铅污染对青紫泥田土壤中苄嘧磺隆降解的影响

Effects of Pb Pollution on Degradation of Bensulfuron-methyl in a Purple Clayey Paddy Soil

在实验室培养条件下,研究了Pb对苄嘧磺隆除草剂在青紫泥田土壤中的残留和消失动态。结果表明Pb抑制了土壤中苄嘧磺隆的降解,使残留量提高、消失率降低。至培养结束(第180天)时,不同Pb浓度处理下土壤中的残留量在0.18～0.57 mg·kg-1之间,消失率在91%～97%之间。苄嘧磺隆降解随培养时间的变化符合一级反应动力学方程,降解半衰期为33.2-57.2天。分析表明,300 mg·kg-1可能是Pb严重抑制苄嘧磺隆降解的临界浓度,而500 mg·kg-1则可能是Pb强烈抑制苄嘧磺隆降解的上限浓度。上述结果对制定土壤环境重金属容量标准具有较好的参考意义。

A laboratory incubation experiment was conducted to study the effects of Pb pollution on residue and dissipation dynamics of bensulfuron-methyl herbicide in a purple clayey paddy soil. The results showed that Pb inhibited degradation of bensulfuron-methyl and thereby increased the amount of residue and decreased the dissipation rate of the herbicide. At the end of incubation,the residual amount of bensulfuron-methyl varied between 0.18-0.57 mg.ks^-1 in the soil with various Pb concentrations,and the dissipation rate varied between 91-97%. The relationship between residual amount and incubation time was well fitted to the first-order kinetic equation,and the half-life varied between 33.2-57.2 days. It is considered that 300 mg.kg^-1 of Pb may be the critical concentration significantly inhibiting the degradation of bensulfuron-methyl,while 500 mg.kg^-1 of Pb may be the up limit concentration strongly inhibiting the degradation of bensulfuron-methyl in the soil. Above results would be significant to establish environmental capacity standard for heavy metals in the soil.