• Journal of The Geomorphological Association of Korea
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• v.19 no.2
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• pp.81-98
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• 2012

This research aims 1) to analyse the spatial occurrence of red soils, in Korea 2) to predict their spatial distribution using terrain analyses, and 3) to interpret results from the perspective of pedogeomorphological processes. Red soils (often called red-yellow soils) in Korea are frequently found on welldrained plains and gently sloping areas. These soils are widely believed paleo-soils that were formed under hot and humid climatic conditions in the past. The spatial distribution of red soils was derived from the soil map of Korea, and a DEM based soil prediction was developed, based on a continuity equation to depict water and material flows over the landscape. About 64.5% of the red soil occurrence can be explained by the prediction. Close examinations between surveyed and predicted red soil maps show few distinctive spatial features. Granitic erosional plains at the inland of Korea show comparatively low occurrence of red soils, which might indicate active geomorphological processes within the basins. The occurrence of red soils at limestone areas is more abundant than that of the predicted, indicating the influence of parent materials on the formation of red soils. At and around lava plateau at Cheulwon and Youncheon, the occurrence of red soils is underestimated, which might partly be explained by the existence of loess-like surface deposits. There are also distinctive difference of prediction results between northern and southern parts of Korea (divided by a line between Seosan and Pohang). The results of this research calls for more detailed field-based investigations to understand forming processes of red soils, focusing on the spatial heterogeneity of pedological processes, the influence of parent materials, and difference in uplift patterns of the Korean peninsula.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.30-44
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• 2001

In this study limnological characteristics of Lake Juam was surveyed from June 1993 to May 1994 in order to provides important information regarding water resources. Secchi disc transparency, epilimnetic chlorophyll a (chi-a), total nitrogen (TN), total phosphorus (TP) concentration and primary productivity were in the range of $2.0{\sim}4.5\;m$, $0.9{\sim}13.6\;mgChl/m^3$, 0.78$\{sim}$2.32 mgN/l, $11{\sim}56\;mgP/m^3$, $270{\sim}2.160\;mgCm^{-2}\;day^{-1}$, respectively. On the basis of TP, Chl-a and Secchi disc depth, the trophic state of Lake Juam can be classied as mesotrophic lake. The phosphorus inputs from non-point sources are concentrated in heavy rain episodes during the monsoon season. As a result, phosphorus concentration are higher in summer than in winter. TP loading from the watershed were estimated to be $0.9\;gPm^{-2}yr^{-1}$, which correspond to a boundary of the critical loading ($1.0\;gPm^{-2}yr^{-1}$) for eutrophication. From the results of the algal assay, both phosphous and nitrogen act as limiting nutrients in algal growth. The seasonal succession of phytoplankton community structure in Lake Juam was similar to that observed in other temperate lakes. Diatoms (Asterionella formosa and Aulacoseira granulate var. angustissima)fujacofeira BraHuJafa uar. aHgusHrsiaia) weredominant in spring and winter, cyanobacteria) were dominant in warm season. The organic carbon, nitrogen and phosphorus content of lake sediment were $9.5{\sim}14.0\;mgC/g$, $1.01{\sim}1.82\;mgN/g$ and $0.51{\sim}0.65\;mgP/g$, respectively. The allochthonous organic carbon loading from the watershed and autochthonous organic carbon loading by primary production of phytoplankton were determined to be 1,122 tC/yr and 6,718 tC/yr, respectively. To prevent eutrophication of Lake Juam, nutrient management of watershed should be focus on reduction of fertilizer application, proper treatment of manure, and conservation of topsoil as well as point source.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.1
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• pp.11-23
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• 2016

