Guo Mingxin, Yates Scott R, Zheng Wei, Papiernik Sharon K
Department of Environmental Sciences, University of California, Riverside, California 92521, USA.
Environ Sci Technol. 2003 Nov 15;37(22):5181-5. doi: 10.1021/es0344112.
Persistent fumigant residues in soil resulting from agricultural pest-control practices may be released into water and leached to groundwater. In this study, the leaching potential of persistent soil fumigant residues was evaluated, and the effect of dissolved organic matter (DOM) and ammonium thiosulfate (ATS) amendment was investigated. A silt loam soil was incubated separately with the fumigants 1,3-dichloropropene (1,3-D), chloropicrin (CP), and methyl isothiocyanate (MITC) at 240-990 mg kg(-1) for 35 d, followed by 48 h of evaporation. The soil was packed into stainless steel columns (1.4 cm x 10 cm) and leached with water, 5 mM ATS, and DOM solution (DOC 250 mg L(-1)) by gravity. Residues of 1,3-D, CP, and MITC in the evaporated soil were 5.61, 11.38, and 1.83 mg kg(-1), respectively. Concentrations of 1,3-D, CP, and MITC in column effluents ranged from 0.05 to 0.73, 0.16 to 0.81, and 0.05 to 0.27 mg L(-1), respectively, when the soil was leached with 10 pore volumes of water. DOM did not promote the leaching of persistent fumigant residues, and ATS remarkably reduced the amount of 1,3-D and CP yet notably increased MITC recovered in the effluents. The results suggest that the leaching of persistent fumigant residues through soil to water is significant, and movement of fumigants in soil is not facilitated by DOM. Amending soil with ATS through irrigation is an effective method to remove persistent residues of halogenated fumigants. To reduce groundwater pollution risks posed by fumigation, persistent soil fumigant residues have to be considered.
农业害虫防治措施导致土壤中残留的持久性熏蒸剂可能会释放到水中并渗入地下水。在本研究中，评估了持久性土壤熏蒸剂残留的淋溶潜力，并研究了溶解有机物（DOM）和硫代硫酸铵（ATS）改良剂的影响。将粉质壤土分别与熏蒸剂1,3 - 二氯丙烯（1,3 - D）、氯化苦（CP）和甲基异硫氰酸酯（MITC）以240 - 990 mg kg(-1) 的剂量孵育35天，然后蒸发48小时。将土壤装入不锈钢柱（1.4 cm×10 cm）中，通过重力用去离子水、5 mM ATS和DOM溶液（DOC 250 mg L(-1)）进行淋溶。蒸发后土壤中1,3 - D、CP和MITC的残留量分别为5.61、11.38和1.83 mg kg(-1)。当用10倍孔隙体积的水淋溶土壤时，柱流出物中1,3 - D、CP和MITC的浓度分别为0.05至0.73、0.16至0.81和0.05至0.27 mg L(-1)。DOM并未促进持久性熏蒸剂残留的淋溶，而ATS显著减少了1,3 - D和CP的量，但显著增加了流出物中回收的MITC的量。结果表明，持久性熏蒸剂残留通过土壤淋溶到水中的现象很显著，DOM对熏蒸剂在土壤中的迁移没有促进作用。通过灌溉用ATS改良土壤是去除卤代熏蒸剂持久性残留的有效方法。为降低熏蒸对地下水造成污染的风险，必须考虑土壤中持久性熏蒸剂残留的问题。
