[Characterization and Health Risk Assessment of Heavy Metals in PM2.5 in Xiamen Port].

PM2.5 samples at Haitian and Songyu container terminals in Xiamen Port were collected in summer and autumn/winter in 2020 and analyzed for 20 elements to investigate their temporal-spatial distribution features, sources, and health risk. The results showed that the levels of PM2.5 were relatively low and did not show significant spatial and diurnal differences. Ca and Si were the main crustal elements, and Zn and Mn were the main heavy metals in PM2.5. Compared with GB 3095-2012 guidelines, Cr(Ⅵ) was in the range of 27.4-28.6 times above the standard. Under the influence of monsoon and port throughput, the concentrations of some elements in summer were higher than those in autumn/winter. Significant diurnal variations were observed for Cu, Zn, SO2, and NO2 but not for V and Ni. Industrial sources were identified as the primary contributor (55.2%-59.4%), followed by traffic (28.7%-31.3%), ship emissions (7.1%-7.7%), and sea salt plus construction dust (4.8%-5.8%). The results of health risk assessment showed that heavy metals in PM2.5in Xiamen Port had potential carcinogenic risk (ECR>1(10-5) to people living near the port, and Cr(Ⅵ), V, and As together accounted for 97.3%-97.5% of the total risks; however, the non-carcinogenic risk was negligible (HI<1), and the major contributors were V, Mn, Ni, and As (89.6%-91.2%). The relative contributions of each contributor to ECR was in the order of traffic (47.2%-49.4%)>industrial (23.8%-24.2%)>ship emissions (16.9%-20.8%)>sea salt plus construction dust (5.7%-12.1%), and the relative contribution to HI was in the order of traffic (38.7%-42.3%)>industrial (24.5%-28.2%)>ship emissions (24.1%-27.2%)>sea salt plus construction dust (5.4%-9.6%).

Solubility of aerosol minor and trace elements in Xiamen Island, Southeast China: Size distribution, health risk and dry deposition.

Aerosol element solubility is essential to evaluate the damage to the environment and human health. In this work, the size distribution of total and soluble elements in eight particle size ranges with diameter <0.25, 0.25-0.44, 0.44-1.0, 1.0-1.4, 1.4-2.5, 2.5-10, 10-16 and >16 µm was investigated in Xiamen Island, southeast China from March 2018 to June 2020. The results showed that both total and soluble elements exhibited significant size dependence without obvious seasonal variations, and their relative contributions to PM1 mass were much lower than in particles larger than 1 µm. The correlations between some elements in soluble fraction were quite different from those in total fraction and the correlations also varied with particle size due to their different solubility. The solubility of Al, Fe, Ag and Cr was relatively low compared with other elements. Moreover, the solubility of Na, Mg, Ca, Mn and Ag was less dependent on particle size while Al, Fe and other trace elements exhibited the highest solubility in PM1 and the lowest in PM>10. Overall, the solubility of elements is primarily a function of aerosol origin and size. The carcinogenic risks of metal exposure via inhalation for children (3.31 × 10-6) and adults (4.42 × 10-6) were slightly higher than the guideline of cancer risk with >60 % from V. As for non-carcinogenic risk, the hazard index values for children and adults were 1.59 and 0.53, respectively, with Mn, V and Ni together accounting for >85 % of the risk. >85 % of the size-dependent dry deposition fluxes of the selected soluble elements over the Xiamen Bay were contributed by particles larger than 10 µm due to their high deposition velocities. The atmospheric inputs of bioavailable Fe and Cu to the sea exceeded the required amounts relative to inorganic nitrogen to meet the growth of phytoplankton.

[Source Apportionment of Black Carbon Aerosol in the North Suburb of Nanjing].

Based on one year real-time measurements from a seven-wavelength Aethalometer combined with an Aethalometer model, the measured aerosol absorption coefficients at different wavelengths have been used to apportion the contribution of fossil fuel and biomass burning sources to the total black carbon (BC) mass concentration in the north suburb of Nanjing. Good consistency in the relationship between the Angstrom absorption exponent(α)and the ratio of BC from biomass burning sources to total BC (BB) was obtained during this period. The α was highest in winter and lowest in summer, which indicates the change in the source of the absorbing aerosols and their relative source strength. The BC and the BC from fossil fuel (BCff) and biomass burning (BCbb) mass concentrations exhibit significant diurnal variation, with higher values during 07:00 to 09:00 (local time) and 18:00 to 21:00. The BCff was three to five times higher than the BCbb and contributes greatest to the BC mass concentrations throughout the day. Night time BC values were about a factor of 1.2 higher than day time BC values. Meanwhile, the concentration weighted trajectory (CWT) analysis indicates that the highest value of BC was concentrated in the Zhejiang, Anhui, Jiangxi, and Fujian provinces.

[Characteristics of Black Carbon Aerosol and Influencing Factors in Northern Suburbs of Nanjing].

Based on the hourly averaged data of black carbon(BC) aerosol, PM2.5, gaseous pollutants, and meteorological data in the northern suburb of Nanjing from January to October 2015, characteristics and influencing factors of BC concentration variation were analyzed. The mean concentration of BC was found to be (2524±1754) ng·m-3 during the observation period. BC concentrations in Nanjing showed strong seasonality, the highest mean concentration of BC occurred during winter reaching (3468±2455) ng·m-3, and the lowest mean BC concentration was found during spring being (2142±1240) ng·m-3; a distinct diurnal variation of BC with two high peaks occurred, one in the morning during 07:00 to 08:00 and the other in late evening during 21:00 to 22:00 local time. The strong correlation between BC and NOx indicated a greater impact of vehicle emissions on BC concentration, while a lower rate of ΔBC/ΔCO was found in the northern suburb of Nanjing, suggesting that biomass burning emission might be another important source of BC in here. BC concentration increased with decreasing wind speed. BC concentration lower than 2000 ng·m-3 mainly occurred in westerly wind and adjacent wind in all seasons, whereas BC concentration higher than 6000 ng·m-3 more frequently appeared in easterly winds in autumn and winter. BC concentration was higher in hazy and heavy hazy weather, which were 2 and 2.3 times as large as that in non-hazy weather, respectively.