Environmental Impacts and Recovery After the Hebei Spirit Oil Spill in Korea.

The Hebei Spirit oil spill (HSOS) on December 7, 2007 was the worst oil spill recorded in Korea, with the release of approximately 10,900 tons of crude oil and 375 km of coastline polluted along the west coast of Korea. Cleanup operation was conducted by official and contract responders as well as volunteers for massive oil containment and removal of heavy accumulations of stranded oil. Together with the oil cleanup, a long-term environmental impact assessment (EIA) of the HSOS was initiated based on the Marine Environmental Management Act, which covers oil contamination in a multimedia environment, toxic effects on organisms, and ecosystem injury. This review summarizes the long-term monitoring results of HSOS EIA focused on (1) pollution status of seawater, sediment, and bivalves, (2) ecotoxicological effects, and (3) ecosystem recovery. Overall, concentrations of petroleum hydrocarbons in the environment indicated that their concentrations were well down to at or near background or pre-spill contamination levels at most sites after 1 year. The potential toxic effects of residual oils in sediments have decreased to background levels in most coastal areas of Taean. The entire ecosystem in the most affected area of the Taean coasts appear to be considerably, but not fully, recovered at present, namely after 8 years of the HSOS. The presence of lingering oil and elevated contamination levels at several sites still require continuous long-term monitoring.

Sand capping for controlling phosphorus release from lake sediments.

In this research, the use of the sand capping technique for controlling phosphorus release from lake sediment was evaluated experimentally. Multiple acrylic columns were prepared to measure the dissolved oxygen, oxidation reduction potential, total phosphorus, and phosphate concentrations of the overlying water on the capping layer with thicknesses of 0, 40, and 80 mm. Sand capping effectively slowed down the reactions that depleted the dissolved oxygen, which as a result, controlled the total phosphorus release from the sediment. Oxidation reduction potential of overlying water was estimated by measuring dissolved oxygen in situ or vice versa by an empirical model proposed in this research. Sediment disturbance should be considered during field construction of the cap system. The experimental results showed that phosphorus existed in a more stable form with capping than without capping.

In vitro response of fish and mammalian cells to complex mixtures of polychlorinated naphthalenes, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons.

In vitro characterization and comparison of responses to different classes of biologically active compounds can increase the utility of bioassays. In this study, the relative potencies (REPs) of mixtures of polychlorinated naphthalenes (PCNs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs), to induce in vitro ethoxyresorufin-O-deethylase (EROD) in PLHC-1 fish hepatoma cells, H4IIE wild type (H4IIE-wt) rat hepatoma cells, and recombinant H4IIE cells (H4IIE-EROD) were determined. The mixtures were also analyzed by in vitro luciferase assay with recombinant H4IIE cells (H4IIE-luc). Halowaxes 1051, 1014, and 1013 caused significant induction in all three H4IIE assays at concentrations less than 10 mg/l, but did not elicit a significant response in the PLHC-1 assay. Based on H4IIE results, the Halowaxes were estimated to have relative potencies (REPs) of approximately 10(-6)-10(-8) relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Less than 5 mg/l of Aroclors 1242, 1248, 1254; Clophens A60, T64; and Chlorofen induced significant responses in the H4IIE assays, while only Clophens A60 and T64 caused a significant response in the PLHC-1 assay. The efficacy of the Aroclor mixtures was generally insufficient to allow for quantitative REP estimates, but, based on their responses in the H4IIE assays, Clophen A60 and Chlorofen were estimated to have REPs of approximately 10(-6) and 10(-7), respectively. A mixture of 16 priority PAHs caused significant induction in all four cell types and was estimated to have a REP of approximately 10(-4). Overall, the results of this study add to a growing database on the dioxin-like potency of complex mixtures of xenobiotics, and suggested that H4IIE-based in vitro bioassays were more sensitive than PLHC-1 cells for detecting dioxin-like activity in complex mixtures.

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) and 2,3,7,8-TCDD equivalents (TEQs) in sediment from the Hyeongsan River, Korea.