An ecological study on subtidal macrobenthic fauna was conducted off the Namhaedo Island, south coast of Korea from July 2012 to April 2013. A total of 247 species of macrobenthos occurred with a mean density of $1,027ind./m^2$ and a mean biomass of $148.7g/m^2$. Polychaetes was the richest and most abundant faunal group that comprised 37% in both total species number and density whereas echinoderms were biomass-dominant faunal group that accounted for 44% of the mean biomass. There was a seasonal variation in the species richness and abundance of macrobenthos with more species in winter and higher density in spring. Mean faunal density was relatively high at the stations near Namhaedo Island, but gradually decreased toward offshore stations. The most dominant species in terms of density was an amphipod species, Eriopisella sechellensis which occurred as a top ranker during three seasons except spring recorded the fourth rank. E. sechellensis showed its high density at the near shore stations of Namhaedo Island, but this species did not occur around the entrance of Gwangyang and Saryang Bays where Theora fragilis and Lumbrineris longifolia showed high densities. In particular, Tharyx sp., recorded high density between Gwangyang Bay entrance and offshore after Sea Prince oil spill, did not occur in the same area during this study period. The bottom temperature and sorting value of the surface sediments were highly correlated to the spatial distribution of macrobenthic fauna from the Bio-Env analysis. From the cluster analysis, the study area has five station groups with more similar faunal affinities from inner area toward offshore area. Based on the SIMPER analysis T. fragilis, Magelona japonica, E. sechellensis, L. longifolia and Paraprionospio cordifolia were mainly contributed to the classification of station groups. From the BPI, benthic communities in the entrance of Gwangyang Bay and Saryang Bay were considered to be in a slightly polluted condition in contrast to the normal healthy community at the offshore of Namhaedo Island. These results suggested that the benthic community of this area should be regularly monitored to assess the health status of this benthic ecosystem.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.70-80
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• 2011

Estuarine ecosystem responds sensitively to natural and anthropogenic perturbations. lt is necessary to identify the direction of the change when the perturbation occurs as well as to understand the structure and functioning of estuarine ecosystem for a proper management of the area. In this study, the estuarine habitats were classified into different ecological districts so as to the switch from one district to another district could be related to the environmental change due to the perturbations. Total 16 ecological districts was defined according to the presence of barrage, salinity and vegetation characteristics. The defined ecological districts were applied to small estuaries in Goseong bay, south sea of Korea (Baedun, Guman, Maam, Goseong) to distinguish different regions which might have characteristic bottom topography, inclinations of river bottom, sediment characteristics, salinity structure and area of vegetation. Total 7 out of 16 ecological district was identified in this region; NFB (natural, fresh, bare), NHB (natural, high salinity, bare), NLV (natural, low salinity, vegetated) in natural (without barrage) estuaries and CFB (closed, fresh, bare), CFV( closed, fresh vegetated), CLV (closed, low salinity, vegetated), CHB (closed, high salinity, bare) in closed (with barrage) estuary. A comparison of environmental factors and biota between CHB and CLV demonstrated the effect of barrage on estuarine ecosystem. The height and sediment characteristics of CHB and CLV were similar but the average salinity was lower in CLV than in CHB due to the barrage, which produced favorable condition for the Phragmites australis in CLV. Information regarding the ecological districts in various sizes and location could be useful for predicting the ecosystem change due to natural and anthropogenic perturbations and for preparing management actions.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.277-288
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• 2005

Perlite, a hydrated volcanic glass, occurs mainly as a bed-like body, and is distributed intermittently along the unconformity surface between the Beomgockri Group and its lower formations, viz. Janggi Group. The perlite is intimately associated with surrounding pumiceous welded tuff and rhyodacites in space and time. Compared to the typical perlite, the perlite is rather silica-poor and impure, and thus, includes lots of phenocrysts and rock fragments. Nearly the perlite is compositionally rather close to a pitchstone than a perlite in water contents. Petrographic comparison between perlite and associated volcanic to volcaniclastic rocks indicates that pumiceous welded tuff and rhyodacite seem to be Protolith of the Perlite. A Zr/$TiO_{2}$-Nb/Y diagram and field occurrence of perlite and their protolithic rocks also conforms the above interpretation. Kn addition, remnant vesicles in perlite strongly reflect that the precursor of perlitic glass appeared to be pumice fragment as well as volcanic glass. The perlite was diagenetically formed by way of a pervasive water-rock interaction at the deposition of the Manghaesan Formation in lacustrine environment. During perlitization, $SiO_{2}$ and alkali tend to be consistently depleted. Preexisting system of the Beomgockri Group based on the perlite formation should be corrected, because the perlite was formed diagenetically without lateral persistence in its occurrence.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.340-347
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• 2001

