Occurrence and source apportionment of PAHs in highly vulnerable karst system.
The concentration and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in topsoil, groundwater and groundwater suspended solids (SS) at Guozhuang karst water system of northern China were investigated. The total concentration of PAHs ranged from 622 to 87,880 ng/g dry weight in topsoil, from 4739 to 59,314 ng/g dry weight in SS, and from 2137 to 9037 ng/L in groundwater, with mean values of 17,174 ng/g, 11,990 ng/g and 5020 ng/L, respectively. High concentrations of PAHs were mainly observed in the coal mining industrial area and the discharge area. The composition of PAHs indicated that low molecular weight PAHs were predominant in groundwater samples, the content of medium molecular weight PAHs was elevated in SS, and carcinogenic high molecular weight PAHs were frequently detected in topsoil. The high contents of low-medium molecular weight PAHs in groundwater and SS suggested relatively recent local sources of PAHs that were transported into the aquifer via leakage of contaminated surface water and/or infiltration of PAH-containing precipitation. The results of evaluating sources of PAHs using ratios of specific PAH compounds showed that PAHs mainly originated from coal and wood combustion. Furthermore, five sources were identified by positive matrix factorization (PMF) model, and the contribution to the total loadings of groundwater PAHs were: 2% for unburnt oil, 32% for coal combustion, 22% for vehicle emission, 27% for biomass combustion and 18% for coke production, respectively. Furthermore, strong correlations of total PAHs with total organic carbon (TOC) in topsoil indicated co-emission of PAHs and TOC. Poor correlations of PAHs with dissolved organic carbon (DOC) in groundwater indicated that other factors exert stronger influences. Therefore, PAHs might have posed a major threat to the quality of potable groundwater in Guozhuang karst water system.
State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China; Geological Research Center for Agricultural Applications, China Geological Survey, Zhejiang 311203, PR China. Electronic address: hdjcsyx@gmail.com.
Yixian
Y
Shao
State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China. Electronic address: yx.wang1108@gmail.com.
Yanxin
Y
Wang
North China Power Engineering Co., Ltd. of China Power Engineering Consulting Group, Beijing 100120, PR China. Electronic address: jingguai54@163.com.
Xiaoqing
X
Xu
State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China. Electronic address: amber901010@gmail.com.
Xiao
X
Wu
State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China. Electronic address: 715243550@qq.com.
Zhou
Z
Jiang
State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China. Electronic address: 565134803@qq.com.
Shanshan
S
He
State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China. Electronic address: 326032477@qq.com.
Kun
K
Qian
D002681:China; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D060587:Groundwater / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical
Groundwater; Karst; PAHs; PMF; Suspended solids