Monday, November 13, 2006

Perchlorate Dynamics in Soils Amended with Drinking-Water Treatment Residuals.

Konstantinos Makris1, Dibyendu Sarkar2, Rachana Nagar1, and Rupali Datta3. (1) University of Texas at San Antonio, Univ. Of Texas, 15801 Chase Hill Blvd. Apt. 612, San Antonio, TX 78256-1039, (2) Earth & Environmental Science Dept., University Of Texas At San Antonio, University Of Texas At San Antonio, San Antonio, TX 78249-0663, United States of America, (3) Dept. of Earth & Env. Sci., "Univ.of TX, 6900 N Loop 1604 W", "Univ.of TX, 6900 N Loop 1604 W", San Antonio, TX 78249, United States of America

Perchlorate (ClO4-) is an emerging inorganic contaminant that has only recently been charged with severe human health effects, such as thyroid hormone and neurodevelopment disruption, especially in infants and pregnant women. Sources of perchlorate are mostly anthropogenic in nature; ammonium and potassium perchlorate salts have been traditionally used as an additive and oxidant, respectively, in missile / rocket propellants and fireworks. Increased perchlorate concentrations in groundwater suggest that perchlorate is relatively mobile in soils, leaching into groundwater. Studies have also shown that a relative amount of perchlorate may not find its way to groundwater due to biological reduction and / or sorption processes occurring in the vadose zone. This exploratory study aims at investigating soil-ClO4 dynamics in the presence of drinking-water treatment residuals (WTRs), a low-cost waste by-product that is being land-applied to immobilize phosphate in agricultural soils. Six soils varying in physicochemical properties were amended with and without a drinking-water treatment residual (Al-WTR) and subjected to a perchlorate batch equilibration study. Soils were spiked with different perchlorate concentrations and allowed to react for 1, 2, 4, 16 and 24-h. Perchlorate sorption isotherms and kinetics for the six soils in the presence or absence of the Al-WTR will be discussed.