Temporal variations and source apportionment of volatile organic compounds at an urban site in Shijiazhuang, China.

Shijiazhuang, the city with the worst air quality in China, is suffering from severe ozone pollution in summer. As the key precursors of ozone generation, it is necessary to control the Volatile Organic Compounds (VOCs) pollution. To have a better understanding of the pollution status and source contribution, the concentrations of 117 ambient VOCs were analyzed from April to August 2018 in an urban site in Shijiazhuang. Results showed that the monthly average concentration of total VOCs was 66.27 ppbv, in which, the oxygenated VOCs (37.89%), alkanes (33.89%), and halogenated hydrocarbons (13.31%) were the main composite on. Eight major sources were identified using Positive Matrix Factorization modeling with an accurate VOCs emission inventory as inter-complementary methods revealed that the petrochemical industry (26.24%), other industrial sources (15.19%), and traffic source (12.24%) were the major sources for ambient VOCs in Shijiazhuang. The spatial distributions of major industrial activities emissions were identified by using geographic information statistics system, which illustrated the VOCs was mainly from the north and southeast of Shijiazhuang. The inverse trajectory analysis using Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) and Potential Source Contribution Function (PSCF) clearly demonstrated the features of pollutant transport to Shijiazhuang. These findings can provide references for local governments regarding control strategies to reduce VOCs emissions.

Assessment of the temporal variability and health risk of atmospheric particle-phase polycyclic aromatic hydrocarbons in a northeastern city in China.

In this study, we examined the sources and temporal variability of 16 polycyclic aromatic hydrocarbons (PAHs) found in fine particulate matter (PM2.5) in a typical industrial city in northern China. We also evaluated the incremental lifetime cancer risk (ILCR) from the inhalation of these PAHs. Atmospheric PM2.5 samples were collected for 7 consecutive days each month from 2014 to 2019, and the 16 PAHs were measured using multiplex gas chromatography-tandem mass spectrometry. The carcinogenic risk of PAH exposure was assessed using the inhalation unit risk (IUR) and cancer slope factor (CSF) methods. The annual average concentrations of PM2.5 for each year from 2014 to 2019 were 102.87±55.25, 86.92±60.43, 69.17±37.74, 58.20±59.15, 56.01±34.52, and 52.54±58.15 µg m-3, and the annual average ΣPAH concentrations were 56.03±81.09, 47.99±79.30, 40.41±57.31, 33.57±51.79, 43.23±74.80, and 25.20±50.91 ng m-3, respectively. Source identification, using diagnostic ratio analysis, indicated that the major PAH sources were coal/biomass combustion, fuel combustion, and traffic emissions. A health risk assessment showed that the ILCR from PAH inhalation decreased throughout the study period and varied with age. The IUR and CSF methods both showed that the adult ILCR exceeded 1.0×10-6. These findings demonstrate the importance of addressing the carcinogenic risk of PM2.5-bound PAHs, particularly in adults.

Assessment of heavy metal content, distribution, and sources in Nansi Lake sediments, China.

Much attention has been paid to the heavy metal contamination of lake sediments in rapidly developing regions. In this study, heavy metal (Cd, Cr, Co, Ni, Mn, Pb, As, Cu, and Zn) concentrations in sediment surface samples and cores from the Nansi Lake were investigated to ascertain the potential sources and environmental risks of heavy metals. The average concentration of heavy metals was 0.16-16.04 times background concentrations. The enrichment factor, Tomlinson pollution load index, geo accumulation index, positive definite matrix factor analysis (PMF), and potential ecological risk index were used to assess heavy metal concentrations and explore the evolution of heavy metal sources, and result indicated that Cd reached moderate pollution levels, which is the most polluted heavy metal in the history and present, while the remaining heavy metals are at low or no pollution levels. The contribution of Cd to RI exceeded 76%, which is the decisive factor in the ecological risk of Nansi Lake. The result of ecological risk showed that the risk level for most of Nansi Lake is medium, and some areas of Zhaoyang Lake and Weishan Lake reach high levels. The PMF results showed that there are four main factors influencing heavy metal concentrations in Nansi Lake sediments, including industrial sources, fertilizers, and herbicides used in agricultural production, traffic-related emissions, and mineral mining. Among these factors, industrial and mineral mining sources were found to be the most important, and the highest contribution rate occurred in the -10cm (1960s). Although the contribution of fertilizers and herbicides is lower than that of other sources, increasing trend should be a warning sign that Cd has reached a high ecological risk level in Nansi Lake sediments.