| Environmental pollution is directly related to human health and sustainable development of the society.In recent years,people have paid more attention to the problem of environmental pollution.Polycyclic aromatic hydrocarbons(PAHs)which is as a kind of persistent organic pollutants was one of the earliest chemical carcinogens known in the world.Because it is universally a kind of persistent organic pollutants in the environment which is non-polarity,hydrophobicity and degradation characteristics,most varieties of PAHs are carcinogenic,teratogenic and mutagenic that will cause great harm to human health through a variety of ways.PAHs has aroused widespread concern now.The PAHs that originates from coking emissions has seriously polluted the environment in Shanxi which is the largest coke producing areas in the world.This study mainly toke farmland,garden land,forest land surface soil which were in the surrounding of coking enterprises of the large coke production base in Shanxi Province as the research object.In the range of about 100KM2,75 distributed sampling sites were set up evenly.The 75 regional soil samples were collected from soil of sampling sites the depth of which was about 0-10cm.The contents of 16 species USEPA priority PAHs which were from the soil samples were measured by GS-MS.The results of this study could not only reflect the pollution status of the research area,but also provide scientific basis for the prevention and control of local environmental pollution and the development of environmental protection laws and regulations.The results were as follow:1.In the soil of cultivated land,forest land,garden in study area,the content range and mean value of 16 species USEPA priority PAHs were as shown below.Cultivated land;230.57-3509.12ng/g,854.74±570.17ng/g;Forest land:399.58-763.83ng/g,548.44 ±154.81ng/g;Garden:541.69-715.26ng/g,603.34197.10ng/g.The concentration of PAHs and total PAHs in the soil of the study areas were positively correlated with the content of TOC.2.The three types of surface soil in the cultivated land,garden and woodland,16 kinds of PAHs were characterized by low or middle ring.The proportion of cultivated land was 90.4%,forest soil was 90.1%,garden soil was 89.4%,and the PAHs in low ring occupied the largest proportion(The respective proportion of cultivated land was 62.6%,woodland was 60.9%,and garden was 57.2%).The advantage of group monomer of PAHs also were relatively similar which was mainly divided into NAP,PHE,FLA,CHR and BbF.3.According to method for classifying pollution degree was used by Maliszewska-Kordybach B(1996)that was on the basis of the sum of 16 kinds of PAHs content in soil,the 75 surface soil samples could be divided into 4 pollution levels.The numbers and proportions of clean,lightly polluted,moderately polluted and heavily polluted samples were 0(0%),34(45.3%),20(26.7%),and 21(28.0%)respectively.It could be seen that the surface soil in the study area was polluted,and the proportion of mild pollution was the highest.4.The results of source apportionment of characteristic ratio method,principal component analysis and multiple linear regression indicate that the PAHs pollution of surface soil in the research area was compound pollution.In the main pollution sources,factorl included coking emissions,industrial coal,traffic source and firewood burningcomposite source,factor 2 mainly included fuelwood,industrial coal and coking coal,factor 3 was oil substances emissions.The contribution ratios of the three main factors to the total pollution were 44.9%,32.4%and 22.7%,respectively.5.The results of risk assessment was showed that for the 75 sampling points in study areas,the numbers and proportions of 7 kinds of PAHs monomer overproof sample in the Canadian evaluation standard respectively were NAP(75,100.0%),PHE(20,26.7%),PYT(2,2.7%),BaA(0,0%),BaP(2,2.7%),IcdP(2,2.7%)and DahA(0,0%).The numbers and proportions of 10 kinds of PAHs monomer overproof sample in the Netherlands evaluation standard respectively were NAP(75,100.0%),ANT(0,0%),PHE(47,62.7%),FLA(71,94.7%),BaA(2,2.7%),CHR(63,84.0%),BaF(71,94.7%),BkF(35,46.7%),DahA(2,2.7%)and BghiP(29,38.7%).Based on the TEF evaluation method,the soil ∑OTEQBap value of 11 sampling sites in the soil of the region was more higher than the standard limit of soil in Holland,and the rate of overproof was 14.7%.Based on Nemero’s comprehensive pollution index method,the results of risk assessment of Nemero’s comprehensive pollution index,the 75 soil samples in the study area were all heavy pollution levels. |
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