Pj. Phillips et al., Metolachlor and its metabolites in tile drain and stream runoff in the canajoharie Greek watershed, ENV SCI TEC, 33(20), 1999, pp. 3531-3537
Citations number
29
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Water samples collected during April-November 1997 from tile drains beneath
cultivated fields in central New York indicate that two metabolites of the
herbicide metolachlor-metolachlor ESA (ethanesulfonic acid) and OA (oxanil
ic acid)-can persist in agricultural soils for 4 or more years after applic
ation and that fine-grained soils favor the transport of metolachlor ESA ov
er metolachlor and metolachlor OA. Concentrations of metolachlor ESA from t
he tile drains ranged from 3.27 to 23.4 mu g/L (200-1800 times higher than
those of metolachlor), metolachlor OA concentrations ranged from 1.14 to 13
.5 mu g/L, and metolachlor concentrations ranged from less than 0.01 to 0.1
mu g/L. In the receiving stream, concentrations of metolachlor ESA were al
ways below 0.6 mu g/L except during a November storm, when concentrations r
eached 0.85 mu g/L. Concentrations of metolachlor ESA in the stream were 2-
45 times higher than those of metolachlor, reflecting the greater relative
concentrations of metolachlor in surface water runoff than in tile drain ru
noff, These results are consistent with findings in other studies that acet
anilide herbicide degredates are found in much higher concentrations than p
arent compounds in both surface water and groundwater.