• Title/Summary/Keyword: Natural river

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Standing Crop Distribution of Aquatic Plants in the West Nakdong River and Riparian Wetlands in the Nakdong River (서낙동강 본류 및 낙동강 둔치 습지의 수생식물 생물량 분포)

  • Kim, Gu-Yeon;Kim, Ji Yoon
    • Korean Journal of Ecology and Environment
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    • v.47 no.1
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    • pp.62-69
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    • 2014
  • Standing crop distribution of aquatic plants in the West Nakdong River and riparian wetlands in the Nakdong River were surveyed in May, July and September, 2010. Total 25 aquatic macrophyte species (submerged: 9, leaf-floating: 3, free-floating: 5, emergent: 8) were observed during the survey periods. Distribution area of aquatic plants and proportion of submerged communities were highest in Garakchi-deung ($212,032m^2$, 72.7%). The distribution area of aquatic plants was highest in Phragmites australis community ($421,584m^2$), followed by Hydrilla verticillata-Vallisneria natans community ($181,511m^2$), Potamogeton wrightii-Vallisneria natans community ($61,604m^2$), and Hydrocharis dubia community ($49,709m^2$). Garakch-ideung (212,032 kg) also had the highest aquatic plant production, followed by Suanchi-deung (15,546 kg), Daedong (5,813 kg), Dunchi-do (3,963 kg), Maekdo (1,463 kg), Yeommak (571 kg), Jungsa-do (530 kg), and Shinan (300 kg). Average standing crop of the study area were $147.8{\pm}20.8g\;DW{\cdot}m^{-2}$ in 1988, $96.1{\pm}20.0g\;DW{\cdot}m^{-2}$ in 2000, and $172.6{\pm}76.1g\;DW{\cdot}m^{-2}$ in 2010. For a sustainable management of river habitat and food source, aquatic plant should concurrently be surveyed with river environmental variables (i.e. sediment, nutrient, flow).

Succession of Cyanobacterial Species and Taxonomical Characteristics of Dolichospermum spp. (Nostocales, Cyanophyceae) in the Weir Regions of the Nakdong River (낙동강 보 구간에서 남조류의 천이 및 Dolichospermum 속(Nostocales, Cyanophyceae)의 분류학적 고찰)

  • Ryu, Hui-Seong;Shin, Ra-Young;Seo, Kyung-Ae;Lee, Jung-Ho;Kim, Kyunghyun
    • Journal of Korean Society on Water Environment
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    • v.34 no.5
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    • pp.503-513
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    • 2018
  • Freshwater cyanobacterial genus Dolichospermum is one of the most commonly spotted types of phytoplankton, whereas a limited number of studies on morphology of Dolichospermum spp. have been performed in South Korea. The purpose of this study is to investigate the succession pattern of cyanobacteria after weir construction, as well as morphological characteristics of Dolichospermum spp. from natural samples collected in the weir regions of Nakdong River. A total of 31 cyanobacterial taxa observed in this study were classified as belonging to 15 genera, 5 families, and 3 orders. Among them, morphological characteristics in the four species were classified into genus Dolichospermum, for most of the planktic former members of the genus Anabaena, were observed through light microscopy. Water bloom frequently occurred in the middle region of Nakdong River, the maximum number of cyanobacterial species appeared in the lower region of Nakdong River. The appearance of order Chrooccocales was only observed during summer when population density of Microcystis aeruginosa reached an annual peak. In contrast, filamentous cyanobacteria was observed throughout the whole year, even if when water temperature was lower than $5^{\circ}C$. It implied that the low-temperature-adapted filamentous cyanobacteria can grow in a range of water temperatures. Coil diameter of D. crassum from natural samples was $75{\sim}140{\mu}m$ ($ave.=91.3{\mu}m$; n = 94), slightly larger than those reported by previous studies. Dolichospemum smithii ($Kom{\grave{a}}rek$) Wacklin et al. 2009, was described for the first time in Nakdong River.

Water Quality and Pollutions of River waters in Gwangju City (광주광역시 하천수의 수질 및 오염)

  • 오강호;고영구
    • Journal of Environmental Science International
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    • v.12 no.3
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    • pp.287-297
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    • 2003
  • To investigate water quality and pollution states of rivers in Gwangju city, total of 30 water samples were taken from the main stream of Yeongsan river, Hwangryong river and Gwangju stream in dry and flood seasons. Physico-chemical characteristics of above streams according to pH-Eh and Piper's diagrams we, typically, assigned to natural river water. In the streams, BOD, COD, T-N and T-P indicating water quality mostly increase toward downstream. Notably, water qualities in area near connection between the Gwangju stream and the main stream of Yeongsan river are polluted over V level in rivers and lakes water quality standard. The pollutions are influenced by lift and agricultural foul waters from Gwangju City and farming areas around upstream branches of the Yeongsan river, reasonably. Besides, heavy metals are below the standard in those streams. So, it is considered that the streams are polluted by not industrial but life/agricultural foul waters.

