ARSENIC REMEDIATION POTENTIAL OF VETIVER GRASS

A variety of arsenical compounds were used as pesticides in the United States until the late eighties, resulting in increased background concentration of this toxic metalloid in agricultural soils. Suburban development on lands previously used for agricultural purposes has tremendously increased the potential for human contact with this carcinogen, particularly by hand-to-mouth activity by children playing in their backyards. The use of plants to clean up soils contaminated with pollutants, a technique known as phytoremediation, is fast emerging as “the” tool for in-situ remediation. This method has distinct advantages, since it maintains the biological properties and physical structure of the soil, is environmentally friendly, and above all, inexpensive. However, effective remediation of contaminated residential soils using a specific plant species is an immensely complex task whose success depends on a multitude of factors including the ability of the target plant to uptake, translocate, detoxify, and accumulate arsenic in its system. It also involves less scientific but more practical issues, such as the lack of seasonal sensitivity of the target plant, it’s potential social/ornamental fit to residential settings, etc. As a first step towards developing an effective phytoremediation system for residential soils, a greenhouse study was performed to evaluate the potential of vetiver (Vetiveria Zizanioides), a high biomass, fast-growing perennial grass, to tolerate and accumulate arsenic from contaminated soils. Vetiver was grown in soils contaminated with sodium arsenate at 5 concentrations: 0 (control), 45, 225, 450, 750 and 1500 mg/kg arsenic. The plants were harvested after 1, 2 and 3 months of growth. Concentration of arsenic in the root and shoot tissues and in the soils was measured using a graphite furnace atomic absorption spectrometer. Inhibition of growth was studied by monitoring root and shoots biomass. Total chlorophyll and protein contents were determined using standard protocols. The results from the study demonstrate the potential of vetiver for remediating arsenic-contaminated residential soils.