title: Aliphatic and polycyclic aromatic hydrocarbons (PAHs) in soils of the northwest Qinling Mountains: Patterns, potential risk and an appraisal of the PAH ratios to infer their source.
abstract: Surface soils from the tourist areas of the northwest Qinling Mountains were analyzed to determine the concentrations, probable sources and potential risks of hydrocarbons. Concentrations of aliphatic and aromatic hydrocarbons ranged from 4.18 to 3240 ng g-1and 0.0462 to 101 ng g-1dry weight, respectively. The extent of soil contamination by hydrocarbons was generally typified by unpolluted to slightly polluted levels. The incremental lifetime cancer risks (ILCRs) for exposure to soil-borne PAHs indicated complete safety for tourists. Early diagenesis of natural products, bacteria activities and petroleum were the three main sources of aliphatic hydrocarbons, while the transport of air pollutants from pyrolytic processes was the main origin of PAHs. Because the photochemical reaction of PAHs in the atmosphere would produce lower ratios for Ant/(Ant + Phe), BaA/(BaA + Chr) and IcdP/(IcdP + BghiP), but a higher ratio for Fla/(Fla + Pyr), the source classification highly depended on the diagnostic ratios chosen. The plot of ΣCOM/Σ13PAH vs. ΣLMW/ΣHMWPAHprovide additional information to distinguish the origins of PAHs, and it showed a cluster of pyrogenic sources except for sample JFS-8. Four sources were resolved by principal component analysis: (1) a low temperature pyrogenic process related to the use of fossil fuel and biomass, such as charcoal, straw and wood, which contributes 63.1% of the measured PAHs; (2) the potential contribution of diagenetic processes, contributing 18.4%; (3) traffic emissions, contributing 9.27%; and (4) bioconversion/bacterial action, contributing 5.82%. Additionally, there was a good exponential relationship (r2= 0.969) between the natural n-alkanes ratio (NAR) and carbon preference index for C23-C35(CPI23-35) for all samples, which is of great use for the determination of the origins of aliphatic hydrocarbon.
authors.affiliation: a Gansu Provincial Key Laboratory of Petroleum Resources; Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences , Lanzhou , China.|b University of Chinese Academy of Sciences , Beijing , China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: a Gansu Provincial Key Laboratory of Petroleum Resources; Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences , Lanzhou , China.
authors.forename: Yingqin
authors.initials: Y
authors.lastname: Wu
authors.affiliation: a Gansu Provincial Key Laboratory of Petroleum Resources; Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences , Lanzhou , China.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Xia
authors.affiliation: a Gansu Provincial Key Laboratory of Petroleum Resources; Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences , Lanzhou , China.
authors.forename: Tianzhu
authors.initials: T
authors.lastname: Lei
authors.affiliation: a Gansu Provincial Key Laboratory of Petroleum Resources; Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences , Lanzhou , China.
authors.forename: Chuntao
authors.initials: C
authors.lastname: Tian
authors.affiliation: a Gansu Provincial Key Laboratory of Petroleum Resources; Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences , Lanzhou , China.|b University of Chinese Academy of Sciences , Beijing , China.
authors.forename: Xiaohuan
authors.initials: X
authors.lastname: Hou
mesh_terms: D002681:China; D004784:Environmental Monitoring; D004787:Environmental Pollution / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D018570:Risk Assessment; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D005227:Fatty Acids; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants
keywords: Pollution monitoring; risk assessment; soil hydrocarbons; source diagnostic ratios; the northwest Qinling Mountains