• Journal of Aquaculture
• /
• v.1 no.1
• /
• pp.13-24
• /
• 1988

In order to investigate a reasonable rearing density and the possibility of high-density rearing, flounder, Paralichthys olivaceus, juveniles of 2.53$\pm$0.24 cm in total length and 1.12$\pm$0.12 cm in body height were used in this study. The initial rearing density of them was 10 (D10), 20 (D20), 30 (D30) and 40 (D40) individuals per 137.75 $cm^2$ of bottom area, respectively. Ranges of water temperature and specific gravity during the rearing period of 65 days were $21.0\~27.0^{\circ}C$ and 1.024$\~$1.026, respectively, showing relatively higher values than that of natural sea water. Dissolved oxygen during the rearing period was 5.4$\~$7.5 ml/$\iota$ and inorganic nitrate was 0.07$\~$0.48 ppm in $NH_4^+-N$, 0.006$\~$0.33 ppm in $NO_2^{-}-N$ and 3.89$\~$34.06 ppm in $NO_3^{-}-N$. Growth in total length and body height of the juveniles in four rearing density at the end of the experiment was 8.17$\pm$0.80 em and 4.16$\pm$0.39 em, the highest in D20 and 7.72$\pm$0.40 cm and 3.94$\pm$0.21 cm, the lowest in D10. Significant differences, however, were not recognized between the slope values of growth regressions in four rearing density. Slope values of the relative growth between total length and body height of the juveniles in four rearing density were 0.5346, the highest in D10 and 0.5165, the lowest in D30, but there were no significant differences in those values. Survival rate of juveniles at the end of the experiment was $90\%$ in D10, D20 and D30, but that of D40 was $75\%$. The relationship between total length X body height (X) and body surface area of ocular side (Y) to calculate the rate of Y to bottom area in rearing tank (covering rate) as an indicator of rearing density was expressed by a linear regression, Y=0.5994X+0.1840. Covering rate in four rearing density at the end of the experiment was ranged 1.2$\~$4.1 times. Judging from the covering rate above 4 times, it seems to be possible rearing the flounder juveniles in high-density.

• Economic and Environmental Geology
• /
• v.50 no.4
• /
• pp.287-302
• /
• 2017

The carbonate rocks of the Daegi Formation are composed of the limestone at the upper and lower zones, and the dolomite at the middle zone, in which the upper zone has higher CaO content than others. The colors of carbonate rock in the Daegi Formation can be divided into five types; white, light brown, light gray, gray, and dark gray. The white to light gray colored rocks correspond to the high purity limestone with 53.15 ~ 55.64 wt. % CaO, and the light brown colored rocks contain 20.71 ~ 21.67 wt. % MgO. The bleaching of carbonate rocks are not related to CaO composition of the rocks, as light gray rocks tend to be higher in CaO content than those of the white rocks at the lower zone. The pelitic components are also occasionally increased in white limestone than light grey one. $Al_2O_3$ is one of the most difficult content to remove during hydrothermal processes, so the interpretation that the limestone is purified together with hydrothemral bleaching, has little merit. The wide range (over 16 ‰) of ${\delta}^{18}O_{SMOW}$, smaller variation (within 2 ‰) of ${\delta}^{13}C_{PDB}$ are apparent in both the upper and lower zones, which indicate the Daegi Formation had been affected overall by hydrothermal fluids. The K-Ar isotopic age of hydrothermal alteration in the GMI limestone mine is $85.1{\pm}1.7Ma$. Gradual change from grey through light grey to white limestone is accompaned by lower oxygen stable isotope values, which is major evidence that the hydrothermal effect is the main process of the bleaching. Although the Daegi Formation has suffered from hydrothermal activity and increase in whiteness, there is no clear evidence demonstrating the relationship between bleaching and high purity of limestone. The purification of limestone has nothing to do with the hydrothermal activity in this area. Instead, it should be considered that the change of sedimentary environment related to see-level fluctuation which can prevent deposition of pelitic components especially $Al_2O_3$ contrbuted to the formation of the high purity limestone in the upper zone of the Daegi Formation. Considering the evidences such as increase in CaO content of limestone by depth, gradual change from calcite to dolomite at the lower zones, and occurring the high purity limestone at the upper zone, the interpretation of sequence stratigraphic aspect to the formation of the high purity Daegi limestone appears to be more suitable than that of hydrothermal alteration origin.

• Journal of Soil and Groundwater Environment
• /
• v.6 no.4
• /
• pp.51-59
• /
• 2001

Column and box tests were performed to investigate the removal efficiency of NAPL using the surfactant enhanced flushing In heterogeneous medium. Homogeneous Ottawa sand and heterogeneous soil were used to verify the increase of remediation efficiency for the surfactant enhanced flushing in column test. Box tests with two different heterogeneous sub-structure were performed to quantify the capability of the surfactant enhanced flushing as a remediation method to remove NAPL from the heterogeneous medium. Two different grain size sand layers were repeated in the box to simulate the heterogeneous layer formation and the modified fault structure was built to simulate the fault system in the box. O-xylene as a LNAPL and PCE as a DNAPL were used and oleamide as a non-ionic surfactant. The maximum NAPL effluent concentration with 1% oleamide flushing in the homogeneous column test increased about 460 times compared to that with only water flushing and about 250 times increased in the real soil column test. In heterogeneous medium, the maximum effluent concentration increased about 150 times in 1% oleamide flushing and most of NAPL were removed from the box within 8 pore volume flushing, suggesting that the removal efficiency increased very much compared to in only water flushing. Results investigated the capability of the surfactant enhanced remediation method to remove NAPL even in heterogeneous medium.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.18 no.4
• /
• pp.327-336
• /
• 2016

The Bagan, the central part of Myanmar, is dry zone where the mean annual precipitation is less than 600 mm for the last ten years. Forest in this region has been degraded due to biotic and abiotic disturbances. While there have been various efforts to rehabilitate the degraded area, the information on growth and physiological characteristics of planting species and the impacts of planting trees in the region still lacks. Therefore, this study was conducted to determine the growth and physiological water use efficiency characteristics of five species (Azadirachta indica A. Juss., Acacia catechu Willd., Eucalyptus camaldulensis Dehn., Acacia leucophloea (Roxb.) Willd. and Albizia lebbek (L.) Willd.) which are utilized as rehabilitation species in the dry zone and to identify the impacts of tree planting on microclimate change in dry zone. The growth and the foliar carbon isotope composition of seedlings and the above mentioned five species planted in 2005 were measured. And from February 2015 to January 2016, microclimatic factors air temperature and relative humidity at 60 cm and 2 m above soil, soil temperature, soil water contents and precipitation were measured at every 30-minute interval from the two weather stations installed in the plantation located in Ngalinpoke Mt. Range. One was established in the center of A. indica plantation, and the other was in the barren land fully exposed to the sunlight. Among the five species, A. indica and A. lebbek which showed higher water use efficiency could be recommended as rehabilitation species in dry zone. Planting trees in the dry area was shown to affect the change of microclimate with shading effects, declining temperature of the land surface and aridity of the air, and to contribute to conserving more water in soil by preventing direct evaporation and containing more water with fine roots of trees.