ENDRIN DECOMPOSITION IN SOILS AS INFLUENCED BY AEROBIC AND ANAEROBIC CONDITIONS

Abstract

The relative persistence of endrin in soils as related to flooding and alternate “anaerobic” (flooded unstirred) and “aerobic” (flooded stirred) conditions was studied in three soils by radiotracer technique. More rapid degradation of endrin occurred in all three soils under flooded conditions than under nonflooded conditions. Autoradiography revealed the formation of six breakdown products in flooded soils as compared to four compounds in nonflooded soils after 25 days of incubation. The breakdown products, detected at the end of 25 days of preincubation under flooded unstirred (predominantly anaerobic) conditions, decreased to low levels following incubation under unstirred conditions for another 30 days. By contrast, when the flooded soils were stirred for 30 days after 25 days of unstirred conditions, undecomposed endrin and some of its breakdown products detected at the end of unstirred conditions persisted and accumulated. The data demonstrated that aerobic conditions in non-flooded soils and in flooded soils subjected to an unstirred cycle increased the persistence of endrin and its breakdown products.