Tracing sediment provenance in Central Jiangsu tidal flat: Quantitative analysis of grain size and geochemical elements

Tidal flats are dynamic coastal systems whose stability relies on continuous sediment supply, yet sediment provenance in the central Jiangsu tidal flats remains poorly constrained, especially under reduced fluvial input and complex tidal forcing. This study aimed to quantify sediment sources, grain-size distributions, and their elevation-dependent patterns across these tidal flats. Surface sediments were collected from 12 transects in 2023 and analyzed using grain-size measurements, geochemical fingerprinting, and quantitative mixing models (FingerPro), incorporating a normalized tidal elevation framework to account for cross-shore and latitudinal variations. The main findings are: (1) The North Jiangsu Radial Sand Ridges (NJRSR) are the dominant sediment source, contributing ∼50 % of surface sediments, followed by the Old Yellow River Delta (∼26 %) and the Yangtze River (∼24 %), highlighting the overlooked but critical role of NJRSR in maintaining the sediment budget. (2) Grain size decreases with increasing tidal elevation, from a wide range (20–120 μm) at low-tide levels to finer, more homogeneous sediments at high-tide flats, reflecting hydrodynamic sorting and shoreline erosion patterns. (3) Mean grain size increases offshore, closely corresponding to NJRSR contributions, supporting the use of sediment texture as a proxy for provenance, although tracer elements were decoupled from grain-size variations due to dynamic redistribution. (4) Integrating elevation-dependent grain-size patterns with geochemical tracers provides a robust framework for interpreting sedimentary processes and source contributions. These results advance understanding of sediment dynamics, tidal flat evolution, and coastal resilience, offering methodological and conceptual insights applicable to other large tidal flat systems worldwide. • NJRSR is the dominant sediment source. • Grain size decreases with tidal elevation. • Offshore fining reflects NJRSR sediment inputs. • Normalized tidal elevation reveals elevation-dependent patterns. • Integrated grain-size and geochemistry trace sediment sources.