• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.50-57
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• 2016

According to the urban gas business legislation, cathodic protection systems should be applied for buried steel gas pipelines to prevent corrosion. In advanced countries including United States, the criteria for Cathodic Protection Potential is at least -850mV with respect to a saturated copper/copper sulfate electrode(CSE) when the CP applied, and the IR drops must be considered for valid interpretation. However, the IR drop through the pipe to soil boundary has been neglected in Korea. According to KGS code, a reference electrode must be placed in proximity to gas pipelines possible when measuring the CP potential. In this study, we have installed several solid reference electrodes around the buried pipeline(1.2m depth), lower surface(0.5m depth), and the surface individually in order to measure the CP potentials through the each reference electrode and find out the IR drops according to the location of each reference electrode. We have found the IR drop is the greatest when measuring the CP potential through the electrode placed on the ground and the IR drop is the smallest through the electrode installed near pipeline. Therefore, we have suggested the solid reference electrode should be installed as close as possible to buried pipeline in order to measure the correct CP potential without IR drop. We have also suggested the amendment of CP criteria considering IR drop.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.549-556
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• 2009

In situ chemical oxidations (ISCO) are technologies for destruction of many contaminants in soil and groundwater, and persulfate has been recently studied as an alternative ISCO oxidant. Trichloroethylene (TCE) and tetrachloroethylene (PCE) were chosen for target organic compounds. The objective of this study is to demonstrate the influence of initial pH (3, 6, 9, 12), oxidant concentrations (0.01, 0.05, 0.1, 0.3, 0.5 M), and contaminants concentrations (10, 30, 50, 70, 100 mg/L) on TCE/PCE degradation by persulfate oxidation. The maximum TCE/PCE degradation occurred at pH 3, and the removal efficiencies with this pH condition were 93.2 and 89.3%, respectively. The minimum TCE/PCE degradation occurred at pH 12, and the removal efficiencies were 55.0 and 31.2%, respectively. This indicated that degradation of TCE/PCE decreased with increasing the initial pH of solution. Degradation of TCE/PCE increased with increasing the concentration of persulfate and with decreasing the concentration of contaminants (TCE/PCE). The optimum conditions for TCE/PCE degradation were pH 3, 0.5 M of persulfate solution, and 10 mg/L of contaminant concentration. At these conditions, the first-order rate constants ($k_{obs}$) for TCE and PCE were 1.04 and 1.31 $h^{-1}$, respectively.

• Analytical Science and Technology
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• v.24 no.1
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• pp.24-37
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• 2011

The ionic compositions of atmospheric aerosols were investigated and characterized in coastal and mountainous sites of Jeju Island, which were Gosan and Mt. Halla-1100 sites respectively. It was found that the concentrations of nss-$SO_4^{2-}$ (non-sea salt sulfate) and $NH_4^+$ at two measurement sites were almost similar and they showed high concentrations in June at the same time. The concentration of soil-originated nss-$Ca^{2+}$ (non-sea salt calcium) was generally associated with that of anthropogenic $NO_3^-$ and its concentration was increased during spring season. From the comparison of time-series variation and regression analysis of ionic species between two measurement sites, TSP (total suspended particulate) in Gosan site was directly influenced by sea salt particles and the concentration levels of nss-$SO_4^{2-}$, $NH_4^+$, nss-$Ca^{2+}$, $K^+$, and $NO_3^-$ were mainly related with long-range transported air pollutants rather than local pollution sources.

• Journal of Life Science
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• v.12 no.1
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• pp.77-86
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• 2002

Chitin, a $\beta$-1,4 polymer of N-acetyl-D-glucosamine, is one of the most abundant organic compounds in nature. Chitinase (EC 3.2.1.14) is an enzyme that degrades chitin to chito-oligosaccharides, diacetyl rhitobiose and N-acetyl-D-glucosamine. An extracellular chitinase-producing bacterial strain was isolated from soil and named to as Bacillus subtilis JK-56. Optimum culture condition of B. subtilis JK-56 for the production of chitinase was 1% chitin, 0.5% polypepton, 0.1% KCl, 0.05% MnS $O_4$.4$H_2O$, 37$^{\circ}C$, initial pH 7.0 and 40 hour culture time. When B. subtilis JK-56 was grown in the optimum medium, one major active band and two minor active bands were detected by native-PAGE and active staining of the gel. Among them, the major band was purified from the culture supernatant by 70% ammonium sulfate precipitation and native-PAGE with BIO-RAD Model 491 Prep-Cell and named as Chi-56A. Its molecular weight was estimated to be 53kDa monomer and the isoelectric point (pI) was pH 4.3. The pH and temperature for the optimum activity of Chi-56A were pH 6.0 and $65^{\circ}C$, respectively. Chi-56A was stable up to $65^{\circ}C$ and in alkaline region. Its $K_{m}$ value for colloidal chitin was 17.33g/L. HPLC analysis of the reaction products confirmed that Chi-56A was an exo type chitinase.e.