Sediment, pore water and water samples from the Hyeongsan River, Korea were analyzed for several classes of halogenated aromatic hydrocarbons (HAHs) and their dioxin-like activities were evaluated using the in vitro H4IIE-luc bioassay. Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were detected in sediments from all six sampling locations with mean concentrations of 2.8 x 10(2) pg/g, 190 pg/g, and 61.4 ng/g, dw, respectively. Polycyclic aromatic hydrocarbons (PAHs) were predominated by 4-6 ring compounds with concentrations in the range of 5.30-7680 ng/g, dw. Chemical profiles of target analytes in sediment and water samples revealed that there was a gradient of concentrations along the river from upstream to downstream, which suggested that the primary source was a wastewater reservoir adjacent to a sewage treatment plant (STP). TEQs derived by summing the product of concentrations of individual congeners by their respective relative potencies (REPs or TEFs) ranged from 4.3 x 10(-1) to 1.1 x 10(3) pg/g, dw. Raw Soxhlet extracts from all six sampling locations induced significant dioxin-like responses in the H4IIE-luc bioassay. TCDD-EQs derived from H4IIE bioassay ranged from 7 x 10(-3) to 1.5 x 10(3) pg/g, dw, which were significantly correlated with TEQs (r2 = 0.994, p < 0.05). Among the three Florisil fractions tested, PCDD/Fs in fraction (F2) induced the greatest magnitude of response (range: 24-83%-TCDD-max.) in the H4IIE-luc assay. Comparison of the TEQ and TCDD-EQ suggested little non-additive interaction between fractions and AhR-active and inactive compounds. Concentrations of individual congeners as well as TEQs and TCDD-EQs suggest inputs from the industrial center waste stream in the Hyeongsan River.

Kinetics of reductive denitrification by nanoscale zero-valent iron.

Zero-valent iron powder (Fe0) has been determined to be potentially useful for the removal of nitrate in the water environment. This research is aimed at subjecting the kinetics of denitrification by nanoscale Fe0 to an analysis of factors affecting the chemical denitrification of nitrate. Nanoscale iron particles with a diameter in the range of 1-100 nm, which are characterized by the large BET specific surface area to mass ratio (31.4 m2/g), removed mostly 50, 100, 200, and 400 mg/l of nitrate within a period of 30 min with little intermediates. Compared with microscale (75-150 microm) Fe0, end product is not ammonia but N2 gas. Kinetics analysis from batch studies revealed that the denitrification reaction with nanoscale Fe0 appeared to be a pseudo first-order with respect to substrate and the observed reaction rate constant (k(obs)) varied with iron content at a relatively low degree of application. The effects of mixing intensity (rpm) on the denitrification rate suggest that the denitrification appears to be coupled with oxidative dissolution of iron through a largely mass transport-limited surface reaction (<40 rpm).

Rapid reductive destruction of hazardous organic compounds by nanoscale Fe0.

Fe0-mediated reductive destruction of hazardous organic compounds such as chlorinated organic compounds (COCs) and nitroaromatic compounds (NACs) in the aqueous phase is one of the latest innovative technologies. In this paper, rapid reductive degradation of COCs and NACs by synthesized nanoscale Fe0 in anaerobic batch systems was presented. The nanoscale Fe0, characterized by high specific surface area and high reactivity, rapidly transformed trichloroethylene (TCE), chloroform (CF), nitrobenzene (NB), nitrotoluene (NT), dinitrobenzene (DNB) and dinitrotoluene (DNT) under ambient conditions, which results in complete disappearance of the parent compounds from the aqueous phase within a few minutes. GC analysis reported that the main products of the dechlorination of TCE and CF were ethane and methane as well as that most of the nitro groups in NACs were reductively transformed to amine groups. These results suggest that the rapid reductive destruction by nanoscale Fe0 is potentially a viable in situ or aboveground treatment of groundwater contaminated with hazardous organic compounds including COCs and NACs.

Sorption and biodegradation of vapor-phase organic compounds with wastewater sludge and food waste compost.

To test the possible use of composted food waste and wastewater sludge as biofilters to treat gas-phase volatile organic compounds (VOCs), batch experiments were conducted with an isolated strain that could degrade aromatic compounds under aerobic conditions. A benzene and trichloroethylene (TCE) mixture was used as the gas-phase pollutant in experiments with composted food waste, sludge, and soil. Under aerobic conditions, benzene was degraded as a primary substrate and TCE was degraded cometabolically, with water contents varying from 6 to 60% (volume of water added/volume of solid). Optimal water content for VOC removal was 12% for the soil, 36% for the composted food waste, and 48% for the sludge. The extent of VOC sorption and biodegradation at the optimal water content was different for each material. With the same initial VOC concentration, more VOCs were removed by sorption onto the composted food waste and the sludge, while less VOCs were biodegraded in comparison with the results using soil. The reason the biodegradation in the soil was greater may be partly attributed to the fact that, due to less sorption, the aqueous-phase concentration of VOCs, which microorganisms could utilize as a carbon source or cometabolize, was higher. We also speculate that the distribution of microorganisms in each medium affects the rate of biodegradation. A large number of microorganisms were attached to the composted food waste and sludge. Mass transfer of VOCs and oxygen to these microorganisms, which appear to have been heterogeneously distributed in clusters, may have been limited, resulting in hindered biodegradation.

