The Effects of Cyperus esculentus on the Phytoremediation of Contaminated Range Soils
Afrachanna D Butler, Jackson State University, Environmental Science Ph.D. Program/US Army Corps of Engineer-Engineer Research and Development Center, Vicksburg, MS

Concurrent Uptake of Semivolatile Organic Compounds and Metals by Desert Plants
Zarhelia Carlo-Rojas, University of Texas at El Paso, El Paso, TX

Plant Organic Matter Deposition Alters Sedimentary Organic Matter Composition and PAH Desorption
Elizabeth Guthrie Nichols, North Carolina State University, Raleigh, NC

Engineering Non-Food Plants for Phytoremediation of Heavy Metals and Metalloids
Om Parkash, University of Massachusetts, Amherst, MA

Investigation of Fluoride Distribution in Deciduous Trees at a Hazardous Waste Landfill
Fan Wang-Cahil, Parsons, Cincinnati, OH  

Phytoextraction of Arsenic in the Mid-Atlantic Area Using Pteris Ferns

Michael J. Blaylock, Edenspace Systems Corporation, 15100 Enterprise Court, Suite 100, Chantilly, VA, 20151 Tel. 703-961-8700, Fax 703-961-8939, Email: blaylock@edenspace.com
Mark P. Elless, Edenspace Systems Corporation, 15100 Enterprise Court, Suite 100, Chantilly, VA, 20151 Tel. 703-961-8700, Fax 703-961-8939, Email: elless@edenspace.com  
Myles Bartos , U.S. Environmental Protection Agency, 1650 Arch Street , Philadelphia , PA 19103 , Tel. 215-814-3342, Fax 215-814-3254, Email: Bartos.Myles@epamail.epa.gov 

Arsenic has been identified as a significant soil contaminant as a result of industrial applications, and its use in pesticides and herbicides in the United States and other countries, posing significant health risks to humans and animals. Because of its past wide-spread use, many large areas exist with elevated arsenic concentrations in the surface soil. Currently, there is no cost-effective method to clean large acreages of arsenic-contaminated soils. Phytoremediation has developed as a promising alternative to excavation and replacement of arsenic-contaminated soil to address some of these areas.

Selection of an appropriate plant species for arsenic phytoremediation is currently limited to ferns belonging to the Pteris genus. These ferns have shown a remarkable ability to tolerate and accumulate high concentrations of arsenic in their fronds. Although naturally adapted to a subtropical climate, these ferns can be grown in phytoremediation systems as annuals in cooler climates to remove arsenic from the soil. From 2004 to 2006 Pteris ferns were used to assist in removing arsenic from targeted residential soils in the Spring Valley area of Washington DC , resulting in more than fifteen properties requiring no further action. Phytoremediation activities at selected properties in Spring Valley will be continued in 2007.

In addition to the work being continued in Washington DC , the largest arsenic phytoremediation project to date was initiated in central Virginia in 2007 with over 20,000 fern plants being used to assist in removing arsenic from soils with elevated arsenic from arsenical pesticide applications.

This paper will present the application of phytoremediation in these two projects and discuss the benefits and challenges of implementing phytoremediation in these areas.

The Effects of Cyperus esculentus on the Phytoremediation of Contaminated Range Soils

Student Presenter

Afrachanna D. Butler, Jackson State University, Environmental Science Ph.D. Program/ US Army Corps of Engineer-Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, Tel: 601-634-3575, Fax: 601-634-3518, Email: afrachanna.d.butler@erdc.usace.army.mil
Victor F. Medina, Ph.D., U.S. Army Corps of Engineer-Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, Tel: 601-634-4283, Fax: 601-634-3518, Email:  victor.f.medina@erdc.usace.army.mil
Maria F. Begonia, Ph.D., Jackson State University, Department of Biology, 1400 J.R. Lynch Street, Jackson, MS 39217, Tel:  601-979-3469, Fax:  601-974-5853, Email:  maria.fatima.begonia@jsums.edu

Range contamination is an issue that challenges the United States Military.  Testing and training are essential elements to maintaining readiness for our armed forces.  During these tactical and strategic operations, weapons and munitions are utilized to practice live-firing.  Because of incomplete combustion and detonation, explosive contamination has documented at some ranges and has resulted in restriction of training activities. 

Explosives, particularly hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and trinitrotoluene (TNT), have contributed to the contamination of soil and groundwater on and nearby firing range sites.  Because live ammunition training is still needed, the cleanup of these contaminants may prove to be expensive.  Also, the application of environmental maintenance designed to support other uses could interfere with routine testing and training operations.  To avoid high cost and site interferences, an alternative being considered is the use of grasses to manage military firing ranges through phytoremediation.  This technology uses vegetation to remediate contaminated soil, sludges, sediments and groundwater.  Research studies have indicated that phytoremediation is effective which concludes that it could be a useful approach at active firing ranges. 

