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Heavy Metal Soil Contamination Analysis

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Heavy Metal Soil Contamination Analysis
by
Kenneth Rosales
5/20/10
ENVS 100W
Winters
Heavy metal contamination in soil occurs in all parts of the world, but most often in
developing, undeveloped, and underde...
and McCarthy, 2009; Olszewski, 2010). Cell phones, car batteries, and computers are products
simultaneously soaring in glo...
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Heavy Metal Soil Contamination Analysis

  1. 1. Heavy Metal Soil Contamination Analysis by Kenneth Rosales 5/20/10 ENVS 100W Winters
  2. 2. Heavy metal contamination in soil occurs in all parts of the world, but most often in developing, undeveloped, and underdeveloped countries. Many measures have been taken to find solutions, but unfortunately, it requires a great amount of time and effort to gain results. Heavy metals may be carcinogenic, non-cancerous, cancerous and toxic, harmless, or essential for life on earth. Non-cancerous consequences are due to toxins that can either have neurological effects, immune effects, and/or endocrine effects (Lim and Schoenung 2010). Some heavy metals include: Antimony (Sb), Arsenic (As), Barium (Ba), Beryllium (Be), Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Lead (Pb), Mercury (Hg) Molybdenum (Mo), Nickel (Ni), Selenium (Se), Silver (Ag), Vanadium (V), and Zinc (Zn) (Lim and Schoenung 2010). Heavy metal contamination usually occurs due to mines, landfills, Waste-to-Energy facilities, or smelters (Bech et al., 1997; DMG, Liao, Probst, and Probst, 2005; 1995; King and McCarthy, 2009). Heavy metals are extracted and refined resources that are used in everyday products people use such as cell phones, speakers, or computers (EPA, 2010). Such activities of generating heavy metal contamination to make merchandises in turn become social issues like in the case of lead smelters adversely affecting low income residents in Boolaroo, Australia or Northern Peru’s copper mining ordeal of farmland contamination (King and McCarthy, 2009; Bech et al., 1997). Fortunately, there have been scientific advances in cleaning up heavy metals, but much more research is needed for its success rate to increase substantially (Evangelou, Ebel, and Schaeffer 2007). The issues of heavy metal pollutants will not only adversely affect localities, but all life on a global scale if left alone. Therefore, the full adverse impacts can only fully be understood and solved with economic, political, sociological, and scientific approaches. Lead is an extremely toxic heavy metal utilized in many electronic products such as cell phones, car batteries, computers, and solar panels (Lim and Schoenung, 2010; EPA, 2010; King
  3. 3. and McCarthy, 2009; Olszewski, 2010). Cell phones, car batteries, and computers are products simultaneously soaring in global demand whereas solar panels are on the rise as humans struggle to find solutions to energy and global warming issues. As the need for lead-based goods increases, so do the social dilemmas residents face in Boolaroo, Australia. Lead contamination in Boolaroo, Australia quantitatively and qualitatively affects women more than children and men (King and McCarthy, 2009). Children have sensitive receptors and are significantly inclined to develop mental retardation, kidney damage, or behavior problems because of lead. Nevertheless, parents also have the potential of obtaining the harmful effects of lead as well because fathers in the lead smelter communities are the individuals who work within the facility that causes the contamination of lead while women have the burden of responsibility over children since most have adopted housewife lifestyles (King and McCarthy, 2009). Public health authorities have published handbooks and posters to residents describing how and what should be done about the spread of lead contamination in households while specifically targeting children (King and McCarthy, 2009). The proposals public authorities have made are skewed due to its diversion from the legitimate problem, the smelters. Some responsibilities households have in Boolaroo are to use diluted mops instead of brooms to clean lead dust multiple times a day, constantly alert children not to put toys in their mouths, keep dust out of the presence of children, under beds, closets, corners, behind furniture, and doors (King and McCarthy, 2009). There are also directives, mainly for housewives, to stop children from sucking their own fingers, wipe surfaces before preparing food, and to cover food and eating utensils from lead dust (King and McCarthy, 2009).Women in the Boolaroo community have the burden of shame, fear, and anxiety when the result of their continuous efforts to have successful housekeeping fails along with the consequent unhealthy development of their children (King and McCarthy, 2009).
