Relation among Subspecies of Cucurbita in Phyto-extraction of Field-weathered p,p’-DDE and Exudation of Citric Acid from Roots
Martin P.N. Gent, Connecticut Agricultural Experiment Station (CAES), New Haven CT
Zakia Parrish, Connecticut Agricultural Experiment Station (CAES), New Haven CT
Jason C. White, Connecticut Agricultural Experiment Station (CAES), New Haven CT

Uptake of Polycyclic Aromatic Hydrocarbons in Spartina Alterniflora – Evaluating Risk in Salt Marsh Vegetation
Alison W. Watts, University of New Hampshire, Durham, NH
Thomas P. Ballestero, University of New Hampshire, Durham, NH
Kevin H. Gardner, University of New Hampshire, Durham, NH

Phytoremediation of Lead Contaminated Soils in the Urban Residential Environment using Seed Mustard
Ilana S. Goldowitz, Cornell University, Ithaca NY
Joshua Goldowitz, Rochester Institute of Technology, Rochester NY

Rhizodegradation of RDX Contaminated Soils Using Grass Exudates
Afrachanna D. Butler, Jackson State University, Vicksburg, MS  
Victor F. Medina, U.S. Army Corps of Engineers-Engineer Research & Development Center, Vicksburg, MS

Plant Assisted Bioremediation of Pollutants from Aquaculture Water
Kishore K. Krishnani, Stevens Institute of Technology, Hoboken, NJ 
Xioaguang Meng, Stevens Institute of Technology, Hoboken, NJ

Phytoremediation Applications for Arsenic in Northern Climates
Michael J. Blaylock, Edenspace Systems Corporation, Dulles, VA
Mark P. Elless, Edenspace Systems Corporation, Dulles, VA Charissa Y. Poynton, Edenspace Systems Corporation, Dulles, VA

Can We Predict the Best Plants for the Phytoremediation of Organic Contaminants?
Chris D. Collins, Imperial College, South Kensington, London
Neil J. Willey, University of the West of England, Frenchay, Bristol

Relation among Subspecies of Cucurbita in Phyto-extraction of Field-weathered p,p’-DDE and Exudation of Citric Acid from Roots

Martin P.N. Gent, Connecticut Agricultural Experiment Station (CAES), Department of Forestry and Horticulture, 123 Huntington Street, New Haven CT 06504, Tel: 203-974-8489, Fax:  203-974-8502, Email:  Martin.Gent@po.state.ct.us
Zakia Parrish, Department of Soil and Water, Connecticut Agricultural Experiment Station (CAES), 123 Huntington Street, New Haven CT 06504
Jason C. White, Department of Soil and Water, Connecticut Agricultural Experiment Station (CAES), 123 Huntington Street, New Haven CT 06504

Field experiments have shown that two subspecies of Cucurbita pepo (summer squash) differ in phyto-extraction of field-weathered p,p’-DDE.  Three cultivars were selected from each of the subspecies; Cucurbita pepo ssp pepo (zucchini) with a greater ability to take up DDE, and Cucurbita pepo ssp ovifera (summer squash) with a lesser ability to take up DDE. When grown in the field, subspecies pepo phyto-extracted about 1.0% of the p,p’-DDE, while subspecies ovifera removed less than 0.2% of the contaminant. To evaluate whether exudation of organic acids from the roots was involved in uptake of weathered DDE, these cultivars were grown under hydroponic conditions. Phosphorus nutrition played a significant role in exudation of organic acids into the hydroponics solution. For both subspecies, the better the phosphorus nutrition, the more tartaric and less citric acid was exuded. However, subspecies pepo showed a greater increase in citric acid exuded under phosphorus depletion than ovifera.  This was the only response to phosphorus depletion that differed among subspecies. Thus, in a comparison among subspecies of Cucurbita pepo, the response to phosphorus depletion of exudation of citric acid was related to the ability to accumulate a higher concentration weathered organic contaminants in soil when grown in the field. 

