W8 AM Agrochemicals and Pesticides
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in 337-338

(ZHE-1117-828542) Reducing Fumigant Emissions by Tarping Reactive Surface Barrier (RSB).

Zheng, Wei^{1, 2}, Yates, Scott², ¹ Department of Environmental Sciences, University of California, Riverside (UCR), Riverside, CA, USA² USDA-ARS, Soil Physics and Pesticides Research Unit, George E. Brown Jr Salinity Laboratory, Riverside, CA, USA

ABSTRACT- Halogenated fumigants have been used extensively in production agriculture to control soilborne pests. These types of pesticides are highly volatile and are prone to affect air quality and imperil public health. In the study, a chemical tarp approach, termed a reactive surface barrier (RSB), was developed to reduce the emission of fumigant 1,3-dichloropropene (1,3-D) from the soil surface. The agrochemicals thiourea and allylthiourea were tested as active reagents for the construction of a RSB, where these soil amendments react with 1,3-D to form nonvolatile isothiuronium ions at the soil surface and, thereby, impede fumigant emission into the atmosphere. The feasibility of the method largely depends on the reactivity of 1,3-D and the RSB agrochemicals in soil as well as on the mobility, persistence, and toxicity of the transformation products. Therefore, the effects of various thiourea amendment factors on the transformation kinetics of 1,3-D were investigated. Also, a stimulated column system was developed to investigate the volatilization of 1,3-D from soil column tarping with thiourea RSB, thereby to evaluate the emission control efficacy of this fumigation strategy. In the column system, emission of 1,3-D decreased with increasing thiourea surface amendment rate and increasing shank injection depth. In a field trial, a thiourea RSB reduced cumulative 1,3-D emissions by >80% relative to bare soils surface. The results clearly indicate that this chemical remediation technology has great potential to control the emissions of volatile halogenated organic contaminants and to mitigate atmospheric pollution.

Key words: Fumigant, Reacttive surface barrier, 1,3-Dichloropropene, Atmospheric emission