  4. 4. Most people in contemporary America own a cell phone, a computer, or a car, but disregard the issues behind its production. Many Americans value the convenience of communicating with one another while being hundreds of miles away from each other with the utilization of cell phones. At the end of 2006, there were over 233 million cell phones in use and its average life is about 18 months, which equates up to 150 million phones needed to be replaced per year (Mireille, et al 2006). As population continues to increment, renewal, disposal, and production of new cell phones will run parallel with the increase. “Cell phones will be thrown away at a rate of 130 million a year by 2005, that equals 65,000 tons of waste containing toxic metals”(Recyclemycellphone.org, 2010). Heavy metals that were listed above may be incinerated at the end life of a cell phone and creates flue gas, fly ash, and bottom ash that disperse into the air, water, and soil, or may be landfilled. In the landfill, heavy metals leach and seep down into soils and eventually reach aquifers (Lim and Schoenung 2010). The end result of improper disposal of cell phones is harm to human health and ecosystems in the result of air, water, and soil contamination. Given most predicaments behind cell phones, it must raise concerns for developing countries because the norm in developed countries is to have a cell phone due to global consumption patterns (Mireille, et al 2006). Cell phones are almost a necessity in developed countries such as the United States and in turn, this behavior is being copied in developing countries where there are no proper waste management practices being implemented (Diamond, 2005).Cell phones can be applied to electronics as a whole because most accessories such as computers and stereos contain lead which would reciprocally affect residents near lead smelters like in Boolaroo, Australia (EPA, 2010). Nonetheless, if heavy metal soil contamination exists, there are scientific solutions to toxic ordeals. Bioremediation may be used to battle toxins in soils because it “is a technique that
  5. 5. uses living organisms in order to degrade or transform contaminants into their less toxic forms” (Kavamura, Esposito, 2010). Phytoremediation uses the same principles as bioremediation except it is organism specific because of its utilization of plants or fungi (Kavamura, Esposito, 2010). Rhizoremeditation is used to assist phytoremediation’s inability of cleaning multiple pollutants simultaneously by using microorganisms to increase the efficiency for the extraction of contaminants (Kavamura, Esposito, 2010). Bioremediation has two methods of cleaning toxins in soils. The first is in situ, where treatment is completed in the premises of the heavy metal contamination and ex situ takes place outside the site by extracting the soil to treat it afterwards (Kavamura, Esposito, 2010). Biosorption is an adhesive procedure in which metals bind with cell surfaces to have the results of adsorption and desorption (Kavamura, Esposito, 2010). Adsorption is the assembly of a gas, liquid, or substance into a thin layer and desorption is the removal of the absorbent (Dictionary.com, 2010). A bacterium classified as Trichoderma reesei adsorp and desorp cadmium and copper ions in soils and water. Another bacterium labeled Amanita rubescens undergoes a process called bioleaching. Bioleaching is a process some organisms go through in order to dissolve metal ions (Kavamura, Esposito, 2010). Amanita ruescens is an extraordinary organism because it has the ability to dissolve the most destructive and harmful toxins, lead and cadmium. Phytoremediation practices are similar to bioremediation except for the fact that plants or fungi are specifically used to treat contaminants in soils. Therefore, a phytoremediation practice called chelate assisted phytoextraction will be explained in detail instead. Phytoremediation with chelate assisted phytoextraction is described as one of many methods that is being used to get rid of adverse heavy metal chemicals from soils. Chelating agents enhance the solubility of heavy
  6. 6. metals in soils which subsequently aids the phytoextraction process of transfering metal concentrations to harvestable areas of roots and surface shoots of plants (Garbitsu and Alkorta 2000). Only a selective number of plants are able to retain large traces of metals. The plants that have the ability to do so are called hyperaccumulators (Garbitsu and Alkorta 2000). In order for these species to be successful in removing a substantial amount of metals, they must fit many requirements such as fast growth rate, deep roots, great biomass production, elevated tolerance to the metals, quick uptake speeds, high reproductive feasibility, and easy gathering of the targeted metal (Evangelou, Ebel, and Schaeffer 2007). Uptaking is the relocation of metal