Bong-Oh Kwon

Perfluorinated compounds in water, sediment, soil and biota from estuarine and coastal areas of Korea

Soil, sediment, water, and biota collected from the western coast of Korea were analyzed to determine occurrence and sources of perfluorinated compounds (PFCs). PFCs were significantly concentrations of PFCs were measured in some water and biological samples, while concentrations of PFCs in soils and sediments were relatively low. The most widely detected compound was found to be perfluorooctanesulfonate (PFOS), with a maximum concentration in water of 450 ng/L and in fish of 612 ng/g, dw. PFOS concentrations in water and biota were both less than those thought to cause toxicity. However, in both cases concentrations were within a factor of 10 of the toxicity threshold concentration. Concentrations of PFCs were significantly greater downstream than those upstream on the same river, suggesting point sources. Overall, the detection of PFCs at relatively great concentrations in various environmental matrixes from this region of Korea suggests that further studies characterizing PFCs and their potential risk to both humans and wildlife are needed.

Distributions and bioconcentration characteristics of perfluorinated compounds in environmental samples collected from the west coast of Korea.

As part of an ongoing study of the status and trends of contaminants in the Yellow Sea, during May of 2009, the concentrations of perfluorinated compounds (PFCs) were determined in water (n=15), sediment (n=12), soil (n=13), and biota (n=74) from estuarine and coastal areas along the west coast of Korea. Of the 12PFCs monitored, PFOS and PFOA were the most frequently detected compounds in water. Greater concentrations of PFCs were found in waters from the inner regions of sea dikes in three artificial lakes, Shihwa, Asan, and Sapgyo, than outer regions. Concentrations were also comparable in two estuarine areas, which indicated that most PFCs in coastal areas originated from industrial and local regions and river water flowing through estuaries. Concentrations of PFCs in soils and sediments were generally less than limits of quantification and were generally less than those measured in biota. Compound-specific bioaccumulation of PFBS and PFOS had the greatest BCF values in crab, while in fish it was PFOS and PFDA, and in gastropods and bivalves it was PFHxS. Distributions of BCFs for PFOS in body-parts of crab showed the greatest values in soft tissues followed by shells and then legs. Distribution among tissues and organs of fishes was more variable than those observed for crab. When compared to a similar study conducted by our group in 2008, concentrations of PFCs in water samples were significantly less in 2009. However, there was little change in bioconcentration from sediments into benthic organisms. Finally, we conducted the assessment of potential adverse effects for PFCs on aquatic life by use of current and previous reported data.

Two Years after the Hebei Spirit Oil Spill: Residual Crude-Derived Hydrocarbons and Potential AhR-Mediated Activities in Coastal Sediments

The Hebei Spirit oil spill occurred in December 2007 approximately 10 km off the coast of Taean, South Korea, on the Yellow Sea. However, the exposure and potential effects remain largely unknown. A total of 50 surface and subsurface sediment samples were collected from 22 sampling locations at the spill site in order to determine the concentration, distribution, composition of residual crudes, and to evaluate the potential ecological risk after two years of oil exposure. Samples were extracted and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), 20 alkyl-PAHs, 15 aliphatic hydrocarbons, and total petroleum hydrocarbons using GC-MSD. AhR-mediated activity associated with organic sediment extracts was screened using the H4IIE-luc cell bioassay. The response of the benthic invertebrate community was assessed by mapping the macrobenthic fauna. Elevated concentrations of residual crudes from the oil spill were primarily found in muddy bottoms, particularly in subsurface layers. In general, the bioassay results were consistent with the chemistry data in a dose-dependent manner, although the mass-balance was incomplete. More weathered samples containing greater fractions of alkylated PAHs exhibited greater AhR activity, due to the occurrence of recalcitrant AhR agonists present in residual oils. The macrobenthic population distribution exhibits signs of species-specific tolerances and/or recolonization of certain species such as Batillaria during weathering periods. Although the Hebei Spirit oil spill was a severe oil exposure, it appears the site is recovering two years later.

AhR-mediated potency of sediments and soils in estuarine and coastal areas of the Yellow Sea region: a comparison between Korea and China.

Extracts of sediments (n = 45) and soils (n = 37) collected from the coast of the Yellow Sea, in Korea and China, were screened for their ability to induce dioxin-like gene expression in vitro using the H4IIE-luc, transactivation bioassay. Significant dioxin-like potency was observed except for a few soils from Korea. Concentrations of TCDD-EQ (2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents) in sediments were comparable between Korea and China, but concentrations of TCDD-EQ in soil were 2-fold greater from Korea. Mass balance analysis indicated that concentrations of TCDD-EQ were to some degree chemical- and/or matrix-dependent, but were much more site-specific. For example, the proportion of the TCDD-EQ that could be identified varied among locations, which suggests different sources. Unidentified AhR-active compounds represented a greater proportion of the TCDD-EQ in samples from Korea, which suggests that sources in Korea were more complex than those in China. Potential sources of TCDD-EQ were investigated by considering land-uses and local activities.

