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Ecosystems and Human Health - Chapter 3

Nước và ô nhiễm đất Ba thành phần của sinh quyển có thể phục vụ như là chìm độc tính: đất, không khí, và nước. Đây là những thường xem xét một cách riêng rẽ, nhưng nó phải được rõ ràng rằng chúng hoạt động như một hệ thống tích hợp. Như vậy, mưa sẽ chuyển chất độc đất và nước, bốc hơi bề mặt nước và đất như bụi trong không khí có thể di chuyển chúng trở lại vào không khí nơi họ có thể được vận chuyển qua khoảng cách rất xa theo gió. Hơn nữa, dòng chảy. | chapter three Water and soil pollution Hang your clothes on a hickory limb but don t go near the water Introduction Three components of the biosphere can serve as toxicological sinks soil air and water. These are often considered separately but it should be obvious that they function as an integrated system. Thus rain will transfer toxicants to soil and water evaporated surface water and soil as airborne dust can move them back into the air where they may be transported over great distances by wind. Moreover runoff from the soil sewage and industrial discharge are the main sources of water contamination. Seepage into deep aquifers from soil and surface water can also occur and freshwater reservoirs are connected to the sea by rivers and estuaries. Thus while this chapter tends to focus on water both as an essential resource for human consumption and as marine and aquatic ecosystems this should not detract from an understanding of the integrated nature of the biosphere. Soil often becomes the repository for our most toxic waste products and the consequences of this are touched upon in this chapter. Chemicals may also enter foodstuffs grown in contaminated soil and the spraying of crops with pesticides has been a matter of considerable public concern. Water pollution is of considerable importance for several reasons. The most obvious is the possibility that xenobiotics may enter drinking water supplies and constitute a direct threat to human health. The contamination of fish and shellfish obtained both from the sea marine organisms and freshwater lakes and rivers aquatic organisms may further threaten human health when these foods are consumed. Larger and older fish often have higher levels of lipid-soluble toxicants but younger ones have higher metabolic rates and can concentrate them more quickly. Many toxicants are taken up initially by unicellular organisms that serve as a food source for larger but still microscopic ones which in turn are food for bigger ones .