Cascade Reservoirs Regulate Molecular Signatures and Biogeochemical Pathways of Dissolved Organic Matters in the Lancang River

flux. Carbon oxidation state (NOSC) emerges as a key molecular selector, with redox-selected preservation of low-energy CHO compounds (NOSC < 0) forming refractory carbon pools, while bioavailable CHON species demonstrate significant correlations of sediment organic carbon with biological index and peptide-like content. These molecular-level insights suggest that cascade reservoirs simultaneously process organic matter through microbial carbon pumps and sequester carbon via selective molecular preservation, benefiting from optimizing hydropower management in riverine ecosystems.