• Journal of Ecology and Environment
• /
• v.37 no.3
• /
• pp.131-137
• /
• 2014

To investigate the solute pattern of salt marsh plants in Suncheon Bay in Korea, plants and soil samples were collected at three sites from July to September 2011. The soil pH around the investigated species was weakly alkaline, 6.9-8.1. The total ion and Cl- content of site 1 gradually increased, while those of site 2 and site 3 were lowest in August and highest in September. The exchangeable $Ca^{2+}$, $Mg^{2+}$ and $K^+$ in the soil were relatively constant during the study period, but the soil exchangeable $Na^+$ content was variable. Carex scabrifolia and Phragmites communis had constant leaf water content and very high concentrations of soluble carbohydrates during the study period. However, Suaeda malacosperma and S. japonica had high leaf water content and constant very low soluble carbohydrate concentrations. Carex scabrifolia accumulated similar amounts of $Na^+$ and $K^+$ ions in its leaves. Phragmites communis contained a high concentration of $K^+$ ions. Suada japonica and S. malacosperma had more $Na^+$ and $Cl^-$ ions than $K^+$ ions in their leaves. Suaeda japonica had higher levels of glycine betaine in its leaves under saline conditions than C. scabrifolia and P. communis. Consequently, the physiological characteristics of salt marsh chenopodiaceous plants (S. japonica and S. malacosperma) were the high storage capacity for inorganic ions (especially alkali cations and chloride) and accumulation of glycine betaine, but monocotyledonous plant species (C. scabrifolia and P. communis) showed high $K^+$concentrations, efficient regulation of ionic uptake, and accumulation of soluble carbohydrates. These characteristics might enable salt marsh plants to grow in saline habitats.

• Journal of Animal Science and Technology
• /
• v.51 no.1
• /
• pp.75-80
• /
• 2009

Composition changes of swine manure and the effects on MAP ($MgNH_4PO_46H_2O$) crystallization by microwave irradiation were examined. The concentration of ${PO_4}^{3-}$ was increased within a fixed period of time and then decreased, but $NH_4$-N was reduced continuously during microwave irradiation. Concentration of ${PO_4}^{3-}$ was started to reduce just from the point of foam formation during microwave irradiation, and the temperature at that time was always $49^{\circ}C$ irrespectively to microwave irradiation rate. Inorganic carbon was reduced with microwave irradiation, but soluble organic carbon (TOCs) was increased proportionally. Crystallization rate under conditions of non-microwave irradiation, irradiation up to $93^{\circ}C$ and $48^{\circ}C$ was 87.8%, 87.3% and 98.5%, respectively, showing 10% enhancement when irradiated up to $48^{\circ}C$. However, removal efficiency of ammonia nitrogen was proportional to the microwave irradiation rate or duration, obtaining 2.5%, 4.5% and 10.2%, respectively. Based on these results, it would be a useful strategy to irradiate microwave up to $49^{\circ}C$ to enhance MAP crystallization rate by changing the ionic pattern of nutrients in the manure. Meanwhile, provision of enough microwave irradiation rate might be needed to achieve high $NH_4$-N removal.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.36 no.1
• /
• pp.22-33
• /
• 1991

The studies aimed to distinguish between initial (ionic or osmotic) effects of salinisation on growth and the longer-term consequences of excessive salt accumulation. Tall and dwarf varieties of rice were used to provide different growth rates. There was no significant effect upon the day-to-day pattern of growth, upon the ultimate length of leaves that were developing at the time of, or shortly after, salinisation with 50 mM NaCl. Leaves that developed after prolonged exposure of the plants to salinity were shorter. Addition of NaCl, KCl or mannitol to the root medium brought about a cessation of leaf elongation within one minute. Growth at a reduced rate restarted abruptly after a lag period that depended upon the external concentration. Elongation rate recovered to its original value within 24 hours after exposure to 50 mM NaCl, though not at higher concentrations. Addition of NaCl at concentrations up to 100 mM elicited no short-term effect upon photsynthetic gas exchange. No change in turgor pressure was detectable in the growing zone with the resolution of the miniature pressure probe used (about 70 kPa). It is concluded that the initial growth reduction in rice caused by salinisation is due to a limitation of water supply. A clear distinction is made between the initial effects of salt which are recoverable, and the long-term effects which result from the accumulation of salt within expanded leaves.

