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Nam S.W.,Chungnam National University | Go D.,Chungnam National University | Son M.,Yeongsan River Environmental Research Center | Shin W.,Chungnam National University
Algae | Year: 2013

Rhinomonas reticulata var. atrorosea G. Novarino is a photosynthetic marine flagellate that is known to have typical characteristics of cryptomonads. We examined the flagellar apparatus of R. reticulata var. atrorosea by transmission electron microscopy. The major components of the flagellar apparatus of R. reticulata var. atrorosea consisted of four types of microtubular roots (1r, 2r, 3r, and mr), a non-keeled rhizostyle (Rhs), mitochondrion-associated lamella (ML), two connections between basal bodies, a striated fibrous root (SR) and a striated fiber-associated microtubular root (SRm). Four types of microtubular roots originated near the ventral basal body and extended toward the left side of the basal bodies. The non-keeled Rhs originated at the Rhs-associated striated fiber, which was located between two basal bodies and extended into the middle of the cell. The ML was a plate-like fibrous structure associated with mitochondria and originating from a Rhs-associated fiber. It split into two parts and extended toward the dorsal-posterior of the cell to a mitochondrion. The SR and SRm extended parallel to the anterior lobe of the cell. The overall configuration of the flagellar apparatus in R. reticulata var. atrorosea was similar to the previously reported descriptions of those of Cryptomonas paramecium, C. pyrenoidifera, C. ovata, Hanusia phi, Guillardia theta, and Proteomonas sulcata. However, the flagellar apparatus system of R. reticulata var. atrorosea was more complex than those of other cryptomonad species due to the presence of an additional microtubular root and other distinctive features, such as a rhizostyle-associated striated fiber and large ML. © The Korean Society of Phycology.


Park T.-J.,Water Environmental Engineering Research Division | Yu M.-N.,National Institute of Environmental Research | Kim H.-S.,National Institute of Environmental Research | Cho H.-S.,National Institute of Environmental Research | And 5 more authors.
Desalination and Water Treatment | Year: 2014

Geosmin and 2-methylisoborneol (2-MIB) are organic compounds known to cause earthy and musty odors in drinking water. In Korea, during the summer of 2012, a geosmin outbreak in the drinking water supply prompted further research to identify the source of the odorous materials, since these occurrences were not well understood or monitored. The purpose of this study was to investigate how important a role actinomycetes play in the production of geosmin and 2-MIB in Paldang Lake by measurement of microbial density (the number of colony-forming units), pyrosequencing of 16S rRNA genes, and determination of the prevalence of the geosmin synthase gene. Three sampling sites (P1, P2, and P3) were selected. The increase in geosmin concentration was paralleled by an increase in actinomycetes (Streptomyces spp.) and cyanobacteria (Anabaena spp.) populations. The bacterial communities in Paldang Lake were characterized by 454 pyrosequencing based on 16S rRNA gene sequences. P1 (North Han River) showed the highest density of actinomycetes, followed by P2 (Paldang Dam), and P3 (South Han River). The density of Streptomyces spp. increased at P1, while that of cyanobacteria increased at P3. No significant density change was noted in those two species at P2, a confluence of two rivers. The genes producing geosmin or 2-MIB were detected in 60 single strains that were isolated from water samples in Paldang Lake. This study confirmed that Streptomyces spp. significantly affect the production of geosmin that causes odors in Paldang Lake. © 2014 Balaban Desalination Publications. All rights reserved.


Cho S.,Gwangju Institute of Science and Technology | Lee D.,Yeongsan River Environmental Research Center | Lim B.,Yeongsan River Environmental Research Center | Cho J.,Gwangju Institute of Science and Technology
Desalination and Water Treatment | Year: 2012

Pretreatment protocols, using preparative liquid chromatography (prep-LC), and high resolution mass spectrometer methods, were developed to identify potential Ni-natural organic matter (NOM) complexation, for a relatively stagnant river water sample. The former and the latter were performed, using a large separation column, packed with C18 and size exclusion resin media, and ion trap-time of flight (IT-TOF) mass spectrometer, respectively. The NOM samples were effectively fractionated into four different peaks, with helps of both RI and UV detections, and further subjected to mass analyses using the IT-TOF, which provided distinct m/z peaks pairs in mass spectra, with m/z peaks difference of ca. 58, as evidence of Ni-complexed NOM. © 2012 Desalination Publications. All rights reserved.


