Social Ecology Education and Demonstration School (SEEDS)
 Bioremediation Home Remedy Program

By

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Very good work overall. Interesting project with real world implications at various levels (research , education, etc.). Also connected to a real world organization. Is one of you doing this for a thesis? Proposal is good with strong background section and broader impacts. Huge improvement over previous draft. Good, detailed thinking about experimental design. Analysis section could be better. For some of the stats test it is not clear what data you are using. For example for the Chi-square tests.  Well organized and clearly written in a technical style.

Paper Submitted in Partial Fulfillment of the Requirements
of the Quantitative and Qualitative Analysis Core Program,
Master of Environmental Studies Program,
The Evergreen State College
May 27, 2010

Abstract
The following is a bioremediation research proposal for the Vashon Island community. The research will use beneficial cultures of microorganisms, shaggy parasol and endomycorrhizae and braken ferns to pull and disseminate (extract and concentrate?) the heavy metals arsenic and lead out of contaminated soils. These heavy metals are the result of the American Smelting and Refining Company (ASARCO) copper smelting plant plume that continually blew north over the islands for a century. The three organisms (what are they? Introduce them here) will be used individually, in pair associations and in guilds (assembly of more than 2 organisms) in order to find the most affordable, efficient and effective remediation process. There will be low and high technological (define here) plots in order to deduce the most affordable and efficient technique for bioremediation.  The research will be carried out under the Social Ecology Education and Demonstration School (SEEDS) enabling community awareness of the remediation process as well as providing hands on learning to better the transfer of information and remediation of the island. This proposed work will  provide funding for the bioremediation research correlated (this is a statistics term. Do you  mean associated?) with the Home Remedy Project. 

Background 
History and Mission of the Social Ecology Education & Demonstration School
Headquartered on Vashon Island in Washington State, the Social Ecology Education and Demonstration School (SEEDS) works to meet the urgent need for an educational ecological project aimed at both local and global communities. The mission of SEEDS is to develop and offer educational experiences that enhance people’s abilities to knowledgeably and creatively address the interwoven social and ecological crisis of our time. Through an intensive and interdisciplinary study, participants gain a critical and comprehensive understanding of social and ecological reconstruction. SEEDS provides participants with opportunities to test various environmental reconstructive strategies by means of individually designed practicum learning experiences.
	Beginning last year, SEEDS has played a key role in the development of what has come to be known as the “Vision for Vashon.” A comprehensive community development effort, Vision for Vashon sparked citizen work groups in food security and grassroots sustainability projects. The food security/food sovereignty group has become a particularly active and robust group, and SEEDS’ goals in relation to food sovereignty include the promotion of collaborative farming/gardening, and education in permaculture approaches. Through SEEDS the following research project is being proposed as a permaculture bioremediation process to alleviate heavy metals in soils.
Heavy Metals and Bioremediation
	Smelting plants have caused long lasting environmental impacts on surrounding environments. Even after smelting plant closings, heavy metals are left behind in soils causing contamination and toxicity. Vashon and Maury Islands of the South Salish Sea presently have high levels of arsenic and lead in the soils due to the American Smelting And Refining Company (ASARCO) smelting plant, operated from 1887 to 1986 in Ruston of Tacoma, Washington (Glass, 2003). The islands are located north of the former plant site, wherein the southern half of Vashon Island and all of Maury Island were under the smelter plume windfall area, leaving the areas contaminated with large amounts of the heavy metals, arsenic and lead. These metals impact the residents’ ability to grow food for personal and market consumption due to the detrimental impact they have on human health. Soil remediation is a necessity for the Vashon community in order to enable reliable, healthy and local food sourcing. 
	While the ASARCO plant continued to operate until 1985, the EPA designated it a Superfund site in 1983. Under Superfund regulations the EPA has documented the contamination of lead and arsenic in the adjacent areas (EPA, 2009). The Washington State Department of Ecology (WDoE) found concentrations of 460 parts per million (ppm) of arsenic and 1300 ppm of lead on certain soils on the south side of Vashon Island (Glass, 2003). The standard background levels for arsenic on the island is roughly 3-4 ppm. The EPA's standard for lead in bare soil in play areas is 400 ppm by weight and 1200 ppm for non-play areas. This regulation applies to cleanup projects using federal funds.This level of contamination is well over the safe limit for bare soils and is more than three times the limit for areas with children (Glass, 2003). These levels are far above Washington State's limit of 20 ppm concentration standard for arsenic and the state's 250 ppm for lead (WDoE). See Table 1. 		
Allowable Concentrations of Lead and Arsenic in Soils	
EPA Arsenic	EPA Lead	Washington State Arsenic	Washington State Lead	
Excavate if above 230ppm	Excavate if above 530ppm	20ppm	250ppm	
Table 1: Concentrations of heavy metals allowed by Federal and State Standards.	

