Environmental Geochemistry and Health - Essay Example

146692 First Question: Groundwater laced with gasoline can create risk factors by increasing cancer possibilities and other health hazards due to toxic substances in the contaminated water. Gasoline, even though unleaded, could be dangerous if gets mixed with drinking water and sewage. Underground leakage usually directly mixes with underground water and in this case, it has happened for sometime. Gasoline is a petrol-derived mixture and is inflammable. It has hydrocarbons, and benzene. It is produced in oil refineries, and has between 5 and 12 carbon atoms per molecule. Unleaded gasoline has at least 15 hazardous substances including toluene (35%) and is classified as highly volatile and will result in vapour lock where combustion does not take place1. When mixed in water, most of the gasoline could evaporate if the water is open, but much of it cannot evaporate in underground water making a big proportion to dissolve and this will be absorbed by sediments. For aquatic organisms, this product will be quite toxic, depending on their size and resistance capability. Estimated cost of separating gasoline from water: Viscosity centistokes 100 degree F. Operating cost c/gal 0.015 https://www.pall.com/pdf/hcp_hcp_dec_1993.pdf Corrective action is necessary starting with site investigation. Hydrocarbon contamination with the groundwater should be stopped immediately. Its discharging point should be plugged and the nearest drains, water bodies should be sealed off, so that further contamination to distant water bodies does not happen. Residents could be evacuated if gasoline has already spread into drinking, using and sewage water or if that is not the case, water supply should be disconnected immediately and alternative water source should be provided. Complete groundwater monitoring should start immediately. Instead of one single action, it is better to perform by-monthly actions to remove all traces of gasoline from ground water, to ensure that dissolved contaminants are effectively vanishing. And groundwater sampling should be done on a regular basis through tracer testing. If widespread presence is detected, human exposure to it should be suspended immediately. Dissolved contamination level should be identified and ecological profile should be drawn, followed by remedial programme identified with the Corrective Action Plan. Public participation may be necessary in the entire operation to some extent. http://www-1.llnl.gov/IPandC/technology/profile/environment/DynamicUndergroundStripping/index.php This method is called Dynamic Underwater Stripping, in which steam drives contaminated water towards extraction wells. Where steam cannot penetrate, electrical heating dries and distils the clays, volcanic rocks and limestone. Heating of the soil also could do the same. It is very difficult to clean the underground contamination and this process is accepted as cost worthy, less cumbersome and minimum time consuming. Cleaning has to be done both above and below the water table. Clay has very low permeability, and the usual pump-and-treat method would be time consuming and more expensive and might not work below water level. Dynamic stripping could work even below water table, and by vacuum extraction, it could remove the gasoline and contaminated water2. This method relies on Steam Injection, Electrical heating, and underground imaging and all have proved very effective and reasonably cheaper. It has many additional advantages like being effective in low permeable soils, being capable of removing contaminant below and above water table. It is not risky to population, because the action is quick and decisive. Question 2: Gasoline (one of the Volatile Organic Compounds) contamination in ground water can cause major health hazards to people and ruin the river and water bodies' ecosystems completely. It can contaminate soil with hazardous results. MTBE in it creates alarming tension whenever leaks happen. Health of all 5,000 populations could be at risk by this environmental hazard, while the river bio system could be very seriously harmed. Restoration and regulation should be taken up immediately to reduce and eradicate the environmental pollution. Gasoline is not classified here and it could be Oxygenated gasoline or reformulated gasoline and both could be risky to people and environment as gasoline consists of a mixture of various hydrocarbons that could cause cancer and many lesser toxic risks. Many things happen when groundwater is contaminated. "Therefore, once contaminants reach groundwater, they tend to form a concentrated plume that flows along with groundwater" http://www.waterencyclopedia.com/Oc-Po/Pollution-of-Groundwater.html The process adapted has to be less time consuming (considering the 5,000 strength population and their temporary evacuation), should be financially viable, and involves protective. The first step is preventing the contaminants from leaking further by plugging the source. Second step is preventing them from spreading into a wider space. Third