Lee S.-H.,Gwangju Institute of Science and Technology | Ra J.-S.,Gwangju Institute of Science and Technology | Choi J.-W.,Water Quality Center | Yim B.-J.,Yeongsan River Environmental Research Center | And 2 more authors.
Science of the Total Environment | Year: 2014

Because of their persistence, bioaccumulation tendency, and toxicity, organochlorine pesticides (OCPs) were banned several decades ago. However, they are still detected in natural water and pose a serious risk to human health and the environment. In the present study, seven OCPs were measured in river water collected from 28 sampling sites between 2010 and 2011 in the Yeongsan (YS) and Seomjin (SJ) Rivers, Korea. Gas chromatography/high-resolution mass spectrometry (HRMS) was used for the chemical analysis. The potential health risks of consuming OCPs in fish were assessed in the monitoring region (YS and SJ River basins) by measuring the residual level of OCPs. The human health risks were characterized by considering both the exposure level and the corresponding cancer slope factors; we incorporated both deterministic and probabilistic approaches. The risks were calculated using the probabilistic Maximum Likelihood Estimation (MLE) method. Risk uncertainty and sensitivity were calculated by performing a Monte Carlo analysis. Of the six OCPs, dieldrin, heptachlor epoxide, and hexachlorobenzene exceeded the acceptable risk level in the heavy and light fish consumer groups. The cancer risks associated with these OCPs were 2.99×10-6, 5.81×10-6 and 3.72×10-6, respectively, using the deterministic approach and 1.64×10-5, 3.36×10-2 and 5.52×10-5, respectively, at the 95th percentile using the probabilistic approach. Because there is a high cancer risk associated with these three OCPs, individuals who consume large amounts of freshwater fish may be subject to a high risk of cancer. However, the calculations may have over- or underestimated the risk because of the uncertainty of the environmental concentration and fish intake rate or the use of left-censored monitoring data. © 2013 Elsevier B.V.


PubMed | Water Quality Center, Yeongsan River Environmental Research Center, Gwangju Institute of Science and Technology and National Water Research Institute
Type: | Journal: The Science of the total environment | Year: 2014

Because of their persistence, bioaccumulation tendency, and toxicity, organochlorine pesticides (OCPs) were banned several decades ago. However, they are still detected in natural water and pose a serious risk to human health and the environment. In the present study, seven OCPs were measured in river water collected from 28 sampling sites between 2010 and 2011 in the Yeongsan (YS) and Seomjin (SJ) Rivers, Korea. Gas chromatography/high-resolution mass spectrometry (HRMS) was used for the chemical analysis. The potential health risks of consuming OCPs in fish were assessed in the monitoring region (YS and SJ River basins) by measuring the residual level of OCPs. The human health risks were characterized by considering both the exposure level and the corresponding cancer slope factors; we incorporated both deterministic and probabilistic approaches. The risks were calculated using the probabilistic Maximum Likelihood Estimation (MLE) method. Risk uncertainty and sensitivity were calculated by performing a Monte Carlo analysis. Of the six OCPs, dieldrin, heptachlor epoxide, and hexachlorobenzene exceeded the acceptable risk level in the heavy and light fish consumer groups. The cancer risks associated with these OCPs were 2.9910(-6), 5.8110(-6) and 3.7210(-6), respectively, using the deterministic approach and 1.6410(-5), 3.3610(-2) and 5.5210(-5), respectively, at the 95th percentile using the probabilistic approach. Because there is a high cancer risk associated with these three OCPs, individuals who consume large amounts of freshwater fish may be subject to a high risk of cancer. However, the calculations may have over- or underestimated the risk because of the uncertainty of the environmental concentration and fish intake rate or the use of left-censored monitoring data.

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