[Characteristics, Sources Apportionment, and Health Risks of PM2.5-bound PAHs and Their Derivatives Before and After Heating in Zibo City].

Atmospheric polycyclic aromatic hydrocarbons (PAHs) and their derivatives are a global problem that influences the environment and threatens human health. To investigate the characteristics, sources, and health risk assessment of PM2.5-bound PAHs and their derivatives, PM2.5 were collected at an urban site in Zibo from November 5 to December 26, 2020, and the concentrations of 16 conventional PAHs, nine NPAHs, and five OPAHs in PM2.5 were analyzed using gas chromatography-mass spectrometry. Source apportionment of PAHs and their derivatives was conducted using diagnostic ratios and a PMF model, and the health risks of PAHs and their derivatives to adult men and women were evaluated using the source-dependent incremental lifetime cancer risk (ILCR) model. The results showed that the average concentrations of ∑16pPAHs, ∑9NPAHs, and ∑5OPAHs in PM2.5 of Zibo City during the sampling period were (41.61 ± 13.40), (6.38 ± 5.70), and (53.20 ± 53.47) ng·m-3, respectively. The concentrations of the three PAHs increased significantly after heating, which were 1.31, 2.04, and 5.24 times larger than those before heating. During the sampling period, Chr, BaP, and BaA were the dominant components of pPAHs; 9N-Ant and 2N-Flt + 3N-Flt were the dominant components of NPAHs; and ATQ and BZO were the dominant components of OPAHs. Source apportionment results showed that motor vehicles were the main source of PAHs and their derivatives in PM2.5 before heating, whereas after heating, the main sources were the mixed source of coal and biomass combustion and secondary formation. The total BaP equivalent (TEQ) was 14.5 ng·m-3 during the sampling period, and the TEQ increased significantly after heating, which was approximately 1.2 times of that before heating. Assisted by the individual PAH source apportionment results, the ILCR of PM2.5-boundPAHs and NPAHs in Zibo City had a certain potential carcinogenic risk for adult males (1.06 × 10-5) and females (9.32 × 10-6). Among them, the health risks of PAHs from gasoline vehicles, diesel vehicles, and coal/biomass combustion were significantly higher than those from other emission sources.

[Agricultural Ammonia Emission Inventory and Its Distribution in Xining City].

Based on the field research activity level, the emission inventory of agricultural ammonia in Xining City in 2018 was established using the emission factor method. The emission characteristics of agricultural ammonia in Xining City were analyzed, a spatial grid distribution of 3 km×3 km was carried out by ArcGIS, and an uncertainty analysis of the ammonia emission inventory of livestock and poultry breeding and nitrogen fertilizer application was carried out via Monte Carlo simulation. The results showed that the total amount of ammonia emissions from agricultural sources in Xining City in 2018 was 4644.58 t. Among them, the total annual ammonia emissions from nitrogen fertilizer application and livestock and poultry farming were 1664.84 t and 2979.75 t, respectively, accounting for 35.84% and 64.16% of the total ammonia emissions from agricultural sources in Xining City. The spatial distribution results showed that the agricultural source ammonia emissions of Xining City mainly came from Datong County, Huangyuan County, and Huangzhong County, which accounted for 40.10%, 30.66%, and 28.05% of the total agricultural source ammonia emissions of Xining City, respectively. From the perspective of monthly distribution, no monthly difference in ammonia emissions was found in livestock and poultry farming. The ammonia emissions from nitrogen fertilizer application mainly existed in June (799.96 t) and July (768.48 t), accounting for 48.05% and 46.16% of the annual emissions. Monte Carlo simulation results showed that under a 95% confidence interval, the uncertainties of ammonia emissions from nitrogen fertilizer application agricultural source ammonia were low, ranging from -24.38% to 26.71%.