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Title: Mitigating 1,3-dichloropropene, chloropicrin, and methyl iodide emissions from fumigated soil with reactive film

Author
item XUAN, RICHENG - University Of California
item Yates, Scott
item ASHWORTH, DANIEL - University Of California
item LUO, LIFANG - University Of California

Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2012
Publication Date: 4/25/2012
Citation: Xuan, R., Yates, S.R., Ashworth, D.J., Luo, L. 2012. Mitigating 1,3-dichloropropene, chloropicrin, and methyl iodide emissions from fumigated soil with reactive film. Environmental Science and Technology. 46:6143-6149.

Interpretive Summary: Methyl bromide (MeBr) has been used for several decades to control plant pests prior to production of many food crops. MeBr has also been identified as an ozone depleting compound and was scheduled for phase out during 2005 in developed countries, and 2015 elsewhere. Alternatives to MeBr also have the potential to pollute the atmosphere and may adversely affect public and ecosystem health. For example, use of methyl iodide (MeI) in soil fumigation can pollute the atmosphere and has the potential to contaminate ground water or harm plants from excessive iodide ion produced from degradation of MeI in soil. Therefore, a great need exists for low-cost and effective methods and technology to reduce fumigant emissions and adverse effects of transformation products to soil and water supplies. This paper describes a research effort to design a gas-tight film that degrades halogenated fumigants before they enter the atmosphere. The methodology also traps degradation products so they do not become contaminants. This research would be of interest to scientists, growers, regulators and film manufacturers.

Technical Abstract: Implicated as a stratospheric ozone-depleting compound, methyl bromide (MeBr) is being phased out despite being considered to be the most effective soil fumigant. Its alternatives, i.e., 1,3-dichloropropene (1,3-D, which includes cis- and trans- isomers), chloropicrin (CP) and methyl iodide (MeI), have been widely used. High emissions of MeI from fumigated soil likely put farm workers and other bystanders at risk of adverse health effects. In this study, two types of constructed reactive film were tested for their ability to mitigate emissions of 1,3-D, CP, and MeI using laboratory permeability cells. These films potentially act both as a physical barrier to trap fumigants leaving soil before activation and also as a sink for the fumigants after activation of the reactive layer containing ammonium thiosulfate solution. Over 97% of trans-1,3-D and 99% of the cis-1,3-D, CP and MeI were depleted when they passed into the reactive film. Half-lives (t1/2) of cis-, trans-1,3-D, CP and MeI under activated reactive film were 1.2, 1.4, 1.6 and 2.0 h, respectively, at 40 °C.