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Title: SORPTION OF 1,3-DICHLOROPROPENE ON SOIL

Author
item Dungan, Robert - Rob
item Park, Moon-ki
item Kim, Jung-ho

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2004
Publication Date: 9/1/2004
Citation: Park, M.-K, Kim, J.-H, Dungan, R.S. 2004. Sorption of 1,3-dichloropropene on soil. Journal of Environmental Science and Health, Part B. 39(4):603-612.

Interpretive Summary: The fumigant pesticide 1,3-dichloropropene (1,3-D) is considered a major replacement to methyl bromide, which is to be phased out of use in the United States by 2005. The main purpose of this study was to evaluate the amount of 1,3-D that is distributed between the soil particles and soil water in two California agricultural soils (Salinas clay loam and Arlington sandy loam). Partition coefficients (which can be used to better understand the amount of 1,3-D that is adsorbed by the soil particles and absorbed by the soil water) were determined by directly measuring the concentration of 1,3-D in the solid phase (Cs) and aqueous phase (Cw) after allowing the system to come to equilibration. At a temperature of 25oC, the soil-water partition coefficients (Kd) of 1,3-D ranged from 0.46 to 0.56. A Kd less than 1.0 suggests that 1,3-D is weakly retained by the soil particles and, therefore, is highly mobile. Due to the high mobility of 1,3-D in soil, 1,3-D may cause undesirable health effects when it is transported into the air and groundwater. Understanding the migratory behavior of 1,3-D in soil is important when developing fumigation practices to reduce offsite movement of 1,3-D.

Technical Abstract: The fumigant 1,3-dichloropropene (1,3-D) is considered a major replacement to methyl bromide, which is to be phased out of use in the United States by 2005. The main purpose of this study was to evaluate soil-water partitioning of 1,3-D in two California agricultural soils (Salinas clay loam and Arlington sandy loam). The partition coefficients (Kd and Kf) were determined by directly measuring the concentration of 1,3-D in the solid phase (Cs) and aqueous phase (Cw) after batch equilibration. In the Salinas clay loam, the Kf of cis-1,3-D in adsorption and desorption isotherms was 0.47 and 0.54, respectively, with respective values of 0.39 and 0.49 for trans-1,3-D. This hysteric effect suggests that a different range of forces are involved in the adsorption and desorption process. Since n was near unity in the Freundlich equation, the Freundlich isotherms can also be approximated using the liner isotherm. At 25oC, the Kd of the 1,3-D isomers in both soils ranged from 0.46 to 0.56, and the Koc (organic matter partition coefficient) ranged from 58 to 70. The relatively low Kd values and Koc that fall within the range of 50-150, suggests that 1,3-D is weakly sorbed and highly mobile in these soils. Understanding the sorption behavior of 1,3-D in soil is important when developing fumigation practices to reduce the movement of 1,3-D to the air and groundwater.