Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/1/2008
Publication Date: 1/13/2009
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2179.pdf
Citation: Yates, S.R. 2009. Analytical Solution Describing Pesticide Volatilization from Soil Affected by a Change in Surface Condition. Journal of Environmental Quality. 38(1):259-267. Interpretive Summary: Pesticides play an important role in crop production and produce quality, but pesticide use can lead to various environmental and health problems. In California, large regions of the state are heavily influenced by agriculture and contribute to increases in volatile organic chemical (VOC) emissions to the atmosphere. In California, 5 of the top 10 active pesticide agents are soil fumigants and 33.7 million pounds were used in 2005. This has become a serious concern because of the new federal 8-hour ozone standard and significant reductions in VOC emissions are required. This has caused regulatory agencies to develop regulations to control emissions. The current methodology used to obtain emission information involves conducting large-scale field experiments and measuring pesticide emissions. Large-scale experiments are time-consuming, costly, and highly complex and often make it difficult to isolate variables that control emissions, which is needed when developing regulations. New methods are needed to quickly and inexpensively estimate emissions that allow isolation of the factors affecting emissions. The purpose of this paper is to report on the development of two analytical solutions that could be used to assist regulators in determining volatilization rates, emission fractions, and the relationship between soil-chemical properties and emissions. This research was motivated by a lack of relatively simple methods that can be used to determine the effect of altering application methods on pesticide efficacy and total emissions into the atmosphere.
Technical Abstract: An analytical solution describing the fate and transport of pesticides applied to soils has been developed. Two pesticide application methods can be simulated: point-source applications such as a hot-gas injection method and a shank-source application method that includes a vertical pesticide distribution in the soil domain (i.e., due to the shank). The solutions allow determination of the volatilization rate and a number of other indices that could be important to understanding fumigant movement and in the development of permitting conditions. The solutions can be used to characterize differences in emissions relative to changes in the soil degradation rate, surface barrier conditions, application depth, and soil packing. In some cases, simple algebraic expressions are provided that can be used to obtain the total emissions and total soil degradation. The solutions provide a consistent methodology for determining the total emissions and can be used with other information, such as field experimental data, to support the development of fumigant regulations. The uses of the models are illustrated by several examples.