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Intake and potential health risk of butyltin compounds from seafood consumption in Korea.
Choi, Minkyu,Moon, Hyo-Bang,Choi, Hee-Gu Springer-Verlag 2012 Archives of environmental contamination and toxico Vol.62 No.2
<P>Concentrations of butyltin compounds (BTs) were determined in 47 species of seafood commonly consumed in Korea to investigate intakes of BTs from seafood consumption and the potential health risks to the Korean population. The concentrations of BTs (the sum of dibutyltin and tributyltin) in seafood ranged from less than the limit of detection to 96.3 ng/g wet weight, which are levels similar to those reported for other countries. The intake of BTs from seafood consumption by the general population was estimated to be 17.2 ng/kg body weight/day. Fish accounted for 50% of the total intakes of BT, and the next contributor was cephalopods (26%). The estimated intakes for males and females were 18.6 and 15.7 ng/ kg body weight/day, respectively. Among the age groups investigated, children (<2 years and 3-6 years) had higher intakes of BTs compared with adults. The estimated intake of BTs for Korean population groups was 5-8% of the tolerable daily intake of 250 ng/ kg body weight/day set by the European Food Safety Authority. Our results suggest that the Korean population is not expected to exceed the threshold value for adverse health effects.</P>
Effective seeding strategy using flat type poly (vinyl alcohol) cryogel for anammox enrichment
Choi, Minkyu,Cho, Kyungjin,Lee, Seockheon,Chung, Yun-Chul,Park, Joonhong,Bae, Hyokwan Elsevier 2018 CHEMOSPHERE - Vol.205 No.-
<P><B>Abstract</B></P> <P>In this study, anammox enrichment reactors were operated using flat type poly (vinyl alcohol) cryogel (cryoPVAG) with precultured anammox bacteria (PAB) and activated sludge (AS) from an anoxic tack of the A2O process to evaluate the effect of different seeding sources on anammox enrichment. In addition, cryoPVAGs with different thicknesses (1, 2, and 3 mm) were used to investigate the effects of the thickness on anammox enrichment. The regression analysis with a modified Gompertz model showed that the start-up period of the anammox enrichment using PAB inoculum was approximately 14 days earlier than that of AS inoculum at a nitrogen loading rate of approximately 1 kg-N m<SUP>−3</SUP> day<SUP>−1</SUP>. Substrate diffusion was limited in 3-mm cryoPVAG with respect to trend in nitrogen removal rate. Quantitative PCR analysis indicated that in the initial phase, the 16S rRNA gene copy numbers of anammox microorganism in cryoPVAG were significantly different according to the seeding source, but finally converged to a similar level after anammox enrichment. The anammox reaction was initially promoted by cryoPVAG. Next, anammox biomass detached from cryoPVAG and enriched in the bulk phase to maximize NRR. Illumina MiSeq sequencing revealed that <I>Candidatus</I> Brocadia sinica led to the active anammox reaction, and its relative abundance decreased with increasing gel thickness.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Flat type cyroPVAG was utilized for anammox enrichment. </LI> <LI> Four anammox reactors with different inocula and thicknesses were used. </LI> <LI> The start-up period of anammox reactors was evaluated by a modified Gompertz model. </LI> <LI> Substrate diffusion limitation of cryoPVAG was verified at different gel thicknesses. </LI> <LI> Candidatus Brocadia sinica was the predominant species after anammox enrichment. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Choi, Minkyu,Cho, Kyungjin,Jeong, Dawoon,Chung, Yun-Chul,Park, Joonhong,Lee, Seockheon,Bae, Hyokwan Informa UK (TaylorFrancis) 2018 Journal of environmental science and health. Part Vol.53 No.8
<P>In this study, the effects of the ammonium loading rate (ALR) and inorganic carbon loading rate (ILR) on the nitrification performance and composition of a nitrifying bacterial community were investigated in a moving bed biofilm reactor, using poly(vinyl alcohol) (PVA) sponge cubes as a supporting carrier. Between the two ALRs of 0.36 and 2.16 kg-N m(-1) d(-1), stable partial nitritation was achieved at the higher ALR. Inorganic carbon was dosed at high levels: 33.1, 22.0, 16.4, 11.0, and 5.4times the theoretical amount. Nonetheless, nitrification efficiency was not affected by the ILR at the two ALRs. Quantitative PCR analysis of ammonia- and nitrite-oxidizing bacteria revealed that ALR is an important determinant of partial nitritation by accumulating ammonia-oxidizing bacteria in the nitrification system. In comparison, two nitrite-oxidizing bacterial genera (Nitrobacter and Nitrospira) showed almost the same relative abundance at various ALRs and ILRs. Terminal restriction fragment length polymorphism targeting the gene of ammonia monooxygenase subunit A revealed that Nitrosomonas europaea dominated under all conditions.</P>
Choi Minkyu,Lee Su-Jeong,Koo Jun Ho,Moon Hyo-Bang,Kim Gui-Young The Korean Society of Fisheries and Aquatic Scienc 2005 Fisheries and Aquatic Sciences Vol.8 No.4
The estrogenic phenolic compounds, nonylphenol (NP), octylphenol(OP), bisphenol A (BPA) and nonylphenol mono- and diethoxylate ($NP_{1-2}EO$) were analyzed in 24 surface water samples from six rivers flowing into Masan Bay. All of the phenolic compounds were detected in all six rivers in high concentrations. The most abundant compound was $NP_{1-2}EO$ (86.0%), followed by NP ($10.1 \%$), BPA ($3.6\%$) and OP ($0.3\%$). The levels of phenolic compounds were 1.42-22.70 ${\mu}g$/L for $NP_{1-2}EO$, 0.15-1.68 ${\mu}g$/L for NP, 0.024-0.610 ${\mu}g$/L for BPA and 0.003-0.067 ${\mu}g$/L for OP. Especially, high concentrations were recorded in the rivers that pass through industrial complexes. The concentrations of phenolic compounds observed in these river waters were 1-2 orders of magnitude lower than the reported acute toxicity levels (hundreds of micrograms per liter). However, they were only slightly lower than the chronic toxicity levels. Most of the water samples also exceeded the Canadian nonylphenolic compounds water quality guideline, 1 ${\mu}g$/L, for the protection of aquatic life and the maximum permissible concentrations (MPC), 0.33 ${\mu}g$/L for NP and 0.12 ${\mu}g$/L for $NP_{1-2}EO$.
Choi, Minkyu,Moon, Hyo-Bang,Yu, Jun,Cho, Hyunseo,Choi, Hee-Gu Springer-Verlag 2013 Archives of environmental contamination and toxico Vol.64 No.3
<P>We investigated the temporal trend in contamination of butyltin compounds (BTs) along the Korean coast using imposex and tributyltin (TBT) burden in gastropods (Thais clavigera) as a biomonitor. Thais clavigera were collected from 26 locations with different shipping activities between 2004 and 2009 after restrictions on TBT-based antifouling paints were imposed in Korea. In the present study, imposex indices and TBT tissue concentrations significantly decreased over time from 2004 to 2009, confirming the effectiveness of TBT regulation. However, imposex in 2009 samples was still found. Significantly high imposex indices and TBT tissue residues were found in large ports containing commercial and ferry services compared with small ports and background areas. Imposex indices in background areas had decreased to zero, suggesting recovery from imposex caused by BT contamination. These results suggest that recovery from TBT contamination occurs faster in areas with very low maritime activities than areas with high maritime activities.</P>