Similarities and differences in PM10 and PM2.5 concentrations, chemical compositions and sources in Hefei City, China.

Atmospheric particulates were sampled in Hefei City, China from October 2016 to January 2017 to compare chemical compositions and sources of PM2.5 (particle size smaller than 2.5 µm) and PM10 (particle size smaller than 10 µm). The mean levels of PM2.5 and PM10 were 81 and 109 µg/m3, which are higher than the health threshold levels regulated by national and international standards. During the sampling period, AQI (Air Quality Index) was strongly correlated with PM2.5 (Pearson's coefficient r = 0.94) rather than PM10 concentrations. The PM2.5/PM10 ratios were approximately 0.7, revealing the characteristics of fine particle pollution. Pollution elements (S, Zn, Cu and Pb) took up a large proportion of the composition and had high enrichment factors of 437, 385, 20 and 53, respectively, in PM10. Coal combustion and high-tech manufacture industry discharges were suggested to be the main pollution sources of both PM2.5 and PM10. The PM2.5/PM10 ratios of anthropogenic element concentrations were much higher than ratios of earth crust element. As compared to PM10, S and Pb in PM2.5 had larger EFs, indicating that pollution elements were predominantly enriched in PM2.5. Furthermore, a paired sample t-test confirmed similar sources of PM2.5 and PM10. Our study provides basic database to evaluate the heavy metal pollution status of atmospheric particulates in Chinese cities.

Levels, characteristics and health risk assessment of VOCs in different functional zones of Hefei.

In order to study the characteristics and health risk of VOCs in the ambient air in the typical developing cities in China, the research was conducted in five functional zones in Hefei from September 2016 to January 2017. The average concentrations of total measured VOCs in traffic zone was the largest (85.94 µg m-3), followed by industrial zone (64.84 µg m-3), development zone (58.92 µg m-3), resident zone (57.31 µg m-3), and background zone (54.94 µg m-3). Cl-VOCs were most abundant species in chlorinated VOCs (85.06%), which showed much higher level in industrial zone. the mean value of BTEX found in presented study was 65.19 µg m-3. Based on the specific VOC ratio method (B/T), the observed sites were greatly affected by the traffic emissions. The ratios of T/B, E/B and X/B were 1.15, 1.35 and 0.47, respectively, possibly due to the aging air mass. Carcinogenic risks for benzene, carbon tetrachloride, trichloroethylene, 1, 2-dichloroethane and chloroform were higher than the general acceptable risk level of 1.00 × 10-6. Potential non-carcinogenic risk assessment showed that hazard quotient (HQ) of 10 VOCs not exceeded unity, but the hazard risk index (HI) at site ED, LY, YH and HD were both higher than 1.

Characteristic and Source of Atmospheric PM10- and PM2.5-bound PAHs in a Typical Metallurgic City Near Yangtze River in China.

The characteristics of atmospheric PM10- and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) were investigated in Tongling city, China. Results showed that the total concentrations of PM10- and PM2.5-bound PAHs exhibited distinct seasonal and spatial variability. The metallurgic sites showed the highest PAH concentrations, which is mainly attributed to the metallurgic activities (mainly copper ore smelting) and coal combustion as the smelting fuel. The rural area showed the lowest concentrations, but exhibited significant increase from summer to autumn. This seasonal fluctuation is mainly caused by the biomass burning at the sites in the harvest season. The diagnostic ratio indicated that the main PAHs sources were vehicle exhausts, coal combustion and biomass burning. The total BaP equivalent concentration (BAP-TEQ) was found to be maximum at DGS site in winter, whereas it was minimum at BGC site in summer. Risk assessment indicates that residential exposure to PAHs in the industrial area, especially in the winter season, may pose a greater inhalation cancer risk than people living in living area and rural area.

Particle-Associated Polycyclic Aromatic Hydrocarbons (PAHs) in the Atmosphere of Hefei, China: Levels, Characterizations and Health Risks.

Airborne PM2.5 and PM10 samples were collected in summertime (August 2015) and wintertime (December 2015-January 2016) in an industrial complex area in Hefei, China. The average concentrations of PM2.5 and PM10 (90.5 and 114.5 µg/m3, respectively) were higher than the regulated levels of China National Ambient Air Quality Standard (grade I) and the WHO Ambient (outdoor) Air Quality and Health Guideline Value. Seasonal variations in PM2.5/PM10 indicated that the secondary sources of particulate matters, formed by gas-to-particle conversion, were enhanced in summer due to longer time of solar radiation and higher temperature. The total concentrations of PM2.5- and PM10-associated PAHs were 5.89 and 17.70 ng/m3 in summer as well as 63.41 and 78.26 ng/m3 in winter, respectively. Both PM2.5- and PM10-associated PAHs were dominated by 4- to 6-ring PAHs, suggesting that the fossil fuel combustion and vehicle emissions were the primary sources of PAHs in atmospheric particulate matters in Hefei. The total concentration of PAHs had a slightly higher correlation coefficient with PM2.5 (R = 0.499, P < 0.05) than PM10 (R = 0.431, P > 0.05), indicating the higher association tendency of PAHs with PM2.5. The coefficient of divergence analysis showed that the compositions of PAH were quite different between summer and winter. Total BaP equivalent concentration (BaP-TEQ) for particulate-bound PAHs in winter (58.87 ng/m3) was higher than that in summer (5.53 ng/m3). In addition, particulate-bound PAHs in winter had an inhalation cancer risk (ICR) value of 2.8 × 10-3, which was higher than the safe range (10-4-10-6).

Levels and Sources of PAHs in Air-borne PM2.5 of Hefei City, China.

This work studied the concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) in air-borne particulate matter of Hefei, China. Samples of PM2.5 were collected daily at two sites during May, 2014, and January, 2015. The average daily concentration of PM2.5 was 96.88 µg m-3, which is higher than the 2012 China Ambient Air Quality Standard (GB3095-2012 24-h grade II) of 75 µg m-3. The concentrations of 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography-mass spectrometry. The PM2.5-bound PAH concentrations ranged from 4.92 to 71.00 ng m-3 (mean = 21.34 ng m-3), and exhibited obvious seasonal (31.38 ng m-3 in winter and 14.05 ng m-3 in summer) and spatial variability (27.23 ng m-3at site ME and 18.20 ng m-3 at site MS). Meteorological conditions such as ambient temperature, wind speed and humidity had influences on the concentrations of PAHs. As an index for PAH carcinogenicity, the annual average concentration of benzo(a)pyrene ranged from 0.46 to 2.31 ng m-3, with a mean of 1.15 ng m-3. This mean was lower than the China Ambient Air Quality Standard (GB3095-2012) of 2.5 ng m-3. The diagnostic PAH ratios and principal component analysis (PCA) suggested that combustion of coal and vehicle emissions were the main sources of PAHs in PM2.5.