Spatial Distribution of Pesticide Residues in a Former Apple Orchard

Abstract

Abstract During the period 1900–1950, considerable amounts of Pb arsenate pesticides were used in apple orchards. Many of these orchards are not in fruit production any longer and are used for home gardening, pasture, or forage and vegetable cropping. This paper examines the spatial distribution of inorganic pesticide residues in an abandoned orchard in central Massachusetts. Maximum Pb and As concentration in surface soils sampled in a grid‐like pattern, were 870 µ g g −1 and 120 µ g g −1 , respectively. Areas high in contaminants were either former tree sites or low spots where spray residues collected. A transect through the approximate location of a former tree site showed Pb and As concentrations under the dripline of 1400 µ g g −1 and 330 µ g g −1 , respectively, and lower values of 170 µ g g −1 and 50 µ g g −1 outside the periphery of the crown. Lead, arsenic, and zinc concentrations decreased with increasing depth, with maximum concentrations in the upper 5 cm. No evidence of significant leaching of Pb, As, Zn, or Cu was observed below the 20‐cm depth. The rather insoluble Pb orthoarsenate appeared to be the predominant species for the Pb and As residues.