Hyeon-Seo Cho

Perfluorinated alkyl substances in water, sediment, plankton and fish from Korean rivers and lakes: A nationwide survey

Water, sediment, plankton, and blood and liver tissues of crucian carp (Carassius auratus) and mandarin fish (Siniperca scherzeri) were collected from six major rivers and lakes in South Korea (including Namhan River, Bukhan River, Nakdong River, Nam River, Yeongsan River and Sangsa Lake) and analyzed for perfluorinated alkyl substances (PFASs). Perfluorooctane sulfonate (PFOS) was consistently detected at the greatest concentrations in all media surveyed with the maximum concentration in water of 15 ng L(-1) and in biota of 234 ng mL(-1) (fish blood). A general ascending order of PFAS concentration of water<sediment<plankton<crucian carp tissues<mandarin fish tissues was found. Except for the Nakdong River and Yeongsan River, the sum PFAS concentrations in water samples were below 10 ng L(-1). The PFOS and perfluorooctanoic acid (PFOA) concentrations in water did not exceed levels for acute and/or chronic effects in aquatic organisms. High concentrations of long chain perfluorocarboxylates (LCPFCAs) were found in sediment samples. PFOS, perfluoroundecanoic acid (PFUnA), perfluorododecanoic acid (PFDoA) and perfluorodecanoic acid (PFDA) accounted for 94-99% of the total PFASs concentration in fish tissues. The mean ratios of PFAS concentration between fish blood and fish liver were above 2 suggesting higher levels in blood than in liver. Significant positive correlations (r>0.80, p<0.001) were observed between PFOS concentration in blood and liver tissues of both crucian carp and mandarin fish. This result suggests that blood can be used for nonlethal monitoring of PFOS in fish. Overall, the rank order of mean bioconcentration factors (BCFs) of PFOS in biota was; phytoplankton (196 L/kg)<zooplankton (3,233 L/kg)<crucian carp liver (4,567 L/kg)<crucian carp blood (11,167 L/kg)<mandarin liver (24,718 L/kg)<mandarin blood (73,612 L/kg).

Detection and molecular characterization of porcine enteric calicivirus in Korea, genetically related to sapoviruses.

Summary Porcine enteric calicivirus (PECV) shares morphological and genetical similarities with Sapoviruses (SVs), which are the leading cause of epidemic, non‐bacterial gastroenteritis in children worldwide. The aim of this study was to identify the prevalence of PECV infection in pig farms in Korea, and to compare the evolutionary inter‐relationships between Korean PECVs and other caliciviruses. Among 102 diarrhoeic faecal samples of sucking (n = 50) and weaned (n = 52) piglets from 31 different farms in Korea, five samples (4.9%) were detected positive by reverse‐transcriptase polymerase chain reaction (PCR), but nine (8.8%) by nested‐PCR. Furthermore, we found that Korean PECVs are closely related to SVs.

Acute toxicity of organotin compounds to the larvae of the rock shell, Thais clavigera, the disk abalone, Haliotis discus discus and the giant abalone, Haliotis madaka

Acute toxicity tests of tributyltin (TBT) and triphenyltin (TPT) were conducted on hte larvae of the rock shell, Thais clavigera, the disk abalone, Haliotis discus discus and the giant abalone, Haliotis madaka. For the rock shell larvae, the LC50 values (based on the nominal concentrations) were 8.4 μg (24 h) and 5.6 μg (48 h) TBT/IL; 8.6 μg (24 h) and 4.6 μg (48 h) TPT/L. For the disk abalone larvae, the 48 h LC50 values were 5.4 μg TBT/L and 1.4 μg TPT/L. For the giant abalone larvae, the LC50 values were 3.9 μg (24 h) and 1.2 μg (48 h) TBT/L; 2.4 μg (24 h) and 1.5 μg (48 h) TPT/L. Some effects on swimming behavior (e.g. unusual swimming behavior or low swimming activity) and irregular movement of cilia due to atrophy of velum compared to that in the control, as well as stripping out of the larvae from the shell, were observed even at lower concentrations than the LC50 values. From these experimental results and actual organotin concentrations in Japanese inshore waters, TBT pollution may have adversely affected the recruitment of the rock shell, the disk abalone and the giant abalone in heavily polluted areas.

