| Autor: |
Zhang JQ; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Wu YJ; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Zhang M; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Wang H; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Chen ZX; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Hu J; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Li H; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Fan XL; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Chai FH; Chinese Research Academy of Environmental Sciences, Beijing 100012, China., Wang SL; Chinese Research Academy of Environmental Sciences, Beijing 100012, China.; Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China. |
| Abstrakt: |
Heavy pollution events frequently occur during fall and winter seasons in northern areas. In order to understand the characteristics and chemical composition of PM 2.5 during heavy pollution in winter in Liaocheng City, ambient PM 2.5 samples were collected between January 7-11,2016. Mass concentration, water-soluble ions, carbonaceous species, and elements were analyzed, as well as the causes of pollution. Results showed that PM 2.5 mass concentration was 238.3 μg·m -3 with the trend clearly that of an inverted V; this concentration represents exceedance of the National Ambient Air Quality Standard (GB 3095-2012) by more than 2.2 times. NO 3 - , SO 4 2- , and NH 4 + (SNA)were the main water-soluble ions. As pollution increased or decreased, NH 4 + , SO 4 2- , NO 3 - , and Cl - exhibited the same trend, which contrasted with that of Ca 2+ . During the peak of pollution, NH 4 + , NO 3 - , and SO 4 2- concentrations were 48.96, 68.45, and 80.55 μg·m -3 , with these representing levels 6.29, 7.31, and 7.84 times those of the initial stage, respectively. During the pollution event, OC and EC concentration variation ranges were 20.8-60.2 μg·m -3 , and 3.0-7.5 μg·m -3 , respectively. The concentration of OC was significantly higher than that of EC and the variation amplitude was significantly larger. During the event, the mass concentrations of 27 inorganic elements on each day were 10.2, 22.4, 16.0, 19.6, and 8.2 μg·m -3 , respectively. Enrichment factors (EF) of all elements were less than 10, indicating lack of enrichment and showing that sources were mainly natural. PM 2.5 mass concentration reconstruction results showed that organic matter (OM), SO 4 2- , and NO 3 - were major components, followed by NH 4 + , crustal material, and other ions. EC and trace element content was relatively low. As PM 2.5 pollution worsened, secondary inorganic salt (NH 4 + , SO 4 2- , NO 3 - ) concentrations and proportions increased, OM concentration increased but its proportion decreased, while crustal material concentration and proportion both decreased, showing that secondary inorganic conversion was the main cause of this pollution event, mainly driven by coal and motor vehicle emissions. |
