• Journal of Microbiology and Biotechnology
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• v.24 no.10
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• pp.1308-1318
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• 2014

The specific freshwater environment of reservoirs formed by streams has not been well studied. In this paper, the bacterioplankton community in such a reservoir, the Huangqian Reservoir in eastern China, was described using culture-independent molecular methods. We found that the most dominant bacterioplankton were affiliated with Cyanobacteria, followed by Betaproteobacteria, Bacteroidetes, Gammaproteobacteria, and Actinobacteria. Both bacterial abundance and diversity increased along the direction of water flow, and the 16S rRNA gene copy number in the water outlet was nearly an order of magnitude higher than that in the water inlet. Pearson correlation analyses indicated that nitrate had a significantly negative correlation with the bacterial abundance (p < 0.05) and that ammonium was positively correlated with bacterial abundance (p < 0.05). Interestingly, owing to a remarkably negative correlation (p < 0.01), the ratio of nitrate and ammonium might serve as a good pre dictor of the relative abundance of bacterioplankton. According to redundancy analysis, nitrate and dissolved oxygen were the major factors influencing the bacterial communities. In addition, we attempted to determine the reasons why such a reservoir could maintain good ecological balance for a period of decades, and we found that the environmental factors and bacterial communities both played critical roles. This research will benefit our understanding of bacterial communities and their surrounding environments in freshwater ecosystems.

• Journal of The Korean Astronomical Society
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• v.29 no.1
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• pp.63-73
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• 1996

The previous study of chemical evolution of the Galaxy is extended to the radial properties of the Galactic disk. The present model includes radial dependency of the time-dependent bimodal IMF, radial flow of material in the disk, and the change of type I supernova explosion rate with radial distance from the disk center as model parameters and observed gas and stellar density distributions and metallicity abundance gradient as observational constraints. The results of two models in this study explain the observed gas and stellar density distributions well, with the slope of the gas density gradient in the region of 4.5 kpc$Y_1$ and -0.123dex/kpc in model $Y_2$, respectively, which fit well the observed gradient of -0.l1dex/kpc. The abundance gradient reproduced in model $Y_1$ is getting flatter with decreasing radius, while that in model $Y_2$ is getting steeper, which fits better the observed abundance gradient. This result shows the necessity of exponentially increasing type I supernova explosion rate with decreasing radius in order to explain the observed abundance gradient in the disk. The fitness of observed density distribution and star formation rate distribution justifies the reliability of time-dependent bimodal IMF as a compound quantitative chemical evolution model of the Galaxy. The temporal variations of metallicity gradients for carbon, nitrogen and oxygen are also shown.

• Journal of Forest and Environmental Science
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• v.31 no.3
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• pp.177-191
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• 2015

The effect of environmental variables on the presence and abundance of tree species in a tropical lowland undisturbed limestone and non-limestone forest in Ben En National Park, Vietnam was investigated. The relationships between 13 environmental variables and 29 tree species with a DBH ${\geq}10cm$, as well as between six 6 physical variables with 26 species of seedling and sapling communities were assessed by canonical correspondence analysis (CCA). Data concerning all tree species ${\geq}10cm$ DBH were collected from eighteen $400m^2$ sample plots, while the abundance of regeneration (all individuals ${\leq}5cm$ DBH) was counted in fifty $2{\times}20m$ strip-plots. The significance of species-environments correlations were tested by distribution-free Monte Carlo tests. The CCA of the 29 examined tree species and 13 environmental variables indicated that the presence and abundance of the tree species were closely related to topographic factors. We may confirm that soil properties including pH, soil moisture content, and soil textures, were the most crucial factor in tree species composition and their distribution. Several species including Pometia pinnata, Amesiodendron chinense, Gironniera cuspidate, Cinnamomum mairei, and Caryodaphnopsis tonkinensis were not controlled by soil properties and topographic variables. The CCA also indicated that the abundance of regeneration tree species at all sites had positive and significant correlations with soil depth, while the occurrence of several other tree species (such as Koilodepas longifolium and Aglaia dasyclada) was positively correlated with a higher slope and rocky outcrop.

