이용호 Yongho Lee , 박대원 Daewon Pak

DOI:10.15681/KSWE.2016.32.5.403 Vol.32(No.5) 403-409, 2016

In this study, a TiO₂ nanotube was grown on a titanium plate by using anodic oxidation method for the evaluation of TiO2 nanotube morphology. The TiO₂ nanotube was grown in an electrolyte containing ethylene glycol, 0.2 wt% of NH4F and 2 vol% of H₂O. Applied voltage varied from 30 to 70 V and the morphology of the TiO₂ nanotube was observed. After anodization, a TiO₂ nanotube plate was immersed in 35°C ethanol for 24 hours. Anatase and rutile crystal forms of TiO₂ nanoutbe were observed after annealing. 4-chrolobenzoic acid, a probe compound for OH radicals, was dissolved in H₂O in order to measure the OH radical. Liquid chromatography was used to check the concentration of the 4-chrolobenzoic acid. The OH radical generation by TiO₂ nanotube plate was proportionate to the length of the TiO₂ nanotube. Furthermore, when the number of TiO₂ nanotube plate increased, the OH radical generation increased as well.

Anodization, Electric Current, Photocatalyst, TiO₂, TiO₂ nanotube plate

윤우현 Woo-hyun Yoon , 이준호 Jun-ho Lee , 이현주 Hyun-ju Lee , 이수원 Su-won Lee , 안재찬 Jae-chan Ahn , 김복순 Bog-soon Kim

DOI:10.15681/KSWE.2016.32.5.410 Vol.32(No.5) 410-418, 2016

This study was conducted to improve the analysis method used for N-nitrosamines and to investigate the occurrences of N-nitrosamines in tributaries of the Han-river, intake stations, water treatment plants and tap water used within the city of Seoul. The samples were pretreated through a solid phase extraction and analyzed using a gas chromatography tandem mass spectrometer (GC-MS/MS). The GC-MS/MS in CI mode was compared with the GC-MS/MS in EI mode by the method detection limits (MDLs). MDLs by GC-CI/MS/MS and GC-EI/MS/MS were 0.2 ~ 1.1 ng/L and 0.2 ~ 1.4 ng/L, respectively. Samples were collected from ten tributaries of the Han-river (T1 ~ T10), six intake stations (II ~ 16), six water treatment plants (P1 ~ P6) and 25 taps in Seoul city. The maximum levels of N-nitrosodimethylamine (NDMA) were 0.013 ㎍/L, 0.008 ㎍/L, 0.006 ㎍/L and 0.002 ㎍/L in tributary water, raw water, finished water and tap water samples, respectively. Detected levels were much lower than 0.1 ㎍/L corresponding to the guideline value of WHO.

Drinking water, GC-MS/MS, NDMA, N-nitrosamines, Tap water

Palas Samanta , 임형준 Hyungjoon Im , 이황구 Hwanggoo Lee , 황순진 Soon-jin Hwang , 김원기 Wonky Kim , Apurba Ratan Ghosh , 정진호 Jinho Jung

DOI:10.15681/KSWE.2016.32.5.419 Vol.32(No.5) 419-432, 2016

The aim of this study is to assess the influence of effluent discharge from a sewage treatment plant by evaluating oxidative stress and histopathological alterations in freshwater crucian carp Carassius auratus collected from the Eungcheon stream, located in Korea. Catalase activity in the gills, liver, and kidneys of C. auratus was collected from mixing zones; the downstream site was notably higher of fish than that of the upstream site. In addition, the activity of glutathione-S-transferase in the gills and liver was significantly higher in samples from the mixing zone than in those from the upstream site (p < 0.05). In addition, significantly elevated lipid peroxidation levels were observed in fish livers sampled from the mixing zone than in those from the upstream site (p < 0.05). Significant histopathological alternations were also observed in C. auratus, with the order of magnitude changes being liver > kidney > gills. These findings suggest that the liver is most affected by effluent discharge. The degree of tissue changes (DTC) indicate that the highest level occurred in samples from the mixing zone (30.98 土 5.40) followed by those from the downstream site (19.28 土 4.31) and was the lowest in samples from the upstream site (4.83 土 2.67). These findings indicate that fish collected from the mixing zone are most affected by effluent discharge and both oxidative stress and histopathological indices are useful tools for monitoring contaminated rivers and streams.

