• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.507-514
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• 2021

A new free-living marine nematode species of the genus Pseudosteineria Wieser, 1956 affiliated with the family Xyalidae is described based on specimens collected from the sediment of a subtidal benthic environmental habitat in the East Sea, Korea. Pseudosteineria varisetis sp. nov differed from its congeners by the combination of the following characteristics: a relatively long body (1,628-1,691 ㎛ long in males), a circular amphideal fovea situated behind the subcephalic setae, the presence of lateral cuticular alae starting from behind the nerve ring, the presence of eight groups of long subcephalic setae, the presence of irregularly distributed variable lengths of somatic setae on the body, solid spicules (43.2-43.9 ㎛ long) with a cephalated proximal end, a long tubular shaped gubernaculum with dorsal swelling, and a conico-cylindrical tail with two to four terminal setae. In this report, we provide a taxonomic description and illustrations of a new species of the genus Pseudosteineria by differential interference contrast microscopy.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.63-63
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• 2021

Bed shear stress is important variable in river flow analysis. The bed shear stress has an effects on bed erosion, sediment transport, and mean flow characteristics. Quadratic formula to estimate bed shear stress is widely used, 𝜏=𝜌c_fu|u| in which friction coefficient, c_f, needs to be assigned to numerical models. The aim of this study is to estimate Chezy coefficient using bathymetry data measured by ADCP. Bed form geometry variables will be estimated form bed profile, then Chezy coefficient will be determined using estimated bed form geometry variables in order to set friction coefficient to numerical model. From the probability density function obtained from the bathymetry data, Chezy coefficient will be randomly generated since Chezy coefficient is not uniform over the space and it does not depend on spatial variables such as water depth and distance from river bank. Numerical test will be performed to find to demonstrate randomly extracted Chezy coefficient is appropriate. The result of this study is valuable in that the friction coefficient is estimated in consideration of the bed profile, and as a result, uncertainty of the friction coefficient can be reduced.

• Journal of Species Research
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• v.12 no.spc2
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• pp.23-32
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• 2023

During screening for indigenous prokaryotic species in Republic of Korea in 2021, a total of 21 bacterial strains assigned to the phylum Bacteroidota were isolated from a variety of environmental habitats including pine cone, seaweed, soil, sea sediment, brackish water and moss. Based on the 16S rRNA gene sequence similarity value of more than 98.7% and formation of a robust phylogenetic clade with the type strain of the closest bacterial species, it was found that the 21 strains belong to independent and recognized bacterial species. There has been no official report that the identified 21 species have been isolated in Republic of Korea up to date. Therefore, 16 species in six genera of two families in the order Flavobacteriales, two species in two genera of two families in the order Cytophagales, one species in one genus of one family in the order Chitinophagales and two species in one genus of one family in the order Sphingobacteriales are proposed as unrecorded species of the phylum Bacteroidota isolated in Republic of Korea. Their Gram reaction, colony and cell morphology, basic phenotypic characteristics, isolation source, taxonomic status, strain ID and other information are described in the species descriptions.

• Journal of The Geomorphological Association of Korea
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• v.27 no.3
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• pp.25-39
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• 2020

This study analyzed the management plan of Seomjin River Chimsil Wetland by identifying landscape changes through aerial photographs analysis and concentrations of sedimentation. Geophysical Landscape Change Analysis showed that vegetation accounts for more than half of the total area. The Barren land and water body was somewhere repeatedly increased and decreased and made an irregular form in the study area. The soil was acidic, and no eurtophication was shown, but it was potential to form wetland. In addition, the research area has been terrestrification of sand bar for a long period of time, forming a soil layer. Although the characteristics of river deposits were shown in the study area, the grain size was a particulate matter, and the sorting was 'very poorly sorted'. In some areas of Seomjin River Chimsil Wetland, sand bars were formed, but most areas were undergoing to terrestrification. Therefore, in order to preserve the riverine area and to serve by a bridge between the land ecosystem and the underwater ecosystem, it is very necessary to remove some vegetation, create a proper waterway, and restore the wetland.