• Journal of Environmental Science International
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• v.28 no.4
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• pp.413-422
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• 2019

The objective of this study was to estimate the trends of air quality in the study area by analyzing monthly and seasonal concentration trends obtained from sampled data. To this aim, the mass concentrations of $PM_{2.5}$ in the air were analyzed, as well as those of metals, ions, and total carbon within the $PM_{2.5}$. The mean concentration of $PM_{2.5}$ was $22.7{\mu}g/m^3$. The mass composition of $PM_{2.5}$ was as follows: 31.1% of ionic species, 2.2% of metallic species, and 26.7% of carbonic species (EC and OC). Ionic species, especially sulfate, ammonium, and nitrate, were the most abundant in the $PM_{2.5}$ and exhibited a high correlation coefficient with the mass concentration of $PM_{2.5}$. Seasonal variations of $PM_{2.5}$ showed a similar pattern to those of ionic and metallic species, with high concentrations during winter and spring. $PM_{2.5}$ also had a high correlation with the ionic species $NO_3{^-}$ and $NH_4{^+}$. In addition, $NH_4{^+}$ was highly correlated with $NO_3{^-}$. Through factor analysis, we identified four controlling factors, and determined the pollution sources using the United States Environmental Protection Agency(U.S. EPA) pollution profile. The first factor, accounting for 19.1% of $PM_{2.5}$ was attributed to motor vehicles and heating-related sources: the second factor indicated industry-related sources and secondary particles, and the other factors indicated soil, industry-related and marine sources. However, the pollution profile used in this study may be somewhat different from the actual situation in Korea, since it was obtained from US EPA. Therefore, to more accurately estimate the pollutants present in the air, a pollution profile for Korea should be produced.

• Journal of Environmental Science International
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• v.12 no.6
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• pp.665-676
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• 2003

To investigate the chemical characteristics of PM$\_$2.5/ in Seoul, Korea, atmospheric particulate matters were collected using a PM$\_$10/ dichotomous sampler including PM$\_$10/ and PM$\_$2.5/ inlet during the period of October 2000 to September 2001. The Inductively Coupled Plasma-Mass Spectromety (ICP-MS), ion Chromatography (IC) methods were used to determine the concentration of both metal and ionic species. A statistical analysis was performed for the heavy metals data set using a principal component analysis (PCA) to derived important factors inherent in the interactions among the variables. The mean concentrations of ambient PM$\_$2.5/ and PM/sub10/ were 24.47 and 45.27 $\mu\textrm{g}$/㎥, respectively. PM$\_$2.5/ masses also showed temporal variations both yearly and seasonally. The ratios of PM$\_$2.5/PM$\_$10/ was 0.54, which similar to the value of 0.60 in North America. Soil-related chemical components (such as Al, Ca, Fe, Si, and Mn) were abundant in PM$\_$10/, while anthropogenic components (such as As, Cd, Cr, V, Zn and Pb) were abundant in PM2s. Total water soluble ions constituted 30∼50 % of PM$\_$2.5/ mass, and sulfate, nitrate and ammonium were main components in water soluble ions. Reactive farms of NH$_4$$\^$+/were considered as NH$_4$NO$_3$ and (NH$_4$)$_2$SO$_4$ during the sampling periods. In the results of PCA for PM$\_$2.5/, we identified three principal components. Major contribution to PM$\_$2.5/ seemed to be soil, oil combustion, unidentified source. Further study, the detailed interpretation of these data will need efforts in order to identify emission sources.

• Korean Journal of Soil Science and Fertilizer
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• v.2 no.1
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• pp.31-38
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• 1969

This experiment was carried out to determine the effect of different levels of phosphate and potash firtilizers applied on yields and quality of leaf tobacco. It was done at all varying levels of phosphate and potassium fertilizers $S_0$ (non-fertilizer plot);N:P:K=0:0:0 (Kg/10a) $S_1$ (1/2 amount plot);N:P:K=10:7.5:10 (Kg/10a) $S_2$ (standard plot);N:P:K=10:15:20 (Kg/10a) $S_3$ (1.5 times plot);N:P:K=10:22.5:30(Kg/10a) $S_4$ (2.0times plot);N:P:K==10:30:40 (Kg/10a) Urea was applied as nitrogen, triple superphosphate as phosphate, potassium sulfate as potash source. The total amount of fertilizers was applied as basal dressing per one plant. This experiment was carried out by using randomized block design with 3 replication. The results obtained in terms of yields and quality are summarized as follows. 1. By increasing the amounts of phosphate and potassium fertilizers, growing status of the largest leaf length, the largest leaf width and stem size of tobacco increased in the order of $S_4>S_3>S_2>S_1>S_0$. 2. By increasing the amount of phosphate and potassium fertilizers, yield was increased in the order of $S_4>S_3>S_2>S_1>S_0$, This increase showed generally high significance among various levels of treatments. 3. The regressive equation was derived from the relationship between treatment levels and tobacco leaf yield. The most desirable treatment level for the maximum yield was estimated as the 2.87 times as much as the treatment level of phosphate and potasium fertilizers of standard plot. 4. By increased application of phosphate and potash fertilizers, the contents of $P_2O_5$ and $K_2O$ in the tobacco leaf became greater while the content of nicotine was decreased. Thus, a negative correlation between fertilizer application and nicotine content has been observed.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.3
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• pp.307-315
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• 1988

