摘要
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。
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,the peak value occurred in 4～6 weeks,15 weeks and 5～7 weeks respectively for three types of soil,and the value was 21.5%,19.7% and 33.3% of applied dosage.The change of bound residue was no more than 4% of applied dosage in the experimental periods.One metabolite was found in methanol ex- traction,the R_1 value was 0.65 when developed by methanol,and the amount of it increased by the time, in 5th week,it was 11.6%,7.5% and 12.7% of methanol extracts for three types of soil respectively.It was also found that non-methanol extracted residues could release out and be extracted by methanol, 25.91% and 32.94% of non-methanol extracted residues could release out for loam soil and loamy paddy soil respectively after six weeks of culture.The behavior of metalaxyl in soil could be described as two compartments dynamic model,and the calculated value agreed well to the measured value.
基金
农业部"八五"课题:核技术及计算机技术在农业研究中的应用
关键词
甲霜灵
残留
降解
动力学模型
metalaxyl
residue
degradation
dynamic model
