PERSISTENT ORGANIC AND INORGANIC PESTICIDE RESIDUES IN ORCHARD SOILS AND VINEYARDS OF SOUTHERN ONTARIO

Abstract

Soils from apple, cherry and peach orchards and vineyards were collected between 1972 and 1975 for analyses of major metals found in inorganic pesticides and for organochlorine and organophosphorus pesticides. The pattern of pesticide use for fruit production in Ontario between 1892 and 1975 was reviewed for those compounds included in this chemical survey. The use of lead arsenates on apple orchards over the past 70 yr elevated arsenic and lead from background levels (7.4 ppm As and 6.4 ppm Pb) to 121 ppm As and 774 ppm Pb. Accumulations in cherry orchard soils, where a lesser volume was used annually, were considerably lower. Levels in both peach and vineyard soils were only slightly above background contents. Twenty years of recommended use of phenyl mercuric acetate, a scab eradicant, elevated the mercury content in apple orchard soils from 0.08 ppm to 0.29 ppm. Copper salts used as fungicides over the past 80 yr have produced only small elevations in copper content of some orchard soils. In apples the increase was from 21 ppm to 63 ppm in a 70-yr time period. The use of compounds containing iron, manganese and zinc had no effect on soil content of these metals. Sixteen organochlorine acaricides and insecticides recommended for use in orchards were sought in the survey. The most frequently found, and no longer used, were DDT, TDE and their metabolite DDE; apple and peach orchards had the highest mean residues of 43.3 and 9.22 ppm ΣDDT, respectively. Other organochlorine insecticides found were endosulfan, endrin, HEOD, and methoxychlor; with the exception of endosulfan, residues were well below 1 ppm. The acaricide dicofol was present in apple, sweet cherry and peach soils. No organochlorine fungicides were detected. Heptachlor epoxide and lindane were found in some orchard soils at trace levels; neither was recommended for use in orchards. Thirteen organophosphorus insecticides recommended for use in orchards were sought in the survey; however, only ethion and parathion were found at trace levels.