Chemical characterization of humic-like substances (HULIS) in PM2.5 in Lanzhou, China

Abstract

Evaporative light scattering detection (ELSD) was applied to quantify HULIS (humic-like substances) for the first time in 2012 winter and 2013 summer at an urban site in Lanzhou. Water soluble organic carbon (WSOC), water soluble inorganic ions, and carbonaceous species (OC/EC) were also analyzed. The results show that OM (Organic Matter = OC × 1.6, constituting 45.8% to PM 2.5 ) was the most abundant species, followed by SNA (SO 4 2− + NO 3 − + NH 4 + , constituting 23.4% to PM 2.5 ). The chemical species were in the order of:The annual average concentration of HULIS was 4.70 μg/m −3 and HULISc (carbon content of HULIS) contributed 6.19% to PM 2.5 and 45.6% to WSOC, indicating that HULIS was the most important components of WSOC. The concentration of HULIS was 2.14 ± 0.80 μg/m 3 in summer and 7.24 ± 2.77 μg/m 3 in winter,respectively. The concentrations of HULIS were relatively low and stable in summer, while high and varied dramatically in winter. The abundance of HULISc in WSOC shows a more concentrated distribution in Lanzhou, with a range between 0.28-0.57. The ratios of HULIS/K + were 6.25 ± 1.41 and 6.14 ± 1.96 in summer and winter, respectively, suggesting there were other significant sources in addition to biomass burning emissions. HULIS and WSOC exhibited similar seasonal variation and had a strong positive correlation. In addition to the good relationship (0.89) between HULIS and Cl − in winter, the great enhancement of HULIS with significantly high Cl − and relatively low K + in winter indicated that residential coal burning was probably an important HULIS source in Contents lists available at ScienceDirectScience of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n v winter. Correlation and back trajectory analysis suggested that biomass burning and secondary formation were also important HULIS sources and the contribution of HULIS from dust could be neglected. Adverse meteorological conditions were also important factors for the accumulation of HULIS in winter.

Summertime Day-Night Differences of PM2.5 Components (Inorganic Ions, OC, EC, WSOC, WSON, HULIS, and PAHs) in Changzhou, China

“…Additionally, linear regression slopes in Figure 5b show that HULIS-C/WSOC ratio (0.64) in daytime was slighter higher that in nighttime (0.57), suggesting that the contribution of photochemical production of HULIS-C in day might be more significant than that during night. The HULIS-C/WSOC ratio in this study is comparable to that observed in Shanghai (0.6) [16] and Hongkong (0.57) [50], but higher than that in Lanzhou (0.46) [51].…”

A review of current knowledge concerning PM<sub>2. 5</sub> chemical composition, aerosol optical properties and their relationships across China

“…Seasonal average contributions are only shown here for Jinan , Zhengzhou , Fuzhou (Xu et al, 2012b), Chengdu (Tao et al, , 2014b, Lanzhou (Tan et al, 2016b;Wang et al, 2016c), Xiamen ), Changsha (Tang et al, 2017 and Haikou due to the incomplete data in Xi'an and Chongqing (Fig. 7).…”

Characteristic and Spatiotemporal Variation of Air Pollution in Northern China Based on Correlation Analysis and Clustering Analysis of Five Air Pollutants

“…To mitigate air pollution in this area, the Chinese government implemented “Law on the Prevention and Control of Atmospheric Pollution” in 2015. In addition, “2+26” cities were selected with critical strategies in 2017 (H. Li et al, 2018), which were designed to manage the primary‐fuel quality, combustion technology, and emission index for residents and industries (Tan et al, 2016; W. Wang et al, 2017). There is no time to delay to assess the risks arising by air pollution and to improve the air quality for human health.…”