	Soils contaminated with heavy metals such as lead and arsenic can be dangerous to humans and may be ingested through many vectors. Simply being outside and tracking the contaminated soil into the house on shoes and clothes is a means of ingestion. Growing vegetables in home gardens is also a vector in which heavy metals enter the body (Department of Ecology State of Washington, 2010). Laboratory testing is the only way for a homeowner to determine the amount of heavy metal contamination in the soil. The soil screening level (SSL) for lead represents a conservative estimate for a level that would be protective of public health in residential soils based on an analysis of the direct ingestion pathway for children. This value is for guidance only and is not enforceable  (Agency for Toxic Substances & Disease Registry, 2007). However, excessive exposure to arsenic can cause lung, bladder and other cancers to humans (Stamets, 2005). Lead exposure affects bones, reproductive and nervous systems and has been shown to be detrimental to the developing human brain.
Bioremediation
	Bioremediation is the method of decontamination of sites utilizing organisms, namely plants, fungi, and microorganisms. There are several advantages to bioremediation methods versus other forms of remediation. Bioremediation actually transforms the contamination, such as lead or arsenic, and even radionuclides such as uranium compounds, present in the soil into something that is less toxic (Iwamoto and Nasu, 2001). More traditional methods of remediation simply remove the contaminated soil and deposit it in another location, and does not address the toxicity leaving it for future generations. Bioremediation practices also tend to be low cost, when compared to other methods for remediation (Lloyd and Renshaw, 2005). This argument is difficult to quantify, as none of the literature read stated the overall cost of their method of bioremediation. However since bioremediation methods have shown to work, the cost would theoretically be lower as the equipment and organisms utilized for bioremediation tend to be less expensive. 
	Another advantage for bioremediation is the multiple organisms that can be used for bioremediation, each with their own strengths. Microorganisms are the most diverse group and are able to live in very harsh environments. In our study, the microorganisms utilized will be from the cocktail BioKleanTM provided by Sustainable Community Development (SCD) for the high-tech plots. This microorganism brew contains Bifidobacterium animalis, B. bifidum, B. longum, Lactobacillus acidophilus, L. buchneri, L. bulgaricus, L. casei, L. delbrueckii, L. plantarum, Lactococcus diacetylactis, L. lactis, and Streptococcus thermophilus. The BioKleanTM cocktail will also contain the yeasts, Saccharomyces cerevisiae, Bacillus subtilis var and the phototrophic bacterium Rhodopseudomonas palustris and R. sphaeroides. For the Low Technology microorganism factor a home compost tea will be made. 
	Beneficial cultures of microorganisms are shown to improve soil microbial ecology. In nature, microbes respond to arsenic in a variety of different ways. Depending on the species of different microorganisms, the responses could be chelation, compartmentalization, exclusion, and immobilization  (Sanita di Toppi and Gabbrielli, 1999). For example, S. cerevisiae alone has two different mechanisms to reduce arsenic toxicity  (Tsai et al., 2009). 
Fungal Bioremediation 
Fungus has been shown to actively accumulate heavy metals out of soils.  “Fungi in particular may be able accumulate…metal(loid)s into their cells. The intracellular uptake of metal ions from a substrate into living cells, otherwise known as bioaccumulation may lead to the biological removal of metals by fungi (Adeyemi, 2009)”. Adeyemi demonstrated the importance of fungus in the detoxification of arsenic in polluted habitats. Fungi are able to do this by rendering the arsenic in the soil from a soluble to an insoluble form, thereby reducing the toxicity. This ability is influenced by the pH of the soil, however since the soil on the islands has been shown to be acidic, the researchers do not see this as an issue.
Mycorrhizal fungi have been coevolving with over ninety percent of the plants on earth through a symbiotic association, exchanging important nutrients. One single mycorrhizae can aid many different plant species to fight off pathogens, compensate for soil nutrients loss and ameliorate the effects of drought. These associations have evolved over millions of year creating a mutuality sharing vital elements for survival (Stamets 2005 Is this a publication? I did not see the refernce in the literature cited section). There are two major types on mycorrhizae:  endomycorrhizae or ectomycorrhizae; When mycorrhizae develop in the cortical cells, resulting in swelling of roots, usually black in color, they are termed “endomycorrhizal”, “endotropic”, or “Vesicular-arbuscular mycorrhizae”, “VAM”). After inhabiting the roots, the fungi project their filaments, known as “mycelia” into the soil, extending the plant’s roots and root absorbing capacity from approximately ten to one thousand fold increase, significantly more than what the plant would be able to hold alone.
For the proposed study, the fungi Shaggy parasol, Macrolepiota rhacodes, will be used. Shaggy parasol is native to the area and is commonly found in polluted soils, hard ground, grassy areas, and trails. Shaggy parasol is able to grow in a range of temperatures in the environment and grows from late fall to early winter. Shaggy parasol has also been shown to be a bioaccumulator of arsenic and mercury (Stamets, 2005). 
Ferns and Remediation
Bracken Ferns remove arsenic from the soil via the phosphate uptake system in the roots. This is called phytoremediation. The arsenic then travels to the shoot whereby the shoot is removed and processed, as it contains the heavy metal in higher concentrations than normal (Chen et al., 2004). 
In order for As phytoremediation to succeed, the phytoremediating plant must fulfill three criteria: the plant root system must be able to take up and deplete the contaminating As in the soil; the plant must translocate and accumulate As in the shoot, which can then be harvested and processed; and the plant must have a mechanism to protect itself from the toxic effects of the As it accumulates. It has recently been shown that the fern Pteris vittata, a member of the Pteridaceae, meets all of these criteria (Ma et al., 2001; Chen et al., 2002; Visoottiviseth et al., 2002 as cited by Gumaelius at al. 2004)

