• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.393-401
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• 2017

The nitrate ($NO_3{^-}$) accumulation of hydroponically grown leafy vegetables may increase in the condition of a closed-type plant production system with low light intensity due to low activity of enzymes involved in nitrogen assimilation and the use of $NO_3-N$ as major nitrogen source. The objective of this study is to investigate the effects of light intensities, nutrient solution compositions and the time of nutrient solution removal before harvest on nitrate contents of hydroponically-grown lettuces in a closed plant production system. The reduction of nitrate contents in leafy lettuces 'Cheongchima' was higher in the treatments of 'TW' (nutrient solution removal) and '$(NH_4)_2CO_3$' (use of ammonium carbonate as nitrogen source) than those in other treatments, which significantly lowered fresh weight and leaf area of the plants. In the light intensity of $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, the nitrate content was effectively reduced without causing any growth retardation, by substitution of the nutrient solution composition that $NO_3-N$ was removed ('$NO_3-N$ removal' treatment) or the half strength of standard nutrient solution was applied ('1/2 S' treatment), for 7days before harvest. The effects of light intensity and the time of nutrient solution removal before harvest on growth and nitrate contents in leafy lettuces were investigated. The nitrate contents in leaves under the light condition of $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ before nutrient solution removal were lower than those of 100 or $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. The removal of nutrient solution for 7 days before harvest quickly reduced the amount of nitrates in leaves in all the light intensities with a greater degree under the $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of light condition, while the 7 days-removal with both 200 and $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of light conditions caused decrease in 16~31% of leaf area and 20~35% of fresh weight, compared to the 3 days-removal treatment. The nitrate contents were greatly reduced from 3,018 to 1,035 in $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and 2,021 to 480 ppm in the light condition of $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, with the nutrient solution removal for 3 days before harvest, without causing any deterioration in growth and product quality. The vitamin C contents in leaves were higher in the treatment of nutrient solution removal for both 3 and 5 days before harvest with the light condition of $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ than those in the light condition of 100 or $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$.

• Economic and Environmental Geology
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• v.43 no.3
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• pp.235-248
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• 2010

To construct the standard methods for evaluation of physicochemical characteristics of tailings in Korea, specific gravity, paste pH, grain size, mineral compositions and heavy metal concentrations of total 26 tailings from 21 metallic mines were analyzed. Specific gravity of tailings ranged from 2.61 to 4.31 (avg. 3.04), and sand and silt grain were dominant in the tailings. Ranges of paste pH were 2.1-9.5 in tailings (7.1-9.2 at magmatic, skarn and hydrothermal replacement deposits and 2.1-9.5 at hydrothermal vein deposits). Additionally, hydrothermal vein deposits could be reclassified into three categories: (1) paste pH>7.0, (2) 4.0

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1720-1725
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• 2011

Aspartic acid chelated iron (Asp-Fe) was synthesized by a new method using calcium carbonate, aspartic acid, and ferrous sulfate. This study was carried out to investigate the bioavailability of Asp-Fe in iron-deficient rats. We divided the rats into four experimental groups. The first was the normal diet control group, or NC. The second was the no treated control group of iron-deficient (ID) rats, or ID+C. The third was the heme-iron (heme-Fe) treated group of ID rats, ID+heme-Fe. And the fourth was the Asp-Fe treated group of ID rats, or ID+Asp-Fe. There were no differences among any of the experimental groups in diet consumption, change of body weight, or the weight of the livers, kidneys, or spleens. After 7 days of feeding, the iron content in the sera of the ID+Asp-Fe group (175.2 ${\mu}g$/dL) and the ID+heme-Fe group (140.8 ${\mu}g$/dL) were significantly higher than that of the ID-C group (96.1 ${\mu}g$/dL). The total iron binding capacity (TIBC) of the ID+Asp-Fe group (735.4 ${\mu}g$/dL) was significantly normalized compared to the ID+C group (841.9 ${\mu}g$/dL) or ID+heme-Fe group (824.6 ${\mu}g$/dL). The hematocrit level of the ID+Asp-Fe group was increased to normal levels, but there was no statistical difference among ID groups. The absorption ratio of heme-Fe was 21.3% and that of Asp-Fe was 50.2%, which indicates a 2.3 times higher ratio in comparison with heme iron. With the above results we found that Asp-Fe seems to be an efficient form of iron to supply iron deficient rats in order to cure them of anemia. Thus, these findings suggest that aspartic acid chelated iron has the potential to serve as a functional food related to iron metabolism.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.739-752
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• 2006

Deep-sea surface sediments acquired by multiple corer from 69 stations in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific, were examined to understand the correlation of mass physical properties and sedimen-tological processes. The seabed of the middle part ($8-12^{\circ}N$) of the study area is mainly covered by biogenic siliceous sediment compared with pelagic red clays in the northern part ($16-17^{\circ}N$). In the southern part ($5-6^{\circ}N$), water depth is shallower than carbonate compensation depth (CCD). The mass physical properties such as grain size distribution, mean grain size, water content, specific grain density, wet bulk density, void ratio, and porosity of sediments are distinctly different among the three parts of the study area. Surface sediments in northern part are characterized by fine grain size and low water contents possibly due to low primary productivity and high detrital input. Conversely, sediments in the middle part are characterized by coarse grain size and high water contents, which might be caused by high surface productivity and deeper depth than CCD. The sediments show low water contents and high density in the southern part, which can be explained by shallower depth than CCD. Our results suggest that the variations in mass physical properties of sediments are influenced by combined effects including biogenic primary productivity of surface water, water depth, especially with respect to CCD, sedimentation rate, detrital input, and the geochemistry of the bottom water (for example, formation of authigenic clay minerals and dissolution of biogenic grains).

