• Journal of Korean Society on Water Environment
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• v.35 no.3
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• pp.257-270
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• 2019

Followingthe Four Rivers Project, cyanobacterial blooms have been frequently observed in the upstream of the installed weirs. The aim of this study was to characterize the major environmental factors that are associated with the cyanobacteria dominance in Baekje Weir (Geum River) and Juksan Weir (Youngsan River) based on intensive experiments and systematic data mining methods. The factors related to the cyanobacteria dominance include7-days cumulative rainfall (APRCP7), 7-days averaged flow (Q7day), water temperature (Temp), stratification strength (${\Delta}T$), electronic conductivity (EC), DO, pH, $NO_3-N$, $NH_3-N$, TN, TP, $PO_4-P$, Chl-a, Fe, BOD, COD, TOC, and $SiO_2$. The most highly correlatedfactors to the dominant cyanobacteria were found to be EC, Temp, Q7day, $PO_4-P$ in theBaekje Weir. On the other hand, those dominant in the Juksan Weir were ${\Delta}T$, TOC, Temp, EC and TN. The EC showed a strong correlation with cyanobacteria dominance in both weirs because a high EC represents a persisted low flow condition. The cyanobacteria dominance was as high as 56 % when the EC was equal or greater than $418{\mu}S/cm$ in Baekje Weir. It was as high as 63% when the ${\Delta}T{\geq}2.1^{\circ}C$ in the Juksan Weir. However, nutrients showed a minor correlation with cyanobacteria dominance in both weirs. The results suggest that the cyanobacteria dominate in astate where the water flow rate is low, water temperature is high and thermal stratification is strengthened. Therefore, the improvement of flow regimes is the most important to prevent persistent thermal stratification and formation of cyanobacteria bloom in theBaekje and JuksanWeirs.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.5
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• pp.685-690
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• 2006

The differences in microbial community structures between planktonic microorganism and biofilm in rivers were investigated using respiratory quinone profiles. The compositions of microbial quinone for 4 tributaries of the Kyongan Stream located in/flowing through Yongin City, Gyeonggi-Do were analyzed. Ubiquinone(UQ)-8, UQ-9, menaquinone(MK)-6 and Plastoquinone(PQ)-9 were observed in all samples of planktonic microorganism and biofilm for the sites investigated, Most planktonic microorganism and biofilm had UQ-8(15 to 30%) and PQ-9(over 30%) as the dominant quinone type. These results indicated that oxygenic phototrophic microbes(cyanobacteria and/or eukaryotic phytoplankton) and UQ-8 containing proteobacteria constituted major microbial populations in the river. The quinone concentration in the river waters tested, which reflects the concentration of planktonic microorganisms, increases with increasing DOC. Further research into this is required. The microbial diversities of planktonic microorganism and biofilm calculated based on the composition of all quinones were in the range from 4.2 to 7.5, which was lower than those for activated sludge(ranging from 11 to 14.8) and soils(ranging from 13.4 to 16.8). The use of quinone profile appears to be a useful tool for the analysis of microbial community structure in river.

• SUVANNABHUMI
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• v.7 no.1
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• pp.157-186
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• 2015

Sittaung-Thanlwin region in Lower Myanmar is an ecological niche for human settlement. Evidences of human activities in the region are seen through various archaeological sites or settlements along the coastal area between the rivers Sittaung and Thanlwin (Salween). In Lower Myanmar, scholar, U Aung Myint, discovered one major site Kyaikkatha and other small scale sites, namely, Sittaung, Kawhtin, Kadaikgyi, Kadaikkalay, Katkadit, Kelatha (little Zothoke), Ayetthama, Winka, Zothoke (big Zothoke), Lagonbyi (Sampannago), Wagaru, Laming and Ye in present day Mon State. In 1980, U Aung Myint undertook an exploration program at Kyaikkatha. After the exploration, an excavation team conducted systematic digging at Kyaikkatha in March 1986. Excavation continued occasionally at Kyaikkatha throughout the years between 1995 and 2000. It is known that Kyaikkatha, the old city, reveals a kind of monumental civilization exposing four religious structures (a stupa and three monasteries). This essay looks into the distribution of features within Kyaikkatha and infers on its social, political, and religious organization. This essay is also about a new discovery of an early urban settlement located at the apex of the Gulf of Muttama (Martaban) where a lost city of Suvannahumi flourished in the ancient days. By means of aerial photographic observations, the site had been noticed recently, which was by followed some excavations. More systematic and detail surveying may be needed to know more about the site and its features for comparison to other similar settlements of through-out mainland South East Asia.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.6-7
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• 2021