• The Korean Journal of Physiology and Pharmacology
• /
• v.6 no.3
• /
• pp.143-147
• /
• 2002

Granule cells in dentate gyrus of hippocampus relay information from entorhinal cortex via perforant fiber to pyramidal cells in CA3 region. Their electrical activities are known to be closely associated with seizure activity as well as memory acquisition. Since action potential is a stereotypic phenomena which is based on all-or-none principle of $Na^+$ current, the neuronal firing pattern is mostly dependent on afterpotentials which follows the stereotypic $Na^+$ spike. Granule cells in dentate gyrus show afterdepolarization (ADP), while interneurons in dentate gyrus have afterhyperpolarizaton. In the present study, we investigated the ionic mechanism of afterdepolarization in hippocampal dentate granule cell. Action potential of dentate granule cells showed afterdepolarization, which was characterized by a sharp notch followed by a depolarizing hump starting at about $-49.04{\pm}1.69\;mV\;(n=43,\;mean{\pm}SD)$ and lasting $3{\sim}7$ ms. Increase of extracellular $Ca^{2+}$ from 2 mM to 10 mM significantly enhanced the ADP both in amplitude and in duration. A $K^+$ channel blocker, 4-aminopyridine (4-AP, 2 mM), enhanced the ADP and often induced burst firings. These effects of 10 mM $Ca^{2+}$ and 4-AP were additive. On the contrary, the ADP was significantly suppressed by removal of external $Ca^{2+},$ even in the presence of 4-AP (2 mM). A $Na^+$ channel blocker, TTX (100 nM), did not affect the ADP. From these results, it is concluded that the extracellular $Ca^{2+}$ influx contributes to the generation of ADP in granule cells.

• Korean Journal of Ecology and Environment
• /
• v.43 no.4
• /
• pp.459-470
• /
• 2010

In this study, we analyzed fish tolerance guilds in mainstems and tributaries of 65 streams and rivers arid their relations to water quality using dataset sampled from April to November, 2009. For the study, water quality parameters including biochemical oxygen demand (BOD), electric conductivity (EC), total nitrogen (TN), total phosphorus (TP), ammonia nitrogen ($NH_3$-N), nitrate nitrogen ($NO_3$-N) and phosphate phosphorus ($PO_4$-P) were analyzed in the laboratory and also tolerance ranges in 3 category fishes of sensitive, intermediate, and tolerant species with high abundance were analyzed. According to fish guild analysis, tolerant species was 58% of the total community and the proportion of omnivore species was 63% of the total, indicating a degradation of habitats and water quality. Water quality was shown typical longitudinal gradients from the headwater to the down-river; TN and TP increased toward the down-rivers except for the big point-source area and ionic contents, based on, electric conductivity showed same pattern. Tolerance guild analysis of 9 major species with high abundance indicated that sensitive groups had narrower tolerance range in the water quality than the groups of intermediate and tolerant species. In contrast, tolerant groups including Zacco platypus, Carassius auratus, and Opsarichthys uncirostris amurensis had wider tolerance ranges than the groups of sensitive and intermediate species. Thus, each group was evidently segregated from the tolerance levels. Principal Component Analysis (PCA) employed for the relations of water quality to fish species in each groups suggests that water quality had highest eigenvalues with fish species in the 1st axis of the PCA and nitrogen (TN, $NH_3$-N, $NO_3$-N) and phosphorus (TP) were key components differentiating three groups of sensitive, intermediate and tolerance guilds.

• Korean Journal of Materials Research
• /
• v.23 no.10
• /
• pp.580-585
• /
• 2013

To observe the formation of defects at the interface between an oxide semiconductor and $SiO_2$, ZnO was prepared on $SiO_2$ with various oxygen gas flow rates by RF magnetron sputtering deposition. The crystallinity of ZnO depends on the characteristic of the surface of the substrate. The crystallinity of ZnO on a Si wafer increased due to the activation of ionic interactions after an annealing process, whereas that of ZnO on $SiO_2$ changed due to the various types of defects which had formed as a result of the deposition conditions and the annealing process. To observe the chemical shift to understand of defect deformations at the interface between the ZnO and $SiO_2$, the O 1s electron spectra were convoluted into three sub-peaks by a Gaussian fitting. The O 1s electron spectra consisted of three peaks as metal oxygen (at 530.5 eV), $O^{2-}$ ions in an oxygen-deficient region (at 531.66 eV) and OH bonding (at 532.5 eV). In view of the crystallinity from the peak (103) in the XRD pattern, the metal oxygen increased with a decrease in the crystallinity. However, the low FWHM (full width at half maximum) at the (103) plane caused by the high crystallinity depended on the increment of the oxygen vacancies at 531.66 eV due to the generation of $O^{2-}$ ions in the oxygen-deficient region formed by thermal activation energy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.35 no.3
• /
• pp.292-296
• /
• 2022

