• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.1
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• pp.13-22
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• 2022

In this study, we investigated the water quality and fish community of the Gudam Wetland, a riverine wetland in the middle-upper reaches of the Nakdong River, during March-October 2020. The main results were as follows: average annual flow rate: 45.0±23.7 m³/s, flow velocity: 0.4±0.3 m/s, water depth: 1.4±0.4 m, water temperature: 17.5±0.8℃, pH: 7.8±0.2, electrical conductivity: 121.6±19.0 ㎲/cm, dissolved oxygen concentration: 11.4±0.9 mg/L, suspended solids concentration: 3.8±2.0 mg/L, and the water quality was classified as Ia (very good). A total of 754 individual fish belonging to 4 orders, 7 families, and 19 species were investigated. Cyprinidae was the dominant group, with 13 species. The dominant species was Zacco platypus (39.3%), followed by Pseudogobio esocinus (17.5%). There were 8 (42.1%) endemic Korean species and 1 exotic species, Micropterus salmoides. Four species were carnivores, six were insectivores, and nine were omnivores. Regarding tolerance to environmental changes, 6 species were tolerant, 11 had intermediate tolerance, and 2 were sensitive. Fish community analysis revealed dominance of 0.57, diversity of 2.04, evenness of 0.69, and richness of 2.72, indicating a diverse and stable fish community. The fish assessment index showed that the assessment class was B (average 62.5), which was higher than that of major streams of the Nakdong River (class C). For sustainable conservation of the Gudam Wetland, management strategies such as minimizing aggregate collection and preventing inflow of non-point pollutants are required.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.54-62
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• 2005

The present study was to determine how seasonal rainfall intensity influences nutrient dynamics, ionic contents, oxygen demands, and suspended solids in a lotic ecosystem. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of rainfall. Dissolved oxygen (DO) had an inverse function of water temperature (r = = = - 0.986, p<0.001). Minimum pH values of<6.5 were observed in the late August when rainfall peaked in the study site, indicating an ionic dilution of stream water by precipitation. Electrical conductivity (EC) was greater during summer than any other seasons, so the overall conductivity values had direct correlation (r = 0.527, p<0.01) with precipitation. Ionic dilution, however, was evident 4 ${\sim}$ 5 days later in short or 1 ${\sim}$ 2 weeks in long after the intense rain, indicating a time-lag phenomenon of conductivity. Daily COD values varied from 0.8 mg $L^{-1}$ to 7.9 mg $L^{-1}$ and their seasonal pattern was similar (r = 0.548, p<0.001) to that of BOD. Total nitrogen (TN) varied little compared to total phosphorus (TP) and was minimum in the base flow of March. In contrast, major input of TP occurred during the period of summer monsoon and this pattern was similar to suspended solids, implying that TP is closely associated (r = 0.890, p<0.01) with suspended inorganic solids. Mass ratios of TN : TP were determined by TP (r= -0.509, p<0.01) rather than TN (r= -0.209, p<0.01). The N : P ratios indicated that phosphorus was a potential primary limiting nutrient for the stream productivity. Overall data suggest that rainfall intensity was considered as a primary key component regulating water chemistry in the stream and maximum variation in water quality was attributed to the largest runoff spate during the summer monsoon.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.346-362
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• 2021

A sediment control dam is an artificial structure built to prolong sedimentation in the main dam by reducing the inflow of suspended solids. These dams can affect changes in dissolved organic matter (DOM) in the water body by changing the river flow regime. The main DOM component for Yeongju Dam sediment control of the Naeseongcheon River was analyzed through 3D excitation-emission matrix (EEM) and parallel factor (PARAFAC) analyses. As a result, four humic-like components (C1~C3, C5), and three proteins, tryptophan-like components (C2, C6~C7) were detected. Among DOM components, humic-like components (autochthonous: C1, allochthonous: C2~C3) were found to be dominant during the sampling period. The total amount of DOM components and the composition ratio of each component did not show a difference for each depth according to the amount of available light (100%, 12%, and 1%). Throughout the study period, the allochthonous organic matter was continuously decomposing and converting into autochthonous organic matter; the DOM indices (fluorescence index, humification index, and freshness index) indicated the dominance of autochthonous organic matter in the river. Considering the relative abundance of cyanobacteria and that the number of bacteria cells and rotifers increased as autochthonous organic matter increased, it was suggested that the algal bloom and consequent activation of the microbial food web was affected by the composition of DOM in the water body. Research on DOM characteristics is important not only for water quality management but also for understanding the cycling of matter through microbial food web activity.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.71-80
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• 2016

