Sources appointment and health risks of PM_(2.5)-bound trace elements in a coastal city of southeastern China

To gain a comprehensive understanding of sources and health risks of trace elements in an area of China with high population densities and low PM_(2.5)concentrations,15 trace elements(Al,K,Ca,Ti,V,Cr,Mn,Fe,Ni,Cu,Zn,As,Sn,Ba,Pb)in PM_(2.5)were monitored from December 2020 to November 2021 in a representative city,Xiamen.The concentrations of trace elements in Xiamen displayed an obvious seasonal variation and were dominated by K,Fe,Al,Ca and Zn.Based on Positive Matrix Factorization analysis,source appointment revealed that the major sources of trace elements in Xiamen were traffic,dust,biomass and firework combustion,industrial manufacture and shipping emission.According to health risk assessment combined with the source appointment results,it indicated that the average noncarcinogenic risk was below the threshold and cancer risk of four hazardous metals(Cr,Ni,As,Pb)exceeded the threshold(10^(-6)).Traffic-related source had almost half amount of contribution to the health risk induced by PM_(2.5)-bound trace elements.During the dust transport period or Spring Festival period,the health risks exceeded an acceptable threshold even an order of magnitude higher,suggesting that the serious health risks still existed in low PM_(2.5)environment at certain times.Health risk assessment reminded that the health risk reduction in PM_(2.5)at southeastern China should prioritize traffic-related hazardous trace elements and highlighted the importance of controlling vehicles emissions in the future.

Atmospheric oxidation capacity and O_(3) formation in a coastal city of southeast China:Results from simulation based on four-season observation

The pollution of atmospheric ozone in China shows an obvious upward trend in the past decade.However,the studies on the atmospheric oxidation capacity and O_(3)formation in four seasons in the southeastern coastal region of China with the rapid urbanization remain limited.Here,a four-season field observation was carried out in a coastal city of southeast China,using an observation-based model combining with the Master Chemical Mechanism,to explore the atmospheric oxidation capacity(AOC),radical chemistry,O_(3)formation pathways and sensitivity.The results showed that the average net O_(3)production rate(14.55 ppbv/hr)in summer was the strongest,but the average O_(3)concentrations in autumn was higher.The AOC and ROx levels presented an obvious seasonal pattern with the maximum value in summer,while the OH reactivity in winter was the highest with an average value of 22.75 sec^(-1).The OH reactivity was dominated by oxygenated VOCs(OVOCs)(30.6%-42.8%),CO(23.2%-26.8%),NO_(2)(13.6%-22.0%),and alkenes(8.4%-12.5%)in different seasons.HONO photolysis dominated OH primary source on daytime in winter,while in other seasons,HONO photolysis in the morning and ozone photolysis in the afternoon contributed mostly.Sensitivity analysis indicated that O_(3)production was controlled by VOCs in spring,autumn and winter,but a VOC-limited and NOx-limited regime in summer,and alkene and aromatic species were the major controlling factors to O_(3)formation.Overall,the study characterized the atmospheric oxidation capacity and elucidated the controlling factors for O_(3)production in the coastal area with the rapid urbanization in China.

Aerosol light absorption in a coastal city in Southeast China:Temporal variations and implications for brown carbon

Light-absorbing carbonaceous aerosols including black carbon(BC) and brown carbon(BrC)play significant roles in atmospheric radiative properties. One-year measurements of aerosol light absorption at multi-wavelength were continuously conducted in Xiamen,southeast of China in 2014 to determine the light absorption properties including absorption coefficients(σabs) and absorption ?ngstr?m exponent(AAE) in the coastal city.Light absorptions of BC and BrC with their contributions to total light absorption were further quantified. Mean σabsat 370 nm and 880 nm were 56.6 ± 34.3 and 16.5 ± 11.2 Mm-1,respectively. σabspresented a double-peaks diurnal pattern with the maximum in the morning and the minimum in the afternoon. σabswas low in warm seasons and high in cold seasons. AAE ranged from 0.26 to 2.58 with the annual mean of 1.46, implying that both fossil fuel combustion and biomass burning influenced aerosol optical properties. σabsof BrC at 370 nm was 24.0 ± 5.7 Mm-1, contributing 42% to the total absorption. The highest AAE(1.52 ± 0.02) and largest BrC contributions(47% ± 4%) in winter suggested the significant influence of biomass burning on aerosol light absorption. Long-distance air masses passing through North China Plain and the Yangtze River Delta led to high AAE and BrC contributions. High AAE value of 1.46 in July indicated that long-range transport of the air pollutants from intense biomass burning in Southeast Asia would affect aerosol light absorption in Southeast China. The study will improve the understanding of light absorption properties of aerosols and the optical impacts of BrC in China.

Pharmaceutical compounds in aquatic environment in China： locally screening and environmental risk assessment

An environmental risk assessment was performed for pharmaceutical compounds present in the aquatic environment of China. Predicted environmental concentration （PEC） of the compounds were calculated according to European Medicines Evaluation Agency （EMEA） guidelines. Available ecotoxicological data compromised by applying a very conservative assessment factor （AF） were employed to calculate the predicted noeffect concentration （PNEC）. The screening principle and the risk assessment were based on risk quotient （RQ）, which derived from the PEC and related PNEC values. PEC results indicated that all the compounds except sulfadimethoxine and levocamitine, should carry out phase II risk assessment in EMEA guideline. RQ values suggested that more than 36 pharmaceuticals may be imposed health threats to the aquatic environment; especially the antibiotic therapeutic class including amoxicillin, sulfasalazine, trimethoprim, oxytetracycline and erythromycin showed high RQ values. These substances with high RQ value （RQ≥ 1） were regarded as top- priority pharmaceuticals for control in the aquatic environment of China. However, the antibiotic substances which had low risk quotient （RQ 〈 1）, should be reassessed by its potentially induced resistance under low concentration in future.

Chemical characterization and source apportionment of atmospheric submicron particles on the western coast of Taiwan Strait, China

Taiwan Strait is a special channel for subtropical East Asian Monsoon and its western coast is an important economic zone in China. In this study, a suburban site in the city of Xiamen on the western coast of Taiwan Strait was selected for fine aerosol study to improve the understanding of air pollution sources in this region. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer（HR-To F-AMS） and an Aethalometer were deployed to measure fine aerosol composition with a time resolution of 5 min from May 1to 18, 2015. The average mass concentration of PM1 was 46.2 ± 26.3 μg/m^3 for the entire campaign. Organics（28.3%）, sulfate（24.9%）, and nitrate（20.6%） were the major components in the fine particles, followed by ammonium, black carbon（BC）, and chloride. Evolution of nitrate concentration and size distribution indicated that local NOx emissions played a key role in high fine particle pollution in Xiamen. In addition, organic nitrate was found to account for 9.0%–13.8% of the total measured nitrate. Positive Matrix Factorization（PMF）conducted with high-resolution organic mass spectra dataset differentiated the organic aerosol into three components, including a hydrocarbon-like organic aerosol（HOA） and two oxygenated organic aerosols（SV-OOA and LV-OOA）, which on average accounted for 27.6%,28.8%, and 43.6% of the total organic mass, respectively. The relationship between the mass concentration of submicron particle species and wind further confirmed that all major fine particle species were influenced by both strong local emissions in the southeastern area of Xiamen and regional transport through the Taiwan Strait.