This research study was conducted to evaluate the biological removal and physical stabilization of RDX and TNT range contaminated soil with the addition of Cyperus esculentus (Yellow Nutsedge) grass.  Lysimeters were designed to assimilate natural rainfall to allow for the collection of leachate flowing through the soil as well as runoff from the soil surface.  A vegetated (grass) vs. non-vegetated (control) cell was used in this study.  The initial concentrations for RDX and TNT were 94mg/kg and 137 mg/kg respectively.  After 15 weeks, results showed that vegetation was a factor in stabilizing RDX and TNT leachate concentrations compared to that of the control.  Biological degradation accounted for 73% RDX and 23% TNT removal.  Decreases in mobility indicate that this technique may stabilize explosive concentrations in addition to increasing degradation rates. 

Keywords:  Phytoremediation, Cyperus esculentus, RDX, TNT, leachate, stabilization, and degradation       

Concurrent Uptake of Semivolatile Organic Compounds and Metals by Desert Plants

Zarhelia Carlo-Rojas, M.S., University of Texas at El Paso, Chemistry Department, El Paso, TX, 79968-0513, Tel: 915-747-6380, Fax: 915-747-5748
Wen-Yee Lee, PhD, University of Texas at El Paso, Chemistry Department, El Paso, TX, 79968-0513, Tel: 915-747-8413, 915-747-5906, Fax: 915-747-5748

Soil matrix plays an important role in the fate of organic and inorganic compounds in the environment. As a temporal and final sink as well, soil is the space where intrinsic properties of the abiotic environment interact with biotic components.  The real characterization of contaminant effect to terrestrial living beings persists as a challenge both to traditional analytical and toxicology methodologies.  In the risk assessment, ecotoxicologic focus is looking for the behavior of toxicants in the natural environment and it include vegetal component. Looking for a closer approach to soil complexity, microcosms essays protocols begin to be used and standardized, allow geographical location in relation to soil units.

The American Society for Testing Materials (ASTM) developed a soil core microcosms protocol (E 1197) which integrate some of these variability factors.  The information generated by this bioassay can be focused at different levels. Soil physics properties, biologic and edaphic conditions can be used to test organisms of regional occurrence as plants. The same parameters will be considered to determinate the distribution of the toxic substances in the natural environment. Toxicology and analytical techniques can be used to study directly the effect of concern organic and inorganic compounds and their possible interaction in the bioavailability to plants. At molecular level, these factors determine the bioavailability in a specific unit of soil.

Soil survey data provide a valuable source to delimiting and to refer the produced data of this study, in the confidence level correspondent to soil survey intensity and homogeneity of the soil area.

Plant Organic Matter Deposition Alters Sedimentary Organic Matter Composition and PAH Desorption

Elizabeth Guthrie Nichols, North Carolina State University, 3136G Jordan Hall, CB 8006, 2800 Faucette Dr. Raleigh, NC 27695, Tel: 919-513-4832, Fax: 919-515-7559, Email: elizabeth_nichols@ncsu.edu
Jennifer Musella, North Carolina State University, 3136G Jordan Hall, CB 8006, 2800 Faucette Dr. Raleigh, NC 27695, Tel: 919-513-4832, Fax: 919-515-7559, Email:  jsmusell@unity.ncsu.edu

PAH desorption behavior from sedimentary organic matter is an important parameter to assess PAH bioavailability.  This study assessed the impact of plant organic matter on PAH desorption from labile and refractory sediments fractions at two different sites that are contaminated with petrogenic PAHs.  Both sites have naturally re-vegetated with Phragmites australis; one site is a coastal refinery distillate waste pit where Phragmites has been present for several decades.  The other site is a fuel-oiled freshwater canal with recent establishment (2-3 years) of Phragmites.  Composite sediment samples were collected in distinct zones of barren and Phragmites areas from both sites; sediments were fractionated into bulk sediment and humin fractions prior to desorption studies.  Desorption isotherms were conducted by two methods, batch aqueous and TenaxÔ beads extractions.  Sediment fractions were analyzed for organic matter composition by 13C nuclear magnetic resonance (13C NMR), D14C AMS (accelerator mass spectrometry), fourier transformed infrared spectroscopy (FTIR), and elemental analyses.  PAH concentrations in sediments, water extracts, and solvent extracts of TenaxÔ beads were determined by gas chromatography mass spectrometry select ion mode monitoring (GC/MS SIM).  Bulk and humin sediment fractions with recently established Phragmites desorbed fewer PAHs than non-vegetated sediments.  Phragmites sediments were also less polar than non-vegetated sediments due to the presence of aliphatic carbon from plant organic matter.  Bulk and humin sediment fractions with established Phragmites desorbed more PAHs than non-vegetated sediment fractions.  Sediment fractions from established Phragmites sediments were more polar due to the presence carbohydrate and aliphatic carbon from plant organic matter.  Thus, at each site, differences in PAH desorption behavior between Phragmites and non-vegetated sediments fractions can be related to changes in sediment polarity due to plant organic matter deposition.  