• 한국해양학회지
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• v.25 no.4
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• pp.189-204
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• 1990

In the KODOS (Korea Deep Ocean Study)-89 area, western part of clarion-Clipperton fracture zones in the northeastern equatorial Pacific, magnate nodules and sediments were sampled during the 'Farnella' cruise in Oct., 1989. Bulk chemical and mineralogical analyses have been made on a suit of ferromanganese nodules and sediments to study the origin and distribution pattern of the nodules. The nodules are classified into three groups based on their origin: diagenetic nodules with high Mn/Fe ratio, Cu, Ni, Zn, Mg, todorokite contents and rough surface texture; hydrogenetic nodules with high Fe, Co, vernadite contents and smooth surface texture; and transitional nodules with intermediate characters between diagenetic and hydrogenetic nodules. Study area is divided into four zones according to the origin and abundance of nodules: far north area where nodules are hydrogenetic and intermediate in abundance; north area where nodules are diagenetic and low in abundance; south area where nodules are diagenetic and intermediate in abundance; seamount area where nodules are hydrogenetic and high in abundance. distribution pattern of manganese nodules in the KODOS-89 area seems to be controlled by latitudinal variation of productivity in water column and sea bottom morphology.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.92-98
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• 2003

The quantification of fish school abundance was carried out by using luminance of pixel on scanning sonar image, and compared with the indices of fish school abundance e.g. school number, school area and weighted school area. The survey was carried out in Funka Bay off southern Hokkaido, Japan using research vessel Ushio-Maru during December 1999. A 180-degree scanning sonar with a frequency of 164kHz was used. The school number was counted both left and right 40-degree radial lines from the center of own vessel mark on a scanning image. The school area was measured approximately as an ellipse from the school length and width. The weighted school area was calculated by multiplying school area and average value of inner pixel luminance. A quantification of pixel luminance was also measured to integrate squared pixel luminance value on these lines. Fish school and school bottom were discriminated by the produced sonar echogram using pixel luminance value on these lines. The relationships between the quantified luminance value and other abundance indices such as school area and weighted school area revealed a good correlation. Therefore, the quantified luminance is a useful method in estimating fish school abundance in the acoustic survey using sonar.

• Mass Spectrometry Letters
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• v.2 no.1
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• pp.1-7
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• 2011

China's rapid economic growth has resulted in significant environmental side effects. Therefore, China has been interested in reducing her dependence on foreign oil and gas by developing technologies needed for hydrogen, in addition to her increasing energy mix of nuclear and renewable energy form, such as solar and wind power. There are three isotopes of hydrogen, i.e. protium (P or H), deuterium (D), and tritium (T). Both deuterium and tritium are important materials in nuclear fuel cycle industry. Tritium is one of the critical radioactive nuclides. Planning for and implementing contamination control as a part of normal operation and maintenance activities is an important function in any hydrogen facility, especially tritium facility. The development of hydrogen isotopes analysis is the key issues in this area. Mass spectrometry (MS) with medium (about 600) and high resolution (> 1,400) is commercially available; however, the routine analysis of hydrogen isotopes is done with low-resolution MS (< 200) in China. This paper summarizes the progress of MS measurement technology for hydrogen isotope abundance in China, focusing on our lab's research program and technical status. An analyzing method has been introduced for accurate measurement of tritium abundance in the H.D.T system by low resolution MAT-253 MS. The quotient of compression ratio coefficient is determined by building up equipment for laboratory-scale preparation of secondary standard gases and by considering the difference in sensitivity between hydrogen isotopes. The results show that the measured value is reproducible within the relative error range of 0.8% for gas samples of different tritium abundance.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.6
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• pp.97-106
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• 2010

Earthworm, a prominent ecosystem engineer within many terrestrial ecosystems, can exert profound influences on various abiotic/biotic environments through bioturbation processes such as burrowing, casting and mixing of litter and soil. In this study, we investigated how the presence or absence of earthworm (Oligochaeta) can alter the soil physico-chemical conditions and ultimately the distribution and abundance of Collembola which constitutes a large proportion of the soil fauna. During September 2010, soil organisms along with soil samples were collected from randomly installed 20 plots in Mt. Gwan-ak. We examined the differences in the abundance of Collembola among plot samples in respect to the presence/absence of earthworm and soil physico-chemical conditions (i.e., pH, $PO_4^{3-}$, $NO_3^{2-}$, organic matter (OM), electrical conductance and water content). Analysis of soil physico-chemical environment revealed a significantly higher organic matter content and electrical conductance in plots with earthworm compared to plots without earthworm. Abundance of Collembola were not only higher in plots with earthworm than in plots without earthworm, but were also positively correlated with availability of OM present in the environment. The results suggest that positive impacts of earthworm on the abundance of Collembola in this study may have been due to their ability to effectively modify soil physico-chemical conditions favored by Collembola. Such conspicuous influence of earthworm's activity on below-ground community suggests their potential significance in forest restoration or revegetation process.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.139-144
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• 2019