This experiment was conducted to find out the effects of fertilizer-N and co-inoculation of the Rhizobium japonicum and the Azospirillum lipoferum on nodulation, $N_2$-fixation, and growth of soybean under in situ conditions. The results obtained were summarized as follows: 1. The yield of soybean dry matter was significantly greater in the R. japonicum alone, and the mixed inoculation of R. japonicum and A. lipoferum than those of un-inoculation. But inoculum applied by different strains did not significant effect on plant growth. The effects of nitrogen applied on soybean dry matter were higher in the ammonium sulfate than potassium nitrate, and decreased with increasing rates of two forms of nitrogen applied regardless of nitrogen source. 2. Acetylene redution activity was more increased in a single inoculation of R. japonicum than those of the mixed inoculation of the R. japonicum and the A. lipoferum, in cases of Danyeup cultivar, regardless of the form of combined nitrogen used. 3. Nodule mass and total nitrogenase activity per plant showed the positively significant effect in the interrelationship between dry matter of soybean and some factors related to nitrogen fixation efficiency. 4. The highest symbiotic effect in Danyeup cultivar was obtained when a single R. japonicum 84 Dy-1 strain was inoculated and fertilized with 18 mM potassium nitrate.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.4
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• pp.194-205
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• 1999

Hydrogeochemical variation and environmental isotope at the some abandoned metal mine (Sanggok, Keumsil, Jangpung and Samdeok) creeks of the Hwanggangri mining district were carried out based upon the physicochemical properties for surface water collected of February in 1998. Hydrogeochemical composition of the all water samples are characterized by the relatively significant enrichment of Ca$^{2}$, alkaline ions, N $O_3$$^{－}$ and Cl$^{－}$ in normal surface water, whereas the surface waters near the mining area are relatively enriched in Ca$^{2+$, Mg$^{2＋}$, heavy metals. HC $O_3$$^{－}$ and S $O_4$$^{2－}$. Surface waters of the mining creek have low pH, high EC and extremely high concentrations of TDS compared with surface water of the non-mining creeks. The range of $\delta$D and $\delta$$^{18}$O values (SMOW) in the waters are shown in －65.0 to－71.2$\textperthousand$ and －9.1 to－10.2$\textperthousand$. The d($\delta$D－$\delta$$^{18}$O) value with those of water samples ranged from 7.3 to 10.9. These $\delta$D and $\delta$$^{18/}$ of the acid mine water are more heavy values than those of surface water. The values have revealed the positive correlation between isotopic compositions and major elements, because those $\delta$D and $\delta$$^{18}$O values increase with increasing TDS. HC $O_3$$^{－}$ , S $O_4$$^{2－}$ and Ca$^{2＋}$ concentration. Using WATEQ4F, saturation index of albite calcite, dolomite and mostly clay minerals in water of the mining area show undersaturated and progressively evolved toward the equilibrium condition due to fresh water mixing, however, surface waters of the non-mining area are nearly saturated and/or supersaturated. Geochemical modeling showed that mostly toxic heavy metals within water in the mining creek may exist largely in the from of metal-sulfate (MS $O_4$$^{2－}$), free metal (M$^{2＋}$/), C $O_3$$^{－}$ and/or OH$^{－}$ complex ions. Based on the geology, water chemistry and environmental istopic data the water compositions from the Sanggok and Keumsil mine creek (consist mainly of Cambro-Ordovician carbonate rocks of the Cho-seon Supergroup) show higher PH, Ca$^{2＋}$, Mg$^{2＋}$ , HC $O_3$$^{－}$ and more heavy $\delta$D and $\delta$$^{18}$O values than those from the Jangpung and Samdeok mine creek (consist of age -unknown metasedimentary rocks of the Ogcheon Supergroup and/or Jurassic grani-toids), but each of these waters represents a similar hydrogeochemical evolution path by the mine water mixing.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.547-561
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• 2005

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a ffw previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about $28\%$ of the shallow groundwaters exceeded the Bangladesh drinking water standard, $50{\mu}g/L$, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of $SO_4^{2-}$ and $NO_3^-$, and high contents of dissolved organic carbon (DOC) and $NH_4^+$ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciatiion during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about $1\%$ of grounwaters have concentrations higher than $10{\mu}g/:L.$ However, it was revealed that $19.3\%$ of mineral waters, and $7\%$ of tube-well waters from Nonsan and Geumsan areas contained As concentrations above $10{\mu}g/:L.$. Also, percentages exceeding this value during detailed groundwater quality surveys were $36\%\;and\;22\%$ from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.