Table 1_Planktic–benthic foraminiferal isotope differentiation and sedimentary carbon variability on the Hupo Basin Slope, Southwestern East Sea.xlsx

Planktic δ¹⁸O generally decreases and δ¹³C increases toward the upper part of the core, whereas benthic isotope records show no comparable directional changes. Consequently, planktic–benthic δ¹⁸O and δ¹³C offsets increase markedly in GLU V, indicating greater surface–bottom isotopic differentiation, consistent with stronger vertical hydrographic and biogeochemical differentiation.

The enriched planktic δ¹³C values, together with the organic geochemical characteristics of GLU V, further suggest enhanced biological carbon utilization and potentially enhanced surface-water productivity. The co-occurrence of greater surface–bottom isotopic differentiation and organic carbon enrichment reveals a close stratigraphic association between vertical water-column differentiation and sedimentary carbon variability.

This association provides a framework for interpreting the potential roles of marine organic matter supply and preservation in shaping sedimentary carbon composition on the Hupo Basin slope.</p>