Mercury contamination of sediments in an open coastal area of the Hupo Basin, East Sea, Korea.

Mercury (Hg) contamination in open coastal areas has attracted public concern regarding safe fish consumption and management of the coastal environment, especially in areas of accidental Hg spills on inland coasts. This study investigated the temporal and spatial distribution of Hg in sediments of Youngil Bay and the Hupo Basin, East Sea, Korea; it also discussed the sources and transport of anthropogenic Hg. Hg hot spots were found in the northern Hupo Basin (elevated by 2-3×) and the river mouth area in Youngil Bay (elevated by approximately 70×). The river mouth contamination resulted from the destruction of a dam impounding landfill waste, while the basin contamination was attributed to atmospheric deposition and Hg enrichment associated with increased organic carbon concentrations driven by high biological production in the coastal upwelling area. Spilled Hg was transported to open coastal areas up to 36.6°N.

Effects of metal-polluted seawater on life parameters and the induction of oxidative stress in the marine rotifer Brachionus koreanus.

Metal pollution is one of the major threats to the aquatic environment due to its high bio-concentrations and toxicity. Although numerous studies have been conducted to understand detoxification and toxicity mechanisms in aquatic invertebrates, most of them were limited in laboratory study. Here, we investigated adverse effects of the contaminated-natural seawater on the marine rotifer Brachionus koreanus. Field seawater was collected from five different sites of Youngil Bay, South Korea where pollution by metals is predicted due to industrial discharges from nearby steel industry complexes. The marine rotifer B. koreanus was exposed to different seawater samples, and we found decreased population growth rates with highly induced transcriptional level of detoxification-related genes. Our finding shows a link between the induction of metal-mediated regulation of detoxification genes in B. koreanus and concentration of heavy metals present in various seawater samples, implying those biomarker genes can be useful to assess the toxicity of metal polluted natural seawaters. Our results are helpful to validate and establish biomarker genes for early risk assessment of metal contamination in the natural sea water.