Nonequilibrium mass transfer of multi-component NAPL in a soil column venting.

This study was conducted to investigate the mass transfer behavior for a multi-component system in the soil venting process. Soil venting experiments were conducted using gasoline-contaminated soil and models of local equilibrium assumption (LEA) and the first-order kinetic approach were used to descnbe the gasoline volatilization process. However, the focus was on the application of the kinetic model. In both models, thirteen major components of gasoline were selected for the model input and the rest of the gasoline was divided into 11 groups based on the retention times in the gas chromatography of gasoline. The LEA model had the tendency of underestimating the gas concentration at the initial phase and overestimating at the later phase due to the different volatilities of multi-components. n the kinetic model, the estimation of mass transfer coefficient values were carried out by adopting the relationship developed in the single-components system and choosing the appropriate modified Sherwood number. This method resulted in the good agreement with the simulation and the experimental results.

Relative potencies of individual polycyclic aromatic hydrocarbons to induce dioxinlike and estrogenic responses in three cell lines.

The dioxinlike and estrogenic relative potencies (REPs) of 16 priority polycyclic aromatic hydrocarbons (PAHs), seven methylated PAHs, and two hydroxylated PAHs were examined using three in vitro cell bioassays. An in vitro ethoxyresorufin-O-deethylase assay with PLHC-1 fish hepatoma cells and in vitro luciferase assay with H4IIE-luc recombinant rat hepatoma cells were used to evaluate dioxinlike potency. An in vitro luciferase assay with MVLN, recombinant human breast carcinoma cells, was used to evaluate estrogenic potency. Seven of the 16 priority PAHs tested induced significant dioxinlike responses. Excluding outliers with large ranges of uncertainty, the dioxinlike REPs for the PAHs ranged from 10(-6) to 10(-3). This is similar to the REPs reported for other xenobiotics of concern including polychlorinated naphthalenes (PCNs) and some polychlorinated biphenyls (PCBs). In general, REP estimates generated in this study were similar to those reported previously. However, a comparison of the estimates of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents derived using assay-specific REPs with REPs reported in other studies indicated that the use of nonspecific REPs could lead to significant error in mass-balance (potency-balance) analyses. A 10-h acid treatment completely destroyed the dioxinlike activity of a PAH mixture. Among the compounds tested, only benzo[a]anthracene and dibenz[a,h]anthracene induced significant responses in the MVLN bioassay. Relative estrogenic potencies were estimated to be approximately 10(-7). Overall, this research contributes to the growing consensus regarding the dioxinlike potency of priority PAHs and PAH derivatives and provides some additional evidence about potentially estrogenic PAHs.

Trace organic contaminants in sediment and water from Ulsan Bay and its vicinity, Korea.

Sediment and water samples collected from 32 locations in Ulsan Bay and adjacent inland areas were analyzed for polycyclic aromatic hydrocabons (PAHs), nonylphenol (NP), octylphenol (OP), bisphenol A (BPA), organochlorine (OC) pesticides (HCB, HCHs, CHLs, and DDTs), and polychlorinated biphenyls (PCBs) to characterize their spatial distribution and contamination status. PAHs were detected in nearly all sediment and water extracts from Ulsan Bay and its inland locations. The sedimentary PAH concentrations ranged from 17 to 3,100 ng/g on a dry weight basis (DW), which were predominated by two- and three-ring aromatic hydrocarbons in river and/or stream, and four- to six-ring compounds in Ulsan Bay sediment. Concentrations of PAHs in pore water samples were generally two or three orders magnitude less than those of corresponding sediment samples. Maximum concentrations of NP, OP, and BPA in sediments were 1,040, 120, and 54 ng/g DW, respectively. Concentrations of OP and BPA were, on average, 5- to 13-fold less than those of NP. PCB concentrations in sediment ranged from 1.4 to 77 ng/g DW, which were predominated by lower chlorinated congeners such as di- through pentachlorinated biphenyls. Among different OC pesticides analyzed, concentrations of DDTs were the greatest, ranging from 0.02 to 41.9 ng/g DW. NP concentrations were greater at inner locations proximal to municipal wastewater discharges into rivers and/or streams, whereas the concentrations of PCBs and PAHs were great near the sites of high industrial activities. Sediment-pore water partitioning coefficients correlated with those of reported Koc or Kow values for selected PAHs in Ulsan Bay, but these varied by an order of magnitude for stream and/or river sediments.

In vitro bioassay determination of dioxin-like and estrogenic activity in sediment and water from Ulsan Bay and its vicinity, Korea.

