Chemical Characterization of Two Seasonal PM2.5 Samples in Nanjing and Its Toxicological Properties in Three Human Cell Lines

Abstract

PM2.5 pollution is of great concern in China due to its adverse health effects. Many diseases have been proven to be associated with PM2.5 components, but the effects of chemical characteristics of PM2.5 on toxicological properties, especially in different human organs, are poorly understood. In this study, two seasonal PM2.5 samples (summer and winter) were collected in Nanjing, and their chemical compositions (heavy metals, water-soluble ions, organic carbon (OC), and elemental carbon (EC)) were analyzed. Human lung epithelial carcinoma cells (A549), human hepatocellular liver carcinoma cells (HepG2), and human neuroblastoma cells (Sh-Sy5y) were employed to evaluate the toxicological properties of the collected PM2.5. The results showed that the average mass concentrations of PM2.5 were lower in summer (51.3 ± 21.4 μg/m3) than those in winter (62.1 ± 21.5 μg/m3). However, the mass fractions of heavy metals, OC, and EC exhibited an opposite seasonal difference. Among all tested fractions, water-soluble ions were the major compositions of particles in both summer and winter, especially the secondary ions (SO42−, NO3− and NH4+). Besides, the ratio of OC/EC in PM2.5 was greater than two, indicating serious secondary pollution in this area. The NO3–/SO42− ratio (< 1) suggested that fixed sources made important contributions. The toxicological results showed that PM2.5 in the summer and winter significantly inhibited cell viability (p < 0.01) and induced intracellular reactive oxygen species (ROS) production (p < 0.01). Moreover, the viability inhibition in A549, Sh-Sy5y, and HepG2 cells was more prominent in summer, especially at high PM2.5 (400 μg/mL) (p < 0.05), and the induction of reactive oxygen species (ROS) in A549 and Sh-Sy5y cells was also more evident in summer. Such seasonal differences might be related to the variations of PM2.5 components.

Chemical Characterization of Seasonal PM2.5 Samples and Their Cytotoxicity in Human Lung Epithelial Cells (A549)

“…In addition, the WSOC had the highest proportion in the summer and fall, followed by winter and spring. Similar measurements were also reported in our previous study [28]. High temperatures and strong sunlight facilitate the production of secondary organic aerosols, which may explain the increased organic carbon proportions in the summer [39].…”

“…Quartz filters containing PM 2.5 were cut into small strips and placed into ultrapure water. The samples were treated using ultrasonic extraction in an ice bath for 20 min and repeated 3 times to extract the PM 2.5 [28,30]. Different filters of the same season were extracted, vacuum freeze-dried and pooled to have a homogeneous batch of particles, representative of the sampling season.…”

“…Generally, emission sources and atmospheric conditions dictate the chemical composition of PM 2.5 in Nanjing, resulting in seasonal differences in PM 2.5 composition, which will further affect its toxic properties [26,27]. For example, the inhibition of cell viability caused by PM 2.5 was higher in summer samples [28]. In this study, PM 2.5 samples were collected from the northern suburbs of Nanjing in four seasons of 2016 to determine the variations in its components, including water-soluble organic carbon (WSOC), water-soluble ions and heavy metal elements.…”

Preface: Special Issue on Air Quality Assessment for Environmental Policy Support: Sources, Emissions, Exposures, and Health Impacts

“…Two studies in this Special Issue of Environments concerned the study of PM 2.5 also deepening its chemical characterization, in order to understand if and how the composition of the particulate could determine a different impact on health and possibly suggest a common source. In particular, Zhang et al [8] performed the chemical characterization of PM 2.5 in Nanjing (China) and evaluated its toxicological properties in three human cell lines. Authors collected two seasonal PM 2.5 samples (summer and winter) and investigated their chemical compositions (heavy metals, water-soluble ions, organic carbon (OC), and elemental carbon (EC)).…”

Variations in Nocturnal Residual Layer Height and Its Effects on Surface PM2.5 over Wuhan, China

“…The environmental pollution caused by high fine particles with diameters <2.5 µm (PM 2.5 ) leads to low visibility, climate change, and health effects [6][7][8]. Moreover, the chemical reactions in the RL directly increase the near-surface nitrate concentration, which has adverse effects on people's health and damages human organs [9][10][11]. Therefore, the characteristics of the RL are worthy of research.…”