Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 9/10/2009
Publication Date: 10/4/2009
Citation: Rice, C., Bialek Kalinski, K.M. 2009. Evidence for atmospheric deposition of pesticides to forests bordering agricultural fields. Meeting Abstract. Interpretive Summary: .
Technical Abstract: We have evaluated the ability of a forested system to intercept herbicides from the air and deliver them directly by rainfall to the forest floor and then to a receiving stream within the forested area. The study was conducted over a four year period at a site in an agricultural watershed in Maryland. The collected rain included rain through-fall, stem-flow, and collections outside the forested area. Herbicides appeared to be deposited on the canopy of the trees and bark, and later washed off during rain events. Late application of herbicides, accompanied by high temperature and high humidity and dense foliage, resulted in a very small portion of the herbicides in rain collected downwind of the forested area, i.e., less than 5% of that measured beneath the tree canopy. In contrast, these values were nearly 50% for metolachlor and around 30% for atrazine for early spring applications, when temperature and humidity were low and tree foliage less developed. Therefore, the removal and delivery of pesticides directly into forested regions through atmospheric processes may be an important contributor of pesticides into these regions and one that has received little attention.