| 摘要: |
| PM2.5水溶性离子特征研究主要集中在大中型城市，为探讨珠海市PM2.5水溶性离子特征及来源，2016年6月至12月采集PM2.5样品，用离子色谱分析9种水溶性离子浓度。结果表明：珠海PM2.5总离子浓度处于较低水平，离子浓度有季节变化特征，表现为冬季＞秋季＞夏季；夏、秋季PM2.5呈碱性，冬季显酸性；从夏季到冬季，SO42-和NH4+在总离子中比例有减小趋势，NO3-比例有增大趋势。SO42-、NO3-、NH4+为主要组成成分，占离子总成分的85.07%，表明珠海市大气PM2.5二次污染较严重，NO3-/ SO42-均值0.2，表明以固定源污染为主。从气团聚类、离子相关性、富集因子分析和主因子分析等角度讨论来源和存在形式，珠海PM2.5水溶性离子受气团影响较大，来自陆地气团的离子浓度高于海洋气团；夏季到冬季，PM2.5受到80.2%的人为源和海洋源的混合源和16%的农业源贡献，离子主要存在形式有NH4HSO4、Mg(NO3)2、KNO3、Ca(NO3)2、NH4NO3、NaCl、KCl和CaCl2。 |
| 关键词: PM2.5 离子 来源 珠海 |
| DOI：10.7515/JEE192027 |
| CSTR： |
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| 基金项目:广东省青年创新人才项目（2015KQNCX215） |
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| Characteristics and sources of water-soluble ions in PM2.5 in the coastal city of Zhuhai, China |
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YU Juan, LI Ming, KANG Hui, WANG Lei, HUANG Jinyong
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1. School of Materials and Environment, Beijing Institute of Technology, Zhuhai 519000, China
2. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
3. Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application, Xi’an AMS Center, Xi’an 710061, China
4. Institute of Polar Environment, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230000, China
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| Abstract: |
| Background, aim, and scope Different sources of PM2.5 influence the chemical composition of airborne particles and ultimately, human health. Studies on the characteristics of water-soluble ions in PM2.5 have largely been conducted in inland areas, particularly for large and medium-sized cities. There are limited studies on water-soluble ions in PM2.5 for coastal cities. This study investigated the characteristics and sources of water-soluble ions in PM2.5 for Zhuhai, a typical coastal city in China. The study collected PM2.5 between June to December, 2016 to gain useful information and insights into pollution control strategies for local governments. Materials and methods PM2.5 samples were collected using a high-volume air sampler with a PM2.5 cutting head. Each sample was run for 48 h with quartz filter, where all filters were pre-combusted at 500℃. Filters were cut at 4 cm×4 cm to determine nine water-soluble ions by ion chromatography. Online data on meteorological parameters in Zhuhai were collected from the National Oceanic and Atmospheric Administration (NOAA). Results The concentrations of water-soluble ions in PM2.5 exhibited a significant seasonal variation, with levels in winter being higher than those in summer. The main components of PM2.5 were SO42-, NO3-, and NH4+, accounting for 85.07% of the total ion composition. From summer to winter, the proportion of SO42- and NH4+ in ions decreased, while the proportion of NO3- increased. Discussion Based on cluster analysis of back trajectory, the seasonal variations in ion concentrations were associated with different air masses. The concentrations associated with terrigenous air masses in winter were higher than the ocean air masses in summer and autumn. Based on the charge balance between total anion and cation equivalents, PM2.5 is alkaline in summer and autumn and acidic in winter. The high concentration of SO42-, NO3- and NH4+ in PM2.5 indicate that the level of secondary ions was relatively high. The mean ratio of NO3-/ SO42- was 0.2, demonstrating that the main source of water soluble ions were stationary source emissions in Zhuhai. Principal factor analysis demonstrated that the mix of man-made sources with oceanic sources contributed 80.2% of the PM2.5 while agricultural sources contributed 16%. Ion and enrichment factor correlations implied the form and sources of ions. Conclusions Anthropogenic activities play an important role in PM2.5 ion concentrations in Zhuhai. PM2.5 is likely to be acidic in winter. Air mass transport plays a major role in PM2.5 ions concentration, particularly in winter. Recommendations and perspectives The government needs be attentive to the possibility of stationary source emissions from the air mass in Zhuhai in winter. |
| Key words: PM2.5 ions sources Zhuhai |
