• Journal of the Mineralogical Society of Korea
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• v.26 no.4
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• pp.229-244
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• 2013

Arsenic contamination may be brought about by a variety of natural and anthropogenic causes. Among diverse naturally-occurring chemical speciations of arsenic, trivalent (As(III), arsenite) and pentavalent (As(V), arsenate) forms have been reported to be the most predominant ones. It has been well known that the behavior of arsenic is chiefly affected by aluminum, iron, and manganese oxides. For this reason, this study was initiated to evaluate the applicability of manganese slag (Mn-slag) containing high level of Mn, Si, and Ca as an efficient sorbent of arsenic. The main properties of Mn-slag as a sorbent were investigated and the sorption of each arsenic species onto Mn-slag was characterized from the aspects of equilibrium as well as kinetics. The specific surface area and point of zero salt effect (PZSE) of Mn-slag were measured to be $4.04m^2/g$ and 7.73, respectively. The results of equilibrium experiments conducted at pH 4, 7 and 10 suggest that the sorbed amount of As(V) was relatively higher than that of As(III), indicating the higher affinity of As(V) onto Mn-slag. As a result of combined effect of pH-dependent chemical speciations of arsenic as well as charge characteristics of Mn-slag surface, the sorption maxima were observed at pH 4 for As(V) and pH 7 for As(III). The sorption of both arsenic species reached equilibrium within 3 h and fitting of the experimental results to various kinetic models shows that the pseudo-second-order and parabolic models are most appropriate to simulate the system of this study.

• Korean Journal of Environmental Agriculture
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• v.5 no.1
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• pp.48-54
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• 1986

Because of the drastic development of nuclear industries, the contamination of natural environments by the disposal of radioactive materials which are released from nuclear facilities have aroused a considerable concern in relation to agricultural practices. Therefore the present investigation, through pot experiment, was performed to find out the aspect of the uptake of $Sr^{90}$ by rice plants and its distribution in them in five different types(physicochemical and minerallogical properties) of paddy soils. The results obtained were as follows; 1) Visual toxic symptoms on the growth of rice plant due to treatment of $Sr^{90}$ up to $40{\mu}Ci/10㎏$ in a pot were not observed even though uptake of $Sr^{90}$ by rice plant was proportionally increased with the $Sr^{90}$ treatment. 2) Distribution of $Sr^{90}$ in the rice plant was the highest in the leaves (84.5%) followed in the order by stems (13.5%) and rough grain (2.0%). The ratio of $Sr^{90}$ to Ca was higher in the leaves (872) and stems (667) than in the rice grain (89). 3) $Sr^{90}$ absorption in the rice plant ranged $0.15{\sim}0.30%$ at harvesting time. Uptake of $Sr^{90}$ by rice plants decreased by the increase of soil pH and exchangeable canons in the soils, but $Sr^{90}$ uptake increased when nitrogen, organic matter and clay content in soil was high, and uptake of this nuclide in the rice plant was higher with low Illite and Vermiculite content in the soils.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.553-562
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• 2017

In these days, agricultural reservoirs are considered as a useful resource for recreational purposes, tour and cultural amenity for vicinity communities as well as irrigation water supply. However, many of the agricultural reservoirs are showing a eutrophic or hyper-eutrophic state and high level of organic contamination. In particular, about 44.7% of the aged agricultural reservoirs that constructed before 1945 exceed the water quality criteria for irrigational water use. In addition to external loading, internal nutrient loading from bottom sediment may play an important role in the nutrient budget of the aged reservoirs. The objectives of this study were to characterize variations of thermal structure of a shallow M reservoir (mean depth 1.7 m) and examine the potential of internal nutrient loading by continuous monitoring of vertical water temperature and dissolved oxygen (DO) concentration profiles in 2015 and 2016. The effect of internal loading on the total loading of the reservoir was evaluated by mass balance analysis. Results showed that a weak thermal stratification and a strong DO stratification were developed in the shallow M Reservoir. And, dynamic temporal variation in DO was observed at the bottom of the reservoir. Persistent hypoxic conditions (DO concentrations less than 2 mg/L) were established for 87 days and 98 days in 2015 and 2016, respectively, during the no-rainy summer periods. The DO concentrations intermittently increased during several events of atmospheric temperature drop and rainfall. According to the mass balance analysis, the amount of internal $PO_4-P$ loading from sediment to the overlying water were 37.9% and 39.7% of total loading during no-rainy season in 2015 and 2016, respectively on August when algae growth is enhanced with increasing water temperature. Consequently, supply of DO to the lower layer of the reservoir could be effective countermeasure to reduce nutrient release under the condition of persistent DO depletion in the bottom of the reservoir.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.587-604
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• 2007