Uptake of Polycyclic Aromatic Hydrocarbons in Spartina Alterniflora – Evaluating Risk in Salt Marsh Vegetation

Alison W. Watts, University of New Hampshire, 35 Colovos Rd, Durham, NH 03824, Tel: 603-312-7654, Fax: 603-862-3957
Thomas P. Ballestero, University of New Hampshire, 35 Colovos Rd, Durham, NH 03824, Tel:  603-862-1405, Fax: 603-862-3957
Kevin H. Gardner, University of New Hampshire, 35 Colovos Rd, Durham, NH 03824, Tel:  603-862-4334, Fax: 603-862-3957

Polycyclic Aromatic Hydrocarbons (PAHs) are present in many coastal and salt marsh sediments.  Sources include oil spills, urban runoff, and coal gasification byproducts.  Plants affect the movement of PAHs in several ways; they may inhibit erosion, enhance microbial degradation, or translocate compounds.  Plant translocation can move a compound from the soil or water into the plant.  The compound is then either stored in plant tissue, or degraded by microbial or metabolic processes, or excreted into the atmosphere.  Contaminants stored in plant tissue may present a risk to the ecological community. 

In this study, uptake of PAHs was measured in Spartina alterniflora, a common salt marsh plant.  For three months Spartina alterniflora was grown outdoors in PAH-contaminated soil and in clean control soil.  The PAH contaminated sediment was collected from an estuary near a former coal gasification plant, and contained an average of 200 ug/g total PAHs.  Plant samples were also collected from a PAH-contaminated estuarine marsh and from an uncontaminated reference site.  Plants grown in uncontaminated soil produced more flowers, and were taller, but plants grown in contaminated soil had more shoots, yielding a shorter, bushier morphology.  The total above-ground biomass at the end of the growing season was similar in the controls and PAH-grown plants.

The harvested samples were separated into leaf and root material and analyzed for individual PAH compounds. Most of the samples were analyzed using a GC/MS/MS system with a chromatoprobe direct-sample-injection device.  Small pieces of plant tissue can be analyzed directly by this method, allowing rapid evaluation of individual leaves or roots.  However, the detection limit is higher than traditional extraction-injection methods due to the small sample size and co-elution of some plant-derived compounds. 

PAHs were detected in both root and leaf tissue.  Concentrations in root tissue were approximately an order of magnitude higher than leaf tissue, and plant concentration increased as soil concentration increased.  PAH concentrations in plant tissue will be compared to ecological risk levels such as the NOAA ERM/ERLs, and potential ecological risks will be evaluated.

Phytoremediation of Lead Contaminated Soils in the Urban Residential Environment using Seed Mustard

Ilana S. Goldowitz, Cornell University, Plant Sciences Dept., Plant Sciences Building, Ithaca NY 14853, Tel: 585-442-2464, Email: picea_spp@yahoo.com
Joshua Goldowitz, Rochester Institute of Technology, Civil Engineering Technology, Environmental Management & Safety Department, 78 Lomb Memorial Drive, Rochester NY 14623, Tel: 585-475-7018, Email: jxgctp@rit.edu

Lead contamination in the urban environment is a continuing serious public health concern. Historically lead entered the urban residential area though paint pigment and gasoline additives. This legacy persists as the two most important lead sources that affect children in the urban environment: contaminated paint residue and contaminated soil. One technique for remediation of lead in urban soils is phytoremediation.. Previous research has shown Brassica juncea (mustard) to be the most promising phytoremediator of lead in soil. Researchers commonly use Southern Giant Curly Leaf Mustard because it is a hyperaccumulator of lead, has extremely high production of mustard green biomass in a short (45 day) growing season, and is adaptable to poor soil conditions. The authors believe that use of this variety in the urban environment may be problematic. The greens are favored as a food, are easily recognized, and may be pilfered and eaten. This research tested the hypothesis that seed mustard, which produces abundant flowers but few greens, would be more suitable. Two 60m² plots were prepared in a Greater Rochester Urban Bounty garden, located at a busy intersection in Rochester New York’s impoverished northeast neighborhood. One plot was sown thickly with Southern Giant, and the other with seed mustard. As the plants approached maturity the entire crop of Southern Giant mustard was pilfered, but the seed mustard remained untouched. At maturity the seed mustard produced 550g dry biomass per m².  Assuming similar maximum lead uptake among mustard varieties, this would yield a lead uptake rate of up to 5 g/m². The research also included a germination study. Five standard seed germination tests (400 seeds each) performed in increasingly concentrated lead contaminated soils indicated little variation in germination rate.  Thus seed mustard is more suitable for phytoremediation of lead in the urban residential environment.  

