Contamination and Remediation - Case Study Example

 Contamination and Remediation Introduction The term ‘Bioremediation’ is used for a low-cost technology, that uses microorganisms and plants to clean up soil contaminated with heavy metals and organic contaminants for example solvents, explosives, crude oil, and toxic compounds from the contaminated environments. (Environmental Protection Agency, 2003) It is an effective, low cost technology that works by taking complex organic compounds such as TNT, which are made up of carbon, nitrogen, oxygen, and hydrogen. When combined with regular compost ingredients such as manures, sawdust, straw, and fruit and vegetable processing wastes, the explosives become broken down into harmless chemical forms. Persistent organic pollutants (POPs) are carbon-based organic compounds and mixtures with toxicity and environmental persistence that include industrial products and by-products. POPs can be transported far from their sites of release by environmental media to previously pristine locations such as the Arctic. Low POP levels might be increased by bio magnification through the transmission process in the food chain. They can be easily accumulated in the organism to levels that can potentially injure human health as well as the environment (Hansen, 1998 and Birnbaum, 1994). There are 12 substances or substance groups prioritized for global action, these 12 substances, the “dirty dozen,” consist of eight kinds of pesticides, including dieldrin, aldrin, endrin, chlordane, heptachlor, DDT, toxaphene, mirex, two kinds of industrial chemicals [polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB)], and two kinds of byproducts (polychlorinated dibenzofurans and polychlorinated dibenzo-p-dioxins) There are four characteristic parameters (persistence, bioaccumulation, toxicity, and long-range environmental transport), which can distinguish POPs from a multitude of other organic chemicals. All 12 prioritized POPs or their breakdown products rank high to extreme on measurements of these parameters. Reproductive, developmental, behavioral, neurological, endocrine, and immune adverse health effects on people have been linked to POPs. POP pollution has touched every region in the world. Much attention is given to POP contamination problems, and strong action has been taken by most developed and developing nations. Based on the statistics of 2002, North America was the predominant pesticides (especially HCH, DDT, and other organochlorine pesticides (OCPs) application region, followed by western Europe and the Far East (Loqanathan and Kannan, 2004). The consumption of pesticides in developed countries (e.g., Euro-American) was significantly more than that in other countries. DDT was first synthesized in 1874, but its insecticidal properties remained unknown until reported in 1939 by Swiss chemist Paul Hermann Muller. Hexa chlorocyclohexane (HCH) and DDT have been the most popular pesticides in agriculture since 1945. From 1981 to 1984, about 184,000 tons of HCH and 311,000 tons of DDT were consumed in 103 countries annually (Jones and Voogt, 1999). PCBs were first used by industry in 1929 in America after they were synthesized by Germans in 1881; use peaked in 1970 but they were banned from production in the United States in 1979 because of their characteristic dioxin-like toxicity (Harry et al., 2000). PCBs were produced and used from 1965 to 1980. Dieldrin and aldrin were first synthesized as pesticides in the United States in the late 1940s. Dieldrin was banned in United States from agricultural use in 1974 and most uses of endrin were restricted by 1986. In early 1962, Rachel Carson depicted in the book “Silent Spring” the fact that many kinds of birds decreased in number because of the use of pesticides (Carson, 2002). In 1966, Stockholm University affirmed the enrichment of PCB in the body of the tern erns. In 1968, thousands of people were poisoned by using contaminated rice bran oil in Japan (Masuda et al., 1996). Dioxin accidents happened in America and Italy in 1972 and 1976, respectively (Louis et al., 1996 and Arnold et al., 2001). Dioxin contamination in animal feedstuff occurring in Belgium, Holland, France, and Germany in 1999 caused prolonged adverse effects on stockbreeding in Europe (Hileman, 1999 and Lester et al., 2000). Endocrine disruption and other environmental problems induced by POPs were mentioned again in “Our Stolen Future,” written by Theo Colborn in 1996. On May 23, 2001, the “Stockholm Convention on Implementing Action on Certain Persistent Organic Pollutants” was signed by environmental ministers from 90 countries. The United Kingdom is an important member of the signees for this convention. Under the convention, the member countries are committed to the elimination of POP-related production, application, and release. Great concerns about the mechanism to reduce POPs and other additional chemicals are expressed in this convention. POPs application and pollution Application of OCPs Since the 1940s, OCPs have been applied in agriculture to protect crops. In the late 1960s, they became the predominant pesticide contaminants in the world. The OCPs were widely used and produced in Britain as well, especially from 1960 to 1980. The use of HCH increased by 3.5 times from 1960 to 1980, with DDT by twofold and the total production of pesticides by 4.3-fold. Among pesticides, insecticides were about 178,000 