The interaction of atrazine with wetland sorbents

Atrazine equilibrium sorption data for sediments, litter, peat, root mat, and soil from three Midwestern USA wetlands fit the Freundlich isotherm model, C-s = K C-w(n). Water atrazine concentrations were in the mu g/dm(3) range. Sorbent analyses recovered most of the atrazine not found in the water. Data errors in sorbent atrazine concentrations were much larger than those in water concentrations. Maximum likelihood and logarithmic regression methods gave similar parameter estimates. Organic carbon (OC) based sorbent concentrations allowed combination of the data into linear isotherm. Estimates for K-OC and n were 760 (mu g/kg OC)(mu g/dm(3))(-n) and 0.90. A linear isotherm null hypothesis was rejected. Fresh sorbents containing identifiable plant fragments had significantly lower K-OC values than aged ones that did not. Atrazine reaction affected K-OC estimation for fresh sorbents, but not for aged ones. Litter had an unexpectedly high weight based K value. K-OC estimates were higher than comparable literature values, mainly for soils at mg/dm(3) concentrations. Drying materials before equilibration may lead to underestimation of sorption capacity of active, wet organic matter. Wetlands have capacity to sorb significant amounts of atrazine onto sediments, litter, and root mats. However, short detention times may prevent full realization of this potential.