Seasonal variation of the elemental and biochemical composition of the suspended particulate matter (SPM) was investigated in terms of quantity and quality of diets for suspension feeders from July 1999 to August 2000 in two coastal bay systems of Gosung and Kangjin Bays in Korea. No clear patterns in the seasonal variations of SPM concentration were found in these two bay systems. The results indicated that the seasonal variation of SPM could not be considered the variation of food available to suspension-feeders. The simultaneous peaks in chlorophyll a and biochemical components in summer indicated that the quantity of the particulate organic matter primarily depended on phytoplankton productivity. However, no correlation between chlorophyll a and biochemical components [particulate protein (PPr), carbohydrate (PCHO) and lipid] were found, indicating that other processes might also contribute to the particulate organic matter in the period when the phytoplankton biomass was low. High C: Chl a and C:N, and carbohydrate peaks during the autumn to spring period suggested that resuspension of surface sediments was a probable process to supply the particulate organic matter. The food material, represented by summing up the total quantity of three biochemical components, was highest in spring with minor peaks during the period from autumn to the next spring, The food index, calculated as the ratio of food material to total SPM, did not generally exceed $6\%$ with short peaks during the year. Therefore, nutritional quality of SPM in the bays are relatively poor than in other more productive coastal waters in the world. Our results confirm that the measurement of a single chemical variable cannot describe fully the nutritive value of the seston available to suspension-feeders as previously proposed, and the biochemical composition of SPM can provide effective information on its origin and nutritive Quality.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.233-242
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• 2010

This study was conducted to know that if ionic liquids can be applicable as control agents of harmful algae in water-ecosystem and to find out problems caused by ionic liquid application. Firstly, the differential selectivity of various fresh-water algal species to several 1-alkyl-3-methylimidazolium chloride ionic liquids was investigated. There was a distinct differential response between alkyl chain lengths from butyl to dodecyl and towards the algal organisms : Generally algicidal activity was increased with increase of chain length and among the algae used in this study, Stephanodiscus hantzschii f. tenuis, Oscillatoria tenuis and Spirulina pratensis were most sensitive to 1-dodecyl-3-methylimidazolium chloride (MAIC12), next was Microcystis aeruginosa, and the others were relatively less sensitive to the chemical. The selectivity degree was about ten to twenty times based on the $EC_{80}$ (Effective concentration required for 80% growth inhibition). Secondly, an activity persistence of ionic liquids was investigated in natural mimic condition (using water bottle containing soil-sediments under the greenhouse condition). At the application of $1.0{\mu}g\;mL^{-1}$ of 1-octyl-3-methylimidazolium chloride (MAIC8), the algal growth did not occur at all until 6 days after treatment(DAT) and observed a only little growth at 9 DAT. But the algae grew rapidly after 9 DAT. So at 20 DAT, total chlorophylls was $264.4{\mu}g\;L^{-1}$ and the growth was inhibited by 58.2% compared to untreatment. On the other hand, MAIC12 also had a similar persistence pattern to MAIC8, showing nearly 5 times more activity than MAIC8. At 20 days after $0.2{\mu}g\;mL^{-1}$ application of MAIC12, that is, total chlorophylls was $251.2{\mu}g\;L^{-1}$ and the growth was inhibited by 55.2% compared to untreatment. In summary, 1-alkyl-3-methylimidazolium chloride ionic liquids is likely to be applicable for selective control of harmful algae as potent compounds having long lasting activity. However, the difficulty of degradation seems to be a limiting factor in an eco-friendly application of the compounds.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.288-297
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• 2010

This study was to evaluate the ecological stream health through the Multimetric Fish Assessment Index (MFAI) along with fish fauna analysis based on the tolerance and trophic guilds at Miho stream in 2008 and 2009. Also, we analysed total mercury concentration in fish tissues to examine heavy metal contamination. Total sampled fish were 40 species and 2,557 individuals and Zacco platypus was the most dominant with 35% relative abundance. It was sampled with 11.4% RA for Korean endemic species (10 species 291 individuals) less than average RA 39.3% for the Geum river watersheds. According to the tolarance guild analysis, tolerant species was more dominant with 58.9% RA (15 species, 1,507 individuals) than sensitive species with 6.6% RA. Trophic guild analysis also suggested that omnivores were more dominant (60.5% RA) than insectivores (31.5% RA). Riffle-benthic species was also sampled with 7.7% RA. Ecological stream health based on the MFAI were averaged 25.3 (n=3) with fair-poor condition in 2008 and also 26.3 (n=3) with fair condition in 2009, just slightly increased than 2008. Qualitative habitat evaluation index was averaged 134 (n=3) with fair condition but most of sites had sediment accumulation that reflected substrate degradations proceeding. From the result of total mercury accumulation in fish tissues, kidney and liver tissues showed the highest but the lowest for gill tissues. Overall mercury concentration were not exceed the national standards by Korean Federation of Drug and Administration (KFDA). Consequently, our result could correspond with the characteristics of Miho stream where point sources such industrial complexes and wastewater treatment plant widely distributed around the stream along the gradient of up and downstream.

