Monday, November 13, 2006

Phytoremediation Potential of Two Perennial Grasses: The Effect of Chelators on Arsenic Phytoextraction.

Nica Klaber, Allen Barker, Baoshan Xing, Julian Tyson, and Guy Lanza. Univ of Massachusetts, Dept of Plant, Soil & Insect Sciences, Bowditch Hall, Amherst, MA 01003

Arsenic is a highly toxic metalloid with significant detrimental effects on human health. Arsenic-contaminated soil is the major contributor to arsenic-contaminated drinking water. Cases have been reported in many parts of the world where naturally occurring arsenic in the soil has reached groundwater endangering the health of local populations.  Phytoremediation of arsenic-contaminated soil and water involves the use of plants and their associated microbial communities to remove or detoxify arsenic contaminants.  More plants need to be studied, so that effective phytoremediation practices can take place in a variety of different climates, soil types, and ecosystems.  To make phytoremediation a viable and competitive soil remediation alternative, much more research is needed on many levels; such as identifying new adaptable flora to grow on contaminated sites in different climates, and in using environmentally friendly soil amendments to aid in plant uptake of pollutants.  Two perennial grasses, a wetland plant: rice cut-grass (Leersia oryzoides) and a turf-grass: tall fescue (Festuca arundinacea) were grown in a greenhouse for eight weeks in agricultural soil contaminated with 30 mg/kg soil arsenic [As (V)].  The grasses were studied to determine the uptake potential of arsenic for each species and to determine their viability for further phytoremediation studies.  Each grass species was treated with two chelators, EDTA and Citric Acid. Each chelator was applied at three different concentrations, dosed at 72-hour intervals.  We report the effect of the two chelators on enhanced arsenic uptake by the plants, and for their potential for site application. High concentrations of EDTA (> 5.0 mmoles/ kg soil) had detrimental effects on both plant species, and may not be suggested for further on-site use.