(La_0.5Nd_0.2Sr_0.3)MnO₃ specimens were prepared by a solid-state reaction. In all specimens, X-ray diffraction patterns of an orthorhombic structure were shown. The fracture surfaces of (La_0.5Nd_0.2Sr_0.3)MnO₃ specimens showed a transgranular fracture pattern be possibly due to La ions (0.122 nm) as a perovskite A-site dopant substituting for Nd ions (0.115 nm) having a small ionic radius. The full-width at half maximum (FWHM) of the Mn 2p XPS spectra showed a value greater than that [8] of the single valence state, which is believed to be due to the overlapping of Mn²⁺, Mn³⁺, and Mn⁴⁺ ions. The dependence of Mn 2p spectra on the Mn³⁺/Mn⁴⁺ ratio according to sintering time was not observed. Electrical resistivity resulted in the minimum value of 100.7 Ω-cm for the specimen sintered for 9 hours. All specimens show a typical negative temperature coefficient of resistance (NTCR) characteristics. In the 9-hour sintered specimen, TCR, activation energy, and B25/65-value were -1.24%/℃, 0.19 eV, and 2,445 K, respectively.

• Korean Journal of Ecology and Environment
• /
• v.43 no.3
• /
• pp.385-399
• /
• 2010

The objective of this study was to analyze long term temporal trends of water chemistry and spatial heterogeneity for 83 sampling sites of Geum-River watershed using water quality dataset during 2003~2007 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (TN), total phosphorus (TP), and electric conductivity (EC), largely varied depending on the landuse patterns, years and seasons. The watershed was classified into three different landuse types: forest stream (Fo), agricultural stream (Ag), and urban stream (Ur). Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summer monsoon rain. Conductivity, used as a key indicator for an ionic dilution during rainy season, and nutrients of TN and TP had inverse functions of precipitation. BOD, COD decrease during the rainy season. Minimum values in the conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of suspended solids (SS) occurred during the period of summer monsoon. The landuse patterns analyses, based on the variables of BOD, COD, TN, TP and SS, showed that the values were greater in the agricultural stream (Ag) than in the forest stream (Fo) and urban stream (Ur) and that water quality was worst in the urban stream (Ur). The overall dataset suggest that efficient water quality management, especially in Gap-Stream and Miho-Stream, which showed worst water quality is required along with some of urban stream (Ur), based on the analysis of landuse patterns.

• Analytical Science and Technology
• /
• v.17 no.3
• /
• pp.230-239
• /
• 2004

Using our PM2.5 and PM10 concentration data obtained from Seoul and Busan during winter 2002, we conducted comparative analysis on the role of inorganic ions in constituting airborne particles in two distinctive urban areas. Whereas the mass concentration of fine particle was more significant in Seoul, no such pattern was found in Busan. In addition, when the major components were compared between different particle fractions and between different sites, clear pattern was apparent between those. Although the major components of fine particles were generally compatible each other ($NH{_4}^+$, $NO{_3}^-$, and NSSS), those of coarse fractions were clearly distinguished. Although anthropogenic signatures were still important in Seoul, the influence of oceanic sources was clear in coarse fraction of Busan ($Cl^-$ and $Na^+$). Detailed statistical analysis of our data consistently supports the importance of different source processes between particle modes and source processes.

• Korean Journal of Ecology and Environment
• /
• v.43 no.4
• /
• pp.471-476
• /
• 2010

Monthly up-river discharge in the riverine zone analysis resulted in large interannual variations and differences in calcium ($Ca^{2+}$), bicarbonate ($HCO_3^-$), and cations in the lacustrine zone (Lz) of Daecheong Reservoir during the wet year (Wy, 1993) vs. dry year (Dy, 1994). Total up-river discharge in the Wy was four times that of the Dy, and the up-river discharge in July~August of the Wy was eight times greater than that of same period of Dy. Annual water retention time in the Lz showed large difference between the two years. Water residence time (WRT) was minimum when the up-river discharge peaked, whereas the WRT was maximum when the up-river discharge was at minimal condition. This peak discharge from the up-river on early July reduced residence time in the Lz on mid-July~late July. Monthly pattern, based on data of May~November, was similar between the two years, but, but mean retention time in the Wy was 50 days shorter than in the Dy. Such hydrology, up-river discharge, and WRT reduced $Ca^{2+}$, $HCO_3^-$, and cations in the Lz. At low up-river discharge in Wy during April~May, the cation content of Ca+Mg+Na+K averaged 1.17meq $L^{-1}$ (range=1.09-1.26meq $L^{-1}$), but as the up-river discharge increased suddenly, the values decreased. Seasonal fluctuations of $Ca^{2+}$ showed exactly same pattern with bicarbonate ion of $HCO_3^-$. The minimum $Ca^{2+}$ (0.03meq $L^{-1}$) was occurred in the early August of wet year and coincided with the minimum $HCO_3^-$. These results suggest that the magnitude of variation in $Ca^{2+}$, bicarbonate, and cations in the lacustrine zone is directly determined by the peak magnitude of up-river discharge. The magnitude of up-river discharge determined water retention time and the magnitude of ionic dilution in the lacustrine zone, resulting in functional changes of the ecosystem.