• The Journal of the Petrological Society of Korea
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• v.9 no.1
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• pp.13-28
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• 2000

Chojeong area is mainly composed of the Ogcheon Group which consists of regionally metamorphosed, age-unknown sedimentary rocks. In the northwestern parts, the Group is intruded by the Jurassic Daebo granite and Cretaceous felsic and mafic dykes. The lowermost, Midongsan Formation which consists of milky white impure quartzite, crops out along the anticline axes with N40E trend. Ungyori quartzite Formation is intercalated with quartzite and slate. Miwon Formation is most widely exposed in the area and consists mainly of phyllitic sandy rocks with a thin crystalline limestone bed. Hwajeonri Formation is divided into two parts, pelitic lower and calcareous upper parts, composed with phyllite and slate. Changri and Hwanggangri Formations are typical members of Ogcheon Group, the former bearing coally graphite seams consists mainly of black slate and phyllite with intercalated greenish grey phyllite, the latter is pebble bearing phyllite formation of which matrix and pebbles are variable in compositions and size. Biotite granite, porphyritic granite and two mica granite belong to Jurassic so-called Dabo granite. They intruded the Ogcheon Group forming vast contact metarnophic zone. Quartz porphyry, mafic dyke and felsite intruded along the marginal zone of porphyritic granite batholith and fracture of NS trend. Main structural lineaments in Ogcheon Group shows N25-45E, NS and N30-45W trends. The N25-45E trends are mainly from general ductile deformation during regional metamorphism, showing isoclinal folding, Fl foliations and lithological erosional characters. Some of these trends are due to normal faults. The NS and N30-45W trends represent brittle deformation including faults and joints. In the area of granitic batholith, NS to N30- 45 trends are from the direction of dykes. In the soils of the area, average contents of heavy metal elements such as Cd, Cr, Cu, Pb, and Zn are 0.2, 50.6, 35.5, 27.9, and 93.4 ppm respectively, which are not higher than the average values of natural soils, under the tolerable level. Enrichment Index does not show any heavy metal pollution in the area. Average depths of weathering(5m vs. 2m), porosities(43.94 vs. 51.80), densities(l.29 vs. 1.15), and permeabilities(2.52 vs. 8.07) are comparable in granite areas and in the phyllite areas of Ogcheon Group.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.273-284
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• 2002

During January 1998-October 1999, the impact of free-floating plants (FFP) on limnology of the wetland ecosystem was evaluated through the investigation of physicochemical characteristics of the Woopo Wetland along with in situ manipulation experiments of aquatic plants. Flooding events occurred in the wetland during the summer period (Jun.-Aug.) and water levels rose to 2-3 m due to precipitation from the catchment and inflow from the main channel of the Nakdong River. Physicochemical parameters and plankton dynamics in the wetland during the summer were greatly influenced by floods and growth of free-floating plants. Dissolved oxygen (Jun.-Sept., 4.5${\pm}$2.5 mg/1; Oct.-May, 8,1 ${\pm}$4.0 mg/1) and pH (Jun.-Sept., 6.9${\pm}$0.4; Oct.-May,7.4${\pm}$0.8) levels were significantly lower during the summer than any other seasons. Three types of enclosure experiments (100 L, treatments with floating plants, screened and opened) were conducted under the presence and absence of sediment for 15 days in the 1999 summer. The treatments with sediment had higher levels of nutrient concentrations than those of the others. Among the treatments with sediment, nutrient concentrations in the treatments with free-floating plants were higher than the others. Zooplankton communities in each treatment showed a similar variation, although the scale of zooplankton densities differed. Rotifer community dominated the zooplankton at the initial phase of the experiment, but decreased drastically along with an increase of cladoceran and copepod communities. In conclusion, low levels of dissolved oxygen and pH in the Woopo Wetland during the summer seemed to be caused by a proliferation of free-floating plants and active decomposition process at the bottom of the sediment.