Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China.
Sci Total Environ. 2022 Jan 10;803:149559. doi: 10.1016/j.scitotenv.2021.149559. Epub 2021 Aug 19.
Nitrate (NO) and ammonium (NH) are the major components in inorganic aerosol. However, their sources and formation processes remain unclear. This study conducted a year-round field measurement of TSP, PM and PM in five different sites in the Beijing-Tianjin-Hebei (BTH) region to determine the concentrations of water-soluble inorganic ions (WSIIs) and the isotopic compositions of inorganic nitrogen (δN-NH, δN-NO, and δO-NO). The results showed the highest concentration of WSIIs in winter and lowest in summer. δN-NO, δO-NO, and δN-NH were in the range of -6.1-18.2, 52.2-103.8, and -28.7-36.2‰, respectively. The seasonal variations of δN-NO and δN-NH were an indication of relative contributions of the main sources and effects of meteorological conditions. The source apportionment identified fossil fuel combustion (38.2-50.6%), agricultural emissions (18-24.7%), biomass burning (16.3-22.7%), and road dust/soil (8.7-23.4%) were the main sources of inorganic aerosols. The local sources and regional migration contributed to the level of inorganic aerosol pollution. In winter, the aerosol in the BTH region was affected by the air mass from the northwest. While in spring and summer, the air mass was mainly from the South China. The low temperature and high relative humidity favored to the formation of inorganic nitrogen aerosol, and solar radiation affected the formation processes of inorganic aerosols by changing the oxidation pathway of NO and accelerating the volatilization and dissociation of ammonium nitrate (NHNO). This study discovered the main source contributions of inorganic nitrogen aerosol using N and O isotopes composition, and the obtained information has a great importance in understanding the effects of meteorological conditions on formation and the contribution of regional transport.
硝酸盐（NO）和铵（NH）是无机气溶胶的主要成分。然而，它们的来源和形成过程仍不清楚。本研究在京津冀地区的五个不同地点进行了为期一年的 TSP、PM 和 PM 的现场测量，以确定水溶性无机离子（WSII）的浓度和无机氮的同位素组成（δN-NH、δN-NO 和 δO-NO）。结果表明，WSII 的浓度冬季最高，夏季最低。δN-NO、δO-NO 和 δN-NH 的范围分别为-6.1-18.2、52.2-103.8 和-28.7-36.2‰。δN-NO 和 δN-NH 的季节性变化表明了主要来源的相对贡献和气象条件的影响。源分配确定了化石燃料燃烧（38.2-50.6%）、农业排放（18-24.7%）、生物质燃烧（16.3-22.7%）和道路灰尘/土壤（8.7-23.4%）是无机气溶胶的主要来源。本地源和区域迁移导致了无机气溶胶污染的水平。在冬季，京津冀地区的气溶胶受到来自西北方向的气团的影响。而在春季和夏季，气团主要来自华南地区。低温和高相对湿度有利于无机氮气溶胶的形成，太阳辐射通过改变 NO 的氧化途径和加速硝酸铵（NHNO）的挥发和解离，影响无机气溶胶的形成过程。本研究利用氮和氧同位素组成发现了无机氮气溶胶的主要来源贡献，获得的信息对于了解气象条件对形成的影响和区域传输的贡献具有重要意义。
