Metolachlor fate and mobility in a tidal wetland soil

A study was conducted to determine the fate of the herbicide metolachlor in a tidal wetland soil located along the James River in Virginia, USA. Soil adsorption/desorption and mineralization characteristics and mobility of me tolachlor were determined on the Levy tidal wetland soil. The metolachlor K -d value was 65.8 L kg(-1) and K-oc value was 810 L kg(-1) C-1, which are m uch greater than would be found on typical agricultural soils. After four 2 4-h desorption periods, the total amount of metolachlor that desorbed range d from 16 to 22% of the amount initially adsorbed. Metolachlor mineralizati on was about 0.46% of the amount applied after 84 days, which indicates tha t it does not mineralize very readily in the Levy soil. The amount of metol achlor that leached from the soil columns averaged 1.64% of the amount appl ied after 84 days, showing a low degree of mobility. These results suggest that the Levy tidal wetland soil can function as an effective filter of met olachlor and other similar herbicides that enter via agricultural runoff, p rotecting surface and ground waters.