Extracts of sediment and water samples collected from Ulsan Bay, Korea, were screened for their ability to induce dioxin-like and estrogenic gene expression in vitro. Each sample was tested as raw extract (RE) and fractionated extract (FE). Based on the initial screening of RE, 23 of 31 sediment samples showed significant dioxin-like activity in H4IIE-luc bioassay, whereas most sediment samples did not elicit estrogenic response in MVLN bioassay. Most of the activities associated with FE samples revealed that mid-polar (F2) and most polar (F3) fractions were responsible for the significant reporter gene expression in H4IIE-luc bioassay. The results suggest that complex interactions may have depressed the activities of the known arylhydrocarbon receptor (AhR) agonists present in F1 samples. The F2 samples were the most active fraction. All F2 samples except one induced significant dioxin-like activity, and over half of the F2 samples induced significant estrogenic activity. Ten of the F2 samples produced magnitudes of response in H4IIE-luc bioassay similar to those induced by a 2,3,7,8-tetrachlorodibenzo-p-dioxin standard. Sediment associated with F2 samples was estimated to contain 24.9-826 pg TCDD-EQ/g DW. Based on a qualitative mass balance analysis, polycyclic aromatic hydrocarbons (PAHs) appeared to account for both the estrogenic and dioxin-like responses observed. Over half of the F3 samples were either cytotoxic or caused morphological changes in both H4IIE-luc and MVLN cells. Known concentrations of alkylphenols and bisphenol A were not great enough to account for both the estrogenic response and cytotoxicity observed for F3 samples. Despite the apparent toxic or stressful effects, most of F3 samples induced significant dioxin-like activity in vitro, adding to a growing body of evidence that suggests the presence of unidentified, relatively polar, AhR agonists in sediment from some areas.

Relative potencies of individual polychlorinated naphthalenes to induce dioxin-like responses in fish and mammalian in vitro bioassays.

A growing body of evidence suggests that polychlorinated naphthalenes (PCNs) may be fairly widespread environmental contaminants. This may be cause for concern because exposure to PCNs has been linked to dioxin-like biological responses in a wide variety of species. This study used three in vitro bioassays to characterize the dioxin-like potency of 18 individual PCN congeners and 1 PCN metabolite. The PLHC-1 fish hepatoma cell bioassay was relatively insensitive to PCNs. At the concentrations tested, only 1, 4 di-CN and 2,4-dichloro-1-napthol caused significant induction of ethoxyresorufin O-deethylase (EROD) activity in the PLHC-1 assay. In vitro EROD and luciferase assays using recombinant H4IIE rat hepatoma cells were more responsive to PCNs. Structure-activity relationships were observed both in terms of the degree of chlorination and the positions of chlorine substitutions. Hexa-chlorinated naphthalenes (CNs), exhibiting relative potencies (REPs) around 10(-3) (relative to TCDD), were the most potent congeners tested. Penta-CNs were also rather potent, yielding REPs between 10(-3) and 10(-7). Tetra-, tri-, di-, and mono-CNs were less active. REPs for the active congeners were similar to those for some PCBs. The relative potency estimates reported here contribute to an emerging body of information that will aid determination of the relative contribution of PCNs to the total dioxin-like activity associated with environmental samples.

Instrumental and bioanalytical measures of persistent organochlorines in blue mussel (Mytilus edulis) from Korean coastal waters.

Blue mussels (Mytilus edulis) collected from 34 locations along the south and east coast of Korea were analyzed for polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides. Maximum concentrations of PCBs and total OC pesticides were 98.5 and 20.5 ng/g, wet weight, respectively. Extracts were fractionated by Florisil chromatography and each fraction was screened for dioxin-like activity in vitro, using recombinant rat hepatoma cells (H4IIE-luc). Fraction 2 (F-2), which contained hexachlorocyclohexanes, chlordanes, p,p'-DDD, and p,p'-DDT, generally elicited significant dioxin-like activity compared to control, whereas Fraction 1 (F-1), which contained PCBs, p,p'-DDE, and hexachlorobenzene, did not. The greatest magnitude of dioxin-like response observed was 44% of the maximum response elicited by a 2,000 pM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) standard. The relatively low magnitudes of dioxin-like response observed for F-1 samples were consistent with the relatively low PCB concentrations. At concentrations equal to the maximum observed in the mussel samples, neither individual OC pesticides nor a mixture of OC pesticides yielded a significant dioxin-like response in the H4IIE-luc assay. Thus, the concentrations of OC pesticides in F-2 did not appear to have accounted for the dioxin-like activity observed. This suggests the presence of unidentified and/or unknown, acid-stable, dioxin-like compounds in F-2. This study suggests that in vitro bioassays are useful in assessing the contamination of mussels collected from coastal marine locations.