Articles | Volume 12, issue 22
https://doi.org/10.5194/bg-12-6605-2015
https://doi.org/10.5194/bg-12-6605-2015
Research article
 | 
19 Nov 2015
Research article |  | 19 Nov 2015

Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

Z. T. Yu, X. J. Wang, E. L. Zhang, C. Y. Zhao, and X. Q. Liu

Abstract. Lake sediment is an important carbon reservoir. However, little is known on the dynamics and sources of sediment organic carbon in Bosten Lake. We collected 13 surface (0–2 cm) sediment samples in Bosten Lake and analyzed total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition in TOC (δ13Corg), and grain size. We found a large spatial variability in TOC content (1.8–4.4 %) and δ 13Corg value (−26.77 to −23.98 ‰). Using a three-end-member mixing model with measured TOC : TN ratio and δ13Corg, we estimated that 54–90 % of TOC was from autochthonous sources. Higher TOC content (> 3.7 %) was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively. The lowest TOC content was found in the mid-west section, which might be a result of high kinetic energy levels. Our study indicated that the spatial distribution of sediment TOC in the Bosten Lake was influenced by multiple and complex processes.

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Short summary
Bosten Lake is the largest inland freshwater lake in China, which has been impacted by land use changes, with implications for carbon burial. Our study showed a large spatial variability in total organic carbon (TOC) (1.8–4.4%); 54–90% of TOC was from autochthonous sources. Higher TOC content was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively.
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