The Sea Journal of the Korean Society of Oceanography ISSN:1226-2978(Print) 2671-8820(Online) 한국해양학회지 바다

Detention basins are environments where cohesive sediments readily absorb and settle together with contaminants originating from urban areas. Consequently, understanding sediment erodibility is essential to assess the behavior and dispersion of accumulated contaminated sediments. This study collected sediment samples at the inner (YH1) and outer (YH2) parts of Yonghyeon tidal creek (Hagik detention basin) located in Incheon to evaluate sediment stability, and to analyze physicochemical properties and heavy metal concentrations of sediments in order to identify spatial variations. YH1 had finer median particle size (YH1: 22.1 μm, YH2: 31.8 μm) and higher organic matter content (YH1: 10.1%, YH2: 5.1%) than YH2. The sediment erodibility experiment showed a lower initial critical shear stress for erosion (YH1: 0.13 Pa, YH2: 0.19 Pa) and a higher cumulative eroded mass (YH1: 121.3 g/m², YH2: 67.6 g/m²) at YH1 compared to YH2. At YH1, weakened current velocity caused by artificial island and continuous organic matter inputs from the sewage outfall reduced the consolidation of fine-grained sediments, resulting in lower sediment stability. At YH2, intermittent strengthened current velocity during the drainage gate opening led to the dominance of coarse sediments, resulting in higher sediment stability. Furthermore, heavy metal concentrations at YH1 were higher than YH2, with Cu, Ni, and Zn exceeding the NOAA Effect Range-Low thresholds by approximately 1.5, 1.1, and 2 times, respectively. Due to the more cohesive sediments at YH1 compared to YH2, contaminants were more readily absorbed from the sewage outfall and more easily released into the external environment through sediment erosion. Because inflows from the tidal creek can affect water circulation in the adjacent harbor, this study evaluated the erosion mechanisms of contaminated sediments and their potential dispersion by investigating sediment stability and contaminant characteristics within a contaminated urban detention basin.