step is detoxifying the water bodies or immobilising the contaminant while it still remains in water. Fourth step is treating the water and make it use-worthy. Fifth step is, if the methods are taking longer time than expected, finding another source of alternative water. Plugging the river water from contaminating other sources is an impossible task. But many methods of containment could be followed with excellent results3. Monitoring wells should be installed to prevent gasoline from spreading and existing wells with uncontaminated water should be segregated. It can cause indigestion, breathing problems due to inhalation of vapours, skin problems, etc. Gasoline with benzene, toluene, ethyl benzene and xylene is a major risk and it is highly mobile in soil. Conventional technologies of pumping large amount of water from site would only contain and not clean and hence, innovating technology has to be adapted. A pump and treat component of (in-situ) (in place) is used for Air Sparging, or Air Stripping or Air volatilization). This can reduce the contaminant from soil and ground water if contaminant-free air is injected into saturated zone enabling the hydrocarbons to disappear in vapour state. http://aehsmag.com/issues/2002/april_may/soil_vapor.htm Question 3: Atrazine is a crystalline, white solid organic compound, very widely used herbicide, mainly in US (now restricted). This can cause health risks, if released to environment, because sunlight and evaporation do not reduce its presence. Conventional remedies have failed in several fronts in totally segregating it from water and soil. It can be removed with natural methods; but these methods are yet to be popular. "Pollution studies are very wide ranging and so extend over a multitude of situations invoking interactions of pollutants with living organisms. Damage to certain groups of organisms arouses more concern than others," Harrison (1999, p.333). After risk assessment, immediate action has to be taken to minimise further spreading of Atrazine. Altrazine could be separated from ground water by bioremediation. In-Situ and Slurry Phase (ex-situ) bioremediation is one of the best methods to be used for contaminated soil and groundwater. This could also be done by using bioaugmentation. "The ability of our mixed culture to mineralize atrazine in the soil environment indicates its possible use for bioremediation of contaminated soils, without production of persistent atrazine metabolites" http://www3.interscience.wiley.com/cgi-bin/fulltext/7163/PDFSTART The initial step of course is plugging further leakage and separating uncontaminated water bodies from the contaminated ones. As the river is involved in contamination, this could be an arduous task. It has been established that mixed microbial culture would be of great value in mineralizing concentrations of altrazine. Bioremediation is one of the main solutions to clean the soil and water contaminated by pesticides like altrazine by adapting the culture system. The system can mineralize altrazine in both environments, though the percentage of water degradation is more than soil degradation4. This system could be leaving the microbial population with a fair amount of atrazine, a fact that cannot be avoided. "Organic matter in water is of environmental importance for several reasons. For one thing, particular compounds may be toxic in varying degrees to living organisms, including humans. Polyaromatic hydrocarbons, polychlorinated biphenyls, and dioxins are all well-known, and have received considerable publicity and study because of their metabolic products can also be carried into water," Duffy (2000, p. 242). The method above is considered now as one of the less time consuming and definitely less elaborate methods of cleansing and disbursing. There are many methods and they are constantly upgraded by further research in all countries. "However, analytical techniques for persistent organic pollutants are becoming more rapid and less expensive and will thus provide more data for use in predictive models," Harrison (2000, p.375). BIBLIOGRAPHY: 1. Harrison, Roy M. (2000), Pollution: causes, effects and Control, 4th edn., Royal Society of Chemistry, Cambridge. 2. Harrison, Roy M. (1999), Understanding Our Environment, 3rd edn., Royal Society of Chemistry, Cambridge. 3. VanLoon, Gary W. and Duffy, Stephen J. (2000), Environmental Chemistry, A Global Perspective, Oxford University Press. ONLINE SOURCES: 1. https://www.pall.com/pdf/hcp_hcp_dec_1993.pdf 2. http://www.imeche.org.uk/formulastudent/pdf/E85%20GASOLINE%20V2%20(june%2006)1.pdf 3. http://www-1.llnl.gov/IPandC/technology/profile/environment/DynamicUndergroundStripping/index.php 4. http://www-1.llnl.gov/IPandC/technology/profile/environment/DynamicUndergroundStripping/index.php 5. http://www.waterencyclopedia.com/Oc-Po/Pollution-of-Groundwater.html 6. http://www.waterencyclopedia.com/Oc-Po/Pollution-of-Groundwater.html 7. http://www3.interscience.wiley.com/cgi-bin/fulltext/7163/PDFSTART 8. Read More

 

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