• The Korean Journal of Malacology
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• v.28 no.3
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• pp.233-244
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• 2012

Goseong bay, located in southeast sea of Korea with an area of 2,100 ha, is a semi-enclosed bay well-known for oyster farming cultured in an extended range of 148 ha. The objective of this study is to provide the fundamental data in order to manage the effective sea area. A total 26 of surface sediment were collected from Goseong bay to evaluate their sedimentary environment and heavy metals. The loss on Ignition (LOI), C/N ratio, acid volatile sulfide (AVS) and heavy metals were analyzed. loss on ignition (LOI) of surface sediment range from 1.00% to 3.03% (average 2.00%). The carbonate content ranges from 0.52% to 4.29% (average 2.37%). C/N ratio of organic matter showed that most part of organic matter comes from neighboring continent. Acid volatile sulfide (AVS) value of surface sediment from 0.02 mg/g to 1.43 mg/g (average 0.24 mg/g). A ten element of surface sediments (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, V, Zn) were calculated by enrichment factor (Ef) and the results show that some areas are highly polluted with respect Cu and Hg. The correlation matrix displays the existence of remarkable levels of correlation with both positive and negative values among different variable pairs. LOI and AVS showed both positive values. LOI and AVS values falls under 2% and 1%. Therefore, Goseong bay showed good in quality of sediment.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.1-7
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• 1992

Sand and silt size fractions of soils which were derived from five major rocks of granite, granite-geniss, limestone, shale, and basalt in Korea were studied. Determination of the mineralogical and chemical composition of rock-forming mineral breakdown which is accompanied by the formation of secondary minerals. The chemical composition of the fraction was largely changed with the content of weatherable and resistant soil minerals such as ferromagenesian minerals, carbonates, and guartz. In the sand fractions of the soils from the granite and granite-gneiss, chlorite-vermiculite mixed layers seem to be an intermediate weathering product prior to the weathering state of the formation of vermiculite from chlorite. Kaolin minerals in the silt fractions of the soils from the granite-gneiss are considered to be formed by the pseudomorphic transformation of plagioclase. In the sand and silt fractions of the soils derived from the limestone, large amount of calcite and dolomite seems to have been inherited from the parent rocks. The primary chloritc, micas, and feldspars are considered to be formed from the weathering remains after leaching of carbonate minerals during the soil formation. In the residual soils(Gueom series) developed from the basalt, quartz and micas were coexisted with plagioclase and augite inherited from the parent rock.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.695-708
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• 2008

In order to evaluate the geochemical behaviors of elements with waste rocks in the abandoned Jangpoong Cu mine area, total concentration analysis and leaching experiments were performed. The content of elements within waste rocks compared with background values decreased in order of As>>Cu>Pb>Cd>Co. Leaching experiments were carried out at various extraction environments, considering the acid rain ($0.00001{\sim}0.001N\;HNO_3$) and the acid mine drainage ($0.001{\sim}0.1N$ HNO3). After 24 hours of reaction with different acidic solution, the leaching characteristics of waste rocks were classified into three types according to final pH of leaching solution. Type I refers to the case that the final pH of leaching solution was lower than that of the reaction solution due to the dissolution of acidic minerals from rocks, while type 2 and 3 refer to the case that the final pH maintained higher than that of the reaction solution. Theses types include in acid buffering minerals such as clay minerals and carbonate minerals. The leaching characteristics of the elements after the reaction could be categorized into As-Co-Fe, Cu-Mn-Cd-Zn, and Pb. As-Co-Fe started to get leached under 2.5 of pH regardless of changes in the final pH, and Cu-Mn-Cd-Zn showed different initial leaching pH according to the types of final pH changes. Based on the pH value where leaching started regardless of leaching concentration, the relative mobility of each element was in the order of Mn Zn>Cd>Cu>>Fe Co>As>Pb. Thus, more higher mobility elements(Zn, Mn and Cu) were leached by reacting with acid rain water. Acid mine drainage may result in distributions of elements having relatively less mobility(As, Fe, Co and Pb).

