异丙甲草胺在砂壤土中行为的研究

FATE OF METOLACHLOR IN A SANDY LOAM SOIL

通过大田试验和实验室降解试验研究异丙甲草胺在砂壤土中的迁移、降解和残留．结果表明，在大田０—１５ｃｍ土壤中，异丙甲草胺在最初７天内消失近５０％，此后变化不大，平均残留量为１３０μｇ·ｋｇ１．实验条件下异丙甲草胺降解的半衰期（Ｔ１／２）为４５天．在大田１３５ｃｍ土层处的水样中异丙甲草胺的检测率为５０％，最高浓度为１２５μｇ·Ｌ－１，平均浓度为２２μｇ·Ｌ－１．３３６个１５—７５ｃｍ各层土样中仅４个检测到有异丙甲草胺．异丙甲草胺在大田土壤中消失是由于淋溶和微生物降解两个过程的结合所致．

Field and laboratory experiments were conducted to investigate the transport, degradation and persistence of metolachlor in a sandy loam soil. About 50% of applied metolachlor was found to dissipate during the first 7 days in the 0—15cm layer soil. From 7 day after application (DAA) up to 107 day, the level of metolachlor in soil did not change significantly, and the average residue level was 130μg/kg. The half dissipation time of metolachlor was found 45 days in laboratory studies . Fifty percent of the field water samples at 135 cm depth contained detectable levels of metolachlor. The maximum and medial detectable concentration of metolachlor were 12.5 and 2.20 μg/kg in water samples, respectively. Metolachlor was detected in only 4 among 336 soil samples taken from 15 to 75 cm. The dissipation of metolachlor in 0 to 15 cm layer soil resulted from the combination of leaching and biological degradation processes.