In order to investigate the vertical variations and speciations of trace elements, and their correlations in Hoidong reservoir, sediment cores (21-41 cm below surface) and interstitial water samples were collected from five sampling locations. The total average concentrations of trace metals in sediment core samples were $232{\pm}30.8mg/kg$ for Zn, $119{\pm}272mg/kg$ for Cu, $58.4{\pm}4.1mg/kg$ for Pb, $15.7{\pm}3.3mg/kg$ for Ni and $1.6{\pm}0.3mg/kg$ for Cd. The total concentrations of trace metals in core sediments generally decreased toward the center of the Hoidong reservoir. The total concentrations of Mn, Pb and Zn decreased with depth for all the sample locations, while Cu and Fe concentrations increased. The trace metal concentrations of interstitial water sample were in the order of Fe>Mn>Cu>Zn, but Cd, Ni and Pb were not detected. The concentrations of Zn, Cu, Fe and Mn in the interstitial water samples showed a tendency of increasing toward the bottom of the core, suggesting a possible upward diffusion. This migration of trace metals may lead to their transfer to the sediment-water interface. These trace elements would be subsequently fixed onto amorphous Fe and Mn-oxides and carbonates in the topmost layer of sediment. Based on the $K_D$ values, the relative mobilities of the studied metals were in the order of Mn>Cu>Zn>Fe. Geochemical partitioning confirmed that surface enrichment by trace metals mainly resulted from a progressive increase of the concentrations in the fractions II and III. Copper, Fe, Mn and Zn concentrations of interstitial water were closely correlated with their exchangeable fractions of sediments.

• Journal of Animal Science and Technology
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• v.53 no.4
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• pp.349-356
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• 2011

This study was conducted to investigate the effects of brown seaweed waste (BSW) fermented with DS-01 microbe on in vitro rumen microbial fermentation. In in vitro trial, three different diets supplemented with 2%, 4%, 6% BSW fermented with DS-01 either for one month or two months was tested at 3 h, 6 h, 9 h, 12 h, and 24 h incubation. The chemical composition (CP, EE, CF, and ash) between brown seaweed waste (BSW) and fermented BSW (FBSW) were not different. The contamination of pathogenic microbes was not detected in FBSW. The pH value tended to be higher with 6% level of supplementation of FBSW for one month than other treatments. The pH at 24 h was significantly higher in FBSW than that of treatments without FBSW (p<0.05). In FBSW for two months, the pH value in 6% FBSW at 3 h in vitro fermentation tended to be higher than 2% or 4% FBSW treatments (p=0.0540), but there were no differences in other fermentation times. Although the concentration of $NH_3$-N of BSW fermented for one month was higher than control at 3 h (p<0.05), the volatile fatty acid values were significantly increased in 4 and 6% FBSW fermented for one month at 6 h incubation (p<0.05). In BSW fermented for two months, the volatile fatty acid values were significantly decreased in 6% treatment at 9 h (p<0.05). As a result of in vitro trial, it was recommended that the 2~4% supplementation level of brown seaweed waste fermented with DS-01 microbe for two months could be utilized for in vivo trial in ruminants.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.253-260
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• 2005