• Journal of Species Research
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• v.12 no.4
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• pp.267-276
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• 2023

To obtain unrecorded bacterial species in Korea, various soils of coastal areas were collected from the Republic of Korea in 2022. After plating the samples on marine agar and incubating aerobically and anaerobically, approximately 1,700 bacterial strains were isolated and identified using 16S rRNA gene sequences. A total of 20 strains showed ≥98.7% 16S rRNA gene sequence similarity with validly published bacterial species but not reported in Korea, indicating they are unrecorded bacterial species in Korea. The unrecorded bacterial strains belonged to four phyla, six classes, 15 orders, 16 families, and 19 genera which were assigned to Blastomonas and Sphingomonas of the class Alphaproteobacteria; Pseudidiomarina, Kushneria, Salinicola, and Salinisphaera of the class Gammaproteobacteria; Evansella, Virgibacillus, and Paenibacillus of the class Bacilli; Cyclobacterium of the class Cytophagia; Pedobacter of the class Sphingobacteriia; and Demequina, Ornithinimicrobium, Blastococcus, Jatrophihabitans, Kineococcus, Glaciihabitans, Aeromicrobium and Streptomyces of the class Actinomycetes. The details of the 20 unreported species, including Gram reaction, morphology, biochemical characteristics, and phylogenetic position are also provided in the description of the strains.

• Animal Systematics, Evolution and Diversity
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• v.40 no.1
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• pp.21-34
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• 2024

Two arenicolus halacarid species, Actacarus ornatus n. sp. and A. pacificus Bartsch, 1979, are recorded from sandy intertidal sediment along the coast of South Korea. Actacarus ornatus n. sp. closely resembles A. karoensis Abé, 1990, recorded from Japan, in having chaetotaxy of the idiosoma, legs, palps of gnathosoma, and perigenital setae in both males and females. However, it differs from A. karoensis by a slightly convex tectum, the presence of a row of foveae on the mid-ventral surfaces of the anterior epimeral plate and genitoanal plate, and the absence of areolae on both the anterior and posterior dorsal plates as well as microplatelets on the membranous cuticle alongside the anterior and posterior dorsal plates. Actacarus pacificus Bartsch, 1979, which is widely distributed in the Indo-Pacific region, is characterized by separated plates, a truncated tectum, the anterior epimeral plate with four pairs of setae, the posterior epimeral plate with one dorsal and two ventral setae, and three pairs of subgenital setae in males. A comparative analysis of the morphological characteristics of A. pacificus was conducted within regional populations, including the Korean population. Moreover, a key to Actacarus species from the northwestern Pacific, including a new species, is provided. The genus Actacarus is reported for the first time from Korea.

• Journal of the Mineralogical Society of Korea
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• v.25 no.3
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• pp.163-173
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• 2012

In this study, we determined the relative clay mineral composition of 51 surface sediments from SEYSM (Southeastern Yellow Sea Mud) (northern part 25, southern part 26) and 30 river sediments inflow to Yellow Sea using the semi-quantitative X-ray diffraction analyses. In addition to we analyzed illite characteristics of the same samples. The clay-mineral assemblage is composed of illite (61~75%), chlorite (14~24%), kaolinite (9~14%), and smectite (1~7%), in decreasing order. The average composition of each clay mineral is not different from northern part to southern part of SEYSM except a little higher kaolinite and lower smectite content in northern part. Smectite content generally has reverse relationship with illite content. Mineralogical characteristics of illite such as illite crystallinity index also is not different between two areas and show very narrow range (0.18~0.24 ${\Delta}^{\circ}2{\theta}$). Our results reveal that clay mineral composition and illite characteristics are nearly the same between northern and southern part of SEYSM. Characteristics of surface sediments in SEYSM is closer to Korean river sediments than Chinese Hanghe sediments, however it is necessary to investigate further study including Yangtze river sediments. This study conclude that most of surface sediments in SEYSM attribute to the supply of considerable amount of sediments from the nearby Korean rivers. The large sediment budget and high accumulation rate in the SEYSM can be explained by erosion and reworking of surface sediments in this area. Tidal and regional current system around SEYSM might contribute these erosional and depositional regimes.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.3
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• pp.100-117
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• 2022

