The vertical distribution of the potential to mineralize ring-U-14{sup left}Cherbicides was investigated in samples from a sandy aquifer. Mecoprop, isoproturon, or atrazine were added to sediments from 0.06 to 7.68 m below the surface, and mineralization at 10 ℃ was monitored as evolved 14{sup left}CO{sub}2. The highest potential for mineralization was found in the plough layer, the upper 0.30 m. Here, approximately 43 of mecoprop, 14 of isoproturon, and 3 of atrazine were recovered as 14{sup left}CO{sub}2 after 85, 267, and 119 days, respectively.. The estimated doubling time, T{sub}d, for 14{sup left}CO{sub}2 evolution from the initially added herbicide was approximately 20 days for mecoprop in the plough layer increasing to more than 5 years below 4.73 m. For isoproturon incubated at 10 ℃, T{sub}d was 700 days in the plough layer increasing to 6 years in the subsurface. At 20 ℃ the rate of mineralization of isoproturon doubled compared to the rate at 10 ℃. Atrazine was mineralized slowly, T{sub}d was 5 years in the plough layer, and mineralization of atrazine below 0.70 m was not observed. None of the herbicides was mineralized anaerobically in the presence of nitrate.
展开▼
