| Summary: | The rapid economic development in the Yangtze River Delta has affected the carbon (C) pool in lake sediments, which has become a serious environmental management issue. To explore the characteristics of composition, spatial distribution and burial of organic C (OC) in lacustrine sediments, a typical shallow lake was targeted to compare the heavy fraction OC (HFOC), light fraction OC (LFOC), and dissolved OC (DOC) in the surface sediments of different lake areas using the specific gravity separation approach. The effects of environmental factors on the form of OC present were identified by a redundancy analysis. The results showed a regional difference of DOC, LFOC, and HFOC concentrations in Taihu Lake, and HFOC was dominant in the OC buried in lake sediments. The deposition rate of OC in Taihu Lake sediments varied in a ranged of 31.91–114.47 g C m−2 a-1. The LFOC levels in the sediments were lower than those in other lakes. Both sedimentary LFOC and HFOC were significantly correlated with the nitrogen (N) content, indicating that the C sink was enhanced by an increase in N in the sediments. The grass-type lake zone stimulated C accumulation in Taihu Lake sediments.
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