This study examines the spatio-temporal characteristics of the macrobenthic community in the coastal areas of South Korea for the past six years(2015-2020). The relationship between the number of individuals of macrobenthic species and the benthic environments were investigated using data collected at a total of 154 stations located in the West (70), the South (61), and the East Seas (23), except for the Jeju Sea. We examined the benthic environmental characteristics such as water depth, sediment, grain size, ignition loss, and total organic carbon. A total of 1,614 macrobenthic species were found in the coastal area, with a mean density of 0.62 ind./m² by station. The mean density was relatively high in the spring and summer seasons (May to August) with more than 450 species. The most dominant species belong to Polychaetes and the top five of them accounted for more than 20% of the total number of populations. The top five species were Heteromastus filiformis, Scoletoma longifolia, Sigambra tentaculata, Sternaspis scutata, and Notomastus latericeus. Cluster analysis was performed on the top five dominant species. The stations were clustered into three groups with similar locations on the West, South, and East Sea. Cluster 1 and 3 represent Heteromastus filiformis (44% each), but cluster 2 represents Scoletoma longifolia (66%). Each cluster has different benthic environmental characteristics, especially in the sediment's sand (31.0%, 51.9%) and clay (15.9%, 9.7%) contents.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.25-36
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• 2016

Heavy metals in the stream sediments around Shihwa Lake were studied not only to investigate the characteristics of spacio-temporal distribution but also to assess the pollution degree and ecological risk using various pollution indices. Among metals, Zn had the highest values (1,311 mg/kg) and Hg showed the lowest value (0.261 mg/kg). The order of mean concentrations (mg/kg) of metals was Zn>Cu>Pb>Cr>Ni>Co>As>Cd>Hg in stream sediments around Shihwa Lake. Metal concentrations showed different pollution pattern with industrial region, indicating that these metals originated from different sources and industrial region had higher metal concentration than rural/urban regions. The results of geoaccumulation index (Igeo) showed that the stream sediments were significantly polluted with Cd, Cu, Zn and Pb, indicating moderately to highly polluted by these metals. According to PLI consideration, industrial region was more seriously polluted by metals whereas an rural/urban region was not polluted. About 85% of sampling site for Cr, Ni, Cu, Zn and Pb from industrial regions were exceeded the PEL values. The mPELQ and SQI values derived from PEL of industrial region were classified as 'highly toxic' and 'very poor' and metal pollution level tend to be worse in wet season. This indicates that the industrial activities and stromwater runoff represents an important sources of heavy metals around Shihwa Lake.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.421-428
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• 2014

Total 20 surface sediments were collected in Anjung bay to investigate the physicochemical environment and heavy metal contents. The physicochemical investigation ranged from 6.41% to 11.68% (average $9.52{\pm}1.28%$) for ignition loss (IL), from 17.99 mg/g to 43.84 mg/g (average $27.53{\pm}6.39mg/g$) for chemical oxygen demand (COD), and from 0.05 mg/g to 0.61 mg/g (average $0.17{\pm}0.14mg/g$) for acid volatile sulfide (AVS) with significant correlation between water content (W/C) and COD. A contour of spatial distribution indicated higher organic pollution at the bottom of ascidian, Stylea clava, cultural waters. Most of metals contents was not exceeded the NOAA's effect range-low (ERL). Estimated enrichment factor (EF) ranging 0.96-1.12 indicated that the sediment environment of the studied waters was relatively pristine from heavy metal pollution in spite of increased vessel traffics, so far.