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United States Department of Agriculture

Agricultural Research Service

Title: Formation and Extraction of Fumigant Residues in Soils

Authors
item Guo, M - UC RIVERSIDE, CA
item Papiernik, S
item Zheng, W - UC RIVERSIDE, CA
item Yates, Scott

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 20, 2003
Publication Date: March 20, 2003
Citation: Guo, M.X., Papiernik, S.K., Zheng, W., Yates, S.R. 2003. Formation and extraction of fumigant residues in soils. American Chemical Society Abstracts 225:U92-U92 0008-AGRO Part 1 Mar 2003.

Interpretive Summary: Fumigants are commonly thought to be short-lived in soil, but residues have been found in soils many years following application. An experiment was conducted to study the formation and extraction of persistent soil fumigant residues. Fumigants 1,3- dichloropropene (1,3-D), chloropicrin (CP), and methyl isothiocyanate (MITC) were spiked into Arlington, Glenelg, and Hagerstown soils and incubated for 30 d under controlled conditions. The incubated soils were evaporated for 20 h prior to extraction with a variety of organic solvents at different temperatures. Extraction with acetonitrile in sealed vials at 80 C for 24 h was the most efficient method to recover persistent soil fumigant residues. At application rates of 1000-1700 mg (kg of soil)-1, persistent residues of 1,3-D, CP, and MITC in the three soils ranged from 5 to 67 mg kg-1. The residue content increased with application rate, correlated positively with silt content, decreased dramatically as indigenous organic matter (OM) was removed, and changed little with external OM addition. Adsorption to clay surfaces was not important in fumigant retention, while pulverization of soil aggregates significantly decreased persistent fumigant residues. The results suggest that persistent fumigant residues are retained in soil intra-aggregate micropores resulting from binding clay flocs and silt particles by humic substances.

Technical Abstract: Fumigants are commonly thought to be short-lived in soil, but residues have been found in soils many years following application. An experiment was conducted to study the formation and extraction of persistent soil fumigant residues. Fumigants 1,3- dichloropropene (1,3-D), chloropicrin (CP), and methyl isothiocyanate (MITC) were spiked into Arlington, Glenelg, and Hagerstown soils and incubated for 30 d under controlled conditions. The incubated soils were evaporated for 20 h prior to extraction with a variety of organic solvents at different temperatures. Extraction with acetonitrile in sealed vials at 80 C for 24 h was the most efficient method to recover persistent soil fumigant residues. At application rates of 1000-1700 mg (kg of soil)-1, persistent residues of 1,3-D, CP, and MITC in the three soils ranged from 5 to 67 mg kg-1. The residue content increased with application rate, correlated positively with silt content, decreased dramatically as indigenous organic matter (OM) was removed, and changed little with external OM addition. Adsorption to clay surfaces was not important in fumigant retention, while pulverization of soil aggregates significantly decreased persistent fumigant residues. The results suggest that persistent fumigant residues are retained in soil intra-aggregate micropores resulting from binding clay flocs and silt particles by humic substances.

Last Modified: 10/23/2014
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