| Yuqiao Reservoir, as the significant regulating reservoir from Luanhe to Tianjin, is the water source to provide life drinking water and production water supply. In recent years, with the rapid development of social economy surrounding the basin and reservoir, the point and non-point source pollution have become increasingly serious, the main sources of influence factor of reservoir area come from water and soil erosion, precipitation, runoff and other processes which make the pollution load increase dramatically, the reservoir water quality deteriorate, the potential harmfulness of heavy metal pollution to reservoir upstream as the only water source water quality problems in Tianjin lead to a serious threat. Large amounts of heavy metals release into the environment, soil and water as important contain heavy metal medium, heavy metal pollution is more and more serious which will cause significant damage to the ecological environment and human health without control. At the same time, the land use/cover change (LUCC) has caused widespread concern at the international level. In this paper, the researchfocuses on the regional studies in the basin, make analysis comparison with the two medium of the water and soil environment, reservoir protection has an important significance for Yuqiao Reservoir.This research firstly makes description statistics of characteristics of heavy metal content in the aquatic upper cover water, suspended matter sediment and soil, then makes analysis about the correlation of source of heavy metal in the two medium with multivariate correlation analysis. Finally, this paper makes an analysis of the degree ofheavy metal pollution for three tributaries in Yuqiao reservoir upstream in order toobtainthe status of heavy metal in oilandsediment according to thegeological accumulation index method and index method of potential ecological harm.The main conclusions are as following:1) Statistical characteristics of overlying water and suspended paniculate matterThe overlying water quality is much better in three basins, including the content of six kinds of heavy metals (Cd, As, Pb, Cu, Cr, Zn) is lower than the surface water environment quality standard class I, heavy metal pollution in the samples ofoverlying water is not serious which could not cause chronic toxicity effect; Including the average of 5 kinds of heavy metal in suspended particulate matter are more than soil background values in Hebei province and national soil element background values, the content of Zn content is lower than soil background value of Hebei province and national soil element background values. Four kinds of heavy metals (Pb, Cu, Cr, Zn) present basically consistent spatial distribution characteristics, Cd and As are different. The contaminated degree is particularly prominent in Shahe and Lin river or Li river reach lesser. The heavy metal in suspended matter descend from upstream to downstream, the enrichment of downstream is lower than the upstream.2) Statistical characteristics of heavy metals of sedimentAnalysis of 33 sub watershed sampling sites, Cd concentration of 18sampling sites were higher than the first class of Chinese soil environmental quality standard, accounting for 54.5% of the total, the maximum value was 1.29 mg·kg-1 the minimum value was 0.04 mg·kg-1, the average value was 0.29 mg·kg-1 which was higher than the first class of Chinese soil environmental quality standard (2.0mg·kg-1). All the sample sites, the concentration of As were higher than the first class of Chinese soil environmental quality standard reaching 100%, the maximum value was 116.92 mg·kg-1, the minimum value was 15.62 mg·kg-1, the average value was 30.39 mg·kg-1 which was higher than he first class of Chinese soil environmental quality standard(15.0mg·kg-1). Pb concentration of 10 sampling sites were higher than the first class of Chinese soil environmental quality standard, accounting for 30% of the total, the maximum value was 139.07mg·kg-1,the minimum value was 9.27mg·kg-1, the average value was 33.49mg·kg-1 which was lower than the first class of Chinese soil environmental quality standard(35.0mg·kg-1).Cu concentration of 27sampling siteswere higher than the first class of Chinese soil environmental quality standard, accounting for 82% of the total, the maximum value was 294.40mg·kg-1,the minimum value was 16.14 mg·kg-1, the average value was 66.96mg·kg-1 which was higher than the first class of Chinese soil environmental quality standard(35.0mg·kg-1).Cr concentration of 14 sampling sites were higher than the first class of Chinese soil environmental quality standard, accounting for 42% of the total, the maximum value was 254.63mg·kg-1,the minimum value was 43.10mg·kg-1, the average value was 90.16 mg·kg-1 which was higher than