A Mu-class glutathione S-transferase (GSTM) from the rock shell Thais clavigera.

The rock shell (Thais clavigera) has attracted interest due to high frequency of imposex induced by endocrine disrupting chemicals (EDCs) in its natural populations. Oxidative stress is one of the mechanisms of action of EDCs. Glutathione S-transferases (GSTs) play an important role in antioxidant defense protecting the cells from oxidative stress. So far, there is no information on antioxidant defense or detoxification genes from T. clavigera. We cloned the full length cDNA sequence for a Mu-class of GST gene from T. clavigera (Tc-GSTM) and purified recombinant Tc-GSTM protein by bacterial expression. The deduced amino acid sequence of Tc-GSTM exhibited 45 to 66% identity with other Mu-class GSTs. Real-time RT-PCR analysis showed highest expression of Tc-GSTM in gill, while reproductive organs showed low expression. The biochemical characteristics of purified recombinant Tc-GSTM were typical, and thus Tc-GSTM showed highest specific activity for the universal GST substrate, 1-chloro-2,4-dinitrobenzene (CDNB). After exposure to prooxidant H(2)O(2), transformed Escherichia coli containing Tc-GSTM showed higher survival rate compared to control bacteria without expressed Tc-GSTM. The present study reveals a conserved antioxidant role for GSTM in rock shells, and the tissue-specific differences in Tc-GSTM transcripts would partly reflect vulnerability of reproductive organs to chemically induced oxidative stress.

A nationwide survey of perfluorinated alkyl substances in waters, sediment and biota collected from aquatic environment in Vietnam: Distributions and bioconcentration profiles

Water, sediment, various tissues of fish, crustacean, gastropod and bivalve were collected from major river basins in Vietnam and analyzed for the presence of perfluorinated alkyl substances (PFASs). Furthermore, the occurrence of PFASs in coastal, tap and well waters collected from eight different regions in Vietnam was investigated. PFOA and PFOS were consistently detected as the dominant PFASs in surface waters. The greatest concentrations of PFOA (53.5ngL-1) and PFOS (40.2ngL-1) were found in a surface water sample collected from a channel that receives wastewater treatment plant discharges. PFOS and PFHxS were found as the predominant PFASs in sediments. The greatest PFAS concentration in biota was 16.9ng PFUnDA g-1 wet weight found in a fish liver. Some long-chain PFCAs including PFNA, PFUnDA and PFTrDA as well as PFHxS were more abundant than short-chain PFASs in biota tissues. The measured concentrations of PFOS and PFOA in surface and tap waters were below the provisional health advisory. The rank order of mean bioconcentration factor of PFOS in biota was; crustacean (115L/kg), gastropod (1117L/kg), fish (1120L/kg) and bivalve (2110L/kg). This study provides baseline information for a better understanding of PFASs contamination in Vietnam.

Specific accumulation of organotin compounds in tissues of the rock shell, Thais clavigera.

Concentrations of organotin compounds (butyltins and phenyltins) were determined in gonad, accessory sex organs, penis, digestive gland, kidney, radula with sac, oesophagus with crop, stomach, hypobranchial gland, rectum, mantle, osphradium, ctenidium, heart, salivary gland, head ganglia and muscle of imposex-exhibiting female and male rock shells (Thais clavigera), by gas chromatography with flame photometric detection (GC-FPD). Different tissue distributions were observed between butyltin and phenyltin compounds. More than 1000 ng TBT/g wet wt. were observed in ovary, digestive gland, kidney, heart, ctenidium, osphradium, stomach, head ganglia and penis, of both imposex-exhibiting females and males. More than 1000 ng TPT/g wet wt. were found in almost all tissues of both sexes. Approximately one-third or more of total TBT was accumulated in the digestive glands of both females and males, respectively. Meanwhile, approximately 40-50% and one-half of total TPT accumulated in the digestive glands of females and males, respectively.

Mitochondrial genome of Thais clavigera (Mollusca: Gastropoda): affirmation of the conserved, ancestral gene pattern within the mollusks.

