Day–night variation and size distribution of water-soluble inorganic ions in particulate matter in Ulsan, South Korea

Abstract

In the present study, 11 size classes of particulate matter were collected from a semi-rural site in the industrial city of Ulsan, South Korea in 2019 to investigate the size distribution and day-night variation of water-soluble inorganic ions (WSIIs). Approximately 70% of the detected WSIIs were found in fine particles, with Na + , Ca 2+ , Cl − , and NO 3 − dominant (~70%) in coarse particles and SO 4 2− , NO 3 − , and NH 4 + (SNA) dominant (~70%) in fine particles. Monthly variation in total WSIIs was observed, with the highest average concentration found in April for both coarse (2.71 μg/m 3 ) and fine particles (5.75 μg/m 3 ). Given that this month is characterized by prevailing southeasterly winds, these high levels may represent the adverse effects of industrial activity.Coefficients of divergence for individual WSIIs exhibited large variability, which is indicative of significant day-night differences in meteorology, chemistry, and source contributions. The size distributions of Na + , K + , F − , Cl − , NO 3 − , and SO 4 2− were bimodal, while Mg 2+ , Ca 2+ , and NH 4 + were unimodal. Peaks were generally found at 1.8-5.6 μm and 0.18-0.56 μm for coarse and fine particles, respectively. By plotting the linear relationship between the mole charge ratios of SNA, we found that coarse NO 3 − particles were mainly the result of heterogeneous reactions between HNO 3 and sea salts or crustal species, while the homogeneous reaction of HNO 3 and NH 3 played a crucial role in the formation of fine NO 3 − particles. In conclusion, though day-night variation in WSIIs was apparent, especially in SNA, the formation pathways for both coarse and fine particles were similar for day and night. Based on the verification of the formation mechanisms for WSIIs at this semirural site, the influence of industrial activity on the secondary formation of PM in urban and industrial areas can be investigated further.

Study on the Characteristics of Size-Segregated Particulate Water-Soluble Inorganic Ions and Potentially Toxic Metals during Wintertime in a High Population Residential Area in Beijing, China

“…Figure 9 show the carcinogenic and non-carcinogenic risks of each toxic elements for children and adults within PM 1.1 , PM 1.1-2.0 , PM 2.0-3.3 , PM 3.3-7.0 , and PM >7.0 in Beijing during the sampling period. As expected, most of the toxic metals exhibited high CR values in the smaller particles (<1.1 µm) because of their high deposition efficiencies [38].The total CR values (reached 2.42 × 10 −6 for children and 66.71 × 10 −6 for adults, respectively) were exceeded the acceptable level (1 × 10 −6 ), indicating that we should pay more attention to these toxic elements [43]. Compared with previous studies, carcinogenic risks for children and adults is lower than those carcinogenic risks in Nanjing (2.57 × 10 −5 for children and 4.59 × 10 −5 for adults) [39], in Linfen (2.91 × 10 −5 for children and 7.75 × 10 −5 for adults) [9], In Changzhi (2.58 × 10 −6 for children and 10.31 × 10 −6 for adults) [33], in Kanpur (1.60 × 10 −5 for children and 3.99 × 10 −6 for adults) [63], and in Ningbo (6.24 × 10 −6 for children and 2.50 × 10 −5 for adults) [64].…”

“…Generally, PM can be classified as coarse particles (PM 10 with an aerodynamic diameter less than 10 µm), fine particles (PM 2.5 ) [42,43]. In our research, in order to facilitate statistical analysis, we regard particles <1.1 µm and 1.1-2.0 µm as fine particles (with an aerodynamic diameter less than 2.0 µm), and others as coarse particles PM >2.0 including (2.0-3.0 µm, 3.3-7.0 µm, >7.0 µm).…”

“…Many studies have reported that the mass concentration of size distribution varies in different conditions [43,44].The characteristics of atmospheric aerosols can be investigated based on the weather conditions [43] (T, RH, WS, and WD and atmospheric pollutants (SO 2 , CO, NO 2 and O 3 ) [29].…”

Size Distribution of Ambient Particulate Matter and Its Constituent Chemical Species Involving Saccharides During Early Summer in a Chinese Megacity

“…The marine salt sources of the Cl − , Na + , and K + were more evident in the coarse fraction. The marine salt sources of Cl − , Na + , and K + increased with the increasing PM size and peaked at the coarse fraction, whereas their coal combustion, biomass burning, and waste incineration sources decreased with the increasing PM size and peaked at the fine fraction (Van Do et al, 2021).…”