Multi-factors influencing the spatial distribution of polycyclic aromatic hydrocarbons in soils surrounding drinking water protection zone

We selected the Guanting Reservoir in Beijing, China as a case where an industrial area locates on the upwind corner to study the influence of human activities and natural processes on the distribution of polycyclic aromatic hydrocarbons （PAHs） in soils. Soil PAH concentrations in the study area follow a log-normal probability distribution function, suggesting that distribution of PAH in soils was affected by human activities. Distribution of PAHs in soils was significantly affected by the point source that high PAH concentrations were observed in near industrial area with an obvious declining trend from the northwest to the southeast which was the prevailing wind direction in this area. Away from the influence of point source, distribution of PAHs in soils was found to significantly correlate with total organic carbon content, while the influences of agricultural land uses and type of soil texture on the total soil PAHs contents and ring compositions were quite limited. The results can provide some evidences and data on the pollutant accumulation in drink water protection area influenced by natural processes and human activities.

Pollution characteristics, sources and lung cancer risk of atmospheric polycyclic aromatic hydrocarbons in a new urban district of Nanjing, China

This paper focused on the pollution characteristics, sources and lung cancer risk of atmospheric polycyclic aromatic hydrocarbons （PAHs） in a new urban district of Nanjing, China. Gaseous and aerosol PM2.5 （particulate matter with aerodynamic diameter smaller than 2.S μm） samples were collected in spring of 2015. Sixteen PAHs were extracted and analyzed after sampling. Firstly, arithmetic mean concentrations of PAHs and BaPeq （benzo[a]pyrene equivalent） were calculated. The mean concentrations of PAHs were 29.26 ± 14.13,18.14 ± 5.37 and 48.47 ± 16.03 ng/m3 in gas phase, particle phase and both phases, respectively. The mean concentrations of BaPeq were 0.87 ± 0.51, 2.71 ± 2.17 and 4.06 ± 2.31 ng/m3 in gas phase, particle phase and both phases, respectively. Secondly, diagnostic ratios and principal component analysis were adopted to identify the sources of PAHs and the outcomes were the same： traffic exhaust was the predominant source followed by fuel combustion and industrial process. Finally, incremental lung cancer risk （ILCR） induced by whole year inhalation exposure to PAHs for population groups of different age and gender were estimated based on a Monte Carlo simulation. ILCR values caused by particle phase PAHs were greater than those caused by gas phase PAHs. ILCR values for adults were greater than those for other age groups. ILCR values caused by total （gas ＋ particle） PAHs for diverse groups were all greater than the significant level （10-6）, indicating high potential lung cancer risk. Sensitivity analysis results showed that cancer slope factor for BaP inhalation exposure and BaPeq concentration had greater impact than body weight and inhalation rate on the ILCR.

Historical records of polycyclic aromatic hydrocarbon deposition in a shallow eutrophic lake:Impacts of sources and sedimentological conditions

Sediment core samples collected from Lake Chaohu were analyzed for 15 priority polycyclic aromatic hydrocarbons（PAHs）to assess the spatial and temporal distributions of the PAHs during lacustrine sedimentary processes and regional economic development.Assessing the PAH sedimentary records over an approximately 100-year time span,we identified two stages in the PAH inputs and sources（before the 1970 s and after the 1970s）in the eastern lake region near a village,whereas three stages（before the 1950 s,1950s–1990s and after the1990s）were identified in the western lake region near urban and industrial areas.Rapid increases in the PAH depositional fluxes occurred during the second stage due to increased human activities in the Lake Chaohu basin.The composition and isomeric ratios of the PAHs revealed that pyrolysis is the main source of PAHs in this lake.Strong positive relationships between PAH concentration and the total organic carbon concentration,sediment grain size（〈 4 μm）,as well as the local population and Gross Domestic Product indicated that the sedimentary conditions impact the depositional characteristics of the PAHs;simultaneously,socioeconomic activities,such as energy consumption and the levels of urban industrialization and civilization,affect both the composition and abundance of the PAHs.