Salt accumulation in the plastic film house soils under continuous cultivation condition causes problems such as salt damages to plants, nitrate accumulation in vegetables, groundwater contamination, etc. due to excess application of fertilizers. Objective of this research was to find an optimum adsorbent to reduce salt concentration in the soil solution of plastic film house soils, where crop injuries have been observed due to the salt accumulation. The soils were significantly high in available P $(1,431{\sim}6,516mg\;kg^{-1}),\;NO_3-N\;(117.60{\sim}395.73mg\;kg^{-1})$, exchangeable Ca $(4.06{\sim}11.07\;cmol_c\;kg^{-1})$ and Mg $(2.59{\sim}18.76\;cmol_c\;kg^{-1})$, as compared to those of the average upland soils in Korea. Soils were treated with each of adsorbent such as ion-exchange resin, zeolite, rice bran, etc. at 2% level and prepared into saturated-paste samples. After equilibrium, soil solution was vacuum-extracted from the soil and measured for changes of the pH, EC, and concentrations of $Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+,\;{NH_4}^+,\;{PO_4}^{3-}\;and\;{NO_3}^-$. Rice bran effectively removed ${PO_4}^{3-}\;and\;{NO_3}^-$ in the soil solution up to 100%. Efficiency was decreased in the orders of rice bran > ion-exchange resin > zeolite. Removal efficiencies of zeolite and ion-exchange resin for $Ca^{2+}$ were ranged from 1 to 65% and from 7 to 61%, respectively. Ion-exchange resin was also effective for removing $Mg^{2+},\;K^+,\;Na^+,\;and\;{NH_4}^+$. Overall results demonstrated that rice bran and ion-exchange resin could be applicable for salt accumulated soil to remove the respective anion and cation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1906-1912
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• 2014

To evaluate the effect of freezing temperature on quality of blueberries, blueberry fruit was frozen at -20, -45, and $-70^{\circ}C$ immediately after harvest. After 24 hr of freezing, frozen blueberries were stored at $-20^{\circ}C$ for 2 months. Blueberries were thawed at $4^{\circ}C$ or $25^{\circ}C$ and subjected to subsequent analyses of drip ratio, fruit hardness, pH of juice, color, and sugar content. Frozen berries at all three temperatures did not show any significant difference in pH or sugar content compared with fresh berries. The drip ratio of berries decreased as the freezing temperature decreased. Thawing conditions significantly affected the drip ratio of berries frozen at $-20^{\circ}C$. Hardness of berries was significantly reduced after freeze-thawing. Freezing and thawing reduced total aerobic bacteria and yeast/mold numbers by more than 2 log regardless of freezing or thawing temperature ($4^{\circ}C$ or $25^{\circ}C$). Cross-section of blueberries did not show different shapes by freezing temperature. Further studies such as sensory evaluation are needed to determine the optimum freezing temperature regarding quality and cost.

• The Korean Journal of Air & Space Law and Policy
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• v.28 no.2
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• pp.259-294
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• 2013

After its experiment involving the exploding of a satellite in space in 2007, China proudly aired news on TV and ran articles in newspapers. However, the event was internationally criticized and drew widespread attention. Many countries denounced the explosion by pointing out that it could be part of the nation's plan to expand its military power to space or that it could pose a danger to the peaceful use of space. However, there is no talk of whether the experiment that produced a huge amount of space debris could have violated an international law, namely the Outer Space Treaty. Although space garbage has been said to be a serious problem, the amount is still on the increase. If we continue to launch new space launch vehicles into orbit at this rate, we will not be able to use it anytime soon like we do today. As the commercial use of space is likely to increase, the situation will certainly get worse. The international community is fully aware of the seriousness of the problem and working together to reduce the amount of space garbage. However, despite the fact that the United States and Soviet Union's ASAT(Anti-Satellite) programs have been implemented for a long time, there have been no complaints about them in terms of military expansion or breach of the Outer Space Treaty. Also, the recent Chinese test is largely viewed to be in accordance with international law. A lot of research has been undertaken with regard to the problem of space garbage. Now people's awareness of dangers being posed has been fully raised. Under the circumstances, the dismissing of China's satellite smashing, leaving a big mess in its wake, as nothing more than an experiment, is a red flag to, if not many, at least some people. By means of this thesis, I would like to review whether the Chinese test has violated an international space law. This thesis presents an overview of the issues surrounding the event and examines the possibility of violating the Outer Space Treaty, formally the Treaty on Principle Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies. After the China test, the UN Scientific and Technical Subcommittee first adopted space debris mitigation guidelines, I'll introduce the content of the guidelines and discuss the characteristics of the guidelines and what can be done to address the issue.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.379-389
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• 2008

