Chemical Constituents of Halophyte Suaeda glauca and Their Therapeutic Potential for Hair Loss.

Suaeda glauca, a halophyte in the Amaranthaceae family, exhibits remarkable resilience to high salt and alkali stresses despite the absence of salt glands or vesicles in its leaves. While there is growing pharmacological interest in S. glauca, research on its secondary metabolites remains limited. In this study, chemical constituents of the aerial parts of S. glauca were identified using 1D- and 2D-NMR experiments, and its biological activity concerning hair loss was newly reported. Eight compounds, including alkaloids (1~3), flavonoids (4~6), and phenolics (7 and 8), were isolated. The compounds, except the flavonoids, were isolated for the first time from S. glauca. In the HPLC chromatogram, quercetin-3-O-ß-d-glucoside, kaempferol-3-O-ß-d-glucoside, and kaempferol were identified as major constituents in the extract of S. glauca. Additionally, the therapeutic potential of the extract of S. glauca and the isolated compounds 1~8 on the expressions of VEGF and IGF-1, as well as the regulation of Wnt/ß-catenin signaling, were evaluated in human follicle dermal papilla cells (HFDPCs) and human umbilical vein endothelial cells (HUVECs). Among the eight compounds, compound 4 was the most potent in terms of increasing the expression of VEGF and IGF-1 and the regulation of Wnt/ß-catenin. These findings suggest that S. glauca extract and its compounds are potential new candidates for preventing or treating hair loss.

Best available technique for the recovery of marine benthic communities in a gravel shore after the oil spill: A mesocosm-based sediment triad assessment.

Ecotoxicological effects of spilled oils are well documented, but study of recovery of marine benthic communities is limited. Long-term recovery of hard bottom communities during physical and biological remediations after a spill was monitored. A 60-day experiment was conducted using a mesocosm with monitoring of eight endpoints by use of the sediment quality triad (SQT). First, physical treatment of hot water + high pressure flushing maximally removed residual oils (max=93%), showing the greatest recovery among SQT variables (mean=72%). Physical cleanup generally involved adverse effects such as depression of the microphytobenthic community during the initial period. Next, biological treatments, such as fertilizer, emulsifier, enzyme and augmentation of the microbes, all facilitated removal of oil (max=66%) enhancing ecological recovery. Analysis of the microbiome confirmed that oil-degrading bacteria, such as Dietzia sp. and Rosevarius sp. were present. A mixed bioremediation, including fertilizer + multi-enzyme + microbes (FMeM) maximized efficacy of remediation as indicated by SQT parameters (mean=47%). Natural attenuation with "no treatment" showed comparable recovery to other remediations. Considering economic availability, environmental performance, and technical applicability, of currently available techniques, combined treatments of physical removal via hand wiping followed by FMeM could be most effective for recovery of the rocky shore benthic community.

Occurrence, distribution and affecting factors of microplastics in agricultural soils along the lower reaches of Yangtze River, China.

Microplastics become one of the serious persistent pollutants in terrestrial environments, and thus may represent a threat to the quality of soil and inhabiting organisms. It is imperative to understand occurrence and distribution of microplastics in soils. In this study, a large-scale field survey encompassing 85 locations along the lower reaches of Yangtze River and estuary was performed to investigate the microplastics abundance in agricultural soils. Microplastics were isolated from all the samples and all depths (0-80 cm). The microplastics abundance in soils ranged from 4.94 items/kg to 252.70 items/kg, with an average of 37.32 items/kg. The most common microplastic type detected was Polypropylene (PP) occurring as white fragments with sizes ranging from 0.1 mm to 0.5 mm. Abiotic parameters such as soil pH and texture were the general factors being associated with microplastic abundance. Meantime, traffic was indicated as one important factor to affect the microplastic abundance. Overall, the road input seems to be the main source of microplastic pollution in agricultural areas along the Yangtze River and estuary. Further studies should elucidate the original of the plastic fragments in order to establish a baseline for regulative initiatives securing environmental protection.

Marinobacter halodurans sp. nov., a halophilic bacterium isolated from sediment of a salt flat.