Engineering Non-Food Plants for Phytoremediation of Heavy Metals and Metalloids

Om Parkash, Dept. of Plant, Soil and Insect Sciences, University of Massachusetts , Amherst, MA-01003, USA ; Tel: 413-545-0062, Fax: 413-545-3075, Email: parkash@psis.umass.edu

 Heavy metals and metalloids contaminated soils, sediments and water supplies are major sources of food chain contamination and thereby endanger human health. We have developed a genetics-based phytoremediation strategy for arsenic (As) by combining the expression of bacterial arsenate reductase (ArsC) and g-glutamylcysteine synthetase (g-ECS) genes into single test plants Arabidopsis and demonstrate dramatic increases in As resistance and hyperaccumulation aboveground. When grown on As, these plants accumulated 4- to 17-fold greater fresh shoot weight and accumulated 2- to 3-fold more As than wild-type or plants expressing g-ECS or ArsC alone (Dhankher et al., 2002, Nature Biotech. 20:1140-45). Additionally, to enhance As movement to aboveground tissues, we examined the endogenous plant activity that affects the electrochemical state and binding of As in roots. Recently, we have identified an endogenous arsenate reductase, AtACR2, from Arabidopsis that reduces arsenate (As^V) to arsenite (As^III) in plants. We knocked down the ACR2 expression using RNAi approach in Arabidopsis and the transgenic lines were more sensitive to As^V. The AtACR2 knockdown plants translocated 10- to 16-fold more As from root to shoot tissues when these plants were exposed to As^V (Dhankher et al., 2006, PNAS 103: 5413-18). For field phytoremediation, we are in the process of creating engineered As hyperaccumulation in a non-food high biomass plant, Crambe abysinica- industrial oil rapeseed, by combining the expression of ArsC and g-ECS with AtACR2 knockdown plants. The synergistic activity of these genes could leads to more than 50-fold levels of As accumulation in aboveground tissues for later harvest. 

Furthermore, we have isolated hundreds of genes from Crambe abysinica that are differentially regulated by As and chromium (Cr) exposure using PCR-Select Subtractive cDNA Hybridization approach. Currently, we are analyzing these genes for expression analysis and functional characterization using both forward and reverse genetic approaches. The candidate genes will be used to engineer non-food high biomass C. abyssinica plants for phytoremediation of As, Cr and other toxic metals contaminated soil and sediments.

Investigation of Fluoride Distribution in Deciduous Trees at a Hazardous Waste Landfill

Dr. Fan Wang-Cahill, Parsons, 2443 Crowne Point Drive, Cincinnati, OH 45241, Tel: 513-552-7008, Fax: 513-552-7044
Karen Fields, Parsons, 2443 Crowne Point Drive, Cincinnati, OH 45241, Tel: 513-552-7016, Fax:  513-552-7044

Phytoremediation is being considered to reduce landfill leachate volumes and mitigate the migration of groundwater that contains elevated fluoride concentrations at a Landfill in Kentucky.  The landfill is a RCRA hazardous waste landfill that was used to dispose spent potliners from a nearby aluminum plant. The purpose of the project is to demonstrate the ability to use phytoremediation to reduce fluoride contamination in groundwater.  Fluoride is anticipated to accumulate in plant tissues.  Leaves, twigs, and trunk tissue samples were collected seasonally from mature sycamore, ash, tulip poplar, oak and sweet gum trees both in non-impacted areas (as background) and impacted areas,  In addition, tulip poplar, ash, and cottonwood bare-root seedlings were planted within the fluoride plume down-gradient of the landfill prior to the leachate being intercepted by a collection trench.  The results show that fluoride predominately accumulated in leaf tissues in tulip poplar trees.  The ratio of accumulation between spring and full in tulip poplar leaves is approximately 5 times.  Therefore, leaf collection in fall may be needed for fluoride phytoremediation using certain species of deciduous trees.

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