Bracken ferns are found at all elevations in moist to wet forests, swamps, thickets, openings, slide-tracks, steam-banks, gullies, meadows and clearings environments. It is able to grow in many types of areas including areas disturbed by fire, avalanches, and humans. That is why it will be used for this study. However there are several disadvantages to using the Bracken fern. The ferns need to be planted about 20 inches apart and grow better in low light  (Rook, 2002). The need to be spaced far apart will lengthen the time it takes to remediate the soil. The need for the dim light will require a shade placed over the ferns. As with the fungi, soil pH is very important to plant growth. Since the soil of the area is acidic, there is no problem growing the ferns. 
Purpose
A research-based educational project has been created for SEEDS to design and implement a system for removing these contaminants using bioremediation methods. Our priority is that the system be affordable, effective and replicable to other communities. We will freely share our findings with other areas facing the challenge of contaminated soils, and we anticipate that our research will benefit countless communities in their quest of restoring land for food production and other community needs.
Bioremediation Home Remedy Program: Goals and Objectives 
	SEEDS envisions a permaculture “make-over” of bioremediated garden spaces that have been largely abandoned through concerns about contamination. The Home Remedy Program aims to provide a proven, replicable, and affordable model for remediating soils contaminated with the arsenic and lead. Bioremediation techniques are inexpensive and holistic, providing healthy living systems for daily life and food production. 
Our goal for the Home Remedy Program is to demonstrate that contaminated soils within the smelter plume area of Vashon can be remediated through ecological and accessible low-technology means for safe food production, according to the rigorous standards of Washington State, which are considerably more stringent than the EPA standards. The objective of this particular study is to compare effectiveness between low and high technological techniques using three different ecological methods: fungi, microorganisms, and ferns. We will then further study these methods’ effectiveness when working together, to view their effectiveness in a “guild.” A guild is a permaculture term meaning “harmonious assembly of species (Mollison, 1988).” 

Study Design
	The Bioremediation Home Remedy initial study will compare bioremediation techniques using low technology (locally based and sustainable resources) with those using higher technology techniques (imported and more expensive resources) within contaminated soils on Vashon Island. By testing three techniques at a low and high technological level, a better understanding will be gained at the local level of different cost variables as well as the bare minimum needed to successfully bioremediate the contaminated soils. The purpose of the two technological levels is to provide replicable practices for people with varying funding resources, while maintaining scientific accuracy. We hypothesize that there will be negligible differences between the low and high technology methods of bioremediation because…this is the important part of the hypothesis. We also hypothesize that the guild bioremediation plots will be more effective at remediating the soil than the individual specie and species plots because….. 
	The research will be designed in a way that incorporates the greater community by allowing observers to learn from the research process through a complimentary educational program and art exhibit. This will occur along side the research by creating interpretive signs on the various biroremediation techniques taking and the different organisms used. This community piece will be pulled form a different budget, but is important to state here in order to realize the broader impacts of this research.