accumulations to harvestable areas of roots and surface shoots of plants (Garbitsu and Alkorta 2000). Unfortunately, hyperaccumulators do not qualify for many of the important success requirements because of their slow growth and small bio mass production (Evangelou, Ebel, and Schaeffer 2007). Non hyperaccumulators quickly grow and have a large bio mass production, but lack metal accumulation and uptake speed (Evangelou, Ebel, and Schaeffer 2007). Therefore, chelating agents have been introduced to certain plant species to enhance its natural occurrences of metal accumulation and uptake speed. Chelating agents increase the removal of metals from soil and increase the concentration of metals into a soil based solution. This augments the uptake of metals within plants (Evangelou, Ebel, and Schaeffer 2007). Consequently, this enlarges phytoextraction rates, but raises questions on which chelates and plants are most effective with which metals. There are two kinds of chelates or aminopolycarboxylic acids (APCAs) that are used to help detoxify heavy metal contaminants; synthetic and natural. The most effective and commonly used synthetic chelating agents for metals such as lead is diamine tetraacetic acid
  7. 7. (EDTA) with the combined use of the Indian mustard plant (Garbitsu and Alkorta 2000). When 3 mmol kg-1 of the agent was added to 23 fold plants available, approximately 26 fold of heavy metal uptake in plants occured (Evangelou, Ebel, and Schaeffer 2007). Although quite successful, synthetic chelating agents face many issues. EDTA’s decreased biodegradability capabilities are toxic to soil microorganisms and plants which drastically decrease the biomass of plant shoots, remain in soils even after cleaning, and its longevity escalate the chances of leaching from heavy metals (Evangelou, Ebel, and Schaeffer 2007). On the contrary, nitrilotriacetic acid is biodegradable, has a decreased rate of leaching metals because of its quick decomposition through photodegredation depending on which metal being used, and has the best heavy metal uptake for zinc and arsenic (Evangelou, Ebel, and Schaeffer 2007). Although the exact numbers aren’t shown for arsenic Evangelou, Ebel, and Schaeffer 2007 states zinc had 20 mmol kg-1 of the agent added to 300-fold of plants available, and around 37 fold of heavy metaluptake took place with the use of Corn and Vetiver grass. Regrettably, there was a biomass decrease in the process of zinc (Evangelou, Ebel, and Schaeffer 2007). Unfortunately, phytoremdiation practices are not as effective when variations of heavy metal pollutants are in one area. On the other hand, rhizoremediation is an adequate resolution to phytoremdiation’s flaws by inputting microorganisms in the treatment system (Kavamura, Esposito, 2010). In rhizoremediation, microorganisms increase the accessibility of heavy metal compounds, while the plant subsequently pulls and removes the compounds (Kavamura, Esposito, 2010). This microorganism and plant relationship is beneficial for both parties because plants provide nutrients for microorganisms to regenerate and multiply to increment the extraction of heavy metal contamination (Kavamura, Esposito, 2010). Effective treatments of cadmium and zinc have been made possible with the use of the Hebeloma fungi and the
  8. 8. bacterium Microccus leteus (Kavamura, Esposito, 2010). Approximately 53 percent of cadmium and 62 percent of zinc were accumulated in the shoots of the fungi. Rhizoremediation is a new procedure for remediation practice and needs to be explored to fully understand and gain substantial results for other contaminants (Kavamura, Esposito, 2010). Economic, political, sociological, and scientific comprehension and resolutions are necessary when dealing with heavy metal soil contamination issues. In the circumstance of Boolaroo, Australia, cap and trade programs for lead, strict facility regulations such as producer responsibility for contamination, and relocation of residents to a safe area away from lead smelters are possible means to achieve successful goals to reduce and eventually eliminate lead contamination. Regrettably, toxic heavy metal constituents from marketable products create environmental perils, and production and consumption issues. Therefore, effective world policies of waste management needs to made because heavy metal soil contamination is a global problem. A way to close open loops in the waste stream in relation to hazardous products is to create local end-user markets that will keep the products in use rather than going to the landfill. As for remediation practices, further research for the discovery of fully effective treatment is pendant. Leaching of heavy metals in soils remains a prolonged predicament and perhaps an amalgamation of chemicals that would stop or substantially reduce heavy metals from leaching can be a temporary solution.
