Relationships between submerged plant productivity and organic carbon burial across Tibetan Plateau lakes during the Holocene

Aquatic submerged plants represent a crucial component of lake ecosystems, yet their influence on lacustrine organic carbon burial remains poorly quantified, particularly regarding historical variations in submerged plant productivity‑carbon burial relationships across different lake types. This study combines new total organic carbon (TOC) δ¹³C data from Lake Sugan (a less-studied site on the northern Tibetan Plateau) and integrate these data with a comprehensive synthesis of published Holocene records, including: 22 lake cores (TOC δ¹³C and content), 7 soil profiles (TOC δ¹³C), 4 lake cores (C₃₁ n -alkane δ¹³C), and modern plant samples across the Tibetan Plateau. Our integrated analysis reveals: (1) TOC δ¹³C of soil profiles (−27‰ to −23‰) and C₃₁ n -alkane δ¹³C of sediments (−33‰ to −29‰) consistently indicate C₃ plants dominance throughout the Holocene; (2) significantly enriched TOC δ¹³C in lake core sediments relative to C₃ plants and soil profiles demonstrates substantial contributions from submerged plants, serving as a robust proxy for submerged plant productivity; and (3) distinct regional patterns emerge, with submerged plant productivity (controlled by water depth and terrestrial vegetation cover) driving organic carbon burial in northeastern and southwestern lakes, while terrestrial biomass dominates in southeastern lakes with minimal submerged plant input. These findings provide new insights into the complex interplay between aquatic and terrestrial carbon sources in high-altitude lake systems, highlighting the need for region-specific assessments of carbon burial mechanisms.