Rhizodegradation of RDX Contaminated Soils Using Grass Exudates 

Afrachanna D. Butler, Jackson State University, Department of Environmental Science, Ph.D. Program, c/o CEERD-EP-E, 3909 Halls Ferry Road, Vicksburg, MS 39180, Tel: 601-634-2808, Fax: 601-634-3518, Email:  Afrachanna.D.Butler@erdc.usace.army.mil     
Victor F. Medina, U.S. Army Corps of Engineers-Engineer Research & 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

Phytoremediation uses living plants for in situ and ex situ remediation of contaminated soil, sludges, sediments and ground water, and is a promising biotechnology for cleanup of contaminated sites.  Some advantages of phytoremediation are low-cost, works well at low-risk sites, and may operate with limited maintenance for decades. Disadvantages of this technology are that it may require large expense for relocating operations, buildings, and roads at operating bases and there may be slow plant establishment that may limit the application. 

Phytoremediation encompasses a range of processes, which includes rhizodegradation.  Rhizodegradation is the breakdown of contaminants in the soil through microbial activity that is enhanced by the presence of the rhizosphere.  Our study focuses on RDX, a widely used military explosive.  It has been indicated in other phytoremediation studies that RDX degradation inside the plant is slow and possibly incomplete.  At the same time, phytoremediation, if effective, could be a useful approach at active firing ranges.  This research investigates whether rhizodegradation can be used to degrade RDX contaminated soils.  In rhizodegradation, natural substances called plant exudates are released by the plants’ roots.  These exudates contain organic carbon that act as nutrient sources for soil microorganisms.  In our study, wild grasses will be grown hydroponically so that the grass exudates are released from the roots into the water.  Those grass exudates will be applied to RDX contaminated soils and RDX degradation will be monitored.  Changes in microbial activity will also be studied.  As a result, we hope to find that the release of the soluble organic matter from the roots of the grasses stimulate RDX degradation.

Plant Assisted Bioremediation of Pollutants from Aquaculture Water 

Dr. Kishore K.Krishnani, Visiting Scientist, Centre for Environmental Engineering, Stevens Institute of Technology, Hoboken, 07030, NJ, Email: krishnanik@hotmail.com
Xioaguang Meng, Centre for Environmental Engineering, Stevens Institute of Technology, Hoboken, 07030, NJ, Email: xmeng@stevens.edu

Brackishwater aquaculture is the fastest growing food sector, especially shrimp farming which has emerged as a main source of employment and income for hundreds of thousands of people. However, agricultural, industrial and sewage wastes can contaminate aquatic ecosystem through the discharge containing nitrogenous toxicants, pesticides and heavy metals and can affect the aquaculture profitability in certain areas. Most of the previous works highlight the use of commercially activated carbons and ion exchange resins, which are relatively expensive and less feasible to use in developing countries. Furthermore, activated carbon loaded with toxicants is generally incinerated or disposed off on land, thereby causing environmental pollution through different routes. An emerging field of interests is employing certain plants which possess the natural ability to uptake heavy metals for the remediation of environment. In addition, plants release exudates and enzymes that stimulate microbial activity and biochemical transformation, which subsequently increase the biodegradation and biosorption potential. This process is often referred to as plant assisted bioremediation. Development of new economically feasible eco-friendly products from natural plants / agricultural wastes is the objective of my continued research in Central Institute of Brackishwater Aquaculture, Chennai, India. In this direction, attempts have been made to develop products for the decontamination of toxicants in the laboratory condition. Further work is in progress to explore the possibility of the use of these plant products for the remediation of shrimp farm culture water in the ponds / wastewater in the water reuse system. Natural plant products are biodegradable and cause no harm to the environment. Hence the natural plant products may offer a selective, harmonious and eco-friendly approach to remove nitrogenous toxicants and successful studies on this material could be beneficial for shrimp farm wastewater treatment.  