Bioaccumulation characteristics of perfluoroalkyl acids (PFAAs) in coastal organisms from the west coast of South Korea

Year-round monitoring for perfluoroalkyl acids (PFAAs) along the west coast of South Korea targeting long-term changes in water and coastal organisms has been conducted since 2008. In this study, we present the most recent 5-years of accumulated data and scrutinize the relationship between concentrations in water and biota highlighting bioaccumulation characteristics. Twelve individual PFAAs in samples of water (n=43) and biota (n=59) were quantified by use of HPLC-MS/MS after solid phase extraction. In recent years, concentrations of PFAAs in water have been generally decreasing, but profiles of relative concentrations of individual PFAAs vary among location and year. Bioaccumulation of PFAAs in various organisms including fishes, bivalves, crabs, gastropods, shrimps, starfish, and polychaetes varied among species. However, overall bioaccumulation of PFAAs was dependent on corresponding concentrations of PFAAs in water within an area. In organ-specific distributions of PFAAs, greater concentrations of PFAAs were found in intestine of fish (green eel goby). This result suggests that PFAAs are mainly accumulated via dietary exposure, while greater concentrations were found in gill and intestine of bivalve (oyster) which suggests both waterborne and dietary exposures to these organisms. Concentrations of PFAAs in biota did not decrease over time (2008-2010), indicating that continuing bioaccumulation followed by slow degradation or excretion of PFAAs accumulated in biota. Overall, spatio-temporal distributions of PFAAs in water and bioaccumulation characteristics seemed to be associated with recent restrictions of PFOS-based products and uses of PFBS-based substitutes.

Lethal and sub-lethal effects of elevated CO2 concentrations on marine benthic invertebrates and fish

Concern about leakage of carbon dioxide (CO2) from deep-sea storage in geological reservoirs is increasing because of its possible adverse effects on marine organisms locally or at nearby coastal areas both in sediment and water column. In the present study, we examined how elevated CO2 affects various intertidal epibenthic (benthic copepod), intertidal endobenthic (Manila clam and Venus clam), sub-tidal benthic (brittle starfish), and free-living (marine medaka) organisms in areas expected to be impacted by leakage. Acute lethal and sub-lethal effects were detected in the adult stage of all test organisms exposed to varying concentrations of CO2, due to the associated decline in pH (8.3 to 5.2) during 96-h exposure. However, intertidal organisms (such as benthic copepods and clams) showed remarkable resistance to elevated CO2, with the Venus clam being the most tolerant (LpH50 = 5.45). Sub-tidal species (such as brittle starfish [LpH50 = 6.16] and marine medaka [LpH50 = 5.91]) were more sensitive to elevated CO2 compared to intertidal species, possibly because they have fewer defensive capabilities. Of note, the exposure duration might regulate the degree of acute sub-lethal effects, as evidenced by the Venus clam, which showed a time-dependent effect to elevated CO2. Finally, copper was chosen as a model toxic element to find out the synergistic or antagonistic effects between ocean acidification and metal pollution. Combination of CO2 and Cu exposure enhances the adverse effects to organisms, generally supporting a synergistic effect scenario. Overall, the significant variation in the degree to which CO2 adversely affected organisms (viz., working range and strength) was clearly observed, supporting the general concept of species-dependent effects of elevated CO2.

The Relationship between Primary Production of Microphytobenthos and Tidal Cycle on the Hwaseong Mudflat, West Coast of Korea

ABSTRACT Kwon, B.-O.; Koh, C.-H.; Khim. J. S.; Park, J.; Kang, S-G., and Hwang, J.H., 2014. The relationship between primary production of microphytobenthos and tidal cycle on the Hwaseong mudflat, west coast of Korea. The present study examined variation in sediment temperature and irradiance with respect to microphytobenthos primary production at the Hwaseong mudflat, west coast of Korea, under different tidal cycles. The study was carried out during March and April 2009, which encompassed two spring tides and one neap tide. It was not possible to continuously measure primary production in situ across the tidal cycles; hence, photosynthesis–irradiance (P-I) curves at different temperatures were obtained experimentally in the laboratory. These readings were then used to calculate primary production, by projecting in situ mooring records of irradiance and temperature onto the P-I curves. The sediment temperature and irradiance were measured continuously, and the averages of 10-minute intervals from the mooring records were used. The results show that changes in primary production simulated from the P-I curves were strongly associated with the tidal cycle. During the two spring tides that were recorded, mean daily primary production was 1005 and 1125 mg C m−2 d−1, respectively. However, primary production was lower during the neap tide (898 mg C m−2 d−1). Temperature appeared to influence these differences in mean daily production. In situ mean daily temperatures during exposure were 14°C and 20°C during the first and second spring tides, respectively. In contrast, mean daily total irradiance was noticeably higher in the first spring tide compared with the second spring tide. During the neap tide, the site was exposed in the morning and afternoon, when light intensity and temperature were relatively low. In contrast, during the spring tide, the site was exposed at noon, when light intensity and temperature were high. The current study provided new insights about how changes in environmental parameters during tidal cycles affect microphytobenthic primary production, indicating the complexity of this process and the requirement for further fine-scale research.

