科研之友
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摘要
Information regarding the mobility of applied chemicals to soils is essential for environmental assessment of potential leaching to groundwater supplies. In this study, the mobility of deltamethrin applied to soil columns with different properties was investigated. The approach used was that of a modified miscible displacement, or transport approach, where soil columns under soil-water-saturated conditions and constant flow velocity were maintained. The extent of deltamethrin leaching losses was measured by quantifying deltamethrin concentration in the effluent solution versus time. After the transport experiments were conducted, each soil column was sectioned into 2-cm increments, and the amount of deltamethrin retained by the soil was determined from sequential methanol extractions. All measured breakthrough curves (BTCs) exhibited extensive asymmetry with sharp adsorption fronts. Extremely low mobility, and thus strong retention for deltamethrin in the soil columns, was observed. With continuous leaching of up to 80 pore volumes, effluent results showed that cumulative leaching of deltamethrin was small and ranged from only 3 to 8% of that applied. Moreover, 92 to 93% of that applied remained within the 0-2-cm layer, with only 0.5-1% extracted from the subsequent lower depths (2-4-cm and 4-6-cm layers). Deltamethrin mobility was relatively higher in a reference sand material. The use of a multireaction and transport model (MRTM) proved successful in describing the BTC from the sand column and was in close agreement with measured deltamethrin results. Based on its extremely low mobility in soils, deltamethrin is considered to be not susceptible to leaching from the soil profile.
- 出版日期2002-9