This study was conducted to assess the microbiological quality of raw and cooked foods served in the elementary school food service. Raw and cooked food samples were collected from 11 selected elementary schools in both June to July and September to October of 2005. Petrifilm plates were used to determine (in duplicate) total aerobic colony counts (PAC), Enterobacteriaceae (PE), coliform counts (PCC), and E. coli counts (PEC). Heavy contamination of Enterobacteriaceae (from 0.08 to 7.40 log CFU/g) and total coliform (0.50 to 6.52 log CFU/g) were observed in raw materials and cooked foods. Escherichia coli (E. coli) were detected in the sample of currant tomato (3.70 log CFU/g), sesame leaf (3.59 log CFU/g), dropwort (0.20 log CFU/g), crown daisy (3.15 log CFU/g), parsley (3.00 log CFU/g), peeled green onion (1.74 log CFU/g), frozen pork (0.65 log CFU/g), frozen beef (0.20 or 1.50 log CFU/g), chicken (1.78 log CFU/g), and young radish leaf seasoned with soybean paste (1.24 log CFU/g). Multiplex PCR system was used to determine the food-borne pathogens: Salmonella spp., Bacillus cereus (B. cereus), E. coli O157:H7, Staphylococcus aureus, Listeria monocytogenes (L. monocytogenes), Vibrio parahaemolyticus, Campylobacter jejuni (C. jejuni), Shigella spp., B. cereus was detected in 19 samples of raw materials and 8 samples of cooked foods. With regard to quantitative analysis, B. cereus counts exceeded 5.46, 3.48 and 1.79 log CFU/g in sesame leaf, peeled green onion and seasoned mungbean jelly, respectively. E. coli O157:H7 was detected on 2 samples of frozen beefs, and its biochemical characteristics of one beef sample was confirmed with API 20E kit (93.7%). L. monocytogenes was detected in fried rice paper dumpling, but the presumptive colonies were not detected onto the conventional plate. C. jejuni was detected in peeled & washed onion.

• Tuberculosis and Respiratory Diseases
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• v.42 no.6
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• pp.838-845
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• 1995

The determination of ADA(adenosine deaminase) activity in pleural fluid is useful in differental diagnosis of pleural effusion. The conventional method of determining ADA activity used by Giusti was influenced by contamination of ammonia. Additionally, because Giusti's method was mannual method a determining the ADA activities in sample, was not easily automated. In 1993, Oosthuizen HM with collegues developed simple kinetic method for determining ADA activity. It was reliable and suiable method for automation. In this study, we have measured ADA activity in 162 patients with various pleural effusion by Hitachi 747 autoanalyser using the Oosthuizen kinetic method for the purpuse of determination of new diagnostic cut-off value for the tuberculous effusion and evaluation of the correlation between the conventional method and new automated method. This new method of an enzymatic reaction involves 2, 6-dichlorophenolindophenol dye(DICP), adenosine, xanthine oxidase(XO), and nucleoside phosphorylase(NP). The results were as follows: 1) The mean pleural ADA activity of the tuberculous effusion was $52.53{\pm}16.43\;U/L$ and significantly higher than that of other groups(p<0.001). If the diagnostic cut-off value of pleural ADA activity for tuberculous effusion is above 30 U/L, the sensitivity is 96% and the specificity is 90%. 2) The mean pleural to serum ADA activity ratio of the tuberculous effusion was $2.29{\pm}0.96$ and it was also significantly higher than that of other pleural groups(p<0.001). If the diagnostic cut-off value of pleural to serum ADA activity ratio is 1.5, the sensitivity is 80% and the specificity is 88% in the diagnosis of tuberculous pleural effusion. 3) The new kinetic method is correlates well to Giuisti's conventional method(r=0.971). In conclusion, the new kinetic method described is easily automated and seems to be suitable for the routine determination of ADA activity.