• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.245-254
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• 2000

This study was conducted to investigate the community structure and distributional pattern of meiobenthos in the deep sea bottoms of northeastern Pacific during July 1998. The faunal samples were collected using the multiple corer at ten stations; eight stations along the transects from 5$^{\circ}$N to 12$^{\circ}$N, and two stations in the Preservation Zone and Impact Zone of the KODOS (Korea Deep Ocean Study) area. The organic carbon content in sediments ranged from 0.79 to 1.76 mg cm$^{-3}$, and higher concentration appeared at stations in lower latitudes than 8$^{\circ}$N. The most abundant meiobenthos was nematodes and followed by foraminiferans; these two taxa comprised more than 70% of the total abundance at all stations. The most abundant meiobenthos occurred with mesh size of 0.063 nm. The maximum density of meiobenthos was 442 ind./10 cm$^2$ at station N5, and the density gradually decreased toward station N8 where the minimum density of 92 md./10 cm$^2$ was found. More than 60% of meiobenthos were distributed at surface sediment layer within 1.0 cm, and the peak abundance was found at 0-0.25 cm layer. The latitudinal distribution pattern of meiobenthos in the study area seemed to be related with the primary productivity of the surface water that is also connected to the water circulation pattern of the Pacific Ocean near the Equator, diverging at latitude of 8$^{\circ}$N and conversing at 5$^{\circ}$N.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.325-333
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• 1992

An investigation was carried out to find out the effects of long-term application (14 and 28 years) of rice straw, compost and wheat straw on changes in soil chemical and physical properities, aspests of releasing potential nitrogen and nitrogen uptake by rice and maize from fine textured paddy soils with double cropping system in warm temperate area. The result obtained were summarized as follows : 1. The long-term application of organic matters improved plow layer and soil physical properties : bulk density and solid phase were decreased, while porosity and gaseous phase were decreased. 2. Average increment of total carbon per year was 0.0371% and 0.0407% for rice straw and compost, respectively, from 1 through 14 years ; it was 0.0007% and 0.0014% for the rice straw and compost, respectively, from 15 years through 28 years. The average increment of total notrogen per year was 0.0025% and 0.038% for the rice straw and compost, respectively, from 1 through 14 years ; 0.0014% and 0.0024% for the same treatments from 15 through 28 years. 3. $NH_4-N$ and amide-N were high in the soils with wheat straw application for 28 years ; the amino sugar-N in the soils with compost application for 28 years ; amino acid -N in the soils with rice straw application for 14 and 28 years ; and unidentified-N, in the control. 4. The released amount of available nitrogen with the submerged condition was higher at $30^{\circ}C$ than at $25^{\circ}C$ during the incubation. The amount of released available nitrogen at the field was aproximately same as that of $25^{\circ}C$ incubation. However, the released amounts from the incubation and the field were always lower than those extracted with reagents. 5. The amount of nitrogen uptake by rice and maize was highly correlated with available nitrogen extracted with phosphate buffer(pH 7.0). 6. The ratio of yield increase(milled rice) was 17, 12 and 7%, respectively, by application of rice straw, compost and wheat straw for 28 years, and 11% by application of rice straw for 14 years.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.438-446
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• 2006

A lab-scale batch test was conducted to develop capping materials to reduce the sediment phosphorus in the stagnant water zone of Gyeongancheon in Paldang Lake. The mean grain size(Mz) of sediment in the investigated area was 7.7 ${\phi}$, which is very fine, and the contents of organic carbon($C_{org}$) was 2.4%, which is very high. For the phosphorous release experiment to select the optimal capping material, sand layer, powder-gypsum($CaSO_4{\cdot}2H_2O$), granule-gypsum, complex layer(gypsum+sand) and the control were compared and evaluated in the 150 L reactor for 45 days. In case of the capping with the sand, it was found that the phosphorous from the sediment could be reduced by around 50%. However, it was found that this caused the reduction of the dissolved oxygen in the water column(by less than 3 mg/L) due to the resuspension of sediment and the organic matter decomposition that comes from the generation of $CH_4$ gas in the 1 cm of the sand layer. Therefore, it is likely that the sand layer has to be thickener in case of the sand capping. Powder-gypsum and granule-Gypsum reduced phosphorous release by more than 80%. However, the concentration of ${SO_4}^{2-}$ in the water column increased, making it difficult to apply it to the drinking water protection zone. We developed Fe-Gypsum and $SiO_2$-gypsum materials to reduce the solubility of ${SO_4}^{2-}$. Powder-Gypsum creates the interception film that does not have any aperture on the sediment layer when it is combined with the water. However phosphorous release caused by the generation of $CH_4$ gas may happen at a time when the gypsum layer has the crack. Capping through the complex layer(granule-Gypsum+sand(1 cm)) found to be suitable for the drinking water protection zone because it was effective to prevent phosphorus release. Moreover, this leads to the lower solubility from the concentration of ${SO_4}^{2-}$ into the water column than the powder-Gypsum and granule-Gypsum. The addition of gypsum($CaSO_4{\cdot}2H_2O$) into the sediment can reduce the progress of methanogensis because fast early diagenesis and sufficient supply of ${SO_4}^{2-}$ to the sediment, stimulate the SRB(sulfate reducing bacteria) highly.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.3
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• pp.179-188
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• 2007