Phytoremediation Applications for Arsenic in Northern Climates

Michael J. Blaylock, Edenspace Systems Corporation, 15100 Enterprise Court, Suite 100, Dulles, 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, Dulles, VA 20151, Tel: 703-961-8700, Fax: 703-961-8939, Email: elless@edenspace.com
Charissa Y. Poynton, Edenspace Systems Corporation, 15100 Enterprise Court, Suite 100, Dulles, VA 20151, Tel: 703-961-8700, Fax: 703-961-8939, Email: cyp@edenspace.com

More than 70% of the United States arsenic consumption, representing approximately 37 million pounds of arsenic per year, is used to produce chromated copper arsenate (CCA), a wood preservative. Weathered lumber in decks, docks, playground equipment and garden construction can leach significant amounts of arsenic into soil and water, where it poses health risks to humans and animals. In addition to CCA sources, arsenic was used extensively  as a component of many pesticides used in agriculture. Phytoremediation techniques using an arsenic-hyperaccumulating fern (Pteris vittata) has been developed as a cost-effective remediation alternative for soils containing elevated arsenic concentrations. One of the key factors in phytoremediation of arsenic is achieving sufficient biomass production by the fern crop to result in significant arsenic removal rates. Pteris vittata, a subtropical species that is perennial in Zones 9 and higher, has been effectively used as a summer annual in northern climates for phytoremediation. However, increased costs from annual replanting combined with reductions in biomass yields with shorter growing seasons reduces the cost-effectiveness at some sites.

Recently, several cold-hardy species in the Pteris genus have been identified that also hyperaccumulate arsenic. Expanding the perennial climate range will provide significant improvements in phytoremediation performance. Growth chamber and field studies were conducted to evaluate the potential performance of these plants with existing arsenic hyperaccumulators for both biomass yield and arsenic uptake. Additonal cultural practices designed to extend the growing season were also investigated. The anticipated result of this research is an improved phytoremediation approach that is applicable to many of the arsenic-contaminated soils in northern climates. The results of these and other studies will be presented.

Can We Predict the Best Plants for the Phytoremediation of Organic Contaminants?

Chris D. Collins, Imperial College, Exhibition Rd., South Kensington, London, SW7 2BP, Tel (+44) 207 594 7378, Email: c.collins@imperial.ac.uk
Neil J. Willey, University of the West of England, Frenchay, Bristol, BS16 1QY, Tel: (+44) 117-965 6261, Email: Neil.Willey@uwe.ac.uk

There is a continuing interest in the clean-up of contaminated sites by biological means, because of the improvements in sustainability that they offer.  One potential tool in this strategy is phytoremediation. To date there have been a number of studies which have indicated that certain plant orders have the ability to accumulate heavy metals. In one study three orders; the Malpighales, Brassicales and Asterales were found to contain c.85% of the hyperaccumulating taxa. These taxonomic approaches can provide important information when choosing appropriate plant species for a given contaminant and ecological situation. Furthermore such approaches will become more useful as plant classification becomes more informed by genetic information, as this is more likely to provide information on a species’ ability to produce enzymes or chelators which may be important in metal accumulation or organic pollutant degradation.  The paper will present our initial findings when using phylogentic screening approaches for those plants which may be beneficial for the phytoremediation of organic pollutants.

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