Sedimentation history and excess metal deposition in estuarine barrier-island system of the Nakdong River, South Korea

Highlights: • Sediment fluxes for metal contaminants increase after the dam construction. • OM-normalized ²¹⁰Pb_XS profile reflects change in sedimentation within estuary. • Large-scale topographical changes influence the spatio-temporal sedimentation rate. Human activities, such as dam construction and reclamation, can affect sedimentation rates as well as sediment topography and transport in estuaries such as the Nakdong River Estuary. To investigate the sedimentation history, two sediment cores (1–2 m long) were sampled in tidal flats of the estuary. In addition, surface sediments were collected to study present sedimentation environments that appear to be three environments locally: 1) fine-grained sediment deposition; 2) sediments under stronger hydraulic energy; and 3) sandy sediments with good sorting. At the fine sediment deposition, environmental sensitive fraction of elements (Cu, Pb, As, and Co) show an increased sedimentation flux after the dam construction. On the other hand, organic matter-normalized Pb-210 concentrations in sediment core reveal that marine-originated organic matter is predominant in the upper ~45 cm of sediment layers, indicating a significant change in sedimentation history related to massive sedimentation within the Nakdong River Estuary.