Persistence of hexazinone and metsulfuron-methyl in a mixed-wood/boreal forest lake

The persistence of hexazinone and metsulfuron-methyl herbicides was investigated in an experiment using in situ enclosures deployed in a mixed-wood/boreal forest lake. Dissipation studies provided evidence that aqueous residues of hexazinone may persist (DT 50 =131-280 days) under conditions typical of northern lentic systems in the mixed-wood/boreal forest. Although dissipation rates of hexazinone differed depending upon initial concentrations (10 4 and 10 3 μg L -1 ), such differences were of little practical significance