Spatial Distribution of Organic Carbon in Surface Sediment of Bosten Lake

Lake sediment is a vital carbon reservoir, which is affected by biogeochemical and hydrological processes in the watershed. To study the dynamics of organic carbon in surface sediment of the Bosten Lake, we analyzed total organic carbon (TOC) and its stable carbon isotopic composition (δ13Corg), total nitrogen (TN), and grain size in the surface (0–2 cm) sediment. Our data showed that there was a large spatial variability in both TOC (2.1–4.2%) and δ13Corg (−26.65 to −24.13‰) in surface sediment of the Bosten Lake. By using a three end member mixing model, we estimated that 54–90% of TOC was from autochthonous source. We found higher TOC concentration (>3.7%) near the mouth of the Kaidu River, in the central-north section and in the east section, which was attributable to autochthonous, autochthonous plus allochthonous, and allochthonous sources, respectively. The lowest TOC was seen in the mid-west section, which might mainly be due to the high kinetic energy levels. Our analyses suggested that the magnitude and spatial distribution of TOC in the surface sediment of Bosten Lake were influenced by complex processes and regulated by multiple factors.