CHEMICAL VERSUS MICROBIAL-DEGRADATION OF CYANAZINE AND ATRAZINE IN SOILS

A laboratory study was performed to investigate the relationship betwe en chemical (non-biological) and microbial degradation of cyanazine an d atrazine in soils ranging in pH from 5.3 to 8.1. Atrazine degradatio n was dominated by chemical processes in both a moderately acidic and a neutral pH soil, but showed a significant microbial involvement in t he neutral pH soil. The primary cyanazine degradative mechanism was de pendent on soil properties. Cyanazine was short-lived in neutral to sl ightly basic soils, due to rapid microbial degradation. Cyanazine amid e and cyanazine acid were the major metabolites formed. In a moderatel y acidic soil, microbial degradation was slowed and and chemical proce sses were the primary means of cyanazine degradation.