Migration And Health Risk Analysis Of Heavy Metal In Soilcrop Systems Of The Peri-urban Composite Pollution Areas

With rapid development of our country, various environmental issues have become the primary factors to limit economic development and harm to human health. Due to its unique lag and difficult recovery, heavy metal pollution to soil has become a hot topic to a lot of scholars, primarily because once the soil is polluted, it will trigger a series of knock-on effects: the impact on agricultural product quality and yield, surface and groundwater pollution caused by runoff, and even harm to human health through the food chain. Urban-rural fringe in Kaifeng eastern outskirts, as the link between urban and rural ties, integrates agriculture, industry, enterprise into a whole. However, in recent years, large amounts of irrigation has come from industrial wastewater for lack of water, and the famous sewage irrigation in this area is within the scope of the study. Therefore, with complex multi-threat, how pollution damages soil and human health, is the focus of this study.In order to fully understand the status of soil pollution, we collect soil on the surface in this research area. Based on the detection of target heavy metals(Zn, Cu, Cd, Pb) in the surface soil samples, we do statistical analysis on the distribution and abundance of target heavy metals in soil. Using the correlation coefficient method to analyze between the various elements, we find the correlation between elements has reached a very significant level, indicating the high possibility of these four heavy metal complex pollution to soil in this research area; then using the single factor pollution index and Nemerow comprehensive pollution index methods to evaluate on each element, we find the area has significant Cd pollution in the soil; and finally by means of inverse distance interpolation weight rights law, we analyze the four heavy metal spatial variability, and find these metals all have peak values on the fertilizer plant and Smelter fertilizer Riverside line, also a large area of high value, which shows heavy metal was influenced by human activities.Secondly, according to the results of surface soil space analysis, we has made a special selection of 23 representative samples, divided into different and typical zones, to do soil- wheat match collection. On the basis of chemical speciation of soil heavy metals on wheat root, we analyze on biological effectiveness of soil heavy metals in each area, and conclude that Cd has top biological activity and mobility among target heavy metals, which indicates that Cd has lowest stability but high bioavailability in the soil.At last, through the measurement analysis of heavy metals in different parts of the wheat samples, together with the heavy metal migration enrichment capability and correlation analysis in soil- wheat system, we find that different parts of wheat have different heavy metal enrichment capability, and heavy metal in different parts of wheat is correlated with that in root part of wheat. Then we evaluate the risk to human health caused by wheat grain dietary approach through health evaluation model proposed by EPA, and find that Cd is the most harmful element to health in this area.Nowadays, human requirements for food quality have gradually increased as environmental pollution. Therefore, the study of health risk caused by heavy metals in soil- wheat system under complex pollution, not only provides a basis for environmental pollution control areas but also has great significance on improving the agricultural product quality, ensuring the safety of human diet and promoting sustainable agriculture.