Antioxidant, Biomarker, Fish, Histology, Sewage

정세웅 Se-woong Chung , 유지수 Ji-su Yoo , 박형석 Hyung-seok Park , S. Geoffrey Schladow

DOI:10.15681/KSWE.2016.32.5.433 Vol.32(No.5) 433-441, 2016

Many large dams have been constructed for water supply, irrigation, flood control and hydropower in Korea for the last century. Meanwhile, recent studies indicated that the artificial reservoirs impounded by these dams are major sources of carbon dioxide (CO₂) to the atmosphere and relevant to global budget of green house gases. However, limited information is available on the seasonal variations of CO₂ evasion from the reservoirs located in the temperate monsoon regions including Korea. The objectives of this study were to estimate daily Net Atmospheric Flux (NAF) of CO₂ in Daecheong Reservoir located in Geum River basin of Korea, and analyze the influencing parameters that characterize the variation of NAF. Daily pH and alkalinity (Alk) data collected in wet year (2012) and dry year (2013) were used for estimating the NAFs in the reservoir. The dissolved inorganic carbon (DIC) was computed using the pH and Alk measurements supposing an equilibrium state among the carbonate species. The results showed seasonal variations of NAF; negative NAFs from May to October when the primary production of the reservoir increased with water temperature increase, while positive NAF for the rest of the period. Overall the reservoir acted as sources of CO2 to the atmosphere. The estimated NAFs were 2,590 and 771 mg CO₂ m^-2d^-1 in 2012 and 2013, respectively, indicating that the NAFs vary a large extent for different hydrological years. Statistical analysis indicated that the NAFs are negatively correlated to pH, water temperature, and Chl-a concentration of the reservoir.

CO₂ emission, Eutrophic reservoirs, Green house gases, Net Atmospheric Flux, Temperate monsoon region

이이내 Leenae Lee , 안경희 Kyunghee Ahn , 민병대 Byungdae Min , 양미희 Mihee Yang , 최인철 Incheol Choi , 정현미 Hyenmi Chung , 박주현 Juhyun Park

DOI:10.15681/KSWE.2016.32.5.442 Vol.32(No.5) 442-449, 2016

The goal of this study is to provide basic data to establish a foundation for the provision of safe drinkable water. The raw water of natural mineral water was analyzed to determine the quantities of anions (F^-, Cl^-, NO₃-N^-, and SO₄^2-) and cations (Ca²⁺, K⁺, Mg²⁺, and Na⁺) during the former and latter half of 2016. Analysis of the current quality of the raw water of natural mineral water among domestic manufacturers showed average anions contents of 0.46㎎/L of fluorine, 8㎎/L of chlorine ion, 1.5㎎/L of nitrate nitrogen, and 12㎎/L of sulfate ion. While the fluorine content was greater than the water quality criterion of 2.0㎎/L at four points, the fluorine level was overall stable. The average cations contents included 21.3㎎/L of calcium, 1.0㎎/L of potassium, 3.4㎎/L of magnesium, and 9.6㎎/L of sodium. The chemical characteristics were compared among the major ions, and the results are presented in a piper diagram. The content ratio of cations was in the order of Ca²⁺>Na⁺>Mg²⁺>K⁺, whereas that of anions was in the order of SO₄^2-〉Cl^->NO_3-N>F^-. While the cations were slightly scattered, the anions were generally concentrated except for at a few points. The Ca-Na-HCO₃ type was dominant overall in water sources from diorite, gneiss, and granite, while the Na-Mg-Ca-HCO₃-Cl type was dominant in basalt sources. Mineral water manufacturers source their water under various conditions, including in-hole casing, excavation depth, and contact state of bedrock; even within the same rocky area, some differences in the water quality type can occur. When the depth of the water source was taken into account, the mean anions contents of F^-, Cl^-, NO₃-N^-, and SO₄^2- were similar, with no significant differences according to depth. Of the cations, K⁺ and Na⁺ showed no significant differences across all the tubular wells, whereas Ca²⁺ and Mg²⁺ decreased in content with depth.

Cation and anion concentration, Mineral, Natural mineral water, Piper-Diagram, Water types

오승영 Seung Young Oh , 한미덕 Mideok Han , 김석규 Seok Gyu Kim , 안기홍 Ki Hong Ahn , 김옥선 Oksun Kim , 김용석 Yong Seok Kim , 박지형 Ji Hyoung Park

DOI:10.15681/KSWE.2016.32.5.450 Vol.32(No.5) 450-457, 2016

The Total Maximum Daily Load (TMDL) is a watershed management system that involves the establishment of the target water quality, the calculation of permission loading (allocation loading), and the control of total pollutants for each unit watershed. Allocation loading is assessed through the comprehensive implementation assessment of the previous year`s plan. Assessment results are used for follow-up management measures such as the limit of development and updating of TMDL Management Implementation Plans for the next planning period. Although detailed assessment criteria are important, they are not currently available. Therefore, we suggested assessment criteria by comparing two methods(‘integration method` and ‘separation method`) using combination point and non-point discharge loading. We also examined the penalty criteria considering controllable load local government and updating methods of the TMDL Management Implementation Plan for the next planning period.

