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| PAHs in surface wetland soils of the Pearl River Delta affected by urbanization: Levels, sources, and toxic risks |
| Received:December 06, 2018 |
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| KeyWord:Pearl River Delta;wetland soils;PAHs;source;risk assessment |
| Author Name | Affiliation | E-mail | | HAN Ling | State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China | | | GAO Zhao-qin | State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
Environmental Development Center of Ministry of Ecology and Environment, Beijing 100029, China | | | BAI Jun-hong | State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China | junhongbai@163.com | | WEN Xiao-jun | State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China | | | ZHANG Guang-liang | State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China | | | WANG Wei | State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China | |
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| Abstract: |
| Surface soil samples (0~10 cm) from a typical rural river wetland (RRW), an urban river wetland (URW) and an artificial wetland (CW) in the Pearl River Delta (PRD) were collected and analyzed using GC-MS to investigate the contents, sources and toxic risk levels of 16 kinds of polycyclic aromatic hydrocarbons (PAHs) in these three wetlands. The results showed that the contents of 16 PAHs in the three types of wetland soils ranged from 625.0 to 789.2 ng·g-1, with an average of 666.3 ng·g-1. The mean PAHs levels of three types of wetland soils followed the order CW (736.4 ng·g-1) > RRW (639.3 ng·g-1) > URW (625 ng·g-1), with higher percentages of 3, 4, and 5 ringed PAHs in RRW (81.42%) and URW (89.35%) soils and higher percentages of 2-4 ringed PAHs in CW soils. Among 16 kinds of PAHs, higher naphthalene (Nap), phenyl (Phe), and benzo[a] pyrene (Bap) contents were observed, with average values in the three types of wetlands being 98.68 ng·g-1, 109.8 ng·g-1 and 140.92 ng·g-1, respectively. The main sources of PAHs in CW and URW soils were derived from the combustion of coal-based fossil fuels (e.g., coal, oil, etc.), while in RRW soils, a mixed source of wood, oil, and other combustion and petroleum emissions was observed. According to the Maliszewska-Kordybach analysis method in the Netherlands, accumulations of PAHs in the three types of wetlands were all in the levels of moderate pollution, with some biotoxicity for fluorene (Fle). Ecological risks of PAHs were assessed using the soil benzo[a]pyrene (∑TEQBap) toxicity equivalent concentration and risk evaluation method for the commercial value of ecological risk of PAHs. The three kinds of wetland soils exhibited medium levels of ecological risks, following the order CW > RRW > URW, and 69% of the isomers (including the Bap, Phe, etc.) were at a medium risk level, while benzo[a]pyrene (Bap) toxicity equivalent concentration was the highest, with the biggest contribution to total toxicity equivalent concentration. The environmental pollution caused by human activities due to urbanization in the PRD cannot be ignored and certain measures should be taken for wetland recovery and remediation. |
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