Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2002
Publication Date: N/A
Interpretive Summary: Volatile emissions of sprayed pesticides can be an important loss pathway. Downwind exposure to surrounding ecosystems can result from such emissions. Better data concerning the factors influencing pesticide volatility are needed for modeling emissions. In this study, pesticide concentrations were measured over soil for 20 days after application and emissions were related to moisture and temperature. The order of the volatile flux losses for the six pesticides was trifluralin > alpha-endosulfan > chlorpyrifos > metolachlor > atrazine > beta-endosulfan. The magnitude of the losses ranged from 14.1% of nominal applied amounts of trifluralin to a low of 2.5% of beta-endosulfan. The soil losses generally followed a steady, definable pattern. Soil moisture and time and extent of precipitation were found to be very important in determining the amount of pesticides volatilized from soil.
Technical Abstract: The volatile and soil loss profiles of six agricultural pesticides were measured for 20 days following application to freshly tilled soil at the Beltsville Agricultural Research Center. The volatile fluxes were determined using the Theoretical Profile Shape (TPS) method. The volatile pesticides were captured using polyurethane foam plugs. Surface-soil (0-8 cm) samples were collected on each day of air sampling. The order of the volatile flux losses were trifluralin > alpha-endosulfan > chlorpyrifos > metolachlor > atrazine > beta-endosulfan. The magnitude of the losses ranged from 14.1% of nominal applied amounts of trifluralin to 2.5% of beta-endosulfan. The daily loss profiles were typical of those observed by others for volatile flux of pesticides from moist soil. Even though heavy rains occurred from the first to third day after treatment, the majority of the losses took place within 4 days of treatment, i.e., 59% of the total applied atrazine and metolachlor and >78 % of the other pesticides. The soil losses generally followed pseudo first-order kinetics. The portion of the soil losses that were accounted for by the volatile fluxes were ordered as follows: alpha-endosulfan-34.5%, trifluralin-26.5%, chlorpyrifos-23.3%, beta-endosulfan-14.5%, metolachlor-12.4% and atrazine-7.5%.