Intergrated Fuzzy Approach For Health Risk Assessment Of Groundwater Contamination Of Heavy Metal

Uncertainties exist in the process of groundwater environmental health riskassessment. The urgent affair is how to dealth with the uncertainties in the assessmentprocess to make sure the result of the assessment is more scientifical. In the traditionassessment process, we always use the average concentration of the contamination.But the concentration of the contamination in the groundwater is variational alongwith the time, therefor only use the average concentration of the contamination toassessment the health risk may ignored the mutative characteristic of the concentrationin a certain extent, consequently the uncertainties of the assessment process. Thisstudy made use of the interval numbers and the fuzzy theory to reduce theuncertainties in the assessment process. Using the interval numbers to express theconcentration of the contaminations, the maximum and the minimum of intervalnumbers are the highist and the lowest value of the monitoring value in the whole year,the interval concertainty is not a number but a range, which include more inrormation,accordingly can reduce the uncertainties of the assessment process compareing to usethe avarage concertainty.Evaluation standard is the importance basis in the health risk assessment.Presently the frequently adoptive evaluation standards are the standards of US EPAand the ICRC. The EPA take for the10-4level is the safe level, but the ICRI think therisk must be less than10-5. Distinction of The two ecaluation standards is very big, sowe can not use a comparatively reasonable evaluation standard to evaluation the healthrisk. This study we use the fuzzy theory describe the risk evaluation standard, fuzzytheory is fixing quantify of those factors which is difficulty to make clear theboundary and difficult to mensurable and the fuzzy theory also is a integrateevaluation method. In this study, the experts consultation method based oninformation was used to eatablish the evaluation standard system. In the system, therisk were classified as six levels of “low”,“low-medium”,“medium”,“medium-high”,“high” and “very-high”, following: C₁={Ⅰ/low}; C₂={Ⅱ/low-medium}; C₃={Ⅲ/medium}; C₄={Ⅳ/medium-high}; C₅={Ⅴ/high}; C₆={Ⅵ/very-high}.On the basis of the interval numbers and fuzzy theory, an integrated fuzzy modelfor groundwater environmental health risk assessment was developed，and the modelwas used to assess the health risk for the heavy metal in the groundwater of Changsha-Zhuzhou-Xiangtan from2004to2006.We can obtain from the assessment conclusion that the integrated fuzzy model forgroundwater environmental health risk assessment can reduce the uncertainty in theassessment process in a certain extent. Compareing from the confirm assessmentmodel, the assessment conclusion of the integrated fuzzy model is more all-aroundand reasonable to reflect the truth of the groundwater environmental health risk level.