Methods
	SEEDS researchers will start with 56 one-meter square plots. There will be seven different sets of plots each with four plots being tested with a control. There will be three plots inoculated with the fungal spawn of Shaggy parasol (Macrolepiota rhacodes), three plots inoculated with the Bio KleanTM cocktail, and three plots planted with three Brake ferns in each plot. The fern used will be the Chinese Braken fern, Pteris vittata, which has been studied for successful arsenic remediation  (Cao et al., 2003; Wei and Chen, 2006). There will be three plots with braken ferns with Shaggy parasol mushrooms, three plots with braken ferns and microorganisms, and three plots with microorganisms with Shaggy parasol mushrooms. The last three plots will be a guild of all three organisms. The seven different sets will then be repeated for a low technology technique. 
	Low technology methods and plots will consist of hand-tilled plots, wild harvested Shaggy parasol mycelium to be cultivated, and compost tea from local sources and wild harvested Lady ferns. The compost tea will be made according to the Home Composting Made Easy How to Make Compost Tea (Home Composting Made Easy, 2010). The high technology plots will be comprised of purchased Shaggy parasol spawn, a specialty blend of Bio KleenTM cocktail, and purchased Braken ferns. For the high technological plots a mechanized tiller will be also be used. All of the site plots will have deer netting and shade cloth to protect from secondary consumers and intense sun as Brake fern generally grows in the understory of forests and shaggy parasol in shaded areas. There will be a total of 96 Chinese Braken ferns, a total of 2,200 liters of Bio KleanTM for the high tech plots and 2,200 liters of compost tea, one culture of shaggy parasol, 3 jars (1.5 gal) of rye grain inoculated with shaggy parasol, and 1 pound of mycorrhizae.
Fig. 1: Plot Diagram
	
Cultivation of Shaggy parasol at both low-tech and high-tech levels are relatively easy to clone. Inoculates of the fungi are placed directly in soils that are 4-6 inches deep. It is suggest that cow or horse manure mixed within the straw or sawdust medium will result in a larger output. Hardwood is an ideal medium for outdoor cultivation (Stamets, 2000).  The initial growth of mycelium is 12-15 days and fruit body development lasts for 5-7 days. Harvesting can occur for two to three days approximately 4-10 days apart. For both high and low technological methods of cultivation we will be using the protocols used in Growing Gourmet and Medicinal Mushrooms (2000) and Mushroom Cultivator (1983). 
Timeline
The study will be conducted over an initial six-month period from June through November to consider a full growing season. Initially, starting in the early summer, the plots will be laid out and analyzed for contaminates. Once that is established, the plots will be inoculated with the microorganisms and fungi, and the ferns will be planted. The process will be fairly autonomous, however mushrooms need to be harvested every four to five days. Samples of the soil will be collected every month and analyzed for arsenic. This process will continue for a six month duration. 
As a part of the research process, a six month education program will be programmed, beginning in June and culminating with a public workshop that highlights the bioremediation program within the framework of “Radical Sustainability,” a vision SEEDS has adopted from Scott Kellogg and Stacy Pettigrew of the Rhizome Collective. Radical Sustainability champions the necessity that resources required for meeting people’s needs be designed, built, maintained, and controlled by those who use them, and materials be likewise accessible, low-cost, and shared. The SEEDS Home Remedy Program works toward this vision. The Home Remedy Program will also feature an educational art exhibit dramatizing the processes and benefits of bioremediation, designed by noted eco-artist Beverly Naidus.

