Persistence of @u1@u4C-labeled atrazine and its residues in a field lysimeter soil after 22years

Twenty-two years after the last application of ring-@u1@u4C-labeled atrazine at customary rate (1.7kg ha@u-@u1) on an agriculturally used outdoor lysimeter, atrazine is still detectable by means of accelerated solvent extraction and LC-MS/MS analysis. Extractions of the 0-10cm soil layer yielded 60% of the residual @u1@u4C-activity. The extracts contained atrazine (1.0kg kg@u-@u1) and 2-hydroxy-atrazine (42.5kg kg@u-@u1). Extractions of the material of the lowest layer 55-60cm consisting of fine gravel yielded 93% of residual @u1@u4C-activity, of which 3.4kg kg@u-@u1 was detected as atrazine and 17.7kg kg@u-@u1 was 2-hydroxy-atrazine. The detection of atrazine in the lowest layer was of almost four times higher mass than in the upper soil layer. These findings highlight the fact that atrazine is unexpectedly persistent in soil. The overall persistence of atrazine in the environment might represent a potential risk for successive groundwater contamination by leaching even after 22years of environmental exposure.