Source Identification/Apportionment And Transfer Route Of Typical Heavy Metal In An Industrial Area

The heavy metal pollution in environment has posed great threat to agro-food products safety andhuman health. In order to control heavy metal pollution, guarantee agro-food products safety and reducethe hazard probability of human health, source identification/apportionment and transfer route ofheavy metal is of great significance. With a case study in an industrial area in Shaanxi Province, China,the heavy metal pollution source, as well as transfer route and the exposure pathway of local residents inenvironment-agro-food-human body system were identified and apportioned. Based on this research,the thesis tries:(1) to explore the law of transfer route of heavy metal inenvironment-agro-food-human body system;(2) to pave the way for heavy metal pollution sourceidentifying and apportioning of the environment-agro-food-human body system; and (3) to providetechnology support for controlling heavy metal pollution in the environment and agro-foods.Biomarker, agro-food products, soil, house dust and atmospheric deposit samples were collected inthe industrial area in northwestern China to analyze heavy metal (Pb, Cd, Zn, Cu and Cr) concentrationsand lead isotope compositions by microwave digest-inductively coupled plasma mass spectrometry(ICP-MS) method. Health risk of local residents in different exposure pathway in object area wasassessed under the guide of exposure model of United States of Environment Protection Agency(USEPA). Based on the result of health risk, the main exposure pathway and most hazardous element oflocal residents were identified. Then, the contribution rate of main pollution source to human body, aswell as transfer route of the most hazardous element, were identified and apportioned by GeographicInformation System (GIS) and lead isotope fingerprint technique. Finally, the transfer route of heavymetal in the environment-human body system was identified.The main conclusions were as follows:(1) Agro-food products, soil, house dust, and atmospheric deposits were all polluted by Pb, Cd, Zn,Cu and Cr in different levels. The exceeding rate of heavy metal in biomarkers (especially scalp hairand finger nail) of local residents proved that heavy metal pollution had brought adverse effects onhuman health.(2) Heavy metal in human body from the industrial area was mainly from agro-food products andhouse dust. Pb in wheat kernel was mainly from atmospheric deposit. Pb in atmospheric deposit wasmainly from Pb-Zn smelting and coal combustion in the local area.(3) The total health risk of local resident exposure to Pb, Cd, Zn, Cu, Cr through dietary pathwayand house dust-human body pathway were beyond the accepted level. Between the two pathways,health risk through dietary one was higher than that of house dust-human body pathway in terms ofTarget Hazard Quotient (THQ). THQ of Pb was higher than that of Cd, Zn, Cu, and Cr. Wheat, as astaple food of local residents, was also the main Pb contributor to human body.(4) Considering dietary pathway exclusively, the main transfer route of Pb from environment tohuman body was atmospheric deposit-wheat-human body route in the environment-agro-food products-human body system. The soil-wheat-human body route was secondary route. Therefore,the transfer of Pb through environment-wheat-human body route should be paid great attention.(5) The effective way to reduce health risk of local residents was to cut down the intake ofagro-food produced local area, as well as reduce the touching frequency of house dust. The effectiveway to control Pb pollution in wheat kernel should start with controlling Pb pollution of atmosphericaerosol. The effective way to control atmospheric aerosol pollution was to reduce the emission of Pb-Znsmelting and coal combustion.Innovative point of this research: The transfer trajectory of heavy metal in theenvironment-agro-food-human body system had been studied systematically. Based on riskassessment,3S and lead isotope fingerprint technique, the contribution rate of Pb pollution source tomedia in environment-wheat-human body system were identified and apportioned. Then the transferroute and law of Pb in the environment-wheat-human body system were effectively explained.