Ecological Risk Assessment And Health Risk Assessment Of Soil Heavy Metals In Xi'an Original Irrigation Area

This study focused on the original irrigated farmland soil in Xichaizhai Village on the northern outskirts of Xi'an City.The soil p H and soil particle size composition in the sewage irrigation area were measured,and the soil organic matter,available phosphorus,available nitrogen,and available potassium were determined.The content of six kinds of heavy metals in the soil of the sewage irrigation area was determined and analyzed.The status of heavy metal pollution in the soil of the sewage irrigation area was evaluated using the Nemerowo and the geological accumulation index method.At the same time,the ecological risk assessment and health risk assessment were conducted on the sewage irrigation area.Get the following conclusions.The average soil p H values in the sewage irrigation and clear irrigation areas were 8.83 and 8.45,respectively,and the soil was alkaline.The soil particle size in the sewage irrigation and irrigation areas was mainly composed of silt grains(accounting for more than 60% of the soil particle size),and the soil texture.The content of organic matter,available phosphorus,available potassium,and available nitrogen in soils of sewage irrigation areas are significantly different from those in clear irrigation areas(P<0.05),and it exceeds that in the soil of clear irrigation areas,and soil nutrients in the sewage irrigation areas are at a rich level(see Tables 3-2,3-3)verify that N,P,and K in the sewage after long-term sewage irrigation accumulate in the soil,thereby increasing soil fertility.The determination and analysis of soil heavy metal content in sewage irrigation and clear irrigation areas resulted in the following conclusions.Compared with the soil background value in Xi'an,the six soil heavy metals in the sewage irrigation area were enriched to varying degrees.Cu and Zn in the soil of the irrigation areas Pb and Cr have a certain degree of enrichment,while the contents of Cd and Ni do not exceed the soil background value.The analysis of the correlation between soil heavy metals in sewage irrigation indicated that soil heavy metals in sewage irrigation areas had similar sources,and long-term sewage irrigation resulted in the accumulation of heavy metals in the sewage irrigation soil.The Nemero pollution index indicates that heavy metal pollution in the surface soil of the sewage irrigation area has reached moderate pollution level,in which metal Cd is heavily polluted,and heavy metal pollution in the surface soil of the irrigation area is mildly polluted;the geological cumulative pollution index indicates that soil heavy metal pollution in the sewage irrigation area reaches With mild pollution levels,the soil in clear irrigation areas is in a safe state.The ecological risk assessment of the irrigated area using the ecological hazard index method showed that the comprehensive ecological risk index(RI)of the irrigated area was 135.28,which was at a slight level(RI<150),but the metal Cd(Er=190.2)was a strong risk level,and the rest Five heavy metal elements are at a slight risk level.Overall,the potential ecological damage in the study area is not serious,but the ecological harm caused by metal Cd needs to be highly valued.The health risk assessment conducted on the irrigated area indicated that soil heavy metals in the irrigated area have non-carcinogenic health risks and there are also carcinogenic health risks.The heavy metals Cr and Pb are risk sources for non-carcinogenic health risks.The heavy metals Cr and Ni are carcinogenic to health.Risk source of risk.At the same time,the degree of risk of heavy metals under different exposure pathways is also different.The most harmful route of exposure to humans is oral intake.