Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2004
Publication Date: 3/20/2004
Citation: Guo, M., Papiernik, S.K., Zheng, W., Yates, S.R. 2004. Effect of environmental factors on 1,3-dichloropropene hydrolysis in water and soil. Journal of Environmental Quality. 33:612-618. Interpretive Summary: The fumigant, 1,3-dichloropropene (1,3-D), is a widely used to control soil-borne nematodes. It has two isomers: cis-1,3-D and trans-1,3-D, with different physical properties, chemical reactivities, and biological toxicities. As a methyl bromide alternative, 1,3-D use is expected to increase significantly and has the potential to cause environmental and human-health problems. Hydrolysis is an important mechanism in 1,3-D degradation. However, the effects of many environmental factors such as pH, sunlight, presence of colloidal particles, soil moisture, texture, mineralogy and microorganisms on the hydrolysis reaction are not completely understood. The objectives of this study are to evaluate the effect of environmental factors such as pH, colloids, DOM, photo irradiation, soil texture, moisture, mineralogy and microbes on 1,3-D hydrolysis and to determine the half-lives of 1,3-D in water and soil. This information will be useful for limiting potential contamination from agricultural use of this fumigant.
Technical Abstract: Hydrolysis is the initial step for degradation of the fumigant 1,3-dicholorpropene (1,3-D) in water and soil. Experiments were conducted to investigate effects of various environmental factors on the hydrolysis reaction. Cis-, trans-1,3-D and their isomeric mixture were spiked into water solutions and Arlington soils (coarse-loamy, mixed, thermic Haplic Durixeralfs) and incubated under different conditions. Hydrolyses of the chemical in water and soil were evaluated based on its residual amount and the Cl- release, respectively. 1,3-D hydrolyzed rapidly in deionised water, with a half-life of 9.9 d at 20C. The hydrolysis was pH dependent, acidic pH inhibiting and alkaline pH favouring the reaction. Other factors such as isomeric difference, photo irradiation, suspended particles, untamed microbes, and small amounts of solutes had little effect on the reaction. In soil, 1,3-D hydrolyzed slowly, and the rate decreased with the initial concentration yet increased with soil moisture content. At 20C, half-lives of 1,3-D with application rates of 10 and 0.61 mg g-1 in 10 percent moisturized soil were 35.7 d and 15.2 d, respectively. The isomeric difference, soil particle size and mineralogy had little effect on the reaction. Organic matter promoted 1,3-D degradation via direct substitution reactions, and trans-isomers showed preference over the cis- to react with certain organic molecules. Microbial contributions were initially insignificant, and became important as soil microorganisms adapted to the fumigant. The results suggest that to accelerate 1,3-D degradation, pH, tamed microbes, soil moisture, and organic amendment should be considered.