Vegetation development in rivers is one of the important issues not only in academic fields such as geomorphology, ecology, hydraulics, etc., but also in river management practices. The problem of river vegetation is directly connected to the harmony of conflicting values of flood management and ecosystem conservation. In Korea, since the 2000s, the issue of river vegetation and land formation has been continuously raised under various conditions, such as the regulating rivers downstream of the dams, the small eutrophicated tributary rivers, and the floodplain sites for the four major river projects. In this background, this study proposes a method for classifying the distribution of vegetation in rivers based on remote sensing data, and presents the results of applying this to the Naeseong Stream. The Naeseong Stream is a representative example of the river landscape that has changed due to vegetation development from 2014 to the latest. The remote sensing data used in the study are images of Sentinel 1 and 2 satellites, which is operated by the European Aerospace Administration (ESA), and provided by Google Earth Engine. For the ground truth, manually classified dataset on the surface of the Naeseong Stream in 2016 were used, where the area is divided into eight types including water, sand and herbaceous and woody vegetation. The classification method used a random forest classification technique, one of the machine learning algorithms. 1,000 samples were extracted from 10 pre-selected polygon regions, each half of them were used as training and verification data. The accuracy based on the verification data was found to be 82~85%. The model established through training was also applied to images from 2016 to 2020, and the process of changes in vegetation zones according to the year was presented. The technical limitations and improvement measures of this paper were considered. By providing quantitative information of the vegetation distribution, this technique is expected to be useful in practical management of vegetation such as thinning and rejuvenation of river vegetation as well as technical fields such as flood level calculation and flow-vegetation coupled modeling in rivers.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.7
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• pp.525-531
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• 2013

In an effort to find a solution to the eutrophication of major Korean rivers, a method to utilize multi-purpose filtration pond was investigated. As literature showed that oyster shell is known to be the most adequate for the removal of dissolved phosphorus in Korean rivers, batch and column experiments were performed using oyster shell as an adsorbent in this study. The results of the batch experiment showed that the removal of dissolved phosphorus from river water through adsorption as a way of preventing algal growth was not practical. The results obtained from the column experiment, however, suggested that oyster shell may be utilized as an adsorbent under limited conditions. Based on the results of the experiments a methodology was proposed to remove algae from river water through the use of multi-purpose filtration pond. This method involves mechanically removing the accumulated algae cake from the surface of the artificial stream in the pond towards the condensing part located at the lower reach of the stream, where particles gather before the final removal. In addition, employment of oyster shell as an adsorbent in the condensing part allows prevention of phosphorus released from the dead algae re-entering the river water.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.225-231
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• 2006

The nonpoint source control is based on TPLMS (Total Pollution Load Management System) program. Recently, the Ministry of Environment in Korea has programed TPLMS for 4 major large rivers to improve the water quality in rivers by controling the total pollutant loadings from the watershed area. Usually the urbanization is the main pollutant sources, particularly for nonpoint pollutants, because of high imperviousness and high pollutant mass emissions. The stormwater runoff from urban areas is containing various pollutants such as sediments, metals and toxic chemicals due to human and vehicle activities. Of the various landuses, the highways are highly polluted landuses because of high pollutant accumulation rate by vehicle activities during dry periods. Therefore, this research is achieved to provide pollutant EMCs (Event Mean Concentrations) and mass loadings washed-off from highways during rainfall periods. Five monitoring locations were equipped with an automatic rainfall gage and an flow meter. The results show that the EMC ranges for 95% confidence intervals in highway land use are 45.52-125.76 mg/L for TSS, 52.04-95.48 mg/L for COD, 1.77-4.48 mg/L for TN, 0.29-0.54 mg/L for TP. The ranges of washed- off mass loading are $712.7-2,418.4mg/m^2$ for TSS and $684.1-1,779.6mg/m^2$ for COD.

• Parasites, Hosts and Diseases
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• v.62 no.1
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• pp.1-29
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• 2024

