草萘胺在黄泥土不同粒径微团聚体上的吸附行为

Napropamide Sorption in Particle Size Fractions of Paddy Soil

采用超声分散法提取了太湖地区黄泥土中不同粒径的团聚体颗粒．用批次吸附试验的方法研究了除草剂草萘胺在各团聚体颗粒组上的吸附特点。结果表明，不同粒径微团聚体的草萘胺吸附等温线均可用Freundlich方程定量描述，Kf值介于5．56～11．40之间，以粒径〈0．002mm和2．00-0．25mm两个粒组吸附容量最大。粒径0．25—0．02mm和0．02—0．002mm两个粒组吸附容量较小。在各团聚体粒组中对土壤吸附草萘胺相对贡献率最大的是粒径〈0．002mm粒组。由于颗粒细小的微团聚体更易于在土壤-水环境巾迁移，因此，草萘胺在黄泥土上的这种分布特点对环境的潜在影响不容忽视。

Batch sorption experiments were conducted for a paddy soil in Taihu Lake region to measure napropamide sorption of bulk soil samples and particle size fraction samples separated by ultrasonic dispersion method. Results showed that adsorption isotherm of napropamide can be described well by the Freundlich eqation, and coefficient Ke values ranged from 5.56 to 11.40. Higher Kf values was found in 〈0.002 mm and 2.00 -0.25 mm size fractions. While taking into consideration of composition of soil size fractions, contribution of 〈0.002 mm size fraction was highest for napropamide. It suggested that potential negative effect of napropamide on environment couldn＇t be neglected because napropamide could migrate more easily in soil-water environment via sorption from soil fine-size particles.