--> Abstract: Long-Term Monitoring of Organoarsenical Degradation in Drinking- Water Treatment Residual-Amended Soils, by Rachana Nagar, Dibyendu Sarkar, Konstantinos C. Makris, and Rupali Datta; #90078 (2008)

Datapages, Inc.Print this page

Long-Term Monitoring of Organoarsenical Degradation in Drinking- Water Treatment Residual-Amended Soils

Rachana Nagar, Dibyendu Sarkar, Konstantinos C. Makris, and Rupali Datta
Environmental Geochemistry Laboratory, University of Texas at San Antonio, San Antonio, TX

Gradual displacement of inorganic arsenical-based pesticides by the less toxic organoarsenical-based pesticides has not discouraged the expression of serious concerns related to potential release of arsenic (As) in the environment. Such concerns have been further propagated by recent evidence reporting biodegradation of organoarsenicals to the more toxic inorganic arsenic in agricultural fields and golf courses. Earlier work in our lab showed that the drinking-water treatment residuals (WTRs) were effective sorbents for both organic and inorganic forms of As. We hypothesized that organoarsenical sorption by WTRs could reduce the potential for organoarsenicals biodegradation in As- contaminated soils that have been amended with WTRs. A long-term (up to 3-years) greenhouse experiment was set up to investigate As release and aqueous speciation in WTR-amended soils that were contaminated with dimethylarsonic acid (DMA). Two soils (one acidic and one basic soil pH) were spiked with DMA (1500 mgAs kg-1) and amended with an Al-WTR and Fe-WTR at two rates (5% and 10% by wt.). Soil sampling was done immediately after spiking (time zero), 0.25, 1, 3, 6, 12 and 36 months of equilibration to monitor long-term changes in the form and oxidation state of As in DMA-contaminated, WTR-amended soils. A traditional water extraction test that has been previously correlated to As losses via runoff and leaching processes was employed to assess changes in soluble As concentrations and forms. Water-extracts were analyzed for total soluble and several known organic and inorganic As species using GFAAS and HPLC-ICPMS, respectively. Potential role of reaction time in minimizing degradation of DMA via sorption by WTRs in contaminated soils is discussed.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas