• Parasites, Hosts and Diseases
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• v.46 no.3
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• pp.133-137
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• 2008

This study was performed to investigate prevalence of clonorchiasis among the inhabitants living in villages along the 4 major rivers, Nakdong-gang (= river), Seomjin-gang, Youngsan-gang, and Guem-gang in southern Korea. From January to December 2006, a total of 24,075 stool samples (1 sample per an inhabitant) were collected in 23 localities and examined by the formalin-ether sedimentation technique. Of the inhabitants examined, 3,441 (14.3%) were found to harbor various types of intestinal parasite eggs, cysts or larvae. Numbers of infected people were 2,661 (11.1%) for Clonorchis sinensis, 431 (1.8%) for heterophyids, 226 (0.9%) for Entamoeba spp., 57 (0.2%) for Giardia lamblia, 30 (0.1%) for Trichuris trichiura, and 18 (0.07%) for echinostomes. Prevalence rates of clonorchiasis according to the river basin were 17.1% in Nakdong-gang, 11.2% in Seomjin-gang, 5.5% in Youngsan-gang and 4.6% in Guem-gang. Of the 2,661 C. sinensis egg-positive cases, 57.7% was male. The present findings suggest that clonorchiasis is still highly prevalent among inhabitants in the riverside areas of southern Korea, and it is necessary to implement a systematic control program in the endemic areas.

• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.514-527
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• 2018

This study formed a scenario to improve a water quality by expecting and analyzing a water quality of Jeollabuk-do Seomjingang water system, so calculated a result. As a result, it was analyzed that a water quality is improved at 15.32 % of the maximum BOD, 7.17 % of T-N, and 62.86 % of T-P according to domestic and livestock cut amount by reinforcing discharge water of sewage disposal plant and improving pollutant management plans. It was analyzed that supplementing various cut plans such as establishment of efficient cut plans, plans to decrease pollution loading amount, plans to increase sewage disposal efficiently, pollutant decrease through an expansion of sewage disposal area, and energy recovery from animal dung of Total Pollutant Load Management System, and developing a study on more efficient improvement plans of water quality by considering natural increase and economic development are efficient in an improvement in a water quality.

• Journal of Korea Water Resources Association
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• v.57 no.1
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• pp.21-33
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• 2024

Recently, the patterns of climate change-induced disasters have become more diverse and extensive. To develop an effective flood control plan, Korea has incorporated the concept of Potential Flood Damage (PFD) into the Long-Term Comprehensive Water Resources Plan to assess flood risk. However, concerns regarding the PFD have prompted numerous studies. Previous research primarily focused on modifying and augmenting the PFD index or introducing new indices. This study aims to enhance the existing flood control safety evaluation method by utilizing a flood risk map that incorporates risk indices, specifically focusing on the Yeong-Seomjin river basin. The study introduces three main evaluation approaches: risk and potential analysis, PFD and flood management level analysis, and flood control safety evaluation. The proposed improved evaluation method is expected to be instrumental in evaluating various flood control safety measures and formulating flood control plans.

• Parasites, Hosts and Diseases
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• v.56 no.6
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• pp.633-637
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• 2018

Present study was performed to survey on infection status of Isthmiophora hortensis (formerly Echinostoma hortense) metacercariae (IhMc) in dark sleepers, Odontobutis spp., from some water systems of the Republic of Korea. A total of 237 Odontobutis spp. was collected in the water systems of 5 rivers, i.e., Mangyeong-gang (gang means river), Geum-gang, Tamjin-gang, Seomjin-gang, and Nakdong-gang. They were all examined with artificial digestion method for 5 years (2013-2017). A total of 137 (57.8%) Odontobutis spp. were infected with 14.8 IhMc in average. The prevalence was the highest in Nakdong-gang areas (62.9%) and followed by in Mangyeong-gang (57.1%), Geum-gang (56.3%), Tamjin-gang (54.8%), and Seomjin-gang (53.9%) areas. Metacercarial densities were 28.1 (Geum-gang), 13.9 (Mangyeong-gang), 13.3 (Nakdong-gang), 13.1 (Tamjin-gang), and 2.3 (Seomjin-gang) per infected fish. Especially, in case of Yugucheon (cheon means stream), a branch of Geum-gang, IhMc were detected in all fish (100%) examined and their density was about 48 per fish. By the present study, it was confirmed that the infection status of IhMc is more or less different by the surveyed areas and the dark sleepers, Odontobutis spp., are suitable fish hosts of I. hortensis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.513-523
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• 2017

We evaluated the viability of phytoplankton along the salinity gradient in the flood and ebb tides of spring tide of February and the ebb tide of neap tide of March 2017 in the Seomjin River Estuary. Additional laboratory experiments were also conducted to determine the reason of the pH changes along the salinity gradient using the field natural sample in February. In field, saltwater was well mixed at downstream vertically and the salinity gradient was horizontally appeared toward upstream of freshwater zone. There were strong negative correlations between salinity and nutrient (nitrate + nitrite R=0.99, p<0.001, and silicate R=0.98, p<0.001), implying that those two nutrients of freshwater origin were gradually diluted with mixing the saltwater. On the other hands, relatively high phosphate concentration was kept in the stations of saltwater over 15 psu, indicating that it was caused by resuspended sediments of Gwangyang Bay and downstream by tidal water mixing.Among phytoplankton community structure in winter, Eucampia zodiacus have occupied to be c.a. 70 % in the most stations. Based on the field survey results for survivability of phytoplankton by phytoPAM instrument, there was positive correlations between salinity and chlorophyll a (R=0.82, p<0.001) and, salinity and active chlorophyll a (R=0.80, p<0.001), implying that the dominant marine diatom species may have significantly damaged in low salinity conditions of upstream. Also, maximum mortality rate of phytoplankton caused by low salinity shock was appered to be 75% in the upstream station. In particular, the pH in spring tides of February had tended to increase with high phytoplankton accmulated stations, suggesting that it was related with absorption of $CO_2$ by the photosynthesis of dominant diatom. In laboratory experiments, phytoplankton mass-mortality caused by low salinity shock was also occurred, which is confirmed with reducing the photosynthetic electron transport activity. Following the phytoplankton mass-mortality, bacteria abundance was significantly increased in 24 hours. As a result, the mass-proliferating bacteria can produce the $CO_2$ in the process of biodegradation of diatoms, which can lead to pH decrease. Therefore, marine phytoplankton species was greatly damaged in freshwater mixing area, depending on along the salinity gradient that was considered to be an important role in elevating and reducing of pH in Seomjin River Estuary.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.5
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• pp.455-461
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• 2002

limiting nutrients for phytoplankton were determined by dissored inorganic nitrogen/phosphorous (DIN/DIP) in situ and algal bioassay experiment in the Seomjin River estuary during a study period from March 1999 to October 2001. DIN/DIP ranged from 14.7 to 681.1 during the study period. DIN/DIP was over 16 at the upper and middle estuarine region where salinity was lower than 25 psu and chlorophyll a concentration was high, probably indicating P-limitation in this region while the ratio was less than 16 at the high saline (> 25 psu) region, reflecting the supply of DIP from Gwangyang Bay and thereby indicating N-limitation at the lower estuarine region. These results suggested that the spatial distribution of DIN/DIP in the study region was controlled by the high supply of phosphate from Gwangyang Bay, the low input from Seomjin River and the active uptake by phytoplankton within the estuarine system. The bioassay experiments using Skeletonema costatum, Thalaasiosira rotula and in situ phytoplankton assemblage displayed relatively higher growth of phytoplankton in the P-added culture media, indicating P-limitation. This result was well consistent with the spatial distribution of inorganic nutrients. S. costatum showed a rapid adaptation to the low salinity compared to other phytoplankton species. This phenomenon seemed to account for the strong (> $90\%$ in total cell number) S. costatum bloom in autumn in this estuary. Moreover, although phytoplankton growth rate was higher in the P-added culture media at the end of culture experiment of in situ phytoplankton, the fast growth in the trace metal-added media at the beginning of the experiment suggested a possibility of limitation by other micro-nutrients such as trace metal and vitamin etc.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.81-96
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• 2011

Sediment oxygen demand(SOD) and denitrification rates were measured in four major estuaries(Suncheon Bay, Seomjin river estuary, Goseong stream estuary and Masan Bay) in south coast of Korean peninsula from March of 2009 to May 2010 to estimate organic matter cleaning capacity. SOD was estimated from the temporal dissolved oxygen concentration change and isotopic pairing technique was employed to measure denitrification. Sediment oxygen demand(SOD) was ranged from -5.1 to 24.6 mmole $O_2m^{-2}d^{-1}$ and denitrification rate was ranged from 0.0 to 3.9 mmole $N_2m^{-2}d^{-1}$in the study area. SOD was the highest in Masan Bay(-2.2 to 19.2, average = 10.2 mmole $O_2m^{-2}d^{-1}$) and Suncheon, Goseong, Tae-an and Seomjin followed. Denitrification was also the highest in Masn Bay(0.0 to 3.9, average = 1.0 mmole $N_2m^{-2}d^{-1}$) and Goseong, Seomjin, Suncheon and Taean followed. The effect of benthic photosynthesis by microphytobenthos on denitrification was evident in some season of Tae-an, Seomjin, and Masn Bay. The increased oxygen level produced by photosynthesis stimulated nitrification without severe adverse effect on denitrification and, as a result, coupled nitrification and denitrification was enhanced in these areas. A difference of seasonal patterns of denitrification at each site depended on relative importance of denitrification on different nitrate source($D_w$: nitrate from water column and $D_n$: nitrated produced during nitrification). Denitrification was maximum during spring in Goseong, Suncheon and Masan Bay. On the contrary, denitrification was the highest during summer in Tae-an and Seomjin estuary.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.1-6
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• 2006

