Читать книгу Environmental and Agricultural Microbiology - Группа авторов - Страница 48

The multiple applications of heavy metals in industrial, domestic, agricultural, medical, and technology sectors is the main reason for their wide spreading in environment [16]. Generally, the heavy metals exist all over the earth surface. The social contact to environment results anthropogenic activities like mining and smelting operation, industrial manufacture and application, and metal and metal containing compound application in domestic and agriculture field [17, 18]. Sometimes, natural incidence like volcanic eruptions on land as well as on the ocean beds are reported to be responsible for heavy metal pollution in soil and water bodies [16]. Industrial sources have a large contribution toward heavy metal pollution from activities including metal melting out in processing plants, coal flaming in power plants, incineration of petroleum products, nuclear power stations and high-tension lines, textiles, plastics, wood conservation, microelectronics, and paper processing plant [19, 20]. The wastage from livestock systems can disturb the micro- and macro-environment such as water, soil, and food chain [21]. The metals’ presence in water reduces their quality and causes human disease, even the essential metals at high concentration gives negative effect and toxicity [21]. The metals and metalloids are common pollutant in waste water [22]. Soil accumulate heavy metals and metalloids by production from quickly growing industrial areas, mine tailings, high metal waste disposal, leaded gasoline and paint, fertilizers applied in land, animal manures, sewage sludge, pesticides in agriculture, coal incineration deposits, petrochemical spillage, and atmospheric deposition [23]. Heavy metals enter to ecosystem and hence human through direct contact with contaminated soil, food chain, and drinking of contaminated ground water. It causes significant reduction in food quality by phytotoxicity, decrease the quality, and hence the fertility of land used for cultivation purpose affecting food safety and land occupation difficulties [23]. Metal ions combine with biological factors such as DNA and nuclear protein result in deterioration of DNA and conformational change which may indicates to variation of cell cycle, carcinogenesis, or apoptosis [16]. The nonessential heavy metals have direct or indirect negative effect on human from tissue level to organ system and from nucleic acid to physiology level.