiner
Department of Forest Ecology, Swedish University of Agricultural Sciences, 901 87 Umeå, Sweden.
Environ Sci Technol. 2006 Jul 1;40(13):4145-50. doi: 10.1021/es0523744.
Sorption may affect the bioavailability and biodegradation of pesticides in soils. The aim of this study was to test the effect of surface sorption on microbial utilization of the herbicide glyphosate as a source of phosphorus, nitrogen, or carbon. We added goethite to a humus soil to manipulate the soil's glyphosate sorption capacity. The addition of glyphosate generally either decreased microbial CO2 production or produced no effect. Additions of glyphosate, in combination with glucose and N, did not change the respiration rate in comparison with the same treatment but without glyphosate. In contrast, glyphosate additions combined with glucose and P decreased microbial growth, whereas the combination with goethite counteracted the negative effect. The different treatments were examined using attenuated total reflectance Fourier transform (ATR-FTIR) spectroscopy; the results suggest that glyphosate was de-carboxylated in the sorbed state. Stimulating microbial growth by the addition of glucose and nitrogen resulted in further oxidation of glyphosate and only phosphate was detectable on the goethite surface after 13 days incubation. Our results show that sorbed glyphosate is microbially degradable, and it retards microbial activity. This study emphasizes the importance of combining quantitative measurements with a molecular-level examination, to better understand biogeochemical processes.
吸附作用可能会影响农药在土壤中的生物有效性和生物降解。本研究的目的是测试表面吸附对微生物利用除草剂草甘膦作为磷、氮或碳源的影响。我们向腐殖土中添加针铁矿以控制土壤对草甘膦的吸附能力。添加草甘膦通常会降低微生物二氧化碳的产生量，或者没有影响。与不添加草甘膦的相同处理相比，添加草甘膦并结合葡萄糖和氮不会改变呼吸速率。相比之下，添加草甘膦并结合葡萄糖和磷会降低微生物生长，而与针铁矿结合则可抵消这种负面影响。使用衰减全反射傅里叶变换（ATR-FTIR）光谱对不同处理进行了检测；结果表明草甘膦在吸附状态下发生了脱羧反应。添加葡萄糖和氮刺激微生物生长导致草甘膦进一步氧化，孵育13天后在针铁矿表面仅检测到磷酸盐。我们的结果表明，吸附态草甘膦可被微生物降解，并且它会抑制微生物活性。本研究强调了将定量测量与分子水平检测相结合以更好地理解生物地球化学过程的重要性。
