Mean Particle Size, Organic Carbon, and Porewater Salinity Distribution of Surface Sediments Using the Dataset in the Hwangdo Tidal Flat, Taean, Western Korea

Abstract

The Hwangdo tidal flats are located in Cheonsu Bay in Taean-gun, Chungcheongnam, on the west coast of Korea. Cheonsu Bay is a semi-closed bay characterized by various geomorphic features including channels, sand bars, small islands, and tidal flats. This study assessed the field measurement of ellipsoid height using a real-time kinematics global positioning system (m) and used laboratory analyses to obtain geological data on sediment type in a pilot study area. Using data collected in October 2022 (n = 107), samples analyzed surface sediment characteristics including the mean particle size, Total Organic Carbon (TOC), Total Nitrogen (TN), Total Carbon (TC), porewater salinity, specific dry bulk density, porosity, and water content, etc. The sedimentary facies were classified following Folk and Ward (1957). The sedimentary facies ranged from coarse sand (sand: mud ratio = 9:1) to sandy mud, as sandy silt (sZ) > muddy sand (mS) > slightly gravelly sandy mud ((g)sM). Organic matter was characterized based on particle size analysis; each experimental result was verified. The TOC/TN ratio was consistently ≤ 10, which suggests the influence of marine rather than terrestrial organisms. The porewater salinity distribution was correlated with the sedimentary phase, tidal flat elevation, latitude value, and organic matter content. The salinity was higher in highland tidal flats where the sedimentary facies was to fine silty, and the exposure time was long. The positive correlations were detected between mean particle size, clay content, TOC and sediment porosity using correlation matrix and factor analysis. These data will be useful for understanding the changes in the sedimentary environment of the Hwangdo tidal flat and establishing conservation management plans for this area. In the future, the geological environment characteristics dataset will be used as basic data to assess changes in the tidal flat topography and sedimentation environments.