The Pollution Characteristics And Source Analysis Of Heavy Metal From Atmospheric PM_2.5 And PM₁₀ In Expressway Around Of Changchun City

The particulate pollution in the atmosphere has become increasingly serious, haze has become a hot topic in the recent two years, the haze weather will harm people’s health, prevent people travel, so the quality of the air attracts more and more people’s attention. Changchun as the capital city, in the past two years, to build urban expressway, the pollution from traffic is an important cause of atmospheric environment. This study the distribution characteristics of the expressway surrounding atmospheric particulate matter and heavy metals, that for the relevant departments of the governance of atmospheric particulate matter and heavy metals pollution, improve the urban atmospheric environment purification, protect the health of the citizens, with very important significance.This research included eight months monitoring for the particulate samples in the southwest of Changchun City.The aim was to investigate the environment characteristics of atmospheric particles PM2.5 and PM10 pollution distribution and the pollution characteristics of heavy metals in the particulate. The pollution condition of the heavy metals in atmospheric particulate matter was also evaluated:1. The concentration characteristic of atmospheric particulate PM2.5 and PM10 in expressway around of Changchun CityThe daily average concentration differences of PM2.5 and PM10 in Changchun City in the southwest variation was greater. The daily mean value of PM2.5 concentration changed in the range of 36.4～424.4μg/m3, with a mean of 176.1μg/m3. The daily mean value of PM10 concentration changed in the range of 59.5～458.1μg/m3, with a mean of 136.5μg/m3. The daily mean maximum of PM2.5 and PM10 concentration was 5.7 times and 3.1 times greater than that of the Air Quality Second Standards, respectively PM2.5 and PM10 concentration decreased from April to September in the Southwest of Changchun City PM2.5 and PM10 concentration in September was the least during the monitoring. The peak value was observed in October for all the PM2.5 and PM10 mean concentration, the average concentration of PM2.5 and PM10 in November is slightly back in October. Sampling during the construction stage and the heating period is significantly higher than operation stage and the heating period, each month were greater than the average net control point, construction dust, greening, factors such as traffic types is probably the main reason of difference.2. Expressway around of Changchun city characteristics of heavy metals in atmospheric particulate matter pollution researchThe concentration distribution characteristics of Zn, Cu, Cr, Cd, Ni, Fe, Mn and Pb in the atmospheric particulate PMio and PM2.5 had the different change trend. In the PM10 and PM2.5 particles, the element Fe content was the highest, Cd content was the lowest, in turn Fe>Zn> Mn>Cu>Pb>Ni>Cr>Cd. Zn in the PM2.5 contributed more than 50% proportion to the of PM10. The heavy metals including Cu, Cr, Cd, Ni, Fe, Mn, Pb in the PM2.5 contributed more than 60% proportion to the of PM10. Moreover Cr, Cd, Pb, Ni contributed more than 70%. Compared with the reference point (Jingyue Site), the analysis showed that Fe in the atmospheric particles PM10 and PM2.5 the Spring, The concentrations of Zn, Cu, Mn were higher in the research area than that of the reference site; Fe, Zn, Cu and Mn had certain pollution phenomenon during the period in the Southwestern City, Except Cr, the other seven heavy metals in the PM10 and PM2.5 during the fall in the Southwest of Changchun City were all higher than that of the reference point Cd, Ni and Mn concentrations in the atmospheric particles PM10 and PM2.5 in the Southwestern City of presented a multiple relations to the reference point; Fe, Zn, Cd, Ni and Mn in the atmospheric particulate matter had pollution phenomenon.3. The assessment of heavy metals pollution in atmospheric particulate PM2.5 and PM10 in expressway around of Changchun CityThrough the analysis calculation, the variation coefficient in particulate matter was abtained. The variation coefficients of Cd and Cr elementin the PM10 and PM2.5 was within 1.The results showed that Zn, Fe, Mn was interfered by human activities in the spatial distribution is lighter, and source is relatively stable. The maximum of coefficient variation oof Cr and Cd changed heavily influenced by human activities.The evaluation result of Mull pollution index shows:In southwest changchun city expressway surrounding PM2.5, Zinc is very heavy pollution; From April to September for Cu in very heavy pollution, October and November to reduce pollution degree; Mn, Fe basic pollution-free; Cd from April to June in pollution-free, July and November to extreme pollution; From April to July, no pollution, Cr in August to November to extreme pollution; Ni, Pb pollution from April to July in the comparatively light, and from August to November heavy pollution. Particulate matter has the same distribution of PM10 and PM2.5.Enrichment factor method the evaluation results are consistent with Mull index method. The main source of zinc, galvanized guardrail and accessories may be vehicle is corrosion, etc; The main source of Cu may be diesel fuel oil and construction dust; Fe and Mn enrichment, from natural source; Straw burning, coal and fuel combustion may be the main source of Cr and Cd; Ni and Pb might be contribution by traffic.