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ATRAZINE DESORPTION KINETICS FROM A FRESH-WATER SEDIMENT
Citation:
Bouchard, D C. ATRAZINE DESORPTION KINETICS FROM A FRESH-WATER SEDIMENT. Presented at 54th Southeast Regional Meeting of the American Chemical Society, Charleston, SC, November 13-16, 2002.
Impact/Purpose:
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological, and geochemical) that describe the species-specific transformation and transport of organic contaminants and nutrients in environmental and biological systems. Develop and integrate chemical behavior parameterization models (e.g., SPARC), chemical-process models, and ecosystem-characterization models into reactive-transport models.
Description:
Research has shown that the sorption and desorption of neutral organic compounds to soils and sediments occurs in two stages, with an initial rapid sorption/desorption phase (usually less than an hour) followed by a slower phase that can last for several months to years for very high Kp solute-sorbent combinations. Hence, the popularity of various "two-step" or "two-domain" conceptualizations and mathematical models for describing solute sorption and desorption. In this study atrazine was incubated with a sediment from a small north Georgia stream for 26 weeks and then desorbed in a sediment column system operated under saturated flow conditions. Atrazine desorption from the column under different experimental parameters was described using a two-step first-order kinetic model. In addition, atrazine desorption from the aged sediment was compared to atrazine transport in the sediment under short-term exposure conditions.