Sedimentary records of polycyclic aromatic hydrocarbons (PAHs) in remote lakes across the Tibetan Plateau

• Published in: Environmental pollution (1987) 2016-07, Vol.214, p.1-7
• Main Authors: Yang, Ruiqiang, Xie, Ting, Li, An, Yang, Handong, Turner, Simon, Wu, Guangjian, Jing, Chuanyong
• Format: Article
• Language: English
• Subjects: China; Freshwater; Geologic Sediments - chemistry; Historical trend; Lakes - chemistry; Long-range atmospheric transport (LRAT); PAHs; Polycyclic Aromatic Hydrocarbons - analysis; Sediment; Tibet; Water Pollutants, Chemical - analysis
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2016.03.068

Sediment cores from five lakes across the Tibetan Plateau were used as natural archives to study the time trends of polycyclic aromatic hydrocarbons (PAHs). The depositional flux of PAHs generally showed an increasing trend from the deeper layers towards the upper layer sediments. The fluxes of PAHs were low with little variability before the 1950s, and then gradually increased to the late 1980s, with a faster increasing rate after the 1990s. This temporal pattern is clearly different compared with those remote lakes across the European mountains when PAHs started to decrease during the period 1960s–1980s. The difference of the temporal trend was attributed to differences in the economic development stages and energy structure between these regions. PAHs are dominated by the lighter 2&3-ring homologues with the averaged percentage over 87%, while it is notable that the percentage of heavier 4–6 ring PAHs generally increased in recent years, which suggests the contribution of local high-temperature combustion sources becoming more predominant. Photographed by the author Ruiqiang Yang. [Display omitted] •Sediment cores across the Tibetan Plateau were analyzed for PAHs.•The depositional flux of PAH generally shows an increasing trend.•The trend of depositional flux is different compared with European mountains.•PAHs are dominated by the lighter 2&3-ring homologues.•Increasing contributions from local sources to PAHs was observed. Increasing contributions from local sources to PAHs in the Tibetan Plateau environment as evidenced from sedimentary records.