Assessment Model For Heavy Metal Pollution In Water Source Based On Cloud Model And Case Study

In recent years, the frequent heavy metal pollution incidents of the water source have caused serious pollution to the source of drinking water quality and the daily consumption water of nearby residents is polluted. Yuancuo is located at the downstream of Minjiang River in Fuzhou, which two water intakes(West and North) and daily water consumption of 75% from here. Especially the rapid development of urbanization lead to the largely increased demand for water, the quality situation of water and spatial distribution of the heavy metals are important for ensuring the safety of drinking water. Based on the known data and the field survey, the paper take the water between Puli drainage pump station and the Hongshan Bridge as a case, select seven heavy metals as an evaluation index (Fe, Cu, Pb, As, Mn, Cr, Cd), set the sampling transects and analysis, which lasted a year. The health risk assessment model is constructed based on cloud model, which is used to assess the harm of heavy metal pollutants through drinking water. Combined with the spatial analysis of arcgis, the paper describe the spatial distribution of heavy metals and a preliminary analysis of its source. The main achievements are as follows:(1)Analyzing the pollutant date in dry, rainy and intermediate seasons, the results showed that seven heavy metal ions can reach the Class III water requirements according to the water function zoning of the region (except for Fe), the concentrated of Fe is exceed and the reason might be the downstream high concentration of iron ions traced back to the study area by the tide effect.(2)According to the arcgis spatial analysis techniques, using of the interpolation method of inversed distance weighted in arcmap, the spatial distribution map of heavy metals were created. Compared to the usual routine sampling points which based on statistical analysis, the evaluation results is more intuitive and easy to analyze the spatial distribution.(3)The deterministic health risk assessment indicated that the carcinogenic risk of heavy metal is far greater than the non carcinogenic risk, the health risk of adults is higher than children by the way of drinking water in the study area. The overall individual annual health risks of adults in the drinking water sources all exceeded the standards recommended by ICRP(5E-05 a-1), but lower than the standards recommended by USEPA(E-04 a-1). The risk of children all exceeded the standards recommended by USEPA, owing to over high mass concentration of Cr and As.(4) Combined with the theory of uncertainty evaluation results, the evaluation results based on interval number theory show that the health risk level of adult and children are grade IV, the evaluation results based on cloud model indicate that adult risks of heavy metals are grade III and children risk value basically belongs to grade Ⅳ in the water source, which describe children have greater harm than adults. Comparing with the evaluation results of interval number theory, the evaluation result based on cloud model is true and reliable, indirectly verified the feasibility and applicability of the method.