A Gram-staining-negative, aerobic, cream-coloured, marine bacterium, with rod-shaped cells, designated strain YJ-S3-2T, was isolated from salt flat sediment of Yongyu-do, Republic of Korea. YJ-S3-2T grew at pH 5.0-9.0 (optimum pH 7.0), 4-45 °C (optimum 30 °C) and with 1-18 % (w/v) NaCl (optimum 6 %). The results of 16S rRNA gene sequence analysis indicated that YJ-S3-2T was closely related to Marinobacter segnicrescens SS011B1-4T (97.0 %) followed by, 'Marinobacter nanhaiticus' D15-8W (96.7 %), Marinobacter bryozoorum 50-11T (96.7 %), Marinobacter koreensis DSMZ 179240T T (96.5 %) and Marinobacter bohaiensis T17T (96.5 %). The average nucleotide identity (ANI) and the genome to genome distance calculator (GGDC) estimate values between YJ-S3-2T and related type strains were 73.7-79.8 and 19.9-22.5 %, and also 73.5 and 20.7 % with Marinobacter hydrocarbonoclasticus. YJ-S3-2T was characterized as having Q-9 as the predominant respiratory quinone and the principal fatty acids (>10 %) were C16 : 0 (22.3 %), summed feature 9 (C17 : 1iso ω9c/C16 : 0 10-methyl, 13.8 %) and 3 (C16 : 1ω7c/C16 : 1ω6c, 11.9 %). The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified aminolipids and two unidentified phospholipids. The DNA G+C content of YJ-S3-2T is 60.9 mol%. On the basis of the polyphasic taxonomic evidence presented in this study, YJ-S3-2T should be classified as representing a novel species within the genus Marinobacter, for which name Marinobacter halodurans sp. nov. is proposed, with the type strain YJ-S3-2T (=KACC 19883T=KCTC 62937T=JCM 33109T).

Rapid recovery of coastal environment and ecosystem to the Hebei Spirit oil spill's impact.

The 2007 Hebei Spirit oil spill (HSOS), the largest in the national history, has negatively impacted the entire environment and ecosystem along the west coast of South Korea. Although many studies have reported the damages and impacts from the HSOS, quantitative assessment evaluating the recovery time and status have not been documented. Here, we first address the recovery timeline of the HSOS, by comprehensive analyses of 10-years accumulated data in quantitative manner. Concentrations of residual oils in seawater, sediments, and oysters rapidly dropped to backgrounds in 16, 75, and 33 months, respectively. Also, damaged benthic communities of intertidal and subtidal areas were fully recovered only after ~6 years. The present results collectively indicated unexpectedly fast recovery of the damaged environment and ecosystem from such a huge oil spill. The high tidal mixing (~9 m tidal height) and intensive human cleanup (~1.2 million volunteers) at the initial cleanup period might have contributed to rapid recovery; cf. 4-5 times faster than the Exxon Valdez oil spill. However, potential risk to human health remains unclear. Thus, it is warranted to conduct more in depth epidemiological studies to address chronic health effects associated with the cleanup volunteers as well as the local residents who have been living nearby the oil spill impacted sites.

Multiple evaluation of the potential toxic effects of sediments and biota collected from an oil-polluted area around Abu Ali Island, Saudi Arabia, Arabian Gulf.

After the Gulf War Oil Spill, there have been many investigations about distributions of oil-derived pollutants nearby areas, but lacking in ecotoxicological assessment. We evaluated the potential toxicity of asphalt mats, sediments, and biota (polychaetes, chitons, snapping shrimps, and crabs) by combining two bioassays (H4IIE-luc and Vibrio fischeri) and in situ microbial community (eDNA). Samples were collected from Abu Ali Island, and organic extracts were bioassayed and further fractionated according to the chemical polarity using silica gel column. Great aryl hydrocarbon receptor (AhR)-mediated potencies and inhibition of bioluminescence were mainly found in aromatics (F2) and saturates (F1) fractions of asphalt mat and sediments, respectively, while great toxicological responses in biota samples were found in resins and polar (F3) fraction. We also confirmed that potential toxicities of biota were species-specific; great AhR-mediated potencies were found in polychaetes and great bioluminescence inhibitions were found in crabs. In microbial communities, most genera (up to 90%) were associated with polycyclic aromatic hydrocarbons (PAHs)-degrading bacteria, supporting that PAHs are the primary stressors of the benthic community around Abu Ali Island. The present study provides useful information on the contamination status, risk assessment of environmental matrices and benthic organisms in Abu Ali Island.

