SPATIAL DISTRIBUTION AND INFLUENCING FACTORS OF SEDIMENT ORGANIC CARBON POOL COMPOSITION IN THE LAKESHORE ZONE OF THE QINGHAI LAKE

Qinghai Lake, a typical plateau lake in the Qinghai-Xizang Plateau, has experienced continuous water level rise due to climate warming, resulting in extensive newly inundated zones in the littoral zone. This study investigated the composition and influencing factors of sedimentary organic carbon pools through sampling at 11 sites around the lake. Results showed that sedimentary organic carbon storage (TOCS) ranged from 1.84 to 135.92 t/hm² (mean 49.40 t/hm²), with a carbon pool management index (CPMI) varying from 13.7% to 502.2% (mean 180.7%). Among labile organic carbon fractions, easily oxidized organic carbon (EOC, 0.37—47.17 g/kg) was the dominant component, followed by dissolved organic carbon (DOC, 0.05—3.12 g/kg) and microbial biomass carbon (MBC, 0.01—3.30 g/kg). Redundancy analysis revealed that particle size, moisture content, total nitrogen (TN), and total phosphorus (TP) significantly promoted organic carbon accumulation, whereas pH, bulk density, and total inorganic carbon (TIC) inhibited carbon sequestration potential. Land use types exhibited pronounced effects on carbon distribution, with flooded vegetation areas showing significantly higher TOCS and CPMI compared to grassland and bare land. This study elucidates the dynamic response of littoral zone carbon pools under water level rise, providing insights for evaluating carbon sink functions and implementing adaptive management strategies in alpine lake ecosystems.