the first class of Chinese soil environmental qualitystandard(90.0mg·kg-1).Zn concentration of 12 sampling sites were higher than the first class of Chinese soil environmental quality standard, accounting for 36% of the total, the maximum value was 184.33mg·kg-1,the minimum value was 52.03 mg·kg-1, the average value was 94.8mg·kg-1 which was lower than the first class of Chinese soil environmental quality standard(100.0mg·kg-1).Ni concentration of 26sampling sites were higher than the first class of Chinese soil environmental quality standard, accounting for 79% of the total, the maximum value was 96.62mg·kg-1,the minimum value was 24.85 mg·kg-1, the average value was 56.10mg·kg-1 which was higher than the first class of Chinese soil environmental quality standard(40.0mg·kg-1).In the three rivers, the average of Pb and Zn concentration were lower than the grade one of Chinese environmental qualitystandard for soils, Cd、As、Cu、Cr and Ni were higher than the grade one of Chinese environmental qualitystandard for soils.Variable coefficient of the seven heavy metal of three rivers decreased in the order of Shahe>Lihe>Linhe, Variable coefficient of seven heavy metal decreased in the order of Cd>Pb>Cu>As> Cr>Ni>Zn,ranging from 33% to 91%. Space variability of sediment was weak in the whole, had strong discreteness,which explained heavy metals in sediment had been affected by human activities.3) The characteristics of soil heavy metalsThe average of As, Pb, Cu, Cr and Zn in addition to Cd exceed national Ⅰ level standard which do not exceed Ⅱ level, but the maximum value of heavy metal elements except Cu has exceeded national standards in the study area. In addition to Cd, the content of other heavy metals exceed soil background value of Hebei province, and the average content of As, Pb, Cu, Cr and Zn are respectively 2.14,3.30,2.44, 2.30,1.40 times ofbackground value. Cd, As, Pb, Cr and Zn are highly variable. It illustrates that the spatial distribution of heavy metal in soil present is non-uniformed, and the discrete is stronger. Heavy metals have certain accumulation which needs to strengthen monitoring.4)Heavy metal source analysisTake advantage of the Pearson correlation analysis to analyze the relation between heavy metals and landuse types area proportion, showed that river sediments in Cdwas mainly natural sources, As and Pb had complexed sources, mainly natural sources, less human disturbance, Zn came mainly from natural source, Cu was from the natural source and human activity, Ni and Cr came from human activity. Sowe can determine seven heavy metals pollution did not belong to non-point source pollution, which were from point source pollution.To analyze seven heavy metal of 33 sub watershed sampling sites,take advantage of cluster analysis and principal component analysis to judge the source, the result was nearly same. The seven heavy metal could be divided into three groups(Ⅰ、Ⅱ、 Ⅱ).Group Ⅰ, Pb and Zn, was lightly polluted which were influenced by natural background;Group Ⅰ, Cd、As and Pb, was heavily polluted which mainly came from industrial and mineral industry;Group Ⅲ, As and Cu, mainly came from natural source and human impact.5) The results of heavy metal pollution evaluation in sediments The result of accumulation exponential method evaluation:14 sampling sites of Cd were in the pollution status, among of them, the 24th was in the middle strong pollution; 13 sampling sites of As were in the pollution status, among of them, the 10th、 21st、27th、32nd, was in the middle pollution;7 sampling sites of Pb were in the pollution status, among of them, the 10th was in the middle pollution; 19 sampling sites of Cu were in the pollution status, among of them, the 21st and 27th were in the middle strong pollution;9 sampling sites of Cr were in the pollution status; 3sampling sites of Zn were in the pollution status; 14 sampling sites of Ni were in the pollution status. The result showed that partial sampling sites had been polluted by Cd、As、Pb、 Cu、Cr、Zn and Ni.Potential ecological risk index showedCd was at medium hazard in the average of seven single heavy metal pollution factorfrom 33 sampling points, the others were at slight hazard. The pollution degree was at slight hazard in the most sampling sites. In the thirty-three sampling sites, Cd had two siteswhich showed strong hazard, six sites which showed stronger hazard, eleven sites which showed middle hazard, others showed slight hazard. Comprehensive potential ecological harm index showed that samples of 10,18,19,20,21,27,33belong to strong ecological hazard,the value of pollution degree of Cd wasthe biggest, followed by the As, Cu, Ni. In the three rivers ecological hazardofShahe was higher than Linhe and Lihe. |
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