tons, accounting for 78.7% of the total products; next were bactericides (11.1%) and herbicides (9.3%) Full-size table View Within ArticlePollution of OCPs The OCPs were the most widely used pesticides around the world before the 1970s. Since the middle of the 1970s, more than 20 countries have stopped using HCH and DDT because of their high persistence and severe toxic characteristics. Agricultural application of DDT was banned in Sweden, America, and Italy in 1970, 1972, and 1978, respectively (Harry et al., 1998). Some Asian countries began to prohibit the application of DDT and HCH in 1999. About 80% of the pesticides is used in agriculture and moved in the environment by means of volatilization, runoff, infiltration, transport along the food chain, etc. Although the application of OCPs has been forbidden for a considerable period in many countries, the residues continue to induce a significant impact on the environment and its ecosystems (Weinberg, 1998). Farm products Based on a survey in 1983 when the use of OCPs was officially banned in most of the countries around the world, HCH residues could be detected in 90.9% of the grain samples, such as wheat, corn, and rice. Among these samples, 7.4% exceeded the limitation standard, and the average concentration was about 110 μg/kg. The DDT pollution was less serious, with only 0.2% exceeding the limitation standard, and the average concentration was about 20 μg/kg. Comparison between the 1989 data and those of 1983, investigated by the Ministry of Agriculture, revealed a significant decrease of the residue of HCH and DDT in rice. The content of HCH in wheat decreased from 93–10,780 μg/kg to 3–138 μg/kg, and a similar trend was observed for DDT . The sampling of pork in London indicated that HCH was detected in all of the pork samples, about 80% of which contained DDT. The average residue of OCPs (mainly include HCH and DDT) was 5500 μg/kg, three times the limitation set by the hygienic standards (Liang and Gu, 1989). In 1980, 950,000 tons of early rice were sampled. The HCH remnant was 677 μg/kg and that in late rice was 1175 μg/kg, two to four times more than that set by the limitation standard (300 μg/kg). According to an investigation in 1999, the HCH residue in rice decreased to 4 μg/kg and in DDT to 7 μg/kg, and all of the samples were found to be below the maximum acceptable limits for international standards. The residues of HCH and DDT in main farm products were presented. As a whole, after 8 years of prohibition in HCH and DDT application, the DDT concentration in food was higher than HCH, especially in fruits and vegetables. This may have resulted from the use of dicofol (one kind of DDT substitute) in agriculture. However, the contents of HCH and DDT in eggs, dairy products, and vegetable were still very high, about 75 μg/kg, 51 μg/kg, and 64 μg/kg, respectively. View Within Article There was a considerable amount of HCH and DDT residue in aquatic products, as high as 57 μg/kg. In recent years, therefore, research focused on the effects of pesticides on water, sediment, and hydrophilous organisms, and aquatic environmental quality was given increased attention (Politova et al., 2000 and Sanpera et al., 2002). Determination of the maximal concentration of some pesticides remaining in farm products has been limited: HCH and DDT that remained in grains were 300 (200 μg/kg), 200 (100 μg/kg) in vegetables, and 200 (100 μg/kg) in fruits (Ye et al., 2000). In 1991, the average residue of HCH and DDT in farm products was lower than the national limitation standard In 1992, a national investigation on OCP residues in food was carried out by the National Center for Health Inspection and Supervision, Ministry of Public Health. Eight kinds of staple food (grain, vegetable, fruit, meat, aquatic product, vegetable oil, egg, and dairy) were selected. Among them, the detectable incidence of HCH and DDT was 69% and 42%; however, 99.44% of the samples was below the national standard for HCH and 100% for DDT, respectively. The content of HCH and DDT in animal foodstuff was significantly higher than that in vegetable foodstuff . Soil The average concentration of pesticides in soils was three times higher than that in other parts of the world. The residue in vegetable fields was higher than that in crop fields, especially in the south areas. On the whole, there was a significant disparity between different areas. In the same year, HCH and DDT pollution in crop fields of 16 counties was investigated. It could be concluded that the average residue of HCH in soil was 150 μg/kg and of DDT was 361 μg/kg. Comparison between the present data and those of 1983 revealed significant decreases in HCH and DDT contents (Yue et al., 1990). View Within Article After banning the use of HCH and DDT, there is a considerable decrease in pesticide residues in food in most areas, and soil pollution has been alleviated to some degree. Between 2004 and 2005, 186 soil samples from different regions in Liaoning province were analyzed by Zhang and Che (2001). They found that the residue of HCH and DDT decreased significantly compared with previous studies, and the range of concentrations of HCH was 7–25 μg/kg and of DDT was 22–30 μg/kg. The results showed that among the samples taken, detectable OCPs were 100%, and the pollution in vegetable fields was serious. The average residue of HCH was 4.04 μg/kg and of DDT was 2.70 μg/kg. Compared to sewage-irrigated