Supplementary material to "Atmospheric aerosol compositions over the South China Sea: Temporal variability and source apportionment"

Author(s):  
Hong-Wei Xiao ◽  
Hua-Yun Xiao ◽  
Li Luo ◽  
Chun-Yan Shen ◽  
Ai-Min Long ◽  
...  
2017 ◽  
Vol 17 (4) ◽  
pp. 3199-3214 ◽  
Author(s):  
Hong-Wei Xiao ◽  
Hua-Yun Xiao ◽  
Li Luo ◽  
Chun-Yan Shen ◽  
Ai-Min Long ◽  
...  

Abstract. In order to evaluate impacts of different source emission on marine atmospheric particles over the South China Sea (SCS), major inorganic ionic concentrations (Na+, Cl−, SO42−, Ca2+, Mg2+, K+, NH4+ and NO3−) were determined in total suspended particulates (TSPs) at Yongxing Island, from March 2014 to February 2015. The annual average concentration of TSPs was 89.6 ± 68.0 µg m−3, with 114.7 ± 82.1, 60.4 ± 27.0 and 59.5 ± 25.6 µg m−3 in cool, warm and transition seasons, respectively. Cl− had the highest concentration, with an annual average of 7.73 ± 5.99 µg m−3, followed by SO42− (5.54 ± 3.65 µg m−3), Na+ (4.00 ± 1.88 µg m−3), Ca2+ (2.15 ± 1.54 µg m−3), NO3− (1.95 ± 1.34 µg m−3), Mg2+ (0.44 ± 0.33 µg m−3), K+ (0.33 ± 0.22 µg m−3) and NH4+ (0.07 ± 0.07 µg m−3). Concentrations of TSPs and the major ions showed seasonal variations, which were higher in the cool season and lower in the warm and transition seasons. Factors of influence were wind speed, temperature, relatively humidity, rain and air mass source region. Back trajectories, concentration-weighted trajectories (CWTs), and positive matrix factorization (PMF) of chemical compositions were analyzed for source apportionment, source contribution and spatiotemporal variation of major ions. Back trajectories and CWTs showed that air masses at Yongxing Island were mainly from the northeast, southwest and southeast in the cool, warm and transition seasons, respectively. The PMF results showed that 77.4 % of Na+ and 99.3 % of Cl− were from sea salt; 60.5 % of NH4+ was from oceanic emission. Anthropogenic sources were very important for atmospheric aerosols over the island. Secondary inorganic aerosol of SO2 and NOx from fossil fuel combustion (especially coal in Chinese coastal regions) was the dominant source of NO3− (69.5 %) and SO42− (57.5 %).


2016 ◽  
Author(s):  
Hong-Wei Xiao ◽  
Hua-Yun Xiao ◽  
Li Luo ◽  
Chun-Yan Shen ◽  
Ai-Min Long ◽  
...  

Abstract. Major inorganic chemical ionic concentrations (Na+, Cl−, SO42−, Ca2+, Mg2+, K+, NH4+, NO3−) were determined in total suspended particulates (TSP) at Yongxing Island in the South China Sea (SCS), from March 2014 to February 2015. The annual average concentration of TSP was 89.6 ± 68.0 μg/m3, with 114.7 ± 82.1, 60.4 ± 27.0, and 59.5 ± 25.6 μg/m3 in cool, warm, and transition seasons, respectively. Cl− had the highest concentration, with an annual average of 7.73 ± 5.99 μg/m3, followed by SO42− (5.54 ± 3.65 μg/m3), Na+ (4.00 ± 1.88 μg/m3), Ca2+ (2.15 ± 1.54 μg/m3), NO3− (1.95 ± 1.34 μg/m3), Mg2+ (0.44 ± 0.33 μg/m3), K+ (0.33 ± 0.22 μg/m3), and NH4+ (0.07 ± 0.07 μg/m3). Concentrations of TSP and the major ions showed seasonal variations, higher in the cool season and lower in the warm and transition seasons, which were influenced by wind speed, temperature, relatively humidity, rain, and air masses. Back trajectories, concentration weighted trajectories (CWT), and positive matrix factorization (PMF) of chemical compositions were analyzed for source apportionment, source contribution, and spatio-temporal variation of major ions. Back trajectories and CWTs showed that air masses at Yongxing Island were mainly from the northeast, southwest, and southeast in the cool, warm, and transition seasons, respectively. Na+ and Cl− were mainly from sea salt, which made up 74 % and 82 %, respectively. Asian dust contributed 50 % of Ca2+ to the marine aerosols. Anthropogenic sources were very important for atmospheric aerosols over the island. Fossil fuel combustion (especially coal in Chinese coastal regions) was the important sources of NO3− (56 %) and SO42− (22 %). Biomass burning in Asia accounted for 41 % of K+. 69 % of NH4+ and 38 % of SO42− were of marine biogenic sources.


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