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Submitted to: Society of Environmental Toxicology and Chemistry (SETAC)
Publication Type: Abstract Only Publication Acceptance Date: 5/30/2001 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Knowledge of hydroxyatrazine (HA) sorption to soils and its pattern of stream water contamination suggest that it is persistent in the environment. Soils with different atrazine use histories were collected from four sites, and sediments were collected from an agricultural watershed. Samples were exhaustively extracted with a mixed-mode extractant, and HA was quantitated using HPLC with UV detection. Atrazine deethylatrazine (DEA), and deisopropylatrazine (DIA) were also measured in all samples. HA concentrations were considerably greater than atrazine, DEA, and DIA in all soils and sediments studied. HA soil concentrations ranged from 14 to 640 ug/kg with a median concentration of 78 ug/kg. HA sediment concentrations ranged from 11 to 96 ug/kg with a median concentration of 14 ug/kg. Correlations of HA and atrazine concentrations to soil properties indicated that HA levels in soils were controlled by sorption of atrazine. Since atrazine hydrolysis is known to be enhanced b sorption and pH extremes, soils with high organic matter and clay content and low pH will result in greater atrazine sorption and subsequent hydrolysis. Significant correlation of HA concentrations to organic matter, pH, and cation exchange capacity of sediments indicated that mixed-mode sorption (i.e., binding by cation exchange and hydrophobic interactions) was the mechanism controlling HA levels in sediment. The presence of HA in soils and stream sediments at the levels observed support existing hypotheses regarding its transport in surface runoff. These results also indicated an additional risk factor associated with atrazine usage is the potential impact of sediment-bound HA on aquatic ecosystems. |