Data Analysis
Testing for the heavy metals arsenic and lead will be done with a Thermo Scientific Niton® XRF analyzer to conduct Positive Material Identification (PMI), with five percent by mass of the samples sent to a King County lab for verification, as dictated by the EPA. The analysis procedure will consist of the following steps:
•	We will take three samples from each plot for initial testing. Each sample will be sieved and grinded with mortar and pestle according to the King County’s Public Health procedures (Public Health Seattle & King County, 2010). Then the three processed samples from the same plot will be mixed together and sub-sampled three times, repeating this for each plot's group. The sub-samples will be compacted into a small testing container and analyzed three times for an average amount of arsenic and lead. We will continue this soil analysis every month for six months. There will be a total of 144 samples taken for the experiment. 
•	Shaggy parasol mushrooms will be harvested each time upon their fruiting. Each mushroom from its specific site will be dehydrated and powdered, then mixed with samples from its plot and sub-sampled three times. Each sub-sample will be compacted into a small testing container and analyzed three times for an average, with five percent of the samples sent to a King County lab. The remaining plant and fungal matter will be taken to the proper contamination holding facilities if necessary.
•	The ferns from each plot will be washed to remove excess soil and dried to the same dry weight. 
•	The categorical data will be analyzed with a χ2 analysis to insure statistical significance. Our categorical independent variables are each plot, while our dependent variables will be the fruiting mushroom bodies, aerial portions of the ferns and the control plot (is this count data?). The before and after levels of lead and arsenic in each plot will then be compared to the control plots using Student’s paired t-tests which is typically used to compare the before and after samples. In order to observe the changes that occur over time, measurements taken each month will be plotted to show changes in concentration. 
•	We will compare the differences between low and high technology methods and each method’s ability to remediate the soil. The guild plots with all three sets of organisms will be compared. Each plot will be examined by progression of change over time and how it effected the remediation. Using a Pearson's χ2 test (I think that you mean R2 . This is the term for the coefficient of determination. The Chi-square test is for differences in proportion means)  we will analyze and test for the correlation between the fruiting mushroom bodies and the soil in which they grew (not sure what type of data you are comparing> counts Vs metal in soil???. The same test will be done for the aerial portion of the fern and its soil. We will also conduct ANOVA which compares three or more means in order to find the most efficient process. Again what is the data that you are running through ANOVA?
Evaluation 
	The Bioremediation Home Remedy Program will be evaluated on three main principles. The first criteria for evaluation will be the ability of the bioremediation process to successfully clean the contaminated soils, confirmed by monthly testing of the soil and aerial bodies of the fungi and Braken ferns. The second component will be the collection of scientific data to gain a better understanding of bioremediation processes and interactions between species. This will give residents, as well as local, state and federal agencies better tools for remediating contaminated soils. The last important principle to be evaluated will be the level of community involvement and education. This will be assessed by the attendance at three public workshops held by SEEDS at the bioremediation sites as well as the community’s feedback and education about the study, including articles in the local newspaper, outreach at the local farmer’s market and other venues, and updates on the SEEDS’ website. Further evaluation will be done as the Home Remedy Program is put into practice throughout the community.

Sustainability and Broader Impact Statement
These test sites will be transformed into sites for on-going community education in both bioremediation and permaculture approaches, providing a positive and lasting impact not only on the health of Vashon Island’s 13,000 residents but on other communities facing similar challenges. The program will also promote food sovereignty, which means not merely food security (which might be obtained through food transported long distances), but the maximizing local resources for food production.
The Bioremediation Home Remedy Program uses and addresses the three pillars of sustainability: incorporating the importance of community education and empowerment, providing economic support and resources, and keeping the ecological environment a priority. SEEDS is funded by workshop tuition fees and a steady stream of small and large private donations, organized partly through membership in our Rhizome Club. SEEDS has also received several small grants and developed earned income products and services. Volunteers and a pulsing Puget Sound community provide the momentum for SEEDS to continue to promote educational experiences that make lasting changes to better the global community.

SEEDS Bioremediation Project Budget	
 	 	High Tech	Low Tech	Total	
On-site work	 	 	 	
 	Pressure Cooker/Sterilizers 21 1/2 qt	 	 	$239.00	
 	Digital Thermohygrometer 	 	 	$55.00	
 	Alcohol Lamp	$15.00	 	$15.00	
 	Parafilm	$25.00	 	$25.00	
 	Digital Psychrometer	$100.00	 	$100.00	
 	1/2 gallons Autoclavable Glass Jars (10)	$15.00	 	$15.00	
 	Synthetic Filter Disks (10)	$13.00	 	$13.00	
 	Micron Filter 12 X 12 X 5.8 (optional)	$90.00	 	$90.00	
 	Malt Extract Agar (MEA)	$30.00	 	$30.00	
 	Incoculation Loops X2	$14.00	 	$14.00	
 	Plastic Petri Dishes; 3 sleeves (20/sleeve)	$20.00	 	$20.00	
 	Mechanized tiller	$390.00	 	$390.00	
 	Shovels (hand tilling)	 	$300.00	$300.00	
 	Site Development (preparation)	$75.00	Donated	$75.00	
 	Labor	Volunteers	Volunteers	 	
Remediation organisms	 	 	 	
 	C. Comatusand and VAM mycorrhizae	$250.00	 	$250.00	
 	BioKlean Culture	$3,200.00	 	$3,200.00	
 	Chinese Brake Fern	$500.00	$105.00	$605.00	
 	Homegrown Culture	 	$30.00	$30.00	
 	Compost Tea	 	$80.00	$80.00	
Other associated costs	 	 	 	
 	Transportation	$250.00	$250.00	$500.00	
 	Lab testing	$300.00	$300.00	$600.00	
 	Education	$350.00	Donated	$350.00	
 	Unforseen Costs	 	 	$250.00	
Total	$5,637.00	$1,065.00	$7,246.00	
Table 2– Budget Calculation	

