The influence of salinity and sediment on the loss of atra8ine from the water column

Two experiments of 128 – 130 days duration were conducted to determine the influence of salinity and sediment type on the loss of atrazine from the water column. In the first experiment, atrazine did not exhibit a significant loss after 128 days in any of the test conditions (atrazine concentrations of 5–5000 μg/L and salinities of 5–35 ppt) prepared with autoclaved water. However, a 17% loss was reported after 128 days in an ambient estuarine condition of 13 ppt. In the second 130 d experiment, the loss of 50 μg/L atrazine from the water column was determined at salinities ranging from 5 to 25 ppt without sediment and with either sand or silt-clay sediment. Results after 130 days were no loss of atrazine in the water only test conditions at the various salinities; loss of atrazine in the water column was significant in both sediment conditions and type of sediment did not appear to influence the loss from the water column; atrazine adsorption to clay-silt sediment was approximately twice as high as sand and loss of atrazine in the water column of both sediment conditions appeared greater at the higher salinity (25 ppt) when compared to the lower salinity (5 ppt).