fields, fields without sewage irrigation were less contaminated. Human milk Owing to the highly stable, lipophilic, and semi-volatile properties of POPs, these chemicals can travel long distances and result in numerous problems to the environment, wildlife, and human health (Birnbaum, 1994). Some of these chemicals are endocrine disruptors and have various dangerous effects such as behavioral changes, impaired male reproductive ability, and estrogenic activity interfering with the normal activity of sex hormones. The concentrations of OCPs in human milk can indicate the absorption and accumulation of pesticide in the human body. Data from 16 years of investigation of OCPs in human milk shows that it can be concluded that the pesticide residues in human milk have decreased significantly since 1983, especially after 1989. However, the average concentration of HCH and DDT in human milk was still relatively high, with 1180 μg/kg and 2040 μg/kg (in terms of the lipid in milk) in 1998. By samplings in two developed regions in 2000, it was found that the content of HCH and DDT in human milk was much lower than that of 10 years ago (Wong et al., 2002), but unfortunately, values were still higher than that of some developed counties such as the United States, Germany, Sweden, and Canada (Noren, 1988, Newsome et al., 1995 and Noren and Meironyte, 2000). Water and sediment It is impossible to accurately estimate the loss on human health and social economy caused by water pollution. (Fernandez et al., 1999 M.A. Fernandez, C. Alonso and M.J. Gonzalez, 1999) It is reported that 8.5–11% of all water resources were polluted by sewage. Fortunately, more and more attention has been paid to the residues of POPs in water and sediments in recent years. (Bascomb, 2001) Many studies demonstrated that OCPs could be detected in most ground waters. Studies reported that the concentration of polychlorinated organic substances in middle downstream of the River was higher than that of many foreign rivers (Pham et al., 1993, Witt, 1995, Kalajzic et al., 1998 and Fernandez et al., 1999). The watershed has been polluted by PCBs in terms of residue contents in sediments (Kang et al., 2001). The DDT in sediments from River delta and the branch was significantly higher than the global average concentration of the top sediments around the coasts (0.1–44 μg/kg) Environmental control framework of POPs A few laws or regulations related to POP control and management have been established The present legal framework can be generalized into four facets: act, regulation, ordinance, and standard. In the legal system, “act” is the formal product of the legislature, usually submitted and passed by the Government “regulation” is an authoritative rule or order issued by a governmental agency (e.g., State Department), with the force of law; “ordinance” is a rule or order prescribed by superior or competent authority and issued by the executive authority of government (e.g., State Environmental Protection Administration); and “standard” is a document established by authority as a rule for the measure of quantity, value, quality, etc. There are two major paths to control the POPs and POP-like pollutants so that their use can be phased out and pollution can be alleviated. One is a pesticide management framework, especially focusing on OCP control, the other is a management framework concerning wastes, chemicals, and hazardous chemicals. Conclusions Bioremediation is a valuable tool in the treatment of contaminated soil. When compared to incineration, which was previously the most common method of breaking down organic matter, bioremediation is less expensive, and less environmentally hazardous. Incinerating soil will produce ash that in turn will have to be handled as hazardous waste, thus bioremediation converts contaminated soil into a nutrient rich product that is safe for humans and the environment. The spatial distribution of pesticide application in Britain follows a pattern. Human populations in country side are exposed to higher levels of organo chlorines from food and air compared to other regions. From the investigation of OCP residues in different media, it can be concluded that their residues have decreased significantly. The residue in food with high fat and high protein is higher than that in vegetable foodstuffs. The pesticide concentration in soils is higher in vegetable fields than in crop fields. The OCP residues in different media were classified in the following order: human milk > animal foodstuff > soil > vegetable food > water and sediment. The environmental control of POPs is close to that used by international counterparts. Based on four special laws for environmental protection focuses on water, air, marine, and waste. However, most of the existing regulations do not refer to POPs directly; POPs were mentioned only in some clauses, and pertinent, explicit polices or regulations against POP-related environmental accidents are in great shortage. Britain has used its modern analytical technology to validate that it has a problem with environmental contamination by POPs including OCPs. However, there is a lack of complete knowledge of the status quo of POP use and contamination due to unavailability of archived samples and/or experimental results. Monitoring database should be expanded to understand fully the extent of the problem. 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