Tianjin Heavy Metals In Sewage Irrigated Soil Pollution Characteristics And Soluble Inorganic Salts On The Morphological And Biological Effects Of Cadmium In Experimental Research

One of the most important environmental questions is soil contamination. About 20 millions hm2 of cultivation were polluted by heavy metals in our country. Heavy metals absorbed by crops from polluted soil came into human body through food chain, and affected human health seriously. The paper is a part of the research on polluted soil.In this thesis, relative importance of heavy mentals pollutants were determined by the method of reformed AHP. Then heavy metals (Hydrargyrum, Cadmium, Plumbum, Zine, Arsenic, Chromium) pollution of soils and vegetables in sewage irrigating region of Tianjin were investigated and evaluated. The results were as follows: The soils in sewage irrigating region of Tianjin were polluted by Cd and Hg , Cd pollution was the most serious. Cadmium contents of vegetables were higher than the restricted standard, in which plant's growth were influenced. The heavy metals in part of seeds of paddy and vegetable were beyond the Standards of foodstuff, which influenced people's health.The main reason of serious soil heavy metals contamination was that the available form content of heavy metal in soil was very high. In order to explain this question, the experiment of the relation between dissolve inorganic salts and form content changes of Cadmium in soil was done. The measures are as follows : First, different densities of CdCl2 were added to the soil samples, then KCl, CaCl2, K2HPO4, KH2PO4, K2CO3 were added to the soil samples after some days. The form contents of Cadmium in the soil samples were measured by Tessier's way. The result of the experiment show: the available form contents of Cadmium in the soil samples were increased with increasement of the content of KCl, K2CO3 , when the density of CdCl2 (≤0. 8mg/kg) was same. When the content of CaCl2 , KH2PO4 increased ,the content of the available form content of Cadmium in soil decrease. The content of K2HPO4 don't influence the content of the available content of Cadmium in soil.The changes of the Cadmium content in soil and plant system were...