| Tangshan, playing an important role in promoting the development of the Bohai Sea economic circle, is the major energy and industrial materials base of Beijing-Tianjin-Hebei region, as well as the whole country. With the rapid economic development of Tangshan in recent years, the more and more heavy industries such as building materials, steel, metallurgy, oil refining, energy generation appeared and vehicle ownership continued to increase, at the same time, interwoven composite emissions of gaseous inorganic and organic contaminants were increasing, so that the regional air pollution was becoming more and more serious. With the consequent photochemical pollution coupled with direct emissions of carbonaceous particles and sulfate particles, the visibility dropped significantly in the Tangshan area,as well as haze. Tangshan has entered a complex era of air pollution. The observational and research of the characteristics of haze gaseous pollutants in Tangshan Industrial Zone is of great significance to find out the control measures of environmental pollution in this region.The essence of the atmospheric haze pollution is that the concentration of fine particles in the atmosphere are too high, resulting in a serious phenomenon of extinction, and turbid visual. In order to clarify the haze distribution, status and influence elements and haze pollution particles and gaseous pollutants, Tangshan has developed an observation site to monitor the major air pollutants (including PM10, PM2.5, SO2, NOX, O3and CO) for continuous observation in2010. The results showed that:(1) Haze pollution in Tangshan region was very serious. In2010,109times haze pollution occured in Tangshan Industrial Zone,30percent of the whole year. Haze pollution mainly occurs in two periods:First, the end of spring and early summer, the reason is that rapid photochemical reactions during this period generates a lot of secondary fine particles; Second,heating season, the combustion of fossil fuel emissions and unfavorable conditions for the diffusion are the main causes of haze.(2) Fine particles had become the primary pollutant of the Tangshan region. The concentration of aerosol particles was very high in haze days, in which PM7.5accounted for60%-80%of PM10,and PM2.5had become the primary pollutant of the region. In haze days, the concentration of PM2.5was bimodal, the traffic during morning rush-hour and factories caused the local emission source intensity increasing, the concentration of PM10and PM2.5reached the peak while the morning temperature inversion junction in9:00-11:00.Around noon the inversion junction was broken, when the favorable dispersion conditions, such as the strong convection and turbulence enhancement occurred, the particle concentrations decreased. With the arrival of late traffic peak, the second peak of the particulate matter concentration is gradually emerging and it would sustained until midnight, as the mixed layer a high degree reduced.(3) Gaseous pollutants change was consistent with the PM2.5. Diurnal and seasonal variation of emission concentrations of gaseous pollutants (SO2, NOx, CO and PM2.5) changed synchronization, especially during the haze pollution accumulation process; they often showed the same trend. The end of spring and early summer, high temperatures and drought drier appeared, higher concentration of O3during the day resulted in enhanced atmospheric oxidation, and the process of homogeneous and heterogeneous atmospheric chemical reactions became the important source of PM2.5.During the heating season in Winter, the combustion of coal leaded to vertical of PM2.5at the same time, the emission of gaseous pollutants SO2and NOX shapely raised. The CO concentration also showed seasonal of high value.(4) Southwest air mass formed the largest contribution in Tangshan haze pollution. The cluster of air mass backward trajectories, combined with changes of the concentration, found:the southwest air mass reached the Tangshan industrial zone pollution in spring and summer, passing through the Bohai Sea and Tianjin Industrial Zone. The intensity of the air mass:Southwest direction>Beijing-Tianjin region direction≈the northeast direction> the northwest direction.the south air mass passing the Bohai sea carried the sea salt particles, the concentrations of Cl", Na+, K+and Mg+and other ion concentration in PM2.1were much higher than in winter, while the northwest wind dominated. The fine sea salt particles was part of the source of the particles in Tangshan Industrial Zone, but according to low concentration of Ca2+, sea salt particle contribution in the total amount of fine particle pollution is very small.(5) Weather conditions were important objective factors during the process of haze pollutions. The breeze, high temperatures and the inversion were the objective conditions in Tangshan Industrial Zone. High speed of wind and rain and snow can significantly reduce aerosol particles, but the humidity change was not significant. |
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