Anthropogenic impacts recorded by a 200-year peat profile from the Zoige Peatland, northeastern Qinghai-Tibetan Plateau

Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) of peatlands are ideal natural archives of anthropogenic activities, but few comprehensive surveys have been carried out on the BC and PAHs of peatlands on the Qinghai-Tibet Plateau (QTP). To establish the fate of anthropogenic pollutants in peatlands, this study analyzed the Pb-210 and Cs-137 activities, concentrations of several chemical parameters, and the correlations between the soil properties, meteorological parameters, BC, and PAHs in a 30-cm peat profile from the Zoige Plateau, northeastern China. Our results reveal BC and total PAH concentration ranges of 39.9-82.6 mg.g(-1) and 27.5-726.9 ng.g(-1), respectively. Based on these results and our knowledge of social development in China and around the world, we divided the peat profile into three groups: 1824-1949 (i.e., before the New China foundation), 1950-1980s, and post-1980 s. The ratios of low- and high-molecular weight PAHs, BaA/(BaA + Chr) and Flu/(Flu + Pyr) were typically less than 1.00 and exceeding 0.35 and 0.40, respectively. These results indicate that anthropogenic impacts have had a serious impact on the QTP, and the PAHs in this area originated from the combustion of coal, biomass, and oil-related products. Moreover, the primary sources have shifted from local emissions to remote sources over the past 200 years.