| Polycyclic aromatic hydrocarbons(PAHs)as a class of persistent organic pollutants are widely found in environmental media,some of which are carcinogenic,of which 16 have been listed as priority pollutants by the US Environmental Protection Agency.Polycyclic aromatic hydrocarbons can migrate long distances through various environmental media and cause harm to animals,plants,and humans.Now it has attracted widespread attentionJinzhong City is an important coal-producing area and industrial base in Shanxi Province.Industrial pollution is serious and representative.The study area is about 35km2 around the perimeter of an independent coking plant in Jinzhong City.The coking plant has only been built for about ten years,and there is no obvious heavy industry plant area around it.It can be used as a relatively single coking area for researchIn this study,the PAHs in the surrounding atmospheric particulates and soil layers of the coking plant were studied on April 27,2017,June 2,2017 and February 2,2018,respectively.The distance from the ground was about 3 m and 25 m.Twenty-four atmospheric particle samples with different particle size ranges were collected.On July 15,2017,19 soil samples of 0-20 cm soil layers were collected in the vicinity of the coking plant.The gas chromatography and mass spectrometer was used and 16 types of US EPA multi-rings were included.The concentrations of 17 PAlls,including aromatics,were detected and analyzed.The results provided scientific evidence for the prevention and control of local PAHs pollutionResearch indicates1.The total suspended particulate concentration in the atmosphere ranges from 129 to 182.9 μg/m3,reaching the national secondary standard(GB 3095-2012,daily average 120-300 μg/m3).The contents of 17 PAHs in atmospheric particulate collected from three typical seasons of different seasons were 96.91 ng/m3,55.90 ng/m3,and 287.91 ng/m3,respectively,and the average concentration was 146.91 ng/m3 Compared with other regions in the country,it is at a medium level.Among them,the most carcinogenic BaP ranged from 3.60 to 12.37 ng/m3,which exceeded the quality of the national second class ambient air functional area(BaP daily average 2.5 ng/m3),and its content was in proportion to the total amount of PAHs.Significant linear correlation.At different times,the content of PAHs in atmospheric particles with particle size ≤ 2.5 μm is much higher than that with particle size ≥2.5 μm2.The concentration range of 17 PAHs in the soil of cultivated layer in the study area was 218.57-855.60ng/g,with an average of 422.54ng/g.The 3 and 4 ring PAHs accounted for the largest proportion,accounting for 30.71%to 47.60%and 22.61%to 40.28%of the total PAHs content,respectively.The highest PHE content was 80.05 ng/g.The most abundant PHE and the most carcinogenic BaP were similar to the total PAHs.Starting from the coking plant,in the northeast and southwest directions,the content of PAHs in different rings showed a tendency to decrease with increasing distance from the coking plant,and the spatial variation of the PAHs in the high-ring PAHs was greater than that in the low-ring3.The characteristic ratio method was used to judge PAHs in airborne particulate matter and soil mainly from coal combuistion and traffic pollution.Principal component analysis-multivariate linear regression was used to analyze the source of PAHs in the soil of the cultivated layer.The results showed that the PAHs in the soil.Mainly from coal combustion,traffic pollution and coking,its contribution rates were 42.1%,27.3%,and 23.0%,respectively,and coking was closely related to coal combustion.The source contribution ratio of the two sources totaled 65.1%.The contribution rate of biomass combustion is less,at 7.6%4.According to the criteria for the total amount of PAHs in soil proposed by Maliszewska-Kordybach,there are no clean soils in the 19 sampling sites in the area,all of which are polluted by PAHs,of which 84.2%(16 sampling sites)belong to mild pollution,15.8%(3 sampling points)are moderately polluted Compared with other regions in the country,the degree of soil pollution in the area is at a lower level. |
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