In this work $^{14}C\;and\;^3H$ distribution characteristics of spent resins from nuclear power plants(NPPs), pressurized water reactors(PWRs), was investigated. It was found that the recovery percent of $^{14}C$ by the wet oxidation-acid stripping was $81%{\sim}100%$ for the added activity range of $^{14}C,\;0.72\;Bq{\sim}460\;Bq$, and it was not affected by the kinds of stripping acids, 3N-HCl, $3\;N-HNO_3\;and\;3\;N-H_2SO_4$. And the recovery percent of $^3H$ by distillation using the same apparatus was $81%{\sim}101%$ for the added activity range of $^3H,\;0.60\;Bq{\sim}435\;Bq$. Among the tested stripping acids, 3\;N-HCl, $3\;N-HNO_3\;and\;3\;N-H_2SO_4$, only the trapped $^3H$ solution by distillation in $3\;N-H_2SO_4$ was compatible with the 3H scintillator, Ultimagold XR. Neither of the $^{14}C\;and\;^3H$ trapping solutions from the spent ion exchange resin samples by the wet oxidation-3 $N-H_2SO_4$ stripping contained gamma nuclides. However, some gamma nuclides, $^{60}Co,\;^{134}Cs,\;^{137}Cs\;and\;^{54}Mn$, were found in the trapped $^3H$ solutions of the spent resins by the wet oxidation-3 N-HCl stripping. It was the same for the $^3H$ trapping solutions of the spent resins by Sample Oxidizer(PACKARD MODEL 307). Meanwhile only two nuclides, $^{134}Cs,\;and\;^{134}Cs$, were found in the $^{14}C$ trapping solutions of the spent resins by Sample Oxidizer(PACKARD MODEL 307). It was found that most of the $^{14}C$ in the spent resins existed as inorganic carbon form, more than about 70% of the total $^{14}C$ content. Among the analyzed 30 spent ion exchange resin samples, the average concentration of $^{14}C$ and $^3C$ for the high radioactive samples, 8 samples, was $19000\;Bq/g{\pm}41000\;Bq/g,\;670\;Bq/g{\pm}460\;Bq/g$ and that for the low radioactive samples, 22 samples, was $4.2\;Bq/g{\pm}4.3\;Bq/g,\;6.0\;Bq/g{\pm}5.3\;Bq/g$, respectively. And the average $^{14}C/^3H$ ratio for the high radioactive samples, was higher, 28, than that of low radioactive samples, 0.70. Some linear relationship trend was found between the activity concentrations of $^{14}C\;and\;^3H$.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.62-69
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• 2008

There has been a recent trend in Korea that treatments for combustible wastes among municipal solid waste (MSW) by those methods, such as incineration and landfill are restricted as much as possible and Mechanical Biological Treatment (MBT) are encouraged actively in order to promote resource recovery. To build and operate properly these facilities, the physicochemical characteristics of MSW should be analyzed precisely beforehand. In particular, designing a crusher or separator properly which is the main process in MBT facilities of MSW. require the information on the size distribution characteristics of MSW, but they are nor sufficient in the qualities and quantities yet as of now. Accordingly, this study aims to evaluate size distribution characteristics of MSW and its physicochemical characteristics by size. The samples of MSW were collected from detached dwelling area, apartment area, business area, and commercial area of A city in Korea. According to the result of analysis, paper records 29.78~60.02% by wet weight basis, so it was the most regardless of the regions where the wastes were generated. And in terms of element analysis, Carbon(C) was 34.77~44.39%, the largest friction, and Oxygen(O) was the next occupying 19.46~33.71%. As indices of RDFs, Chlorine(Cl) was 0.39~0.83%, so it was less than the standard, 2.0%(by dry weight basis); moreover, Sulfur(S) did not exceed the standard, 0.6%, either. In the size distribution of MSW, waste fraction ranging 50~80mm in diameter was the most in combustible waste while 30~50mm was in incombustible waste.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.248-255
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• 2011

