Characteristics Of Heavy Metals And Its Affecting Factors In Vegetable Fields In Jinan

The total amount of heavy metal in soils is the important indexes which candetermine the pollution levels and environmental capacity. The environmental impactsof various of heavy metals in soils is different，they can have effects on biologicaleffectiveness, toxicity, mobility and circle in the nature. At present, BCR continuousextraction method to evaluate the soil heavy metal toxicity and biological validity hadbeen widely applied. Analysis of the chemical speciation of heavy metals can reflectthe nature and sources of human activities on the soil heavy metal and its ecologicaltoxicity. The transformation of the chemical speciation of heavy metals to make soilheavy metals have different toxicity and environmental behavior.In this paper, the major vegetable producing locations in Jinan were studied. Thedistribution scope of sampling locations includes Shanghe, Jiyang, Zhangqiu, Licheng,Changqing and Pingyin. Continuous position sampling in the fields was used in thestudy. Soil and plant were analyzed in the laboratory. Total amount of soil heavy metal,effective state of soil heavy metal and vegetables total amount of heavy metals wereanalyzed to evaluate the pollution condition. The main factor influence the heavymetal pollution and its biological effect were analysis from the perspective of soilphysical and chemical properties. In this paper, using the BCR continuous extractionto Jinan vegetable soil heavy metal Pb, Cr, Cu, and four kinds of heavy metals such aszinc chemical morphological characteristics and its influencing factors were analyzed.The purpose is to understand main vegetables in Jinan and bio-availability of soilheavy metals, to ensure the objective assessment of the risk of soil heavy metalspollution of vegetable, to make the vegetables safety.The results of the study are as follows:(1) According to the second level standard of soil environmental quality, totalconcentration of Pb, Cr, Cu, Zn, Ni, Hg in vegetable soils were not exceed thestandard, belonging to the clean state, while Cd exceeded the standard seriously.Contrast to the background value in soil and the second level standard of soil environmental quality of heavy metals in Jinan, the contaminated degree of Cd in soilis most serious that exceeding standard rate of Cd is100%and the mean exceedingstandard are21.5and3.36times of Cd in vegetable soils, respectively.(2) It is concluded that in addition to the correlation between Cr and Cd in thesubsoil, the other heavy metals were significantly related to each other in Jinanvegetable field by using correlation analysis. It showed that subsoil had small artificialdisturbance in Jinan. Via principal component analysis and cluster analysis, it wasconcluded that the source of Pb, Cd, Cr, Cu, Zn in Jinan vegetable soil can be dividedinto two factors: the factor one include Cd, Pb, Cu, summarized as derived fromindustrial and agricultural activities and road traffic, Factor two including Cr and Zn,and summarized as derived from the soil parent material.(4) The chemical forms of heavy metals in Jinan vegetable soil distribution order:residual state> can be oxidized state> can also types> acid soluble state. Residue inPb, Cr, Cu, Zn, is the highest proportion of66%,66%,57%and67%respectively.The pH and active organic matter of soil could affect the formation distribution ofheavy metals.(3) Pb in the edible parts of vegetable in Jinan exceeded badly. Spinach had thestrongest ability to enrich Pb, Cd, Zn and potato had the strongest ability to enrich Cr,Cu, while cucumber was not easy to enrich heavy metals.(5) The correlation analysis showed that spatial distribution of available Pb, Cd,Cr, Cu, Zn had been affected significantly by the soil basic physical chemistrycharacter. It had negative correlation between available Cd, Cr, Cu, and Zn with pHand CaCO3matter. There was a significant correlation between the available contentsand the total contents, the soil pH and the CaCO3matter, suggesting that soil pH andCaCO3matter were also important factors affecting the spatial distribution of theavailable contents of heavy metals in Jinan vegetable soils.