• Applied Biological Chemistry
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• v.14 no.1
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• pp.9-18
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• 1971

In order to obtain basic information on the production of single cell protein from petroleum, more than 400 yeast strains were isolated from various soil samples in Korea utilizing petroleum hydrocarbon as the sole carbon source. A yeast strain showing the highest cell yield among the isolated strains was selected and identified. The optimal culture condition was searched in the flasks shaken throughout the procedure. And the growing characteristics for the selected yeast strain and chemical analysis of the yeast cell component were carried out. The results obtained were as follows: 1. The selected yeast strain was identified as Candida curvata and we named it Candida curvata-SNU 70. 2. The composition of the medium proposed for the present yeast strain is: Light Gas Oil 30ml, Urea 400mg, Ammonium sulfate 100mg, Potasium phosphate (monobasic) 670mg, Sodium phosphate (dibasic) 330mg, Magnesium sulfate 500mg, Calcium carbonate 3g, Yeast extract 50mg, Tween 20 0.05ml, Tap water 1,000ml. 3. Other culture conditions employed for the yeast were pH 5.5-7.0, temp. $30^{\circ}C$ under an affluent aerobic state. 4. Addition of light gas oil in portions to the culture media as the growth proceeded was more effective, especially in the cultivation on the higher oil concentration media. 5. Studies on the propagation of the yeast cells in the light gas oil medium revealed that the yeast has the lag phase lasted 16 hours and the logarithmic growth phase covered 16 to 28 hours. The specific growth rate was about $0.22\;hr^{-1}$ and doubling time was 3.2 hrs. during the logarithmic growth phase. 6. Under the cultural condition employed, the cell yield against the amount of light gas oil (wt%) was 16.1% and the protein content of the dried yeast cells was 48.4%.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.557-576
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• 2015

Groundwaters in granite, gneiss, and two-mica granite formations, including faults, in the Hoengseong area are examined to determine the relationship between their uranium and radon-222 contents and rock types. The chemical compositions of 38 groundwater samples and four surface water samples collected in the study area were analyzed. Sixteen of the samples showing high uranium and radon-222 contents were repeatedly analyzed. Surface radioactivities were measured at 30 points. The uranium and radon-222 concentrations in the groundwater samples were in the ranges of 0.02-49.3 μg/L and 20-906 Bq/L, respectively. Four samples for uranium and 35 samples for radon had concentrations exceeding the alternative maximum contaminant level of the US EPA. The chemical compositions of groundwaters indicated Ca(Na)-HCO₃ and Ca(Na)-NO₃(HCO₃+Cl) types. The pH values ranged from 5.71 to 8.66. High uranium and radon-222 contents in the groundwaters occurred mainly at the boundary between granite and gneiss, and in the granite area. The occurrence of uranium did not show any distinct relationship to that of radon-222. The radon-222, an inert gas, appeared to be dissolved in the groundwater of the aquifer after wide diffusion along rock fractures, having been derived from the decay of uranium in underground rocks. The results in this study indicate that groundwater of neutral or weakly alkaline pH, under oxidizing conditions and with a high bicarbonate content is favorable for the dissolution of uranium and uranium complexes such as uranyl or uranyl-carbonate.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.179-189
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• 2002

The Geology of the Shizhuyuan W-Sn-Bi-Mo deposits, situated 16 Ian southeast of Chengzhou City, Hunan Province, China, consist of Proterozoic metasedimentary rocks, Devonian carbonate rocks, Jurassic granitic rocks, Cretaceous granite porphyry and ultramafic dykes. The Shizhuyuan polymetallic deposits were associated with medium- to coarse-grained biotite granite of stage I. According to occurrences of ore body, ore minerals and assemblages, they might be classified into three stages such as skarn, greisen and hydrothernlal stages. The skarn is mainly calcic skarn, which develops around the Qianlishan granite, and consists of garnet, pyroxene, vesuvianite, wollastonite, amphibolite, fluorite, epidote, calcite, scheelite, wolframite, bismuthinite, molybdenite, cassiterite, native bismuth, unidetified Bi- Te-S system mineral, magnetite, and hematite. The greisen was related to residual fluid of medium- to coarse-grained biotite granite, and is classified into planar and vein types. It is composed of quartz, feldspar, muscovite, chlorite, tourmaline, topaz, apatite, beryl, scheelite, wolframite, bismuthinite, molybdenite, cassiterite, native bismuth, unknown uranium mineral, unknown REE mineral, pyrite, magnetite, and chalcopyrite with minor hematite. The hydrothermal stage was related to Cretaceous porphyry, and consist of quartz, pyrite and chalcopyrite. Scheelite shows a zonal texture, and higher MoO) content as 9.17% in central part. Wolframite is WO); 71.20 to 77.37 wt.%, FeO; 9.37 to 18.40 wt.%, MnO; 8.17 to 15.31 wt.% and CaO; 0.01 to 4.82 wt.%. FeO contents of cassiterite are 0.49 to 4.75 wt.%, and show higher contents (4.]7 to 4.75 wt.%) in skarn stage (Stage I). Te and Se contents of native bismuth range from 0.00 to 1.06 wt.% and from 0.00 to 0.57 wt.%, respectively. Unidentified Bi-Te-S system mineral is Bi; 78.62 to 80.75 wt.%, Te; 12.26 to 14.76 wt.%, Cu; 0.00 to 0.42 wt.%, S; 5.68 to 6.84 wt.%, Se; 0.44 to 0.78 wt.%.