Great job with developing a budget. Not required for this exercise, but an essential component of doing real world research,

Literature Cited – if these are in alphabetical order there is no need to number the citations

1.  Adeyemi, Ademola O. "Bioaccumulation of Arsenic by Fungi." American Journal of Environmental Sciences 5, no. 3 (2009): 364-370.
2.  Agency for Toxic Substances & Disease Registry, "Toxicological Profile for Arsenic" http://www.atsdr.cdc.gov/toxprofiles/tp2.html#bookmark08 (accessed May 26th, 2010).
3.  Cao, Xinde, Ma, Lena Q., and Shiralipour, Aziz. "Effects of Compost and Phosphate Amendments on Arsenic Mobility in Soils and Arsenic Uptake by the Hyperaccumulator, Pteris Vittata L." Environmental Pollution 126, no. 2 (2003): 157-167.
4.  Department of Ecology State of Washington, "Reducing Toxic Exposure in the Soil" http://www.ecy.wa.gov/toxics/soil.htm (accessed May 26th, 2010).
5.  EPA, "American Smelting and Refining Company (Asarco) Bankruptcy Settlement
Epa Funded Sites and Communities" http://www.epa.gov/compliance/resources/cases/cleanup/cercla/asarco/community.html#tacoma (accessed May 25, 2010).
6.  Glass, Gregory. Tacoma Smelter Plume Site Credible Evidence Report: The Asarco Tacoma Smelter and Regional Soil Contamination in Puget Sound. 2003.
7.  Glass, Gregory L. Public Health - Seattle & King County Final Report Vashon/Maury Island Soil Study 1999-2000. 2000.
8.  Home Composting Made Easy, "How to Make Compost Tea" http://www.homecompostingmadeeasy.com/composttea.html (accessed May 25th, 2010).
9.  Iwamoto, Tomotada, and Nasu, Masao. "Current Bioremediation Practice and Perspective." Journal of Bioscience and Bioengineering 92, no. 1 (2001): 1-8.
10.  Kellog, Scott, and Pettigrew, Stacy. Toolbox for Sustainable City Loving: A Doi-It Ourselves Guide, 2008.
11.  Lloyd, Jonathan R., and Renshaw, Joanna C. "Bioremediation of Radioactive Waste: Radionuclide-Microbe Interactions in Laboratory and Field-Scale Studies." Current Opinion in Biotechnology 16, no. 3 (2005): 254-260.
12.  Madejón, Paula, and Lepp, Nicholas W. "Arsenic in Soils and Plants of Woodland Regenerated on an Arsenic-Contaminated Substrate: A Sustainable Natural Remediation?" Science of The Total Environment 379, no. 2-3 (2007): 256-262.
13.  Mollison, Bill. Permaculture: A Designer's Manual, 1988.
14.  Public Health Seattle & King County, "Resident Self-Testing Protocol for Testing Soil" http://www.kingcounty.gov/healthservices/health/ehs/toxic/ResidentTesting.aspx (accessed May 25th, 2010).
15.  Rook, Earl J.S., "Pteridium Aquilinum Braken Fern" http://www.rook.org/earl/bwca/nature/ferns/pteridiumaqui.html.
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17.  Social Ecology Education and Demonstration School,  http://www.socialecologyvashon.org/ (accessed May 12th, 2010).
18.  Tsai, Shen-Long, Singh, Shailendra, and Chen, Wilfred. "Arsenic Metabolism by Microbes in Nature and the Impact on Arsenic Remediation." Current Opinion in Biotechnology 20, no. 6 (2009): 659-667.
19.  White, Philip J., and Broadley, Martin R. "Mechanisms of Caesium Uptake by Plants." New Phytologist 147 (2000): 241-256.