Characterization of PM2.5 Major Components and Source Investigation in Suburban Hong Kong: A One Year Monitoring Study

Abstract

PM 2.5 filter sampling was conducted on a daily basis at the HKUST Air Quality Research Supersite (AQRS) for one year from March 2011 to February 2012. Approximately one fifth of the filter samples were subjected to full chemical analysis including major ions, elements, organic carbon (OC), elemental carbon (EC), and non-polar organic compounds (NPOCs). The major ions (sulfate, nitrate, and ammonium) were compared with those measured online by a MARGA system and the two sets of data were found in agreement within 25% or better. The major PM 2.5 components (crustal materials, organic matter, soot, ammonium sulfate, ammonium nitrate, and non-crustal trace elements) accounted for 90% of the measured mass with sulfate being the most abundant (32.0%), followed by organic matter (23.5%) and ammonium (11.8%). The monthly variation patterns for different components suggested variable regional/super-regional sources, reflecting variation of transport contribution caused by shifts in synoptic weather conditions.Receptor modeling analysis by Positive Matrix Factorization revealed that secondary sulfate formation process (annual average of 31%), biomass burning (23%), and secondary nitrate formation process (13%) were the three dominant contributing sources to the observed PM 2.5 at HKUST AQRS throughout the sampling year. The PM 2.5 mass concentrations of all the individual sampling days were within the recently-proposed AQOs standards by the Hong Kong government (35 µg/m 3 for annual average and 75 µg/m 3 for 24-hr average) while approx. 52% of the sampling days were recorded with PM 2.5 concentrations exceeding the WHO health 24-hr standards of 25 µg/m 3 . Major composition and source analysis showed that the increased mass concentrations on high PM days were mainly caused by air pollutant transport from the outside-Hong Kong regions. Results from this study indicate the importance of regional/super-regional strategies such as reduction in SO 2 , NO 2 (precursors for secondary inorganic aerosols) and restricting biomass burning for lowering PM 2.5 in Hong Kong.

Physical and chemical characterization of ambient aerosol by HR‐ToF‐AMS at a suburban site in Hong Kong during springtime 2011

“…On average, the AMS measured only about 60% of SO 4 2À , 50% of NH 4 + , and only 33% of NO 3 À as compared to MARGA. The 24 h averaged SO 4 2À concentrations measured by MARGA agree well with filter-based measurements with a slope of 0.99 and R 2 of 0.70 [Huang et al, 2013]. Hence, MARGA denuder efficiency is not an issue.…”

Source Apportionment of Sulfate and Nitrate over the Pearl River Delta Region in China

“…Table 1 presents the evaluation (37 stations on average) of the 2-m temperature, wind speed, and wind direction as simulated by WRF. The index of agreement (IOA) formula used for wind direction in this study differs from the formulation for scalar variables; it follows that introduced by Kwok et al [9]. For the wind speed simulation results, the root-mean-square error (RMSE) ranged from 1.4 to 1.8, the normalized mean bias (NMB) ranged from 0.29 to 0.37, and the IOA ranged from 0.68 to 0.7.…”

Investigation of Biomass Burning Chemical Components over Northern Southeast Asia during 7-SEAS/BASELInE 2014 Campaign

“…Zn probably originated from vehicles and fossil fuel combustion (Nava et al, 2015;Longhin et al, 2016), while Al and Ca 2+ mostly characterize crustal origins (Al-Khashman, 2009;Tao et al, 2013;Wang et al, 2016). The second component reflected high loadings of NO 3 -, K + and levoglucosan, representing the contribution of BB (Ruy et al, 2007;Zhang et al, 2007;Jung et al, 2014;Huang et al, 2014). Levels of K + and NO 3 -have been shown to increase during agricultural waste burning periods (Ezcurra et al, 2001).…”

“…The first part (32% of variance) showed high loading of SO 4 2-, NH 4 + , Ca 2+ , Al and Zn. SO 4 2-is a source associated with the formation of secondary sulfate aerosols from combustion sources (Tao et al, 2013;Huang et al, 2014), while NH 4 + originates from agricultural activity (Zhang et al, 2007). Zn probably originated from vehicles and fossil fuel combustion (Nava et al, 2015;Longhin et al, 2016), while Al and Ca 2+ mostly characterize crustal origins (Al-Khashman, 2009;Tao et al, 2013;Wang et al, 2016).…”