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REMEDIATION OF ATRAZINE-CONTAMINATED SOIL AND WATER USING ZEROVALENT IRON

Addition of Fe0 (10% w/w) to aqueous solution containing 0.02 mg atrazine L-1 removed 93% of the atrazine within 48 h. After 48 h, about 5% of the adsorbed atrazine was extractable from the Fe° with 3 mM CaCl2 ("readily available" pool) and 33% was extractable with CH3CN ("restricted" pool). The remaining 62% consisted of atrazine transformation products or unextractable residues.

Treating an aqueous solution containing 20 mg atrazine L-1 (spiked with 14C-atrazine) with Fe 0 (20% w/w) removed 88% of the 14C from solution within 48 h. Low concentrations of deisopropylatrazine were found in the solution after treatment. Of the total 14C removed from solution, 6% was readily available (3 mM CaC12 extractable) and 72% was in the restricted pool (CH3CN-extractable), primarily as atrazine. The remaining unextractable 14C is believed to be hydroxytriazine products, resulting from hydrolysis induced by oxidation of Fe0 and subsequently bound to iron oxyhydroxides on the iron surface.

When Fe0 (2% w/w) was used to treat atrazine-contaminated soil (Sharpsburg silty clay loam, Ap horizon, 2 mg atrazine kg-1), 14C-atrazine mineralization was quadrupled in a 120-d experiment. Addition of 2% Fe0 (w/w) and 100 mg NO3- kg-1 to subsurface Sharpsburg soil increased atrazine mineralization ten-fold and unextractable bound residue more than doubled above the control (no Fe0).

Our results indicate that Fe0 can readily remove atrazine from water and increase mineralization in soil by promoting reductive transformations and chlorotriazine hydrolysis.

Key words: atrazine, iron, remediation, transformation