14 C-甲霜灵在土壤中的残留与降解动态

在实验室中研究了甲霜灵在3种土壤中的残留和降解动态。结果表明在土壤中,甲霜灵的降解主要为土壤微生物的作用,不同的土壤降解速率差别很大。其中甲醇提取残留的降解半衰期对于中国北方潮土、水稻土和粉沙土分别为69,84和159 d。甲醇提取后的土壤用1%NaCl 再提取的残留呈抛物线变化,对于不同土壤峰值出现的时间不同,其中北京潮土为4～7周,水稻土为5～7周,粉沙土为15周,峰值分别为引入量的21.5%,33.3%和19.7%。1%NaCl 提取后的土样用燃烧法测得的残留量在实验期间不超过引入量的4%。甲醇提取相发现一种降解产物,其在甲醇展开系统中的 R_1值为0.65,并随时间的延长而增加,在5周时上述3种土壤中甲醇相的降解物分别占提取量的11.6%,12.7%和7.5%。~(14)C-甲霜灵土壤经3个月培养,用甲醇提取后,引入新鲜的土壤,继续培养,发现甲醇未提取残留可以重新释放出来,并为甲醇提取,在第6周时,对于北方潮土和水稻土提取量可分别占到培养前甲醇未提取残留量的25.91%和32.94%。甲霜灵在土壤中的行为符合两室一阶动力学模型,理论数据与实验数据能够很好拟合。

Study on the Residues and Degradation of14 C-Metalaxyl in Soil

Residues and degradation of ~(14)C-metalaxyl in loam soil,sandy loam soil and loamy paddy soil were studied in laboratory.The results showed that the degradation of metalaxyl in the soil was main biodegradation,the rate of degradation was different in different soil,and the half life of methanol ex- tractable residues were 69 days,159 days and 84 days,respectively.After extraction with methanol,soil samples were extracted by 1% NaCl again,and change of the residues in 1%NaCl could be described as a parabola...