BACKGROUND: Epigeic arthropods participate in ecological functions as predators, decomposers and herbivores. The purpose of this study was to investigate the responses of some dominant arthropods in rice fields to different forms of agricultural land management. METHODS AND RESULTS: The abundance of microarthropods was compared between rice fields and uplands in the non-growing season. Collembola, Oribatida and Mesostigmata were more abundant in the upland fields than in the paddy fields. The community composition and diversity of epigeic arthropods were compared between fallow and rice fields. The total abundance and species richness of spiders and ground beetles were not significantly different in the two types of agricultural fields. The abundance of Arctosa kwangreungensis was greater in fallow fields than in cultivated fields. The community structure of arthropods was compared between paddy fields with and without barley. The cropping system altered the community composition of spiders but not their biodiversity. Barley cultivation increased the abundance of ground beetles but decreased that of spiders. We suggest that this contrast was partly due to the availability of plants that provided shelter and food for ground beetles. CONCLUSION: These results show that soil use intensity and cropping system alter the community composition of epigeic spiders and ground beetles. This could result in ecosystem-level alterations with respect to the control of pests and weeds. Our results also suggest that biodiversity of ground-dwelling arthropods may not increase during short fallow periods.

• The Journal of Korean Philosophical History
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• no.58
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• pp.65-96
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• 2018

Modern and contemporary humanities and social sciences supported the freedom and abundance of people. Today, however, freedom and abundance do not support human dignity, and are not sustainable. Therefore, we must reflect again on the direction of today's life and civilization. As part of this project, this essay analyzes the modern and contemporary humanities and social sciences and examines the meaning of Korean traditional thoughts. The lines presented to us by Korean traditional thought can be summed up 'the Three Elements of the Universe(Heaven, Earth and Man)' and 'Perfect Harmony between the Soul and the Body' and 'true humanitarianism.' These lines can be a starting point to overcome the problems posed by the lines of freedom and abundance in two contexts : First, while the lines of freedom and abundance today were biased toward the elements of the Earth or the Body, the traditional Korean thoughts have been both elements of the Heaven and the Soul since the beginning, which can therefore serve as a true humanitarian. Second, the true humanitarian line is as much sustainable as it criticizes the uncontrolled freedom and abundance, and seeks the right moderation to become a man of dignity.

• Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.268-281
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• 2023

Coral reef fisheries are prominent for the archipelagic countries' food sufficiency and security. Studies showed that fish abundance and biomass are affected by biophysical variables. The present study determines which biophysical variables are important predictors of fish diversity, abundance, and biomass. The study used available monitoring data from the Indonesian Research Center for Oceanography, the National Board for Research and Innovation. Data were collected from 245 transects in 19 locations distributed across the Indonesian Archipelago, including the eastern Indian Ocean, Sunda Shelf (Karimata Sea), Wallacea (Flores and Banda Seas), and the western Pacific Ocean. Principal component analysis and multiple regression model were administered to 13 biophysical metrics against 11 variables of coral reef fishes, i.e., diversity, abundance, and biomass of coral reef fishes at three trophic levels. The results showed for the first time that the covers of other fauna, coral rubbles, and soft corals were the three most important predictor variables for nearly all coral reef fish variables. Other fauna cover was the important predictor for all 11 coral reef fish variables. Coral rubble cover was the predictor for ten variables, but carnivore fish abundance. Soft coral cover was a good predictor for corallivore, carnivore, and targeted fishes. Despite important predictors for corallivore and carnivore fish variables, hard coral cover was not the critical predictor for herbivore fish variables. The other important predictor variables with a consistent pattern were dead coral covered with algae and rocks. Dead coral covered with algae was an important predictor for herbivore fishes, while the rock was good for only carnivore fishes.