Groundwater residues of atrazine, alachlor, and cyanazine under no-tillage practices

Groundwater from no-till corn plots treated with atrazine, alachlor, and cyanazine was analyzed for residues of these herbicides over a 3-year period. Detectable levels of atrazine, alachlor, and cyanazine were found in 75, 18, and 13% of the recovered samples, respectively. Maximum residue levels were 5.9, 3.6, and 1.0 μg L −1 for atrazine, cyanazine, and alachlor, respectively. Rapid vertical transport to the shallow unconfined groundwater (ca. 1 m depth), as well as substantial lateral subsurface flow, was indicated.