Proxy‑indicator data of core SJLW‑2 from Sanjiao Longwan

The first 20 cm of the core was continuously sampled at a 0.5 cm resolution, and the 20–47 cm section was also continuously sampled at a 0.5 cm resolution, providing a high temporal resolution.The dataset includes the following variables:Depth (cm): Core depth, representing the vertical distance from the sediment-water interface.Age (cal. a BP): The calibrated age obtained based on AMS 14C, 210Pb and 137Cs dating, combined with the Bayesian age-depth model (Bacon).TOC (wt.%): Total organic carbon content, which reflects the lake primary productivity and organic matter input from the watershed.TN (wt.%): Total nitrogen content, which reflects the nitrogen enrichment status in sediments.

It is often used together with TOC to determine the source of organic matter.C/N: Carbon-nitrogen ratio, used to distinguish between endogenous (algae, low value) and exogenous (terrestrial plants, high value) organic matter, and to indicate the degree of organic matter degradation.δ13C（wt.‰）: Stable carbon isotope ratio, indicating the source of organic matter and paleoclimate environment changes.δ15N（wt.‰）: Stable nitrogen isotope ratio, reflecting the intensity of the nitrogen cycle process and the source of nitrogen.Sediment accumulation rate（cm/yr）: Linear sediment accumulation rate, reflecting the vertical accumulation thickness of sediments, and indicating the stability of the sedimentary environment and hydrodynamic conditions.Mass accumulation rate(g/cm2/yr): Mass accumulation rate (MAR), which reflects the accumulated mass of dry sediment matter.