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Arsenic is a chemical element with the symbol As and the atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is a notoriously toxic heavy metal. It occurs naturally in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry.
Environmental remediation is the cleanup of hazardous substances dealing with the removal, treatment and containment of pollution or contaminants from environmental media such as soil, groundwater, sediment. Remediation may be required by regulations before development of land revitalization projects. Developers who agree to voluntary cleanup may be offered incentives under state or municipal programs like New York State's Brownfield Cleanup Program. If remediation is done by removal the waste materials are simply transported off-site for disposal at another location. The waste material can also be contained by physical barriers like slurry walls. The use of slurry walls is well-established in the construction industry. The application of (low) pressure grouting, used to mitigate soil liquefaction risks in San Francisco and other earthquake zones, has achieved mixed results in field tests to create barriers, and site-specific results depend upon many variable conditions that can greatly impact outcomes.
Bioremediation broadly refers to any process wherein a biological system, living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc., in natural or artificial settings. The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment. In comparison to conventional physicochemical treatment methods bioremediation may offer advantages as it aims to be sustainable, eco-friendly, cheap, and scalable.
Phytoremediation technologies use living plants to clean up soil, air and water contaminated with hazardous contaminants. It is defined as "the use of green plants and the associated microorganisms, along with proper soil amendments and agronomic techniques to either contain, remove or render toxic environmental contaminants harmless". The term is an amalgam of the Greek phyto (plant) and Latin remedium. Although attractive for its cost, phytoremediation has not been demonstrated to redress any significant environmental challenge to the extent that contaminated space has been reclaimed.
Soil contamination, soil pollution, or land pollution as a part of land degradation is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical substance. The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapour from the contaminants, or from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting clean ups are time-consuming and expensive tasks, and require expertise in geology, hydrology, chemistry, computer modelling, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.
In the United States, an environmental site assessment is a report prepared for a real estate holding that identifies potential or existing environmental contamination liabilities. The analysis, often called an ESA, typically addresses both the underlying land as well as physical improvements to the property. A proportion of contaminated sites are "brownfield sites." In severe cases, brownfield sites may be added to the National Priorities List where they will be subject to the U.S. Environmental Protection Agency's Superfund program.
Contaminated land contains substances in or under the land that are definitively or potentially hazardous to health or the environment. These areas often have a long history of industrial production and industrial farming. Many sites may be affected by their former uses such as mining, industry, chemical and oil spills and waste disposal. Areas that were previously industrial areas, called brownfield sites, are higher risk areas.
Rhizofiltration is a form of phytoremediation that involves filtering contaminated groundwater, surface water and wastewater through a mass of roots to remove toxic substances or excess nutrients.
Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater is water present below the ground surface that saturates the pore space in the subsurface. Globally, between 25 per cent and 40 per cent of the world's drinking water is drawn from boreholes and dug wells. Groundwater is also used by farmers to irrigate crops and by industries to produce everyday goods. Most groundwater is clean, but groundwater can become polluted, or contaminated as a result of human activities or as a result of natural conditions.
Environmental monitoring is the processes and activities that are done to characterize and describe the state of the environment. It is used in the preparation of environmental impact assessments, and in many circumstances in which human activities may cause harmful effects on the natural environment. Monitoring strategies and programs are generally designed to establish the current status of an environment or to establish a baseline and trends in environmental parameters. The results of monitoring are usually reviewed, analyzed statistically, and published. A monitoring program is designed around the intended use of the data before monitoring starts.
The Del Amo Superfund Site is located in southern Los Angeles County between the cities of Torrance and Carson. It is a U.S. EPA Region 9 Superfund Site. The waste-disposal site of a rubber manufacturer is one of 94 Superfund Sites in California as of November 29, 2010.
In situ chemical oxidation (ISCO), a form of advanced oxidation process, is an environmental remediation technique used for soil and/or groundwater remediation to lower the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by introducing strong chemical oxidizers into the contaminated medium to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. The in situ in ISCO is just Latin for "in place", signifying that ISCO is a chemical oxidation reaction that occurs at the site of the contamination.
A permeable reactive barrier (PRB), also referred to as a permeable reactive treatment zone (PRTZ), is a developing technology that has been recognized as being a cost-effective technology for in situ groundwater remediation. PRBs are barriers which allow some—but not all—materials to pass through. One definition for PRBs is an in situ treatment zone that passively captures a plume of contaminants and removes or breaks down the contaminants, releasing uncontaminated water. The primary removal methods include: (1) sorption and precipitation, (2) chemical reaction, and (3) reactions involving biological mechanisms.
