Phytoextraction And Phytovolatilization Of Arsenic From As-Contaminated Soils By Pteris vittata

Phytoremediation of metal contaminated soil and water is a low cost method of remediation, which allow some extracted metals to be recycled for economic use. The use of phytoextraction and phytovolatilization of metals by plants offers a viable remediation on commercial projects. Arsenic is of great environmental concern due to its extensive contamination and toxicity. Ma et al. (2001) recently discovered the first known and extremely efficient arsenic hyperaccumulating plant, Pteris vittata. If we can use phytovolatilization for As-contaminated soils, it could minimize the production of As-laden plant material and the duration of remediation. Several greenhouse experiments conducted by us have shown that the material balance of As between uptake by P. vittata and reduction from As-polluted soils has not been maintained. Vapor samples were collected to determine volatilization of arsenic compounds from fronds of P. vittata grown in As-polluted soil. A low-density polyethylene bottle was placed over a stem and sealed at the open bottleneck with sealant and tape to produce a tight seal around the stem and chambers for a period of 2–7 days. Concentration of arsenic in trap samples was measured by ICP-MS and speciation of arsenic was analyzed using HPLC/ICP-MS system. Concentrations in collected water samples (ca. 0.6–5.9ml) reached 10.7&#;30.8 &#;g-As/L (2–7 days). Percentages of arsenic components in one sample were 37% for arsenite and 63% for arsenate. Our results suggest that P. vittata is a plant species that is effective at volatilizing As; it removed about 90% of the total uptake of As from As-contaminated soils in the greenhouse, where the environment was similar to the subtropics. However, if a large amount of arsenic had been released from the contaminated site into the atmosphere by the fern, the process may have caused a secondary As-contamination to the surrounding environments