Leaching of phenoxyalkanoic acid herbicides from farmland

The content of the phenoxyalkanoic acid herbicides 2,4-d, dichlorprop, MCPA, and mecoprop was measured over a 2-year period in drainage water from three clayey soils in Denmark. The herbicide content in 17 out of 65 water samples was above 0.1 μg l−1 which is the maximum residue limit for drinking water in Europe. Application of mecoprop in the autumn did not cause the expected leaching. The highest concentrations for 2,4-d, dichlorprop, MCPA and mecoprop were 0.24, 0.30, 0.29 and 0.34 μg l−1, respectively.