For the environmental friendly soil management on the cultivation of crops in the greenhouse, organic materials, such as the by product-fertilizer derived from livestock manure, rice straw, mushroom media, rice hulls, wood sawdust, and cocopeat, were used as carbon sources adjusting the ratio of carbon to nitrogen to 10, 20, and 30 based on the inorganic soil N. In each C/N ratio of greenhouse soil, watermelon was cultivated in the greenhouse as crop for experiment for the spring and summer of the year and the experimental results were summarized as follows. The concentration of T-C in the organic materials applied were between $289{\sim}429g\;kg^{-1}$, In the C/N ratio of 10, using watermelon as the crop cultivated during the second half of the year in the greenhouse soil, the $NO_3$-N and EC were reduced by 21 to 37%, and 26 to 33%, respectively, except the by product-fertilizer from livestock manure, compared to the soil $NO_3$-N and EC used in the experiment. After the watermelon was cultivated in soils that C/N ratios were controlled as 10, 20, and 30 with wood sawdust adding as carbon sources in the three soils with the different EC values, EC values of the soils were reduced by 33, 42, and 39%, respectively, compared to the soil EC used in the experiment. The weight of watermelon was 10.1-13.4 kg per one unit, and, of the three soils with different EC values. In the soils with three different EC values controlled at C/N ratio of 20, the weight of watermelon was good. The degree of sugar of watermelon were 11.8 to 12.3 Brix, which means that the difference between the treatments was not significant. In conclusion, the C/N ratio of 20 controlled by the proper supply of organic materials according to the representative EC values shown in the greenhouse soils was optimal condition enough to maintain the soil management for the organic culture with the proper nutrient cycling.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.327-339
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• 2001

Community structure of macrobenthos was studied at forty one stations of Hampyung Bay, southwest coast of Korea. Three replicate sediment samples were taken at each station in October 1997, using a van Veen grab (surface area $0.1\;m^2$). The types of surface sediment in the sampling area were muddy sandy gravel between bay mouth and bay proper, and gravelly sandy mud between bay proper and inner bay stations. The particulate organic carbon content in the surface sediment was $0.23\sim0.69\%\;(0.44\pm0.10\%)$. A total of 168 species collected during the study period is composed of 58 of polychaetes, 54 of crustaceans, 34 of molluscs and 22 of miscellaneous. The former two taxa together were accounted for $66.6\%$ of the total number of species. The mean density was $1,168 ind./m^2$, comprising $684 ind./m^2$of molluscs ($58.6\%$), $381 ind./m^2$of polychaetes ($32.6\%$), and $90 ind./m^2$of crustaceans ($13.2\%$). The mean biomass was $358.65 g/m^2$, which is consisted of $302.97 g/m^2$of molluscs ($84.5\%$), $24.20 g/m^2$of echinoderms ($6.7\%$), and $19.16 g/m^2$of crustaceans ($5.4\%$). Major dominant species at the inner stations of the study area was Ruditapes philippinarum with a density of $520ind./m^2$($44.5\%$), and Lumbrineris lontifolia with $183ind./m^2$($15.7\%$), while that at bay mouth stations Pitar indecoroides with $56ind./m^2$. Reticunassa festiva, Heteromastus sp., Praxillella affinis, Chone sp. and Tharyx sp. were at from all stations. Based on the cluster analysis, the macrobenthic community in the bay was classified into five station groups depending on sediment types: Group A, a high gravel content in the sediment; Group B, stations with high mud content from bay mouth to bay proper, Group C, stations with fine and poorly sorted sediment from bay proper to the inner bay. The distribution pattern of the number of species, abundance and biomass is discussed in relation to environmental variables.

