A Simulated Study On The Sources Of Haze And PM_2.5 In The Cities Of The Southern Hebei Area

Resent years, haze pollution presented an aggravated trend in Beijing, Tianjin andHebei region, and already received widespead attentions from both scientists andpolicy-makers，especially in Shijiazhuang and Xingtai, which located in the South ofHebei Province. High concentrations of haze pollutants caused serious risk to humanhealth and ecological environment damage. It is a crucial prerequisite to developeffective haze pullution control strategies by obtaining information on the sources ofhaze and PM_2.5in the region of Southern Hebei Province. The Models-3/CMAQmodeling system was used to analyze the sources of haze and PM_2.5by using senarioanalysis method in this area.Firstly, it compared the results of observed and simulated PM₁₀concentrations insix cities in Hebei and surrounding areas. It showed that the prediction valus had a goodagreement with observations.The model perfomance is acceptable to simulate hazepullutants.Secondlly, it discussed sources of haze and PM_2.5in Shijiazhuang and Xingtai indifferent month, July and December2007. The results shows that the contribution ratesof sector sources in Hebei area to daily average PM_2.5concentration ranged from2.7%-38.3%and2.2%-30.4%in July in two cities. Local contribution of traffic sourceis the smallest, and the greatest contributer is industrial sources. For ions in PM_2.5,including SO₄^2-, NH₄⁺and NO₃^-, their contributions are from0(SO₄^2-) to36.4%（NO₃^-）and from0.1%(SO₄^2-) to25.5%（NO₃^-） in Shijiazhuang and Xingtai. The major sourcesof OC and EC are civilian combustion and industry, about40%and30%, respectively.Among sector sources in the surrounding regions, industry and power plant are majorcontributers to haze and PM_2.5. And the total contributions to PM_2.5, ions in PM_2.5,carbon components （OC and EC） and extinction coefficient in Shijiazhuang are7.4%（Shanxi Province）-11.3%（Beijing and Tianjin area）,29.3%（Shanxi Province）-80.2%（Beijing and Tianjin area）,-2.5%（Beijing and Tianjin area）-10.7%（ShanxiProvince） and7.5%（Shanxi Province）-15.6%（Beijing and Tianjin area）. Similarly, theyare6.5%（Shanxi Province）-20.4%（Henan Province）,27.6%（Shanxi Province）-86.8%（Henan Province）,-2.1%（Beijing and Tianjin area）-13.2%（Henan Province） and6.9%（Shanxi Province）-14.7%（Henan Province） in Xingtai, respectively. In December2007, local industry sector in Hebei has the highest effect on theconcentrations of PM_2.5, SO₄^2-and NH₄⁺in Shijiazhuang, with average contributionratios of31.8%,36.7%and20.8%. For NO₃^-, OC, EC and extinction coefficient fromlocal civilian combustion sector, which is also highest contributer, the contributions are8.5%,64.8%,54.3%and27.2%respectively. But the highest sector source for thosecomponents is slightly different in Xingtai, with contributions of29.1%,9.0%,66.5%,54.7%and29.1%for PM_2.5, NO₃^-, OC, EC and extinction coefficient from local localcivilian combustion sector, while they are37.0%and17.9%for SO₄^2-and NH₄⁺fromlocal industry sector. In the surrounding areas, five department sources from ShanxiProvince have highest contributions to haze and PM_2.5in Shijiazhuang and Xingtai.During these sources, civilian non-combustion sector is the smallest while industry isstill the highest. The contribution rates to PM_2.5, water-soluble ions in PM_2.5, carboncomponents and extinction coefficient in Shijiazhuang are0.7%-7.0%,7.9%-22.5%,0.3%-14.2%and0.9%-6.1%, whearas they are0.8%-5.5%,8.4%-19.7%,0.2%-10.3%and1.1%-4.8%in Xingtai respectively.Additionally, this paper compared different contributions of sector sources fromHebei area to pollutants in Shijiazhuang and Xingtai in haze and non-haze days. Thecontribution ratios in non-haze days are1.0-1.3times that of in haze days in July. Theyare0.9-4.5times in December.Lastly, it analyzed two heavy pollution processes in Shijiazhuang and Xingtai. Thefact is that the pollutants concentrations are very high with smaller wind speed whenheavy pollution occures, which is not conducive to the diffusion of contaminants. Thepaper also discussed souces of haze and PM_2.5when this process happened. During theperiod in July, local industy and power plant sectors have significant effect on PM_2.5,ions in PM_2.5and extinction coefficient. For carbon components, it is civiliancombustion and industry sectors. In the surrounding areas, industry department fromBeijing and Tianjin region and power plant department from Henan Province havehigher contributions to those componernts in Shijiazhuang and Xingtai except carboncomponents. The contributions from local civilian combustion source in Hebei areaexceed those from local industry source, sector sources from Shanxi Province to hazepollutants in two cities exceed those sources from the surrounding areas when heavypollution process occurred in December.