The fauna of freshwater fish and water chemistry characteristics were investigated from June, 2014 to October, 2014 at 10 sites in Taebaeksan Provincial Park. A total of 7 species under three families were collected from the survey sites and among them one endangered species - Koreocobitis naktongensis - was identified. The endemic species of Korea were 2 species: Koreocobitis naktongensis, Iksookimia koreensis. Dominant species was Rhynchocypris oxycephalus(89%) and subdominant species was Orthrias nudus(8.9%). Water quality including conductivity, turbidity, pH and total dissolved solids(TDS) varied largely depending on the sampling locations. Values of ambient conductivity and TDS were greater in the upstream than in the downstream, and seasonal variabilities were also higher in the upstream. The pH decreased towards the downstream, and especially showed a sharp decrease in S5. This phenomenon was evident due to a dilution by the influx in the acid mine drainage(AMD) of S4. Physical habit conditions, based on qualitative habitat evaluation index(QHEI) model, indicated a "Sub-optimal" condition(mean: 157.3; range: 78 ~ 194) in the Sodo stream watersheds.

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.385-399
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• 2010

The objective of this study was to analyze long term temporal trends of water chemistry and spatial heterogeneity for 83 sampling sites of Geum-River watershed using water quality dataset during 2003~2007 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (TN), total phosphorus (TP), and electric conductivity (EC), largely varied depending on the landuse patterns, years and seasons. The watershed was classified into three different landuse types: forest stream (Fo), agricultural stream (Ag), and urban stream (Ur). Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summer monsoon rain. Conductivity, used as a key indicator for an ionic dilution during rainy season, and nutrients of TN and TP had inverse functions of precipitation. BOD, COD decrease during the rainy season. Minimum values in the conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of suspended solids (SS) occurred during the period of summer monsoon. The landuse patterns analyses, based on the variables of BOD, COD, TN, TP and SS, showed that the values were greater in the agricultural stream (Ag) than in the forest stream (Fo) and urban stream (Ur) and that water quality was worst in the urban stream (Ur). The overall dataset suggest that efficient water quality management, especially in Gap-Stream and Miho-Stream, which showed worst water quality is required along with some of urban stream (Ur), based on the analysis of landuse patterns.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.2
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• pp.79-86
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• 2016

The purpose of this study is to efficiently improve biological sequencing batch reactor (SBR) system of high-concentrated nitrate nitrogen in reverse osmosis (RO) concentrates by total dissolved solids (TDS) regulation. Since a laboratory-scale SBR system had been operated, we had analyzed specific denitrification rate (SDNR) and specific oxygen uptake rate (SOUR) for microbial activity in according to various injection concentration of TDS. As a result, higher injection concentration of TDS decreased SDNR, and delayed denitrification within denitrification process. Moreover, the higher injection concentration of TDS was, the lower microbial activity was during operation of laboratory-scale SBR system. Therefore, the regulation of TDS injection concentration is necessary to improve efficiency of nitrate nitrogen in the biological SBR system, and treatment of calcium ion ($Ca^{2+}$) is also specifically focused to remove nitrate nitrogen. Moreover, analytical data of SDNR and SOUR can be the effective kinetic design parameters to application of biological treatment of RO concentrate by aerobic granular sludge (AGS).

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.369-376
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• 2010

A novel or canal-type continuous removal of organic matter (C-CROM) with combined freshwater bivalves (Unio douglasiae and Anodonta woodiana) was developed to improve the water quality (IWQ) of eutrophic reservoirs. The first experiment was performed for 12 days to measure the IWQ using 256 individuals of combined bivalves (ca. 7:3), at the same density that distributed in the collection stream. The second experiment was conducted to evaluate the efficacy of IWQ with the addition of each 30% of two mussels for 14 days. Results indicated that a novel C-CROM significantly decreased suspended solids, chlorophyll-$\alpha$, transparency, total nitrogen and phosphorus, and increased ammonium and biodeposition (t-test, P<0.001 for all), while other dissolved inorganic nutrients such as $NO_2$, $NO_3$, and SRP did not change (t-test, P>0.5). Daily IWQ performances of C-CROM with combined mussels was about two times higher to the previous studies using single species where less suspended inorganic nutrients were released except for ammonia. Collectively, a C-CROM is more strategic to the water quality improvement of eutrophic lake.

