The influence of climate change on the accumulation of polycyclic aromatic hydrocarbons, black carbon and mercury in a shrinking remote lake of the southern Tibetan Plateau.

A sediment core from a remote lake, Pumoyum Co, located in the southern TP, was analyzed for polycyclic aromatic hydrocarbons (PAHs), black carbon (BC) and mercury. Concentrations ranged from 30 to 229ng/g for PAHs, 0.46 to 1.48mg/g for BC and 10 to 30ng/g for mercury. Significant correlations were found among the concentrations of PAHs, BC and mercury, suggesting the sources of these pollutants to be similar; mainly from combustion processes. Further diagnosis of the likely sources of BC and PAHs suggested that petroleum combustion has been one of the increasing sources in the last few decades, but biomass burning remains the dominant source of these pollutants. The historic trends of the three pollutants closely followed historic BC emission trends from Europe (before 1970) and southern Asia (after 2000). With economic development in southern Asia, concentrations of pollutants in the sediments of Pumoyum Co have increased during the past decade. However, the accumulation fluxes of the pollutants during that period remained stable, which may be due to the recent low precipitation and less catchment erosion of Pumoyum Co (experienced a drier climate and shrinking of lake area).