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United States Department of Agriculture

Agricultural Research Service

Research Project: Alternatives to MEBR for California Cropping Systems

Location: Water Management Research

Title: Distribution and emission of chloropicrin applied as gelatin capsules

Authors
item Wang, Q -
item Wang, Dong
item Tang, J -
item Wei, S -
item Yan, D -
item Zhang, H -
item Wang, F -
item Guo, M -
item Cao, A -

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 8, 2010
Publication Date: March 15, 2010
Citation: Wang, Q.X., Wang, D., Tang, J., Wei, S., Yan, D.D., Zhang, H., Wang, F.Y., Guo, M., Cao, A. 2010. Distribution and emission of chloropicrin applied as gelatin capsules. Journal of Environmental Quality. 39:917-922.

Interpretive Summary: The use of methyl bromide in pre-plant soil fumigation for controlling soil-borne pests will be phased out in China in 2015. A gelatin capsule formulation was developed as a potential means of reducing atmospheric chloropicrin (CP) emissions and safe application by farmers. Laboratory studies were conducted to determine the distribution, emission, leaching and soil residue of CP after applying the gelatin capsules in soil columns. The application of CP gelatin capsules reduced total CP emission by ~3 times compared to liquid injection with film cover. Daily irrigation after gelatin capsule application reduced CP emission to non-detectable levels. CP gelatin capsules developed in this research were a promising new formulation that could reduce adverse impacts on the environment such as CP emissions to the atmosphere or leaching to the groundwater. Furthermore, the CP gelatin capsules had no bad smell due to the encapsulation of the CP in the gelatin shell materials, which prevent workers and bystanders from contacting the highly irritant CP during fumigation.

Technical Abstract: Chloropicrin (CP) is a potential methyl bromide alternative for controlling soil-borne pests. However, the compound is highly volatile that poses strong exposure risks for humans and the environment because of volatile organic compound (VOC) emissions. A gelatin capsule formulation was developed as a potential means of reducing atmospheric CP emissions and safe application by farmers. The objective of this study was to determine the distribution, emission, leaching and soil residue of CP after applying the gelatin capsules in soil columns. Comparable CP soil gas concentrations were obtained between a conventional liquid injection control and the gelatin capsule application with film treatment. When soil surface was irrigated with 39.6 mm water in 6 h per day, CP soil gas concentration was similar to the film treatments at depths below 20 cm, but lower concentrations were observed at 0-20 cm depth. The application of CP gelatin capsules reduced total CP emission by ~3 times compared to liquid injection with film cover. Daily irrigation after gelatin capsule application reduced CP emission to non-detectable levels. Leachate CP concentration in the irrigation treatment was also found to be non-detectable. Similar residual soil CP was found between the liquid injection and the two gelatin capsule treatments. The results indicated that CP gelatin capsules could be a promising new technology for reducing environmental emissions and potential human exposure.

Last Modified: 9/2/2014
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