Krutz L J, Senseman S A, McInnes K J, Hoffman D W, Tierney D P
Department of Soil and Crop Science, Texas Agricultural Experiment Station, Texas A&M University College Station, TX 77843-2142, USA.
J Environ Qual. 2004 May-Jun;33(3):939-45. doi: 10.2134/jeq2004.0939.
Previous studies have indicated that dissolved-phase metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(methoxy-1-methylethyl) acetamide] transported in surface runoff is retained by vegetative filter strips to a greater degree than either metolachlor oxanilic acid 12-[(2-ethyl-6-methylphenyl) (2-methoxy-1-methylethyl)amino]-2-oxo-acetic acid] (OA) or metolachlor ethanesulfonic acid [2-[(2-ethyl-6-methylphenyl) (2-methoxy-1-methylethyl-1)amino]-2-oxoethanesul-fonic acid] (ESA), two primary metabolites of metolachlor. Adsorption-desorption of ESA and OA in vegetated filter strip soil (VFSS) has not been evaluated, yet these data are required to assess the mobility of these compounds in VFSS. The objective of this experiment was to compare metolachlor, ESA, and OA adsorption and desorption parameters between VFSS and cultivated soil (CS). Adsorption and desorption isotherms were determined using the batch equilibrium procedure. With the exception of a 1.7-fold increase in organic carbon content in the VFSS, the evaluated chemical and physical properties of the soils were similar. Sorption coefficients for metolachlor were 88% higher in VFSS than in CS. In contrast, sorption coefficients for ESA and OA were not different between soils. Relative to metolachlor, sorption coefficients for ESA and OA were at least 79% lower in both soils. Metolachlor desorption coefficients were 59% higher in the VFSS than in the CS. Desorption coefficients for ESA and OA were not different between soils. Relative to metolachlor, desorption coefficients for ESA and OA were at least 66% lower in both soils. These data indicate that the mobility of ESA and OA will be greater than metolachlor in both soils. However, higher organic carbon content in VFSS relative to CS may limit the subsequent transport of metolachlor from the vegetated filter strip.
以往研究表明，在地表径流中迁移的溶解态异丙甲草胺[2-氯-N-(2-乙基-6-甲基苯基)-N-(甲氧基-1-甲基乙基)乙酰胺]比异丙甲草胺的两种主要代谢物——异恶草酮酸12-[(2-乙基-6-甲基苯基)(2-甲氧基-1-甲基乙基)氨基]-2-氧代乙酸或异丙甲草胺乙磺酸盐2-[(2-乙基-6-甲基苯基)(2-甲氧基-1-甲基乙基-1)氨基]-2-氧代乙磺酸盐，在植被过滤带中保留程度更高。尚未评估ESA和OA在植被过滤带土壤(VFSS)中的吸附-解吸情况，但评估这些化合物在VFSS中的迁移性需要这些数据。本试验的目的是比较VFSS和耕地土壤(CS)之间异丙甲草胺、ESA和OA的吸附和解吸参数。采用批次平衡法测定吸附和解吸等温线。除VFSS中有机碳含量增加1.7倍外，所评估的土壤化学和物理性质相似。VFSS中异丙甲草胺的吸附系数比CS中高88%。相比之下，土壤之间ESA和OA的吸附系数没有差异。相对于异丙甲草胺，两种土壤中ESA和OA的吸附系数至少低79%。VFSS中异丙甲草胺的解吸系数比CS中高59%。土壤之间ESA和OA的解吸系数没有差异。相对于异丙甲草胺，两种土壤中ESA和OA的解吸系数至少低66%。这些数据表明，在两种土壤中，ESA和OA的迁移性将大于异丙甲草胺。然而，相对于CS，VFSS中较高的有机碳含量可能会限制异丙甲草胺从植被过滤带的后续迁移。
