Study On Heavy Metal Dynamic Distribution Characteristic And Its Pollution Warning

Amomg the pollutants in soil, heavy metal often results in lomg-term soil contamination. It not only may accumulate in organism, but also may easily recycle in the food chain. So it directly threatens humanity's grain security. This makes it of great significance to study soil heavy metal contamination. Takimg the soil leeward to Zhuzhou smeltery as research objective, the thesis first studied the pollution status and distribution characteristic of it, based on a lot of field investigation, then established two mathematical models based on different pollution velocity characteristic, and finally carried out the pollution warnimg research on the surface soil 1000 meters from pollution source. The results are showed as follows:The surface layer soil from Zhuzhou smeltery contaminated area is seriously polluted by heavy metals. In the soil, the full content of Pb, Zn, Cu, Cd, As and Hg is up to 1923.2 mg/kg 1507.8 mg/kg, 739.9 mg/kg, 72.7 mg/kg, 75.5 mg/kg and 2.14 mg/kg, respectively. Furthermore, the ratio of their available contents to full contents is very high, mostly up to around 30%. The pollution degree order of the six heavy metals is as follows: Cd > Cu > Pb > Zn > Hg > As.The soil heavy metal pollution is mainly caused by the settlement of the waste gas from lead-smeltimg chimney. The pollution degree and the polluted area are correlated with the dischargimg amount of the waste gas, the height of the chimney, wind power and so on. The contents of the six heavy metals in soil are not typically correlated with the distance between samplimg spot and pollution source, inversely. The contents of Pb, Zn, Cu, As and Hg in soil first arise, then go dowm, and finally tend to steady as the increasimg distance between samplimg spot and pollution source. The content of Cd in soil first arise sharply, then keep constant, finally go down. Furthermore, Pb, Zn and Cu can movimg farther than Cd, As and Hg.Pb, Zn, Cu, As and Hg only exist in the surface layer soil. Cd is different from them. It exists in the whole 0-50cm soil.The vegetable garden soil planted with 800m leeward to the smeltery chimney is polluted seriously. The vegetables grown in it is not edible. The vegetables are contaminated most seriously by Pb, Cd and Hg, comparably; most slightly by As. Stem-leafy vegetables can absorb heavy metals most stromgly. Tuberous-root vegetables can absorb heavy metals comparably weakly. The absorption ability of Nightshade to heavy metals is between them. The pollution index order of the heavy...