  9. 9. Works Cited Bech, J., Poschenrieder, C., Llugany, M., Barcelo, J., & Tume, P. et al. (1997). Arsenic and heavy metal contamination of soil and vegetation around a copper mine in northern peru. The Science of the Total Environment, 203, 83-91. Decision Maker’ Guide to Solid Waste Management, Volume II. (1995). Washington D.C.: U.S. Environmental Protection Agency. Diamond, J. (2005). Collapse. New York: Penguin Books. Evangelou, M.W.H. , Ebel, M., & Schaeffer, A. (2007). Chelate assisted phytoextraction of heavy metals from soil. effect, mechanism, toxicity, and fate of chelating agents. Chemosphere, 68, 989-1003. Garbisu, C, & Alkorta, I. (2000). Phytoextraction: a cost-effective plant-based technology for the removal of metals from the environment. Bioresource Technology, 77, 229-236. Kavamura, V.N, & Esposito, Elisa. (2010). Biotechnological strategies applied to the decontamination of soils polluted with heavy metals. Biotechnology Advances, 28. Retrieved from http://www.sciencedirect.com.libaccess.sjlibrary.org/science? _ob=ArticleURL&_udi=B6 T4X-4X908RR- 1&_user=521825&_coverDate=02%2F28%2F2010&_alid=1342783951&_rdoc=1&_fmt =high&_orig=search&_cdi=4986&_sort=r&_docanchor=&view=c&_ct=44&_acct=C00 0059578&_version=1&_urlVersion=0&_userid=521825&md5=94baf540312df8da5a72a 2545747bfe4 King, Leslie, & McCarthy, Deborah. (2009). Environmental sociology. Lanham: Rowman & Littlefield Pub Inc. Liao, B., Guo, Z., Probst, A., & Probst., J. (2005). Soil heavy metal contamination and acid deposition: experimental approach on two forest soils in hunan, southern china. Geoderma, 127, 91-103. Lim, S.R., & Schoenung, J.M. (2010). Toxicity potentials from waste cellular phones, and a waste management policy integrating consumer, corporate, and government responsibilities . Waste Management, Retrieved from http://www.sciencedirect.com.libaccess.sjlibrary.org/science?_ob=ArticleURL&_udi=B6 VFR-4YXMNXF- 2&_user=521825&_coverDate=04%2F24%2F2010&_alid=1328683752&_rdoc=1&_fmt =high&_orig=search&_cdi=6017&_sort=r&_docanchor=&view=c&_ct=17&_acct=C00 0059578&_version=1&_urlVersion=0&_userid=521825&md5=7ea04ea0994611a2b494 d1997bf8a929
  10. 10. Mireille Faist Emmenegger, et al. (2006). Life Cycle Assessment of the Mobile Communication System UMTS: Towards Eco-Efficient Systems. International Journal of Life Cycle Assessment. Olszewski, Bruce. (2010). Toward a Just and Sustainable Solar Energy Industry [Power Point Slides]. Retrieved from Northern California Recycling Association website: http://www.ncrarecycles.org/ru/ru10.html Recyclemycellphone.org. (2010). Recycle My Cell phone Campaigns Fact Sheet and Contact List. Retrieved from http://recyclemycellphone.org/RMCP_factsheet.pdf U.S. Environmental Protection Agency. (2010). Electronics Recycling (Ecycling). Retrieved from http://www.epa.gov/region2/ecycling/

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