Xie Tian, Cao Fang, Zhang Yan-Lin, Lin Yu-Chi, Fan Mei-Yi, Song Wen-Huai, Bao Meng-Ying, Xiang Yan-Kun, Zhao Zhu-Yu, Yang Xiao-Ying, Xie Feng, Zhang Yu-Xian, Yu Hao-Ran, Zhang Zi-Jin, Xing Jia-Li
International Joint Laboratory on Climate and Environment Change (ILCEC), Yale-NUIST Center on Atmospheric Environment, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China.
Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science & Technology, Nanjing 210044, China.
Huan Jing Ke Xue. 2022 Jun 8;43(6):2858-2866. doi: 10.13227/j.hjkx.202110088.
Carbonaceous aerosol is an important component of atmospheric fine particles that has an important impact on air quality, human health, and climate change. In order to explore the long-term changes in carbonaceous aerosol under the background of emission reduction, this study measured the mass concentrations of organic carbon (OC) and elemental carbon (EC) of PM, which collected in the northern suburbs of Nanjing for five years (December 17, 2014 to January 5, 2020). The results showed that the five-year average (OC) and (EC) were (10.2±5.3) μg·m and (1.6±1.1) μg·m, accounting for 31.1% and 5.2% of PM, respectively. OC and EC concentrations were both high in winter and low in summer. According to the nonparametric Mann-Kendall test and Sen's slope, the mass concentrations of OC and PM decreased significantly[OC:<0.0001, -0.79 μg·(m·a), -0.29%·a; PM:<0.0001, -4.59 μg·(m·a), -1.58%·a]. Although EC had an upward trend, the significance and range of change were not obvious[=0.02, 0.05 μg·(m·a), 0.02%·a]. OC and EC decreased significantly during winter from 2014 to 2019[OC:<0.0001, -2.05 μg·(m·a), -0.74%·a; EC:=0.001, -0.15 μg·(m·a), -0.05%·a], and the decline was more obvious than the whole. The correlation between OC and EC showed that the sources in winter and summer were more complex than those in spring and autumn. According to the characteristic ratio of OC and EC, the contribution of coal combustion and biomass burning decreased from 2015 to 2019, whereas the impact of industrial sources and vehicle emissions became more significant. Corresponding to this was the obvious decline in OC and the slight recovery of EC. The OC/EC ratio was over 2.0, indicating that there was secondary pollution in the study area. Further calculation revealed that the variation in SOC was consistent with that in OC, showing a significant decrease[<0.0001, -0.47 μg·(m·a), -0.17%·a]. The average mass concentration of SOC was (5.0±3.5) μg·m, accounting for 49.2% of OC. These changes indicate clear effects of the prevention and control of air pollution in Nanjing in recent years. Furthermore, future control can focus on the emissions of VOCs to reduce secondary pollution.
碳质气溶胶是大气细颗粒物的重要组成部分，对空气质量、人类健康和气候变化具有重要影响。为探究减排背景下碳质气溶胶的长期变化，本研究对南京北郊2014年12月17日至2020年1月5日连续五年采集的PM中有机碳（OC）和元素碳（EC）的质量浓度进行了测定。结果表明，五年平均OC和EC分别为（10.2±5.3）μg·m和（1.6±1.1）μg·m，分别占PM的31.1%和5.2%。OC和EC浓度均冬季高、夏季低。根据非参数Mann-Kendall检验和Sen斜率，OC和PM的质量浓度显著下降[OC：<0.0001，-0.79 μg·（m·a），-0.29%·a；PM：<0.0001，-4.59 μg·（m·a），-1.58%·a]。虽然EC呈上升趋势，但变化的显著性和幅度不明显[=0.02，0.05 μg·（m·a），0.02%·a]。2014 - 2019年冬季OC和EC显著下降[OC：<0.0001，-2.05 μg·（m·a），-0.74%·a；EC：=0.001，-0.15 μg·（m·a），-0.05%·a]，且下降幅度比整体更明显。OC与EC的相关性表明，冬夏季来源比春秋季更复杂。根据OC和EC的特征比值，2015 - 2019年煤炭燃烧和生物质燃烧的贡献下降，而工业源和机动车排放的影响变得更显著。与此相应的是OC明显下降，EC略有回升。OC/EC比值大于2.0，表明研究区域存在二次污染。进一步计算表明，SOC的变化与OC一致，呈显著下降趋势[<0.0001，-0.47 μg·（m·a），-0.17%·a]。SOC的平均质量浓度为（5.0±3.5）μg·m，占OC的49.2%。这些变化表明近年来南京空气污染防治成效明显。此外，未来管控可聚焦于挥发性有机物排放以减少二次污染。