Fuzzy logic model for the prediction of concrete compressive strength by incorporating green foundry sand

  • Rashid, Khuram;Rashid, Tabasam
    • Computers and Concrete
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    • v.19 no.6
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    • pp.617-623
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    • 2017
  • This work is conducted with the aim of using waste material to reserve the natural resources. The objective is accomplished by conducting experimentation and verify by modeling based on fuzzy logic. In experimentation, concrete is casted by using natural/river sand as fine aggregate and termed as control specimen. Natural sand is conserved by replacing it with used foundry sand (UFS) by an amount of 10, 20 and 30% by weight. Fresh and hardened properties of concrete are investigated at different ages. It is observed that compressive strength and modulus of elasticity reduced with the increase in amount of UFS. Furthermore, concrete compressive strength is predicted by using fuzzy logic model and verified at different replacement ratio and age with experimental observations.

Distribution and Activity of Hheterotrophic Bacteria in the Mudflat of Nakdong River Estuary (난동감 하구 간석지에 존재하는 세균의 분포 및 생리적 활성도)

  • Kim, Sang-Jong;Hong, Soon-Woo;Rhie, Youn;Choi, Sung-Chan
    • Korean Journal of Microbiology
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    • v.23 no.3
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    • pp.215-222
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    • 1985
  • Distribution pattern and activity of heterotrophec bacteria were measured in the mudflat of Nakdong river estuary. In March and June, 1985, community sizes of amylolytic, lipolytic and proteolytic bacteria as well as total viable counts were measured. Vertical distribution of bacterial community size increased a few orders of magnitude from Narch to June. Heterotrophic activity was estimated in turnover time with $U-[^{14}C]-glucose$. Turnover time reduced considerably in June compared to that of March. To sxamine correlations for measured bacterial groups, turnover time and environmental factors, correlation coefficient matrix was obtained. These measured characteristics did not consistently correlate well with one another.

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Vertical composition and character analysis of saprophytic bacteria isolated from the mudflat of Nakdong river estuary (낙동강 하구 간석지에서 분리된 세균의 층별 종조성 및 특성에 관하여)

  • Hong, Soon-Woo;Kim, Sang-Jong;Rhie, Youn;Choi, Sung-Chan
    • Korean Journal of Microbiology
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    • v.23 no.2
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    • pp.157-165
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    • 1985
  • Bacterial identification was performed with morphological, physiological and biochemical tests to the isolates from the mudflat of 30cm depth sampled in Nakdong river estuary in March and June, 1985. Flavobacterium and Cnterobacteriaceae were regarded as dominants. Pseudomonas, Bacillus, Micrococcus, Vibrio, Aerococcus, Aerononas, Acinetobacter and Staphylococcus were founded in various depth. Vertical composition of bacterial genera in March was more diversiform than that of June. Character analysis was carried out with the calculation of similarity index (S). At a level of 85% similarity, the isolates were clustered into 5 groups and ungrouped 2 strains. Classifying groups of bacterial strains with determination schemes and groups from similarity index were in good agreement.

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Characteristics of Anthropogenic Soil Formed from Paddy near the River

  • Sonn, Yeon-Kyu;Zhang, Yong-Seon;Hyun, Byung-Keun;Kim, Keun-Tae;Lee, Chang-Hoon
    • Korean Journal of Soil Science and Fertilizer
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    • v.49 no.5
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    • pp.434-439
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    • 2016
  • Anthropogenic soil in cropland is formed in the process of subsoil reversal and the refill of soil into cropland. However, there was little information on the chemical properties within soil profiles in anthropogenic soil under rice paddy near the river. In this study, we investigated the chemical properties within soil profiles in the anthropogenic soil located at 4 sites in Gumi, Kimhae, Chungju, and Euiseong to compare with the natural paddy soil near the river. Among particle sizes, the sand content decreased under soil profiles but the silt and clay contents increased compared to the natural paddy soil in soil profiles. Organic matter content in topsoil of anthropogenic soil was lower than in that of natural soil, which was shown the contrary tendency within soil profiles. Also, the soil pH, available $P_2O_5$, and exchangeable cations were higher in anthropogenic soil compared to natural paddy soil at topsoil, which was maintained these tendency into soil depth. Nutrients may be equally distributed in anthropogenic soil during the process of refill in paddy soil near the river. This results indicated that anthropogenic soil would contribute to carbon sequestration, the mitigation of compaction, and reduction of fertilizer application in paddy soil. Therefore, characteristics of anthropogenic soil can be used for the soil management in cropland.

Development of Axially Periodic Transient Storage Zone Model for the Solute Mixing in Natural Streams and Rivers with Various Bottom Boundaries (하상변화가 있는 자연하천에서의 오염물질 거동해석을 위한 주기적저장대모형 개발)

  • Cheeong, Tae Sung;Seo, Il Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6B
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    • pp.623-631
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    • 2006
  • A new model, the periodic transient storage zone model, is developed to describe solute transport mixing in natural streams and rivers with various bottom boundaries. To assess the effects of storage zones structure on transient storage exchange, we analyze data from salt and dye injection experiments in a recirculating laboratory flume with four spatially periodic pool-riffle sequences characteristic of natural river systems under low flow conditions. Dye injections show that solute transport mixing controlled by surface shapes of both the bed and the side in channels. As no existing transient storage model could represent these effects, we developed a new axially periodic transient storage zone model that better represent the effects of channel characteristics in natural river systems. The new model is also fitted to data from salt tracer injection experiments in four reaches of the upper Sabin River, Texas, USA. The proposed model is in good agreement with the field experimental data.