Herbicide transport on wind-eroded sediment

Although wind erosion is a pervasive soil degradation problem on the semiarid Canadian prairies, few studies have been conducted on wind-eroded sediment as an environmental pathway for herbicide transport. An experiment was conducted on a clay loam soil at Leth-bridge, AB, in 1993 to 1994, to examine Hind-eroded sediment as a transport mechanism for two soil-incorporated [trifluralin (2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline) and triallate (S-2,3,3-trichloroallyl diisopropylthiorarbamate)] and four surface-applied herbicides [diclofop {(+/-)-2-[4-(2,4-dichlorophenoxy)phenoxy]propanoic acid}, bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), mecoprop {(+/-)-2-(4-chloro-2-methylphenoxy)propanoic acid), and 2,4-D (2,4-dichlorophenoxyacetic acid)]. The concentrations of diclofop and bromoxynil in sediments decreased with increasing capture height, with the 100-cm height having significantly lower concentrations (diclofop, 627 mu g kg(-1); bromoxynil, 70 mu g kg(-1)) than the 10-cm height (diclofop, 1132 mu g kg(-1); bromoxynil, 231 mu g kg(-1)). This implies that these herbicides were primarily associated with larger soil particles captured closer to the soil surface. For the soil-incorporated herbicides, concentrations were significantly higher in the surface soil (0-2.5 em) than in the wind-eroded sediment, whereas concentrations of surface-applied herbicides vt ere generally higher in wind-eroded sediment than in surface soil. Overall wind erosion losses (expressed as a percent of amount applied) of the two soil-incorporated herbicides (1.5%) were about three times lower than those of the four surface-applied herbicides (average loss, 4.5%). The results demonstrate the potential hazard of environmental transport of herbicides on wind-eroded sediment and its associated implications for off-site air and water quality.