Monday, November 13, 2006

Phytoremediation of Heavy Metal Contaminated Soils with Warm Season Grasses.

J.J. Sloan1, A.D. Genovesi1, M.C. Engelke1, and Richard White2. (1) Texas A&M Univ, Dallas, 17360 Coit Road, Dallas, TX 75252, (2) Soil & Crop Sciences Dept, Texas A&M Univ, College Station, TX 77843-2474

Turf grasses could potentially play an important environmental role in the stabilization and decontamination of heavy-metal contaminated soils that are relatively common in urban areas.  The objective of this study was to evaluate the potential of warm season turf grasses to phytoextract heavy metals from contaminated soil.  Twenty grass types representing eleven grass species common to the Southern United States were grown in soil moderately contaminated with heavy metals (133, 112, 60, 19, 41, and 84 mg/kg Pb, Zn, Cr, Cd, Ni, and Cu, respectively).  Biomass production was quantified by harvesting and weighing grass clippings, which were subsequently analyzed for total concentrations of Pb, Zn, Cr, Cd, Ni, and Cu.  Total heavy metal uptake for each grass was calculated by multiplying clipping weights by the heavy metal concentration in the tissue.  The grasses were compared for their ability to accumulate heavy metals in their tissue (concentration) and their overall ability to extract heavy metals from the soil (uptake).  No single grass stood out as the best candidate for phyto-extracting heavy metals from contaminated soils.  In general, grasses that produced the most biomass were the most effective at extracting heavy metals from the soil.  The uptake trend among grasses was different for each heavy metal suggesting that the type of grass selected to phytoremediate a contaminated soil will depend on the predominant heavy metal present in the soil.