Serinicoccus sediminis sp. nov., isolated from tidal flat sediment.

A novel Gram-strain-positive, non-spore-forming bacterial strain, designated GP-T3-3T, was isolated from sediment sampled at a tidal flat in Gopado, Republic of Korea. Cells were aerobic, catalase-negative, oxidase-positive, non-motile cocci that occurred singly, in pairs or in clusters. Strain GP-T3-3T grew at 4-45 °C (optimum, 28-37 °C), at pH 4.0-12.0 (pH 8.0-9.0) and in the presence of 0-15 % (w/v) NaCl (3-5 %). Colonies of strain GP-T3-3T were deep-yellow, circular, smooth and pulvinate. The results of the phylogenetic analyses based on 16S rRNA gene sequences indicated that strain GP-T3-3T was closely related to Serinicoccus profundi MCCC 1A05965T (99.1 %), Serinicoccus chungangensis CAU 9536T (99.0 %) and Serinicoccus marinus JC1078T (98.0 %). The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The predominant respiratory quinone was MK-8(H4) and the major fatty acids were anteiso-C17 : 0, iso-C16 : 0, iso-C15 : 0 and anteiso-C15 : 0. The polar lipid profile consisted of diphosphadidylglycerol, phosphadidylglycerol, phosphatidylcholine, phosphatidylinositol and two unidentified phospholipids. The DNA G+C content was 72.9 mol%. DNA-DNA relatedness values between strain GP-T3-3T and type strains of the genus Serinicoccus ranged from 28.9 to 50.5 %. On the basis of the phenotypic differences and DNA-DNA relatedness data, the isolate represents a new species of the genus Serinicoccus, for which the name Serinicoccussediminis sp. nov. is proposed. The type strain is GP-T3-3T (=KCTC 49173T=JCM 32825T=KCCM 43309T=KACC 19850T).

Comparative evaluation of bioremediation techniques on oil contaminated sediments in long-term recovery of benthic community health.

While various bioremediation techniques have been widely used at oil spill sites, the in situ efficiency of such techniques on recovering the benthic communities in intertidal areas has not been quantified. Here, the performance of several bioremediation tools such as emulsifiers, multi-enzyme liquid (MEL), microbes, and rice-straw was evaluated by a 90-days semi-field experiment, particularly targeting recovery of benthic community. Temporal efficiency in the removal of sedimentary total petroleum hydrocarbons (TPH), reduction of residual toxicity, and recovery of bacterial diversity, microalgal growth, and benthic production was comprehensively determined. Concentrations of TPH and amphipod mortality for all treatments rapidly decreased within the first 10 days. In addition, the density of bacteria and microphytobenthos generally increased over time for all treatments, indicating recovery in the benthic community health. However, the recovery of some nitrifying bacteria, such as the class Nitrospinia (which are sensitive to oil components) remained incomplete (13-56%) during 90 days. Combination of microbe treatments showed rapid and effective for recovering the benthic community, but after 90 days, all treatments showed high recovery efficiency. Of consideration, the "no action" treatment showed a similar level of recovery to those of microbe and MEL treatments, indicating that the natural recovery process could prevail in certain situations.

Gemmobacter lutimaris sp. nov., a marine bacterium isolated from a tidal flat.

