Soil organic carbon fractions, reactive minerals, organic matter sources, and heavy metals across an inundation gradient in the Three Gorges Reservoir water-level fluctuation zone

Soil samples were collected in June 2024 across four elevation zones, including 145–155 m, 155–165 m, 165–175 m, and >175 m, representing different inundation durations.

The dataset includes soil physicochemical properties, particulate organic matter (POM), mineral-associated organic matter (MAOM), reactive Fe minerals, Fe-associated organic carbon, enzyme activities, microbial carbon use efficiency, DOM optical and fluorescence indices, carbon source apportionment based on δ¹³C and N/C, and heavy metal concentrations in bulk soil, POM, and MAOM fractions. These data support analyses of how prolonged inundation regulates MAOM accumulation and heavy metal retention in reservoir water-level fluctuation zone soils.