唐山市2017年采暖期不同污染等级PM2.5化学组分特征对比与来源分析

为深入了解唐山市采暖期PM_2.5污染成因与来源，采用在线监测设备于2017年12月1日-2018年1月28日连续监测了唐山市PM_2.5及其水溶性离子和碳质组分（OC、EC）的质量浓度变化，并结合部分常规气体污染物及气象数据进行对比分析.结果表明:①相对湿度的增加和风速的降低促进了污染的发展.②清洁、轻中度污染和重污染时，SOR（硫氧化率）分别为0.05、0.08、0.20，NOR（氮氧化率）分别为0.05、0.12、0.26，随着污染的加重，SO₂、NO_x向PM_2.5中SO₄2-、NO₃-的二次转化现象更加明显.③清洁时，ρ（OC）、ρ（EC）、ρ（SO₄2-）和ρ（Cl-）占PM_2.5化学组分（水溶性离子、碳质组分）质量浓度总和的68%，主要污染源为燃煤；清洁、轻中度污染和重污染时，ρ（NO₂）/ρ（SO₂）分别为0.96、1.14、1.44，ρ（NO₃-）/ρ（SO₄2-）分别为0.94、1.57和1.75；重污染时，ρ（SO₄2-）、ρ（NO₃-）、ρ（NH₄+）三者之和占PM_2.5化学组分质量浓度总和的61%，二次污染物成为主要污染源.④观测期，唐山市轻中度污染和重污染时，受经北京市、天津市等唐山市西部地区方向气团影响频率分别为61%、63%，受该方向气团影响时，ρ（NO₂）/ρ（SO₂）、ρ（NO₃-）/ρ（SO₄2-）明显增大.研究显示，相较于燃煤排放物在大气污染物中的占比变化，随着污染的加重，工业工艺和机动车尾气排放产生的污染物占比明显增大，区域传输对大气污染影响不可忽略，政府有必要开展区域联防联控、停产限产和限行限号的措施. 

Comparison and Analysis of PM2.5 Chemical Composition Characteristics and Source of Different Grade Pollution in Tangshan City during 2017 Heating Period

For insight into the causes and sources of PM_2.5 pollution during the heating period in Tangshan City, the on-line monitoring equipment was used to continuously monitor the mass concentration changes of water-soluble ions and the carbon component (OC, EC) in PM_2.5 from December 1^st, 2017 to January 28^th, 2018 in Tangshan City. The analysis combined with some conventional gas pollutants and meteorological data. The results showed that:(1) The increase in relative humidity and the reduction of wind speed promoted the development of the pollution. (2) When no air pollution, mild-to-moderate pollution and heavy pollution, SOR (sulfur oxidation rate) values were 0.05, 0.08, 0.20, and NOR (nitrogen oxidation rate) values were 0.05, 0.12, 0.26, respectively. With the increase in pollution degree, the quadratic transformation phenomenon of sulfur dioxide and nitrogen dioxide to sulfate and nitrate in PM_2.5 was more obvious. (3) When no pollution, the mass concentration of OC (organic carbon), EC (elemental carbon), SO₄^2- and Cl^- accounted for 68% of the sum of PM_2.5 chemical compositions (water-soluble ions, carbon component), the coal combustion was the main pollution sources. When no pollution, mild-to-moderate pollution and heavy pollution, the mass concentration ratio of NO₂ and SO₂ was 0.96, 1.14, 1.44, and the mass concentration ratio of NO₃^- and SO₄^2- was 0.94, 1.57 and 1.75, respectively. When heavy pollution, the mass concentration of SO₄^2-, NO₃^- and NH₄⁺ accounted for 61% of the sum of PM_2.5 chemical composition and secondary pollutants were the main pollution sources. (4) During the observation period, when mild-to-moderate pollution and heavy pollution occurred, Tangshan City was affected by the transmission air masses in the direction of the western part of Tangshan City such as Beijing and Tianjin City, respectively, with a frequency of 61% and 63%. Influenced by the air mass in this direction, the mass concentration ratio of NO₂ and SO₂, NO₃^- and SO₄^2- increased significantly. The results shown that compared with coal percentage change in atmospheric pollutants, the pollutants from the industrial process and motor vehicle exhaust emission increased significantly along with aggravating air pollution. The impact of regional transmission on atmospheric pollution should not be neglected. It is necessary for the government to carry out measures for joint prevention and control, production and production limits, and limit restrictions.