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Title: PREDICTING PESTICIDE VOLATILIZATION FROM SOILS.

Author
item Yates, Scott
item Schneider, Sharon
item MA, Q. - UC RIVERSIDE, CA
item GAN, J. - UC RIVERSIDE, CA

Submitted to: Journal of Environmetrics
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2001
Publication Date: 4/1/2002
Citation: Yates, S.R., Papiernik, S.K., Ma, Q.L., Gan, J. 2002. Predicting pesticide volatilization from soils.. Journal of Environmetrics. 13:569-578.

Interpretive Summary: The purpose of this paper is to investigate the influence of three methods used to describe pesticide movement from soil into the atmosphere. This is accomplished by using a model to simulate pesticide emission rates and comparing the simulated rates to field measurements. A model was developed to simulate methyl bromide degradation and movement in soil, and emission into the atmosphere. Three methods were used to describe the emission process at the soil surface, each with greater complexity: (1) emissions under isothermal conditions, (2) emissions in response to solar- driven temperature changes at the soil surface, and (3) emissions from soil coupled to atmospheric processes. The method that couples soil and atmospheric processes was found to be superior to other methods for simulating pesticide emissions.

Technical Abstract: Due to concerns about public health and environmental contamination, there has been great interest in improving our understanding of the processes and mechanisms that affect pesticide emissions from fields. For many situations, predicting pesticide volatilization has been limited to simple situations that often neglect important environmental conditions such as changes in ambient temperature and/or the effect of atmospheric conditions above the field. Little research has been conducted that couples atmospheric processes to the volatilization of pesticides from soils. A field study was conducted to measure the volatilization of methyl bromide from a 3.5 ha field. Four methods were used to obtain the volatilization rate as a function of time. A 1-D numerical model was developed and used to simulate the fate and transport of methyl bromide from the fumigated field. A boundary condition that couples soil and atmospheric processes was found to provide an accurate and credible simulation of the instantaneous volatilization rates compared to simpler stagnant boundary layer solutions.