Phytoextraction of Heavy Metals with California Grass (Brachiaria mutica)
Jamie L. Anderson, AMEC Earth & Environmental, Inc.
Eric E. Wetzstein, PG, AMEC Earth & Environmental, Inc.
Kim Markillie, Environmental Chemical Corporation ( ECC )

Hyperaccumulation of Cadmium by Wheat (Triticum vulgare) Plant- A Phytoremedial Approach
Dr. Rashmi Nigam

Analysis of Arsenic-Induced Transciptomal Response of Crambe abyssinica to Identify Genes involved in Arsenic metabolism
Bibin Paulose, University of Massachusetts , Amherst , MA

Overcoming Current Limitations to Phytoremediation of Trichloroethene
Sarah M. Strycharz, University of Massachusetts , Amherst , MA

Dual Use of Energy Crops for Addressing Areawide Soil Lead
Mark P. Elless, Edenspace Systems Corporation
Michael J. Blaylock, Edenspace Systems Corporation

Phytoextraction of Heavy Metals with California Grass (Brachiaria mutica)
Jamie L. Anderson, AMEC Earth & Environmental, Inc, 3375 Koapaka Street, Suite F-251, Honolulu, HI  96819, Tel: 808-545-2462 x105, Email: jamie.anderson@amec.com
Eric E. Wetzstein, PG, AMEC Earth & Environmental, Inc., 3375 Koapaka Street, Suite F-251, Honolulu, HI  96819, Tel: 808-545-2462 x104, Email: eric.wetzstein@amec.com
Kim Markillie, Environmental Chemical Corporation ( ECC ), 99-1151 Iwaena Street, Aiea, HI 96701, Tel: 808-486-3707 x4015, Email: kmarkillie@ecc.net

A phytoextraction treatability study was conducted under contract by the U.S. Navy to evaluate the technology as a potential remedial alternative at a former bulk fuel storage facility.  The study was conducted to evaluate the feasibility of phytoextraction in remediating soil impacted with antimony, arsenic, and lead.  Three plant species were selected for the study, including: ferns (pteris cretica), sunflowers (helianthus annuus), and California grass (brachiaria mutica).  Six monitoring events were conducted to measure total contaminant concentrations in soil, leachate, roots, and aboveground biomass.  Bioavailability testing was also conducted on selected samples. 

The findings of the study suggest that California grass may be a viable remedial alternative to extract the target metals.  Soil samples collected from test cells with ferns and sunflowers suggest that observed variations in contaminant concentrations are most likely attributed to soil heterogeneities.  Conversely, the California grass resulted in a significant decrease in the mean antimony, arsenic, and lead concentrations in soil with at least a 90% confidence level.  The overall mean metal concentrations in soil samples obtained from Test Cell 4 ( California grass) were reduced 43.5% for antimony, 26.4% for arsenic, and 35.9% for lead.  These decreases occurred early in the study with a maximum observed reduction occurring by the first and second monthly sampling events, which were conducted after a two-month plant establishment period.  This pattern suggests that enhanced contaminant removal may be achieved by successive crops of California grass grown and harvested at approximately 3-month intervals.  Because the metals tend to concentrate in the roots, the entire plant would have to be harvested during each growth cycle.  It is uncertain if the observed trends of decreasing contaminant concentrations would continue with additional grass crops and would need to be investigated further.  Equilibrium or bioavailability limits may be reached when concentrations achieve a specific level.

Hyperaccumulation of Cadmium by Wheat (Triticum vulgare) Plant- A Phytoremedial Approach
Rashmi Nigam, Doctorate, 42-49 Colden St, Apt#1B, Flushing, NY 11355, Tel:  718-878-2072, Email: rashmiphd@rediffmail.com

Recently, the importance of metal- accumulating plants for environmental remediation has been highly realized, giving birth to a new technology PHYTOREMEDIATION. The phytoremediation involves plant hyperaccumulation of the metals and is used to reduce the concentration of heavy metals in soil to environmentally acceptable levels. Research is recently focused towards the elucidation of the uptake mechanism of hyperaccumulation. In this regard, the increased solubility and mobility of metal chelates forming in the soil rhizosphere, adds a new dimension to the mechanism of plant hyperaccumulation of metals. Naturally occurring phytochelators (low molecular weight organic acids) are likely to interact with metal ions increasing their solubility/mobility causing them to hyperaccumulate in the plants. Out of various toxic metals, cadmium is of particular concern because of its highly toxic and non-essential nature, therefore, it is considered for the present study. Pot experiments were conducted to investigate the effect of various carboxylic and amino acids on the uptake and translocation of root absorbed cadmium by Wheat (Triticum vulgare) plants grown in sand and soil culture. Statistically significant increase in Cd accumulation from Cd treated plants in the presence of increasing concentration of organic acids suggest the existence of Cd-organic acids interactions in the soil-plant system. In order to support the hypothesis, separate experiments were performed to synthesize and estimate the various forms of organically bound Cd viz. cationic, anionic and neutral using the combination of radiotracer, ion exchangers and electrophoretic assay. The significant finding that the interaction of cadmium with organic ligands (phytochelators) may result into metal solubilisation/mobilisation adds an important dimension to the strategies of plant enrichment of the metals.

Dual Use of Energy Crops for Addressing Areawide Soil Lead
Mark P. Elless, Edenspace Systems Corporation, 3810 Concorde Parkway, Suite 100, Dulles, VA, 20151-1131 Tel. 703-961-8700, Fax 703-961-8939, Email: elless@edenspace.com
Michael J. Blaylock, Edenspace Systems Corporation, 3810 Concorde Parkway, Suite 100, Dulles, VA, 20151-1131 Tel. 703-961-8700, Fax 703-961-8939, Email: blaylock@edenspace.com

Areawide lead (Pb) soil contamination poses significant risks to large populations in the United States . Current remedial methods that address localized, small-scale lead contamination, such as excavation and replacement of soil, are too expensive for such large-scale applications. This study seeks to apply phytoremediation techniques to areawide Pb-contaminated soils for lead hazard control through vegetative capping and lead removal. Preliminary growth chamber results demonstrated the potential of two high biomass grasses targeted for production of power and cellulosic ethanol, switchgrass and Miscanthus, to remove lead from smelter-contaminated soils, without any observed detrimental effects of the accumulated lead on hydrolyis and production of fermentable sugars. These two energy crops may therefore be useful for environmental mitigation while simultaneously producing a feedstock for cellulosic ethanol. This presentation will evaluate switchgrass and elephant grass for dual use as a phytoremediation tool and celllosic ethanol feedstock by (a) examining the ability of these grasses to stabilize the soil and reduce offsite contaminant migration from water and wind erosion under field conditions and (b) verifying that the field-grown biomass can be used to produce ethanol without unacceptable losses in fermentable sugars due to inhibition of enzymatic hydrolysis or fermentation from the accumulated lead. Successful completion of the project is expected to reduce liability associated with runoff of lead contaminants to neighboring properties as well as reap the benefits of providing a low-cost crop feedstock for the cellulosic ethanol industry.