Evaluation of Pollution Level for Organic Matter and Trace Metals in Sediments around Taehwa River Estuary, Ulsan

Abstract

Grain size, the content of ignition loss (IL), and the concentrations of chemical oxygen demand (COD), acid volatile sulfide (AVS), and trace metals (Fe, Mn, Cu, Pb, Zn, Cd, Cr, As, and Hg) in surface sediments from the Taehwa River estuary, Ulsan, were measured to evaluate pollution levels and potential ecological risks of organic matter and trace metals in estuarine sediment. The mean grain size (Mz) of sediments in the study region ranged from -0.8-7.7 φ (mean 2.8 ± 2.4 φ). Surface sediments in the upstream region of the Taehwa River were mainly composed of coarse sediments compared to the downstream region. The concentrations of IL, COD, AVS and trace metals in the sediment were much higher at downstream sites of Myeongchon Bridge in the vicinity of industrial complexes than at upstream sites of those in the vicinity of the residential areas due to the anthropogenic input of organic matter and trace metals by industrial activities. On the basis of several geochemical assessment techniques [sediment quality guidelines (SQGs), enrichment factor (EF), geoaccumulation index (I geo ), pollution load index (PLI) and ecological risk index (ERI)], the surfaces sediments in the study region are not highly polluted for trace metals, except for As. However, the higher concentrations in downstream study regions of the Taehwa River could impact benthic organisms including shellfish (i.e. Manila clam) in sediments.

16S rRNA Gene Amplicon Sequencing of Contaminated Coastal Sediment Collected from the Taehwa River Estuary, South Korea

“…The Taehwa River (length, 48 km; basin area, 644 km 2 ) is an urban river that flows through Ulsan, the largest industrial city in South Korea ( 1 , 2 ). After the construction of industrial complexes and Ulsan Port, large amounts of industrial wastewater and domestic sewage began to flow into the Taehwa River, and the coastal environment deteriorated dramatically ( 3 ).…”