Class Gastropoda includes a large number of described species, many with extensively rearranged mitochondrial genomes. We sequenced the mitogenome of the rock shell, Thais clavigera (Gastropoda: Muricidae), an intertidal snail, using long PCR with primers designed on the basis of expressed sequence tags. The mitogenome of T. clavigera consists of 2 rRNAs, 22 tRNAs, and 13 protein-coding genes, but no control region. Structural comparisons revealed that the order Sorbeoconcha, including T. clavigera, have nearly identical mitochondrial gene patterns. However, they have an inversion between a tRNA(Phe)-tRNA(Glu) cluster that comprises 21 genes, but most of the remaining structure is similar to the putative mollusk ground pattern. These findings will provide a better insight into mitochondrial gene rearrangement over the course of gastropod evolution.

Contamination and bioaccumulation of polybrominated diphenyl ethers (PBDEs) in Gwangyang Bay, Korea

Concentrations of polybrominated diphenyl ethers (PBDEs) were determined in seawater, sediment and biota collected from Gwangyang Bay, Korea. Total concentrations of PBDEs in seawater and sediment ranged from 56.1 to 343 pg/L and from 1.16 to 43.6 ng/g dry weight, respectively. Total concentrations of PBDEs in edible tissue and liver samples ranged from 1.79 to 67.9 ng/g lipid weight and from 1.69 to 10.5 ng/g lipid weight, respectively. The concentrations of PBDEs in sediment measured in our study were moderate or lower than those reported for rivers and coasts from other countries. The highest concentrations of PBDEs in seawater and sediment were found at several stations near petrochemical and steel industrial complexes, suggesting industrial activities contributed to the PBDE contamination in the bay. The major congener of PBDEs in seawater and sediment was BDE 209, which is consistent with a consumption pattern of brominated-flame retardant market in Korea. Fish, bivalve and crustacean had different accumulation patterns of PBDEs, suggesting different diet, habitat and/or bioaccumulation behavior for PBDEs. The bioconcentration factors (BCFs) of all of the PBDE congeners ranged from 102 to 105. The BCFs of PBDE congeners in fish species increased as the octanol-water partition coefficient (Kow) was close to log Kow≈8, above which they decreased. Bivalves appeared slightly bioaccumulation potentials for higher-brominated congeners such as BDE 209 with a high log Kow. Our results suggest that Kow can be a major factor governing bioconcentration mechanism of PBDEs, with minor factor by habitat of target species.

Organotins and new antifouling biocides in water and sediments from three Korean Special Management Sea Areas following ten years of tributyltin regulation: Contamination profiles and risk assessment

A simultaneous monitoring study on organotins (butyltins and phenyltins) and most frequently used alternative antifouling biocides (Irgarol 1051, Diuron, Sea-Nine 211 and M1) in water and sediments (n=44) collected from three Special Management Sea Areas operated by Korean government. The lower concentration of butyltins (BTs) than that of new antifouling biocides (NEW) was found in water but the significant greater concentration of BTs than that of NEW was still found in sediments. The tributyltin (TBT) levels in water exceeded the chronic criterion to protect seawater aquatic life at several sites. Even ten years after the ban of the use of TBT-based antifouling paint, the concentrations of TBT, Diuron and Irgarol 1051 in sediments from shipyards exceeded global sediment quality guidelines and potentially poses adverse risks on marine organisms and extremely high concentration of TBT up to 2304ng/g was found for a sediment collected at a shipyard.

Organotins pollutions in seawater and sediment around a shipyard

Six organotins including monobutyltin, debutyltin, tributyltin (TBT), monophenyltin, dephenyltin (DBT), triphenyltin were analyzed to investigate a status and effects of a shipyard to organotins pollution in seawater and sediment from 31 sampling sites, in total, in Jinhae Bay. TBT (mean concentration=2.24 ng/L as Cl) and DBT (mean concentration=3.69 ng/L as Cl) were found as two dominant organotins in water samples. In sediment samples, TBT, which has mean concentration of 53.4 ng/g wet weight as Cl and accounted for 74% in total organotins concentration, in average, was consistently found as the predominant organotin. Phenyltins were not found or found as low concentrations comparing with butyltins. Remarkable geographic distribution of TBT and butyltin compounds showed lower concentrations of those compounds in sampling sites located far from the shipyard.