A novel cream-pigmented marine bacterium, designated strain YJ-T1-11T, was isolated from a tidal flat at Yeongjong-do, Republic of Korea. Cells were rod-shaped, non-motile, aerobic, Gram-reaction-negative, oxidase-positive and catalase-positive. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain YJ-T1-11T clustered with Gemmobacter fontiphilus JS43T (98.3 %) within the genus Gemmobacter and its closest neighbours were G.emmobacter aquatilis DSM 3857T (98.5 %), Gemmobacter aquaticus A1-9T (98.4 %), Gemmobacterlanyuensis Orc-4T (98.4 %), Gemmobacterfontiphilus JS43T (98.3 %), Gemmobactercaeni DCA-1T (98.2 %), Gemmobacternanjingensis Y12T (97.5 %) and Gemmobactertilapiae Ruye-53T (97.2 %). Average nucleotide identity values between the genome sequences of strain YJ-T1-11T and the related type strains ranged from 77.08 to 90.48 %. The predominant fatty acid of strain YJ-T1-11T was summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c). The major isoprenoid quinone was Q-10 and the DNA G+C content was 65.6 mol%. The polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol and three unidentified lipids. The DNA-DNA relatedness values between strain YJ-T1-11T and the type strains of the 12 phylogenetically related species of the genus Gemmobacter were 23.6-53.7 %. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain YJ-T1-11T is considered to represent a novel species of the genus Gemmobacter, for which the name Gemmobacter lutimaris sp. nov. is proposed. The type strain is YJ-T1-11T (=KCTC 62715T=JCM 32828T).

Importance of functional diversity in assessing the recovery of the microbial community after the Hebei Spirit oil spill in Korea.

Over 10 years after the Hebei Spirit oil spill (HSOS), the concentrations of pollutants, such as TPH and PAHs, in spilled crude oil have recovered to background levels, but in some areas, the environment has not fully recovered. In particular, PAHs were more resistant to degradation, and their persistence could have deleterious impacts on the sediment ecosystem. This study aimed to evaluate the microbial recovery of coastal sediments from the HSOS by analyzing the structure and diversity of the microbial community and its functional contribution to PAHs degradation. High-throughput sequencing on the MiSeq platform was conducted using tidal flat sediments collected in 2014 and 2016 from the area contaminated by the HSOS. The microbial recovery was evaluated by various diversity factors, including microbial composition and structure and functional diversity based on PICRUSt analysis. The abundance of microbial taxa associated with TPH degradation was higher in 2014 than that in 2016, but the taxa associated with PAHs degradation were similar between years. These results are consistent with the dynamics of microbes associated with the fate of pollutants, and they also showed similar tendency in functional profiles. That is, even if the pollutants are completely degraded, the microbial community has not yet completely recovered from the HSOS. The evaluation of microbial ecosystems in contaminated environments should consider both the fate of pollutants and the dynamics of microbial species that make functional contributions to the degradation of pollutants.

Bioaccumulation of Polycyclic Aromatic Hydrocarbons (PAHs) by the Marine Clam, Mactra veneriformis, Chronically Exposed to Oil-Suspended Particulate Matter Aggregates.

Dispersion and biodegradation of petroleum hydrocarbons are significantly enhanced by formation of oil-suspended particulate matter aggregates (OSAs), but little is known about their adverse effects on benthic invertebrates or microbes. In this study, we investigated: (1) bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) by the marine bivalve, Mactra veneriformis and (2) changes in composition and relative abundances of microbes, during 50-d of an OSAs feeding experiment. Total concentrations of PAHs increased more rapidly during the first week of exposure, peaked at Day 30, then gradually declined to the end of experiment. While bioaccumulation of PAHs by clams varied among the 20 target compounds, two major groups of PAHs were identified by cluster analysis. One group including 3-methylphenanthrene, 1,6-dimethylphenanthrene, 1,2,6,9-tetramethylphenanthrene, and benzo[ a]anthracene showed a fairly constant rate of accumulation, while the second group including 2-methyldibenzothiophene, 2,4-dimethyldibenzothiophene, 2,4,7-trimethyldibenzothiophene, 3-methylchrysene, 6-ethylchrysene, and 1,3,6-trimethylchrysene exhibited a bell-shaped pattern. Bioaccumulation of PAHs by clams was dependent on changes in abundance of Gammaproteobacteria, indicating active degradations of hydrocarbons by selected species. Six key species included: Porticoccus litoralis, Porticoccus hydrocarbonoclasticus, Cycloclasticus spirillensus, Alcanivorax borkumensis, Alcanivorax dieselolei, and Alkalimarinus sediminis. These results are the first to demonstrate interactions of OSAs and macrofauna/microbe in oil cleanup operations.

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.

Integrated assessment of persistent toxic substances in sediments from Masan Bay, South Korea: Comparison between 1998 and 2014.

Complexity of anthropogenic influences on coastal ecosystems necessitates use of an integrated assessment strategy for effective interpretation and subsequent management. In this study a multiple lines of evidence (LOE) approach for sediment assessment, that combined use of chemistry, toxicity, and benthic community structure in the sediment quality triad was used to assess spatiotemporal changes and potential risks of persistent toxic substances (PTSs) in sediments of Masan Bay highlighting "long-term changes" between 1998 and 2014. Specific target objectives encompassed sedimentary PTSs (PAHs, alkylphenols (APs), and styrene oligomers), potential aryl hydrocarbon receptor (AhR; H4IIE-luc assay)- and estrogen receptor (ER; MVLN assay)-mediated activities, and finally several ecological quality (EcoQ) indices of benthic community structure. Concentrations of target PTSs in Masan Bay sediments were generally less by half in 2014 compared to those measured in 1998. Second, AhR-mediated potencies in sediments also decreased during this time interval, whereas ER-mediated potencies increased (+3790%), indicating that there has been substantial ongoing, input of ER agonists over the past 16 years. Potency balance analysis revealed that only 3% and 22% of the AhR- and ER-mediated potencies could be explained by identified known chemicals, such as PAHs and APs, respectively. This result indicated that non-targeted AhR and ER agonists had a considerable presence in the sediments over time. Third, EcoQ indices tended to reflect PTSs contamination in the region. Finally, ratio-to-mean values obtained from the aforementioned three LOEs indicated that quality of sediments from the outer region of the bay had recovery more during the period of 16-years than did the inner region. Overall, the results showed that even with the progress supported by recent efforts from the Korean governmental pollution control, PTSs remain a threat to local ecosystem, especially in the inner region of Masan Bay.

Microbial community composition and PAHs removal potential of indigenous bacteria in oil contaminated sediment of Taean coast, Korea.

The tidal flats near Sinduri beach in Taean, Korea, have been severely contaminated by heavy crude oils due to the Korea's worst oil spill accident, say the Hebei Spirit Oil Spill, in 2007. Crude oil compounds, including polycyclic aromatic hydrocarbons (PAHs), pose significant environmental damages due to their wide distribution, persistence, high toxicity, mutagenicity, and carcinogenicity. Microbial community of Sinduri beach sediments samples was analyzed by metagenomic data with 16S rRNA gene amplicons. Three phyla (Proteobacteria, Firmicutes, and Bacteroidetes) accounted for approximately ≥93.0% of the total phyla based on metagenomic analysis. Proteobacteria was the dominant phylum in Sinduri beach sediments. Cultivable bacteria were isolated from PAH-enriched cultures, and bacterial diversity was investigated through performing culture characterization followed by molecular biology methods. Sixty-seven isolates were obtained, comprising representatives of Actinobacteria, Firmicutes, α- and γ-Proteobacteria, and Bacteroidetes. PAH catabolism genes, such as naphthalene dioxygenase (NDO) and aromatic ring hydroxylating dioxygenase (ARHDO), were used as genetic markers to assess biodegradation of PAHs in the cultivable bacteria. The ability to degrade PAHs was demonstrated by monitoring the removal of PAHs using a gas chromatography mass spectrometer. Overall, various PAH-degrading bacteria were widely present in Sinduri beach sediments and generally reflected the restored microbial community. Among them, Cobetia marina, Rhodococcus soli, and Pseudoalteromonas agarivorans were found to be significant in degradation of PAHs. This large collection of PAH-degrading strains represents a valuable resource for studies investigating mechanisms of PAH degradation and bioremediation in oil contaminated coastal environment, elsewhere.

Long-term changes in distributions of dioxin-like and estrogenic compounds in sediments of Lake Sihwa, Korea: Revisited mass balance.

