Sediment organic carbon dynamics response to land use change in diverse watershed anthropogenic activities

The effects of different disturbing background watersheds on sedimentary organic carbon in the inlet. Dovetail arrows were the impact pathways. The arrow indicated the direct effect, the curved arrow was the indirect effect, and the sum of them was the total effect. Red showed a negative effect, and blue was positive. [Display omitted] •The rising SR in lake estuary since the 1960s coincided with the global growth inflection.•Effect of afforestation and cropland on SOC was the key human driver.•SOC did not generate positive feedback on the elevated SR due to key land use change.•SOC dynamics reveal the role of humans in diverse anthropogenic contexts. Sediment organic carbon (SOC) is a precious archive that synthesizes anthropogenic processes that remove geochemical fluxes from watersheds. However, the scarcity of inspection about the dynamic mechanisms of anthropogenic activities on SOC limits understanding into how key human factors drive carbon dynamics. Here, four typical basins with similar natural but significantly diverse human contexts (high-moderate-low disturbance: XJ-ZS and YJ-LS) were selected to reconstruct sedimentation rates (SR) and SOC dynamics nearly a century based on 200-cm corers. A partial least squares path model (PLS-PM) was used to establish successive (70 years) and multiple anthropogenic data (population, agriculture, land use, etc.) quantification methods for SOC. Intensified anthropogenic disturbances shifted all SR from pre-stable to post-1960s fluctuating increases (total coefficient: high: 0.63