HR: 11:15h
AN: NB52A-04    [Abstracts]
TI: Phytoavailability of Arsenic in pesticide-Applied Soils: Effect of Chemical Remediation
AU: * Mohamed, H
EM: hussein.mohamed@utsa.edu
AU: Therapong, C
EM: chacharee.therapong@utsa.edu
AU: Andra, S
EM: sspagri@rediffmail.com
AU: Datta, R
EM: rupali.datta@utsa.edu
AU: Sarkar, D
EM: dibyendu.sarkar@utsa.edu
AB: Arsenic (As) occurs naturally in rocks and soils and in the water in contact with them. Arsenic contamination is also caused by a variety of anthropogenic activities such as the use of arsenical pesticides, mining, and other industrial processes. In humans, chronic exposure to As has been found to cause a number of cancers, peripheral nerve damage, and skin hyper-pigmentation. In plants, As causes growth inhibition, chlorosis, defoliation, and water-deficiency stress. The main objective of the present study was to evaluate the efficacy of water treatment residuals (WTRs) in reducing the phytoavailability of As in soils. WTRs are the by-products from drinking water purification plants and contain sediments, organic material from the raw water, Al/Fe oxides and activated C. They are amorphous and have an affinity for oxyanions (e.g., arsenate and arsenite), due to the high positive surface charge they generally possess. A greenhouse study was performed using two different types of soils, chosen on the basis of their potential differences with respect to reactivity and phytoavailability of As: Immokalee series (bleached sand with low pH) and Orelia series (sandy loam with high percentage of Ca; Mg and high pH). Rice (Oryza sativa var. M202) was used as the test crop to study the effect of WTR amendment on the plant availability of As. The soils were amended with two arsenical pesticides; sodium arsenate and dimethylarsenic acid (DMA) at two rates: 675 and 1500 mg/kg of As, representing the high end of As contamination, simulating Superfund site conditions. Rice plants were grown with and without WTRs for a period of 6 months. Growth parameters (germination percentage, plant biomass, root and shoot length) as well as As accumulation in plant tissues were studied. Soils were analyzed to determine the levels of plant available As in WTR-treated and untreated soils. Results obtained indicate that WTR-amendment of sodium arsenate contaminated soils resulted in considerable decrease in the levels of phytoavailabe As, and hence, increased seed germination and plant growth. In contrast, in soils contaminated with DMA, seed germination and plant growth was inhibited, with no significant effect of WTR.
DE: 0400 Biogeosciences
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly