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Title: Assessing the fate of an aromatic hydrocarbon fluid in agricultural spray applications using the three-stage ADVOCATE model framework

item TOOSE, LILSA - Ltec
item WARREN, CHRISTOPHER - Exxonmobil
item MACKAY, DONALD - Canadian Centre For Environmental Modeling And Chemistry
item PINKERTON, THOMAS - Exxonmobil
item LETINSKI, DANIEL - Exxonmobil
item MANNING, RYAN - Exxonmobil
item CONNELLY, MARTIN - Exxonmobil
item ROHDE, ARLEAN - Exxonmobil
item Fritz, Bradley - Brad
item Hoffmann, Wesley

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2015
Publication Date: 7/31/2015
Citation: Toose, L., Warren, C., Mackay, D., Pinkerton, T., Letinski, D., Manning, R., Connelly, M., Rohde, A., Fritz, B.K., Hoffmann, W.C. 2015. Assessing the fate of an aromatic hydrocarbon fluid in agricultural spray applications using the three-stage ADVOCATE model framework. Journal of Agricultural and Food Chemistry. 63(31):6866-6875.

Interpretive Summary: With increasing concerns with respect to ozone formation as a result of emission of volatile organic compounds after agrochemical applications, the need to better understand and predict, and ultimately reduce these emissions, is critical. USDA ARS agricultural engineers from College Station, Texas, in cooperation with researchers from a variety of chemical manufacturing and research institutes, conducted a series of spray application and chemical emission experiments with the resulting data being used to develop a predicted model for determining the fate of agrochemical volatile organic compounds immediately after field applications. Increased understanding of, and the ability to predict losses from, hydrocarbon volatilization ultimately allows for better estimation of ozone formation potential for designing of agrochemical products with lower emissions and environmental impact.

Technical Abstract: Components of emulsifiable concentrates (ECs) used in pesticide formulations may be emitted to air following application in agricultural use and contribute to ozone formation. A key consideration is the fraction of the ECs that is volatilized. This study is designed to provide a mechanistic model framework for estimating emissions of an aromatic hydrocarbon fluid used in ECs based on the results of spray chamber experiments that simulate fate as the fluids become subject to volatilization, sorption to soil, and biodegradation. The results indicate the need to treat the volatilization losses in three stages: (i) losses during spraying, (ii) losses up to 12 h after spraying in which the soil is coated with the ECs, and (iii) subsequent longer term losses in which the ECs become increasingly sorbed and subject to biodegradation. A mass balance model, the agrochemical derived volatile organic compound air transfer evaluation (ADVOCATE) tool, is developed, treating the ECs as seven hydrocarbon component groups, to estimate the volatilization and biodegradation losses using parameters fitted to empirical data. This enables losses to be estimated for each hydrocarbon component under field conditions, thereby providing a basis for improved estimation of ozone formation potential and for designing ECs that have lower emissions.