Risk Assessment Of Vegetable Plot Soil Heavy Metals In Jinan

The safety of the soil environment is the basis of vegetable quality and safety, which isalso the core issue of agricultural ecological environment security. Vegetables areindispensable food of human beings in daily life, it has inevitably become one of theimportant ways that heavy metals enters the body. With the continuous improvement of livingstandards, the people for the quantity and quality of vegetables put forward higherrequirements. Therefore, a comprehensive understanding of vegetable plot heavy metalpollution and research on different vegetables to absorb and accumulate heavy metal haveimportant practical significance for optimizing the planting structure and ensuring the safetyof vegetable in Jinan.In this study,60soil samples and56vegetable samples of10sampling points wereselected in major vegetable producing locations in Jinan. The distribution scope of samplinglocations includes Shanghe County, Jiyang County, Zhangqiu City, Licheng District,Changqing District and Pingyin County. Soil samples were collected at0-20cm and20-40cmlayers which involved3types of soil: alluvial soil, cinnamon soil and brown soil, andvegetable samples involved garlic, cucumbers, lettuce, onions, spinach, potatoes. Aquaregia-perchloric acid digestion method and nitrate-perchloric acid digestion method were usedto determine the content of lead, cadmium, chromium, copper and zinc in soil and vegetablesamples. The available content of heavy metal in soil was determined by TCLP and thecontent of the chemical state of heavy metal in soil was analyzed by BCR continuousextraction method. Then the distribution pattern of heavy metal in the vegetable soil wasdiscussed in Jinan in different areas, different soil depths and different soil types, and theevaluation of cumulative risk, contamination risk, ecological risk and health risk of heavymetal contamination of the vegetable soil were analyzed in Jinan. Meanwhile, the biologicalavailability of heavy metal of the vegetable soil were analyzed which included the ability thatdifferent kinds of vegetables accumulate different kinds of heavy metals, and the correlationthat the content of heavy metal in vegetables with the total content, available content andchemical state content in soil. Conclusions are as follows:(1) There were significant differences between the content of heavy metal in differentsampling points, different soil depths, different soil types and different chemical states. Thecontent of Lead and chromium in soil did not exceed the soil background values of Jinan City, while the content of cadmium, copper and zinc are higher than the background values indifferent degrees.(2) With single pollution index method and comprehensive pollution index method, andaccording to the second evaluation level of heavy metal contamination of soil to state thatlead, chromium, copper and zinc did not exceed the standard, belonging to the clean state,while cadmium exceeded the standard seriously; according to the sanitation standard ofvegetables and food to state that in addition to lead of garlic and cadmium of potatoesexceeded the standard of heavy metal, other vegetables did not exceed the standard,vegetables of Jinan City almost were unpolluted and could be ate safely.(3) According to the comparative analysis of the content of soil heavy metal extracted byTCLP and international standard values, in addition to the lead in soil is ecological risk, otherheavy metals such as chromium, copper and zinc are risk-free, and cadmium was not checkedout.(4) DI values that daily intake of lead, cadmium, chromium, copper and zinc aboutresidents of Jinan City by eating vegetables did not exceed the allowed ADI values that dailyintake of heavy metal about human beings, analyzing THQ values of lead, cadmium,chromium, copper and zinc that enter the human body by eating vegetables with exposedcontacts, found that in addition to THQ value of cadmium content of spinach exceeded one,while THQ values of heavy metals of other vegetables were less than one, explaining that itwas not obvious for the effect of residents’ health of Jinan about intake of heavy metal byeating vegetables.(5) It was found that the order of accumulation ability of vegetables for lead in soil wasgarlic, spinach, potatoes, onion, lettuce, cucumber by using the enrichment coefficient method;the order that accumulation ability on cadmium was spinach, potatoes, onion, lettuce, garlic,cucumber; the order that accumulation ability on chromium was potatoes, garlic, spinachonion, lettuce, cucumber; the order that accumulation ability on copper was potatoes,garlic,spinach, lettuce, onion, cucumber; the order that accumulation ability on zinc was spinach,potatoes, garlic, lettuce, onion cucumber.(6) The relevance of the total content of heavy metal, available content and chemicalstate content were discussed by grey incidence degree analysis in vegetables and soil. Theresults showed that the correlation that between lead of garlic, onions and lettuce and acidsoluble state was the biggest; the correlation that between lead of cucumbers and potatoes andavailable content was the biggest; the correlation that between lead of spinach and oxidationstate was the biggest. The correlation between chromium of garlic and onions and oxidation state was the biggest; the correlation between chromium of cucumbers and acid soluble statewas the biggest; the correlation between chromium of spinach and total chromium was thebiggest; the correlation between chromium of lettuce and potatoes and available content wasthe biggest. The correlation between copper of garlic and lettuce and reduced state was thebiggest; the correlation between copper of cucumbers, spinach and onions and acid solublestate was the biggest; the correlation between copper of potatoes and available content wasthe biggest. The correlation between zinc of garlic and lettuce and reduced state was thebiggest; the correlation between zinc of cucumbers and onions and oxidation state was thebiggest; the correlation between zinc of spinach and total zinc was the biggest; the correlationbetween zinc of potatoes and available content was the biggest.