The Center for NanoBioEarth, Virginia Tech, Blacksburg, Virginia, USA.
Environ Toxicol Chem. 2011 Mar;30(3):596-601. doi: 10.1002/etc.424. Epub 2011 Jan 7.
A systematic investigation into lowered degradation rates of glyphosate in metal-contaminated soils was performed by measuring mineralization of [(14)C]glyphosate to (14)CO(2) in two mineral soils that had been spiked with Cu and/or Zn at various loadings. Cumulative (14)CO(2) release was estimated to be approximately 6% or less of the amount of [(14)C]glyphosate originally added in both soils over an 80-d incubation. For all but the highest Cu treatments (400 mg kg(-1)) in the coarse-textured Arkport soil, mineralization began without a lag phase and declined over time. No inhibition of mineralization was observed for Zn up to 400 mg kg(-1) in either soil, suggesting differential sensitivity of glyphosate mineralization to the types of metal and soil. Interestingly, Zn appeared to alleviate high-Cu inhibition of mineralization in the Arkport soil. The protective role of Zn against Cu toxicity was also observed in the pure culture study with Pseudomonas aeruginosa, suggesting that increased mineralization rates in high Cu soil with Zn additions might have been due to alleviation of cellular toxicity by Zn rather than a mineralization specific mechanism. Extensive use of glyphosate combined with its reduced degradation in Cu-contaminated, coarse-textured soils may increase glyphosate persistence in soil and consequently facilitate Cu and glyphosate mobilization in the soil environment.
采用 [(14)C] 草甘膦矿化生成 (14)CO(2) 的方法，对添加不同浓度 Cu 和/或 Zn 的两种矿物质土壤中草甘膦的降解率降低问题进行了系统研究。80d 培养期内，两种土壤中累积释放的 (14)CO(2) 估计仅为初始添加 [(14)C] 草甘膦量的 6%左右。对于质地较粗的阿克斯波特土壤中除最高 Cu 处理（400mg/kg）外的所有处理，矿化作用无滞后期且随时间而减少。在两种土壤中，Zn 的添加量高达 400mg/kg 时，均未观察到矿化作用抑制，这表明草甘膦矿化作用对金属和土壤类型的敏感性存在差异。有趣的是，Zn 似乎缓解了阿克斯波特土壤中高 Cu 对矿化作用的抑制。在铜绿假单胞菌纯培养研究中也观察到 Zn 对 Cu 毒性的保护作用，这表明在添加 Zn 的高 Cu 土壤中矿化率增加可能是由于 Zn 缓解了细胞毒性，而不是由于特定的矿化作用机制。草甘膦的大量使用及其在 Cu 污染的粗质地土壤中的降解减少，可能会增加土壤中草甘膦的持久性，并因此促进 Cu 和草甘膦在土壤环境中的迁移。