Spatiotemporal distributions of butyltin compounds in various intertidal organisms along the Samcheok and Tongyeong coasts of Korea

Thirteen years ago, the Korean Government introduced a regulation prohibiting the use of tributyltin (TBT), which was a component of antifouling paints. A subsequent decline in the concentration of butyltins (BTs) was recorded in seawater and the sediment, however, the current concentration of BTs in biota has not been well documented. The spatiotemporal distribution and concentration of BTs was recorded in biota from 2013 to 2015 along the coasts of Samcheok and Tongyeong using GS/MSD analysis. Crustaceans contained the greatest concentrations of BTs, followed by gastropods, fishes, and bivalves. We found that the concentration of BTs was greater at Tongyeong compared to Samcheok, because of the geographical characteristics of the area. We also confirmed that the regulation has been effective by showing that the TBT concentration decreased over the 3-year study period. The TBT levels of gastropods and bivalves fell within the limits of the guidelines and/or the effective concentration of the toxicological endpoint reported previously. The concentration of BTs also varied among species, being dependent on the weight of the soft tissue. Furthermore, the greater quantities of BTs degradation products compared to TBT confirmed the absence of recent inputs of pollutants during the study periods. However, compared with other Asian countries, biota BTs were greater in Korea, with noticeably greater concentrations along the south coast. Thus, further investigation of the distribution of BTs along the Korean coasts is required in the future. In conclusion, our results provide useful information about the recent trends of BTs in Korea.

Biosurfactant-assisted bioremediation of crude oil by indigenous bacteria isolated from Taean beach sediment

Crude oil and its derivatives are considered as one group of the most pervasive environmental pollutants in marine environments. Bioremediation using oil-degrading bacteria has emerged as a promising green cleanup alternative in more recent years. The employment of biosurfactant-producing and hydrocarbon-utilizing indigenous bacteria enhances the effectiveness of bioremediation by making hydrocarbons bioavailable for degradation. In this study, the best candidates of biosurfactant-producing indigenous bacteria were selected by screening of biochemical tests. The selected bacteria include Bacillus algicola (003-Phe1), Rhodococcus soli (102-Na5), Isoptericola chiayiensis (103-Na4), and Pseudoalteromonas agarivorans (SDRB-Py1). In general, these isolated species caused low surface tension values (33.9-41.3 mN m-1), high oil spreading (1.2-2.4 cm), and hydrocarbon emulsification (up to 65%) warranting active degradation of hydrocarbons. FT-IR and LC-MS analyses indicated that the monorhamnolipid (Rha-C16:1) and dirhamnolipid (Rha-Rha-C6-C6:1) were commonly produced by the bacteria as potent biosurfactants. The residual crude oil after the biodegradation test was quantitated using GC-MS analysis. The bacteria utilized crude oil as their sole carbon source while the amount of residual crude oil significantly decreased. In addition the cell-free broth containing biosurfactants produced by bacterial strains significantly desorbed crude oil in oil-polluted marine sediment. The selected bacteria might hold additional capacity in crude oil degradation. Biosurfactant-producing indigenous bacteria therefore degrade crude oil hydrocarbon compounds, produce biosurfactants that can increase the emulsification of crude oil and are thus more conducive to the degradation of crude oil.

Seasonal variability of estuarine dynamics due to freshwater discharge and its influence on biological productivity in Yeongsan River Estuary, Korea

In order to evaluate water quality and biological productivity, observation data sets were collected and analyzed in Yeongsan River Estuary, Korea. We also set up a numerical model to resolve hydrodynamics and fate of water quality variables in the system. Results show that most of nutrients loading are trapped in the lake and higher concentrations of nutrients and organic matters (OM) are present only inside of the artificial sea dike. There exist episodial discharges at the dam, which coincide mostly with rainfall events during summer monsoon periods. During this discharge event, lower salinity and higher suspended solids, nutrients, and OM are observed in surface layer of the estuarine section. Hydrodynamic model results show that circulation in the estuarine section is governed by freshwater discharge from the lake, resulting in an enhanced two-layer estuarine circulation being dominated, during and after the freshwater is discharged. Such two-layer estuarine circulation combined with higher concentration of nutrients in the surface layer results in that outfluxes of nutrients in the surface layer dominate over the influxes in the bottom layer during summer high precipitation periods. Meanwhile, numerical dye experiment results show that the discharged water with elevated nutrients levels have a short residence time (∼5-10 days) in the estuarine section. Due to this fast flushing rate, excessive nutrient loadings are not used to produce biological matters in the estuarine section. This limited biological productivity, characterized by seaward side of the artificial sea dike, makes Yeongsan estuarine system excluded from acting as an active carbon sink.