• Journal of Environmental Impact Assessment
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• v.19 no.3
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• pp.281-296
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• 2010

방그라데시 북부에 위치한 풀바리 우파질라 지역의 지하수에서 pH, EC, 주요 양이온 ($Ca^{2+}$, $Mg^{2+}$, $Na^+$, $K^+$, $Zn^{2+}$, $Cu^{2+}$, $Mn^{2+}$, $Fe^{3+}$, and $As^{3+}$), 주요 음이온 (${CO_3}^{2-}$, $HCO_3{^-}$, $NO_3{^-}$, ${SO_4}^{2-}$ and $Cl^-$) 그리고 total dissolved solids (TDS) 등의 용존물질 함량을 측정하였다. 또한 sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), 경도 등의 지표도 계산하였다. 전체적으로 지하수의 pH는 약알칼리성 (6.24 - 8.10)을 띄었으며, 주요 양이온은 $Ca^{2+}$, $Mg^{2+}$ and $Na^+$ 이었고, 주요 음이온은 $HCO_3{^-}$ and $Cl^-$ 으로서 전형적인 담수의 이온조성을 보였다. $Cu^{2+}$, $Mn^{2+}$ and $Fe^{3+}$ 의 최대 농도는 각각 1.71, 0.606, 0.125 mg/L 이었다. 방글라데시의 여러 지역에서는 비소에 의한 지하수의 오염이 흔히 나 타나고 있으나 이지역에서 비소의 최대농도가 0.41 mg/L로서 기준치인 0.05 mg/L 보다 낮은 오 염도를 보였다. TDS와 SAR, SSP 등으로 볼 때 이 지역의 지하수는 대부분 양호한 수질을 가지는 담수인 것으로 평가된다. $As^{3+}$, $Zn^{2+}$, $Mn^{2+}$, $Fe^{3+}$, ${SO_4}^{2-}$, $NO_3{^-}$ and $Cl^-$ 등의 농도는 음용수로 적합한 수준이었으나 일부 항목은 특정 산업용도로는 부적합한 농도를 보였다. 현재로서는 이지역 의 지하수는 대부분 음용이 가능하고 일부 산업용에 대해서만 부적합성을 보였다. 그러나 앞으로 지 하수의 이용과 산업활동이 증가하면 방글라데시의 많은 다른 지역의 지하수에서 발생한 사례와 같 이 용존물질의 농도가 증가하여 물의 용도에 제한을 받게 될 우려가 있다.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.34-41
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• 2016

Using UF-SWRO hybrid process, pre-blending tests of seawater and brackish water were performed to investigate the effects on removal of boron and humic acid (HA). Feedwater pre-blending was set based on TDS concentration from 15,000 mg/L to 27,000 mg/L and analyzed for boron removal characteristics. Also organics rejection at same TDS concentration range was investigated by injecting HA. Boron concentration appeared to be high as TDS concentration was high ranging from 76.60% to 83.27%, but boron concentration in final produced water was increased up to 0.69 mg/L from 0.48 mg/L. In cases of HA tests at 10 mg/L, 22,500 mg/L TDS appeared to be higher removal rate of 17.59% than a very poor result of 8.43% in 27,000 mg/L. But high HA removal rate of 57.14% was obtained in produced water with 22,500 mg/L TDS containing 10 mg/L of HA and 27,000 mg/L TDS yielded lower boron removal rate of 54.49%. Meanwhile it was found that a relatively high flux and recovery rate were obtained following process when feedwater was injected with HA. It is considered that most of fouling substances were eliminated by binding between HA and $Ca^{2+}$. Thus, when desalination using UF-SWRO with respect to boron and HA, TDS concentration is determined to be advantageous as lower.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.7-13
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• 1983

Laboratory determinations of saturated hydraulic conductivity were conducted with four soils varying in texture from sand to clay and with five waters with different salinity level. The waters varied in total dissolved solids from 1,250 to $15,000mg/{\ell}$ and in SAR from 16 to 57 and were representative of saline waters in New Mexico. Saturated hydraulic conductivities of the soils were not significantly affected by water salinity if these waters were the sole source of irrigation water. However, small additions of distilled water, assuming simulated to rain, to soils previously equilibrated with the saline waters significantly decreased soil permeability. Dispersion and short or long-distance transport of clay apparently clogged conducting pores when distilled water was introduced. Swelling was an important mechanism in reducing soil permeability only in the clay soil. The data suggest that, when saline water is the dominant irrigation source and is supplemented by rain, (1) all saline waters could be used on very sandy soils, (2) no saline waters should be used on very heavy soils, and (3) slightly saline, but not very saline, waters could be used on medium-textured soils.