Amount of coastal ground water discharge(CGD) of surficial aquifer via coastlines of Nakdong River watershed, Seomjin River watershed, Youngsan River watershed and Keum River watershed is estimated. Compared to other major hydrological components, such as evapo-transpiration and river discharge, CGD is not so large in the amount. However, it is important since coastal ground water can be developed relatively free of environmental impact on downstream area and since most of coastal areas currently suffers water shortage. Regional groundwater investigation data and assessment based on Darcy's law are used for estimating coastal groundwater discharge. In this work the amount of CGD across the coastlines of the four rivers is estimated as 1.8 billion cubic meter per year and that is about 2.3 percentage of total amount of annual precipitation. Nakdong River watershed is most appropriate region in view of developing groundwater.

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.169-187
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• 2023

Aggregates from 84 cities and counties in Korea were tested for quality to allow analysis of the physical characteristics of aggregates from river, land, and forest environments. River and land aggregates were analyzed for 18 test items, and forest aggregates for 12 test items. They were classified according to watershed and geology, respectively. The observed physical characteristics of the river aggregates by basin were as follows: aggregates from the Geum River basin passed through 2.5, 1.2, 0.6, 0.3, 0.15, and 0.08 mm sieves; clay lumps constituted the Nakdong River basin material; aggregates from the Seomjin River basin passed through 10, 5, and 2.5 mm sieves; those from the Youngsang River basin passed through 1.2, 0.6, 0.3, 0.15, and 0.08 mm sieves; and aggregates from the Han River basin passed through 10, 5, 2.5, 1.2, 0.6, 0.3, and 0.08 mm sieves, Stability; Standard errors were analyzed for the average amount passing through 10, 0.6, and 0.08 mm silver sieves, and performance rate showed different distribution patterns from other physical characteristics. Analysis of variance found that 16 of the 18 items, excluding the absorption rate and the performance rate, had statistically significant differences in their averages by region. Considering land aggregates by basin, those from the Nakdong River basin excluding the Geum River basin had clay lumps, those from the Seomjin River basin had 10 and 5 mm sieve passage, aggregates from the Youngsang River basin had 0.08 mm sieve passage, and those from the Han River basin had 10, 0.6, and 0.08 mm sieve passage. The standard error of the mean of the quantity showed a different distribution pattern from the other physical characteristics. Analysis of variance found a statistically significant difference in the average of all 18 items by region. Analyzing forest aggregates by geology showed distributions of porosity patterns different from those of other physical characteristics in metamorphic rocks (but not igneous rocks), and distributions of wear rate and porosity were different from those of sedimentary rocks. There were statistically significant differences in the average volume mass, water absorption rate, wear rate, and Sc/Rc items by lipid.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.274-294
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• 2007

The most reasonable method of counting the number of the estuaries in Korea may be counting the number of streams flowing into the sea. The number counting of the streams should be carried out based on the river classes (National River, Regional 1st Class River and Regional 2nd Class River) given by the River Act. The National River scale estuaries are totaled to thirteen, i.e. Han River(including Imjin River), Anseongcheon, Sapgyocheon, Geum River, Mankyeong River, Dongjin River, Yeoungsan River, Tamjin River, Seomjin River, Gawhacheon, Nakdong River(including West Nakdong River), Taewha River, and Hyeongsan River estuaries. The Regional 1st Class River scale estuaries are counted as four, i.e. Yeoungdeok Osipcheon, Samcheok Osipcheon, Gangneung Namdaecheon, and Yangyang Namdaecheon. While, the Regional 2nd Class River estuaries are arranged as the Province and counted as total 444; Jeonnam, Gyeongnam, Chungnam, Jeju Province have the 108, 94, 52, and 35 estuaries, respectively. The counted estuary numbers, however, can be slightly increased/decreased on what references are applied, e.g. whether or not including the streams lost estuary functions by the sea-dike construction or integrated nearby streams, and so on.