Marine Ecological Risk Assessment: Case Study in Masan Bay, Korea

Abstract

Since the 2000s, environmental risk assessment has been preliminary adopted in the special management areas in Korea. A recent application has been made in Masan Bay which is one of most polluted coastal environments of Korea. The environmental risk assessment applied in Masan Bay is basically consists of exposure and effect analyses. The exposure analysis includes monitoring known toxicants (heavy metals, dioxins, dibenzufrans, PBDEs, PCBs, OCPs, PAHs, phenolic compounds and organotins) and tracing sewage input and range of effects using alkylphenols and fecal sterols. In addition, three in vitro screening assays were concurrently applied to sediment samples with chemical analysis : 1) DR-CALUX for dioxin-like compounds, 2) two-hybrid yeast for estrogenicity, and 3) fish brain cell for acetylcholinesterase inhibition. The effect analyses are consist of sediment toxicity tests using invertebrates (mussel, sea urchin, and amphipod), and biomarker studies (EROD, GST, AChE, MT and DNA breakage) for both feral and caged fish in the study area. Furthermore, sediment toxicity reduction and evaluation study, using pretreatment of sediment samples with EDTA, thiosulfate, C18 and cation exchange, were conducted to identify potential toxicity of group of contaminants in sediments. The measurable amount of effects in bioassays and biomarker studies indicate that toxicants of the bay can cause adverse effects on both invertebrates and fish. Accompanying with the exposure analysis, it was revealed the areas and chemicals of concern in the bay. There were three major hot spots in the bay, which are closed to urbanized areas and (or) sewage outfalls. Although the causality of effects on marine organisms and ecosystem were not clearly revealed in all the field studies, the qualitative environmental risk assessment in Masan Bay can partly answer the questions raised.