1,2,3-Trichloropropane (TCP) is an organic compound with the formula CHCl(CH2Cl)2. It is a colorless liquid that is used as a solvent and in other specialty applications.
Air sparging, also known as in situ air stripping and in situ volatilization is an in situ remediation technique, used for the treatment of saturated soils and groundwater contaminated by volatile organic compounds (VOCs) like petroleum hydrocarbons, a widespread problem for the ground water and soil health. Vapor extraction has become a very successful and practical method of VOC remediation. In saturated zone remediation, air sparging refers to the injection a hydrocarbon-free gaseous medium into the ground where contamination has been found. When it comes to situ air sparging it became an intricate phase process that was proven to be successful in Europe since the 1980s. Currently, there have been further developments into bettering the engineering design and process of air sparging.
Nanoremediation is the use of nanoparticles for environmental remediation. It is being explored to treat ground water, wastewater, soil, sediment, or other contaminated environmental materials. Nanoremediation is an emerging industry; by 2009, nanoremediation technologies had been documented in at least 44 cleanup sites around the world, predominantly in the United States. In Europe, nanoremediation is being investigated by the EC funded NanoRem Project. A report produced by the NanoRem consortium has identified around 70 nanoremediation projects worldwide at pilot or full scale. During nanoremediation, a nanoparticle agent must be brought into contact with the target contaminant under conditions that allow a detoxifying or immobilizing reaction. This process typically involves a pump-and-treat process or in situ application.
Groundwater pollution occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted constituent, contaminant, or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution. Groundwater pollution can occur from on-site sanitation systems, landfill leachate, effluent from wastewater treatment plants, leaking sewers, petrol filling stations, hydraulic fracturing (fracking) or from over application of fertilizers in agriculture. Pollution can also occur from naturally occurring contaminants, such as arsenic or fluoride. Using polluted groundwater causes hazards to public health through poisoning or the spread of disease.
The Horseshoe Road Complex Superfund Site in Sayreville, New Jersey is a 12 acres (4.9 ha) property located near the Raritan River. The industrial site has been out of operation since the early 1980s after a fire revealed 70 drums containing silver cyanide, ethyl acetate, and acetonitrile. The drums caught the attention of the Environmental Protection Agency (EPA) and by 1995 the Horseshoe Road Complex was on the National Priorities List. The site had three areas consisting of the Atlantic Development Corporation (ADC), Horseshoe Road Drum Dump, and Sayreville Pesticide Dump. The neighboring Atlantic Resources Corporation, the location for precious metal recovery, is addressed with the Horseshoe Road Complex (HRC) site due to the intermixing of chemical contamination. The on-site contamination is not an immediate threat to the surrounding community, although prolonged or repeated exposure to the site itself, will result in health effects. The HRC Superfund site is now in its final steps of cleanup in accordance to the EPA's plan.
The Chernobyl disaster remains the major and most detrimental nuclear catastrophe which completely altered the radioactive background of the Northern Hemisphere. It happened in April 1986 on the territory of the former Soviet Union. The catastrophe led to the increase of radiation in nearly one million times in some parts of Europe and North America compared to the pre-disaster state. Air, water, soils, vegetation and animals were contaminated to a varying degree. Apart from Ukraine and Belarus as the worst hit areas, adversely affected countries included Russia, Austria, Finland and Sweden. The full impact on the aquatic systems, including primarily adjacent valleys of Pripyat river and Dnieper river, are still unexplored.
Pollution in Korea has become diversified and serious due to rapid industrialization and urbanization since the 1960s. The causes of environmental pollution, both in South and North Korea, can be found in population growth, urban concentration, and industrial structure, similar to the rest of the world.
References
- ↑ Intervention values 2010 [ permanent dead link ]
- ↑ Annex 1, Table 1, Section 1
- ↑ Annex 1, Table 1, Section 2
- ↑ Annex 1, Table 1, Section 3
- ↑ Annex 1, Table 1, Section 4
- ↑ Annex 1, Table 1, Section 5
- ↑ Annex 1, Table 1, Section 6
- ↑ Annex 1, Table 1, Section 7