Paleoenvironment change and its impact on carbon and nitrogen accumulation in the Zoige wetland, northeastern Qinghai-Tibetan Plateau over the past 14,000 years

Abstract

As the largest alpine wetland and peat deposition area in China, the Zoige wetland is climatically sensitive. The organic matter (OM) in peat stores copious environmental information. Here we report new data on the organic geochemistry of a 4.5 m peat profile HY2014 from southern Zoige wetland. Based on closely spaced accelerator mass spectrometry (AMS) 14C dating, we established a high-resolution geochronological framework beginning at 14,057 a BP. Moreover, we estimated the sedimentation flux of TOC and TN (SFs) and their influencing factors. Before 10,916 a BP, the lake shrunk and peat began to develop under cold and dry conditions, and SFs were at their lowest values due to low productivity. More OM originated from hydrophyte and marsh plants. From 10,916 to 3050 a BP, peat was widely and well developed, and the climate was warm and humid, despite a cooling and drying trend. The HY2014 profile experienced an optimum climate during 10,916 − 6000 a BP, when SFs had the highest values that benefited from high productivity, and OM mainly originated from terrestrial plants. After 3050 a BP, the climate was the coldest and driest. The high SFs over the past 2000 a BP were mainly resulted from the low decomposition rate. The plant community, primary productivity, and decomposition rate were closely linked with the temporal variation of SFs. The environment change was mainly controlled by summer solar insolation, and the Zoige wetland was significantly influenced by the Indian summer monsoon.