Laboratory study on the interaction between herbicides and sediments in water systems.

Interaction between herbicides and sediments in water systems is an important process occurring in water, which influences the behaviour of the herbicides in water. This paper reports on the sorption of herbicides norflurazon, oxadiazon and trifluralin on soil and the interaction between the herbicides and sediments under stirred and non-stirred conditions. The sorption coefficients of the herbicides on soils are 3.58 and 5.41 for norflurazon, 23.43 and 28.07 for oxadiazon and 890.73 and 1217.20 for trifluralin. The sorption of the herbicides is related to the organic carbon content in the soils. This study shows a greater sorption of the herbicides on stirred sediments than on non-stirred sediments due to more significant contact under stirred conditions. The relative concentrations of the herbicides in water systems containing sediments were higher than those in pure water 6 and 13 days after treatment. When these herbicides were sorbed on sediments, their persistence in water increased. Sorption of herbicides on sediments in aquatic systems could protect them from degradation in water.