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

Interaction between herbicides and sediments in water systems is an importa nt process occurring in water, which influences the behaviour of the herbic ides in water. This paper reports on the sorption of herbicides norflurazon , oxadiazon and trifluralin on soil and the interaction between the herbici des and sediments under stirred and non-stirred conditions. The sorption co efficients 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 sor ption of the herbicides is related to the organic carbon content in the soi ls. This study shows a greater sorption of the herbicides on stirred sedime nts than on non-stirred sediments due to more significant contact under sti rred conditions. The relative concentrations of the herbicides in water sys tems containing sediments were higher than those in pure water 6 and 13 day s after treatment. When these herbicides were sorbed on sediments, their pe rsistence in water increased. Sorption of herbicides on sediments in aquati c systems could protect them from degradation in water. (C) 2000 Elsevier S cience Ltd. All rights reserved.