• Journal of the Mineralogical Society of Korea
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• v.22 no.1
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• pp.23-34
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• 2009

The adsorption of iodide on untreated bentonite and bentonites modified with organic cation (i.e., hexadecylpyridinium chloride monohydrate ($HDP^+$)) was investigated, and the organobentonites were characterized using uptake measurements, ${\mu}$-XRD, and electrophoretic mobilities measurement. Uptake measurements indicate that bentonite has a high affinity for $HDP^+$. Our ${\mu}$-XRD study indicates that organobentonites significantly expanded in basal spacing and organic cations were substantially intercalated into the interlayer spaces of bentonite. The electrophoretic mobility indicates that organobentonite tht is modified with organic cations in excess of the CEC of bentonite is completely different from untreated bentonite in the surface charge distribution. We found significant differences in adsorption capacities of iodide depending on the bentonite properties as follows: iodide adsorption capacities were 439 mmol/kg for the bentonite modified with $HDP^+$ at an equivalent amount corresponding to 200% of the CEC of bentonite whereas no adsorption of iodide was observed for the untreated bentonite. The molecular environments of iodine adsorbed on organobentonites were further studied using I K-edge and $L_{III}$-edge x-ray absorption spectroscopy (XAS). The X-ray absorption near-edge structure (XANES) of iodine spectra from organobentonites was similar to that of KI reference solution. Linear combination fitting of EXAFS data suggests the fraction of iodine reacted with the organic compound increased with increasing loading of the organic compound on organobentonites. In this study, we observed significant differences in the adsorption environments of iodide depending on the modified property of bentonite and suggest that an organobentonite has potential as reactive barrier material around a nuclear waste repository containing anionic radioactive iodide.

• The Journal of the Petrological Society of Korea
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• v.25 no.4
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• pp.373-388
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• 2016

To understand human activity in the past, the information about past environmental change including geomorphological and climatic conditions is essential and this can be traced by using age dating and geochemical analysis of sediments from the prehistoric sites. The sedimentary sequence of Seokgwan-dong Paleolithic Site located in Seoul was 5m long unconsolidated sediments and consists of lower part bedrock weathering sediments, slope deposits and upper-part fluvial deposits. In this study, upper part sediments were used to reconstruct past environmental change through age dating and various physical and chemical analyses including grain size, magnetic susceptibility and mineral and elements. The fluvial sediments can be divided into 4 units including three organic layers. Grain size analysis results showed that the sediments were very poorly sorted with fining upward features. Magnetic susceptibility was relatively high in the organic layers, indicating environmental changes causing mineral composition change at that times. The mineral and major element composition are similar to Jurassic biotite granite which mainly consists of quartz, K-feldspar, biotite and muscovite. The radiocarbon age of $14,240{\pm}80yr$ BP was obtained from the lower most organic layer of Unit III(O), suggesting that the fluvial sediments formed at least from the early stage of deglacial period after the end of Last Glacial Maximum. Subsequent wet and warm climates and resultant fluvial process including slope sedimentation during the Holocene may have been responsible for the sedimentary sequence in Seokgwan-dong paleolithic site and surrounding area. The observed organic layers suggests frequent wetland occurrence combined with natural levee changes in this area.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.3
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• pp.159-163
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• 1973

A by-product from glutamic acid fermentation prepared by treating the fermentation residue with sulfuric acid and ammonium hydroxide was studied in the light of its chemical properties by chemical analysis and X-ray diffraction technique. Its effectiveness as fertilizer was also investigated with corn as test plant. The results are summarized as following. 1. The chemical analyses and study with X-ray diffraction technique revealed that the by-product contains an appreciable quantity of water soluble ammonium as ammonium sulfate and ammonium chloride, water soluble amino acid and in-soluble organic carbon. Particularly, the X-diffraction pattern of the material indicated the presence of unidentified water soluble double salt of ammonium sulfate and ammonium chloride. 2. The water soluble ammonium in this material was found to be as effective as urea on the growth of corn plant. 3. The organic portion of the material was found to be equally effective on the growth of corn plant as the other sources of organic matter such as compost and rice bran. It was, however found that the organic matter in the fermentation residue is more persisting in the soil than the compost and rice bran. 4. It was noticed that the application of the fermentation by-product, lowers the soil pH significantly. Inspite of the pH lowering effect, the absorption of iron by corn plant was surpressed by the application of this material.