This article analyzed the infection characteristics of metacercariae of Metagonimus spp. (MsMc) in fish from 9 major water systems in Korea. A total of 19,568 fish in 87 species were examined over a period of 10 years (2011-2020). MsMc were detected in fish from all 44 survey areas in 9 water systems. Most of the surveyed sites showed very low and low infection levels (66.7%), while 33.3% of the areas, such as Tamjin-gang and Seomjin-gang, revealed moderate and high infection levels. High endemicity depends on the abundance of susceptible fish species, especially sweet smelt (Plecoglosus altivelis). The susceptibility index (SI) with MsMc in index fish, Zacco spp., was very low and low levels in 62.0%, moderate in 28.0%, and high in 10.0% regions. The SI was highest in the following order: Yeongam-cheon (283.8), Hoeng-cheon (192.3), Togyo-jeosuji (131.2), Deokcheon-gang (119.1), and Joyang-gang (106.3). The recent infection status of MsMc in P. altivelis was analyzed by the survey localities. In addition, except for P. altivelis, 9 fish species were highly infected with MsMc in some survey areas, including Zacco platypus, Z. koreanus, Z. temminckii, Opsariichthys uncirostris, Rhynchocypris oxycephalus, Carassius auratus, Acheilognathus rhombeus, Onchorhynchus masou, and Tribolodon hakonensis. In Korea, 74 fish species (15 families) are collectively listed as second intermediate hosts of Metagonimus spp. This review provides several novel characteristics of MsMc infection and clarifies the fish species of second intermediate host of Metagonimus spp. in this country.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1135-1140
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• 2006

Concentration and speciation of trihalomethanes(THMs) and haloacetic acids(HAAs) that can be created during chlorine disinfection as disinfection by-products(DBPs) in Korean water treatment plants(WTPs) were investigated. 4 WTPs that adopted conventional water treatment processes were chosen for investigation and each represented a typical WTP on the Han, Keum, Sumjin and Nakdong Rivers. The average concentration of THMs was 26.9 ppb, and the maximum and minimum concentrations were 47.6 ppb and 11.0 ppb respectively, while the average concentration of HAAs was 25.4 ppb, and the maximum and minimum concentrations were 57.1 ppb and 9.7 ppb respectively. DBPs concentration was lower in the winter than the summer. The major species of THMs was chloroform and its average percentage was 77%, and the second highest was bromodichloromethane(20%), while the concentration of bromoform was below detection limits. The sum of dichloroacetic acid(DCAA) and trichloroacetic acid(TCAA) was 97% of $HAA_5 $ on average base. But its percentage was 90% in the Han River WTP, especially it was the lowest during the winter. On the other hand, the concentration of DCAA was higher than TCAA except during the summer.

• Journal of the Korean association of regional geographers
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• v.19 no.2
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• pp.352-361
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• 2013

This paper aims to analyze the root mean square errors of MODIS LST data and inland water temperature measurement data in order to use MODIS LST data as an input of numerical weather prediction model. MODIS LST data from July 2011 to June 2012 were compared to water temperature measurement data in the automated water quality measurement network. MODIS data have two composites: day-time and night-time. Monthly errors of day-time and night-time LST range $2{\sim}8^{\circ}C$ and $3{\sim}12^{\circ}C$, respectively. Temporally, monthly errors of day-time LST are less in fall and those of night-time LST are less in summer. Spatially, on the four major rivers including the Han, Nakdong, Geum, and Yeongsan rivers, the errors of Yeongsan river were the smallest, which location is the south-most among them. In this study, the errors of MODIS LST as an input of numerical weather prediction model were analyzed and the results can be used as an error level of MODIS LST data for inaccessible areas such as North Korea.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.93-101
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• 2024

Background: As pollutants caused by non-point sources flow into rivers, river water quality monitoring for fecal pollution is becoming increasingly important. Objectives: This study was conducted to investigate the distribution of microbial communities in the Yeongsangang River water system and sewage treatment plants in Gwangju and to evaluate their antibiotic resistance. Methods: In the experiment, samples were distributed to five selective media at each point and then cultured for 18 to 24 hours. When bacteria were observed, they were sub-cultured by size and shape and identified using MALDI-TOF MS equipment. When identification was completed, 17 types of antibiotic susceptibility tests were performed using VITEK II equipment, focusing on gram-negative dominant species among the identified strains. Results: During the study period, a total of 266 strains were isolated from 39 samples. Gram-positive bacteria were 37 strains in four genera, or 13.9% of the total, and Gram-negative bacteria were 229 strains in 23 genera, or 86.1% of the total. Antibiotic susceptibility testing of 23 strains, the major dominant species, showed that one strain (4.3%) was resistant to only one antibiotic, and two strains (8.7%) were 100% susceptible to the 17 antibiotics tested. The other 20 strains (87.0%) were multidrug resistant bacteria resistant to two or more antibiotics. There were various types of multidrug resistance. Among them, penicillin and cephalosporin series showed the highest resistance. Conclusions: Based on the results of this study, it was found that the bacterial community structure changed according to regional and environmental factors, and it was judged that continuous research such as genetic analysis of antibiotic-resistant bacteria present in natural rivers is necessary.