The Pollution And Health Risk Assessment Of Heavy Metals In Agricultural Soils And Crops Around A Taolongs In Hunan Province

The pollution status and total concentration of soil heavy metals were analyzed in agricultural soils and crops around a tailing in Hunan Province, 45 soil samples and 34 vegetable samples were obtained and analyzed for Cu, Pb, Cd, Hg and As. The heavy metals from farmland soil and crops in these environmental and geochemistry landscape areas were sampled and investigated to evaluate the pollution of soil and heavy metals as well as analyzing the correlation between them. Based on the average content of heavy metals in the sample and using human health risk assessment model recommended, the authors calculated adult and children health risk probability derived form oral ingestion(soil, crops), skin contact(soil), respiratory pathway(soil). The main contents and results are as follows:(1)The average single factor pollution index of 45 soil samples in the study area of the heavy metal elements Cu?Pb?Cd?Hg and As were 0.96?1.24?4.01?0.84 and 1.38. The samples standard rate reached were 26.7 percent?75.6 percent?95.6 percent?20.0 percent and 37.8 percent, And the pollution degree was in the following order: Cd>As>Pb>Cu>Hg. where Cd was heavily polluted, As ? Pb were light pollution. The integrated pollution index of agricultural soils was 2.83, and it was moderately polluted by heavy metals.(2)Using the improved method of BCR researched Forms of soils heavy metals in study area and discussed its relevance. The results showed that the correlation of five heavy metals in soil were some differences between them.Overall, the five heavy metals among various forms of correlation was not significant, and it was less likely to come from the same sources, the combined pollution may be caused by multiple factors. Such as pesticides-fertilizers abused,sewage irrigation, atmospheric particles to settle, tailing leakage of heavy metals and other elements.(3)38 crop samples was contaminated Pb and Cd, Hg and As was substantially not contaminated.Sample lead exceeded the rate of up to 100%.30 leafy vegetable?brasserie crops Cd exceeded the rate of 63.3%, and 8 underground root crops Cd exceeded the rate of 75.0%. Pb and Cd were the main crops in the study area pollutants. The correlation between the soil and the cropper heavy metals was also analyzed in this thesis. The result showed there was no notable relation between heavy metals in crops and soils except Pb and Cd.Consequently, the heavy metals in the crops were not always from soil. The content of heavy metals of crops adsorbed from atmosphere in this soil pollution area. The specific ways further studies were needed to explore.(4)In four routes of exposure of non-cancer risk and cancer risk in study area for adults and children were exceed the recommended human by USEPA acceptable risk threshold. Wherein the non-cancer risk children were value 2.83, 2.4 times than the adult, and children were more sensitive to non-cancer risk indicate of the local environment. As was leading to excessive health risks locals main elements, and oral ingestion(soil, crops) were the main way the health risks caused by excessive local residents.