In the late 1990s, severe pollution by persistent organic contaminants (POCs) was observed in Lake Sihwa by use of a combination of instrumental analyses and in vitro bioassays. To determine long-term changes (>15-year gaps) in distributions of POCs and their potential toxic potencies in the given region, sediment assessments were reconducted. Target chemicals include polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and recently reported emerging chemicals, styrene oligomers (SOs). We employed in vitro bioassays (such as H4IIE-luc and MVLN) to determine potential sediment toxicities. The reduction rates of mean concentrations of APs and SOs in sediments between the two sampling years (1998 vs. 2015) were estimated to be 99% and 67%, respectively. Although APs and SOs significantly declined over the 15-year period, concentrations of PAHs were consistent. Results of the bioassays were consistent with the instrumental data, with relatively great concentrations of all target compounds being detected, particularly in inland creeks. Compositions of all target compounds exhibited changes in homologue patterns over the 15 years considered. This result indicated varying and/or continuing sources in this region. In particular, PAHs were dominated by higher-molecular-weight PAHs (e.g., benzo[g,h,i]perylene and benzo[b]fluoranthene) in recent years. This result might indicate consumption of oil-related fuels. Quantitative potency balance analysis revealed that concentrations of instrumentally-derived equivalents accounted for as little as 18.5% of bioassay-derived equivalents, which indicated significant amounts of unknown and/or unmeasured compounds were present. The present study documented the continuing severe pollution by selected POCs in the Lake Sihwa region over the last 15 years, indicating a lack of management in the area studied.

Assessment of potential biological activities and distributions of endocrine-disrupting chemicals in sediments of the west coast of South Korea.

The west coast of Korea has experienced environmental deterioration for more than half a century. In the present study, we specifically aimed to: i) evaluate potential toxicities of contaminants in sediments that cause effects mediated through the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER); ii) determine spatio-temporal distributions of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs); and iii) identify causes of greater potencies of samples. From 2010 to 2014, sediments were collected from 12 major estuarine and coastal regions along the west coast of South Korea. In vitro cell bioassays were performed to determine AhR- and ER-mediated potencies using H4IIE-luc and MVLN cells, respectively. Fifteen PAHs and six APs in sediments were identified by GC/MSD. Results of bioassays generally showed a low-to-moderate degree of contamination, however, greater AhR- and ER-mediated potencies were measured at some locations. Concentrations of PAHs and APs varied among locations, which indicated that sources were independently affected by the surrounding environment (e.g., industrial complex and cities). Results of bioassays were generally well correlated with concentrations of putative causative chemicals. Benzo[k]fluoranthene, dibenz[a,h]anthracene, and benzo[b]fluoranthene were the major AhR agonists, explaining approximately 30% of the bioassay-derived benzo[a]pyrene equivalent concentration (BaP-EQ). Unknown AhR and ER agonists and potential mixture effects remain in question. Overall, the present study provides baseline information on chemical contaminations and potential toxicity of sediments in a fairly wide geographical region of the west coast of South Korea.

Effect-directed analysis and mixture effects of AhR-active PAHs in crude oil and coastal sediments contaminated by the Hebei Spirit oil spill.

The major AhR-active PAHs were identified in crude oil and oil-contaminated sediments by use of effect-directed analysis. As part of the study, an enhanced potency balance analysis was conducted by establishing the novel relative potency values of (alkyl)-PAHs from the H4IIE-luc bioassay. Silica gel column fractionation of crude oil resulted in greater AhR-mediated potencies in fractions of aromatics (F2) and resins (F3), and such trend was also observed for field collected sediment samples. AhR-mediated potencies of six F2 sub-fractions from HPLC indicated that the majority of F2 responses were attributable to 3-4 ring aromatics. Target PAHs including C4-phenanthrene, C1-chrysene, and C3-chrysene in sediments explained ∼ 18% of the bioassay-derived TCDD-EQs, however, the unknown AhR agonists and potential mixture effects remain in question. Overall, the AhR-potency and antagonistic potential of residual oil in sediment tended to decrease over time, thus monitoring of weathering process would be key for the post management of oil-contaminated sites.

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.