Tangshan Cadmium Anomaly Source Tracking And Ecological Effects Evaluation

The program of "Hebei province agriculture geological investigation" carried on sampling test to farmland soil in Qin Tang district of Hebei province. According to the soil sample analysis result, the author divides Tangqin plain into four big districts and eleven geochemistry subranges after analyzing factors like geology background, soil, landform, hydrology .etc of Tang Qin plain synthetically. The author compares the element content of both surface layer and deep layer soil and studies the content distribution characteristic of Cd using the statistical method. According to the findings, the author thinks that geochemistry background of Tang Qin district is mainly under control of the regional geology background. The fact that some elements content in surface layer soil is remarkably higher than what in deep layer soil shows the human influence.The author delimit the cadmium unusual area scope through sample analysis data contrast between deep and shallow layer soil in this region and fractal theory to determine cadmium geochemical background and the unusual lower limit of this local., In this region, Cd shows characteristics as follow: enrichment area is as big as 180 km2; content difference between shallow and deep soil is disparate and the cadmium content in the shallow layer soil is 1.6 times than the deep soil; kisses with the elements such as lead, zinc is good while bad with element such as nitrogen, phosphorus.With Cd content analysis of irrigate water sample, the irrigation ditch bottom putty, crops, and chemical fertilizer sample, the author makes preliminary judgment on Cd anomaly source. The findings show that Cd originates from exterior artificial source. The main factor for pollution is the long-term use of cadmium contained sewage to irrigate farmland and phosphate fertilizer with high cadmium content. According to the sample test data, cadmium high content in local phosphate fertilizer achieves to 33mg/kg. Cd input research area every year from irrigation water and chemical fertilizer may reach 0.05mg.The author makes ecological environment appraisal with methods of environment risk exponent and single factor exponent. The appraisal result shows that Cd is the only latent heavy metal pollutant while the environment condition is good at present. But partial areas have already had preliminary pollution. The local biology grows have not yet come under the influence, and the quantity of cadmium gathers at the paddy rice root to be more while the stem department and the fruit also have part of Cd gathers. The author make division on cadmium pollution threat degree of local cadmium anomaly area soil using intimate data method according to distribution condition of local Cd in order to direct key pollution area and make better monitor to local ecological environment change. The result shows that the west part is easier to be polluted than the eastern part in this area.