Allocation loading, Assessment method, Exceedance load, Penalty criteria, TM인

엄한기 Han Ki Eom , 이진헌 Jin Heon Lee , 주현종 Hyun Jong Joo

DOI:10.15681/KSWE.2016.32.5.458 Vol.32(No.5) 458-464, 2016

This study evaluated the dewatering efficiency of inorganic dehydrating agents that contain oyster shells. A filter press dehydrator was used for this study. The experiments were performed by the single injection of calcium-based chemicals, the single injection of oyster shells, and the mixed injection of oyster shells and calcium-based chemicals. The moisture content of the dewatered cake generated after dehydration confirmed that the best dewatering efficiency was found at the mixing ratios of CaCO₃ to sludge, oyster shell to sludge, and inorganic dehydrating agent to sludge of 3:1, 10:1, and 1.5:2.5:1, respectively. The moisture contents exhibited less than 58% when the injection mixing ratio of inorganic dehydrating agent to sludge was 1.5:2.5:1. From EPS, SEM, and EDX analysis, it was found that the calcium adsorbed on the sludge surface could reduce extracellular polymeric substances (EPSs) and enhanced the dewaterbility. Based on the above results, it is considered possible to apply inorganic dehydrating agents containing recycled oyster shells in sludge dewatering in order to reduce sludge.

Dewatering, Filter Press, Moisture content, Oyster shell, Recycling

안지홍 Ji Hong An , 임치홍 Chi Hong Lim , 임윤경 Yun Kyung Lim , 남경배 Kyeong Bae Nam , 피정훈 Jung Hun Pi , 이창석 Chang Seok Lee

DOI:10.15681/KSWE.2016.32.5.465 Vol.32(No.5) 465-474, 2016

Since Gyungan stream is included in the protected zone of the water supply source of the Metropolitan area in Korea, the water quality needs to be continuously managed. Therefore, a measure is required that can inhibit the flow of water pollutant into the water body and facilitate the ecological restoration of riparian vegetation. A field survey was conducted on the hydrological characteristics of the landscape elements established on the downstream catchment of the Gyungan stream, the result of which showed that the paddy field and urbanized area can be regarded as point pollution sources. The upland field can be regarded as a non-point pollution source. In order to improve the water quality in the Paldang lake, we first recommended creating a riparian vegetation belt. We also suggested introducing a treatment wetland and an artificial plant island to places in which the creation of a riparian vegetation belt is not ensured. We recommend creating a treatment wetland equipped with diverse functional groups. For creating the plant island, we recommend Zizania latifolia and Typha orientalis, which showed the highest productivity among aquatic plants. The former could be introduced around the outlet of a paddy field and the estuary of tributaries, while the latter could be introduced to a water body directly sourced from mountainous land.

Artificial plant island, Land use type, Riparian vegetation belt, Treatment wetland

안지홍 Ji Hong An , 임치홍 Chi Hong Lim , 정성희 Song Hie Jung , 김아름 A Reum Kim , 우동민 Dong Min Woo , 이창석 Chang Seok Lee

DOI:10.15681/KSWE.2016.32.5.475 Vol.32(No.5) 475-491, 2016

The Changwon and Nam streams that run through the Changwon city were evaluated based on longitudinal and horizontal configurations and vegetation state in order to prepare a restoration plan. Riparian vegetation of the Changwon and Nam streams are normally dominated by herbaceous plants. However, the woody plants, Salix pseudolasiogyne, Rubus parvifolius, Salix koreensis, Robinia pseudoacacia，and Amorpha fruticosa have appeared. Planting to introduce various types of plants for landscape architecture has also been observed. Evaluation of naturalness based on the vegetation state of both Changwon and Nam streams showed very low naturalness of degree 1 or 2, with the exception of a few reaches of the upstream sector. In these few reaches of the upstream sector, Salix koreensis and Salix chaenomeloides showed heights at the subtree level, however, they were located at the position of shrubland close to the waterway. These reaches were, therefore, evaluated as degree 3 rather than degree 4 in naturalness. The result of diagnostic evaluation classified by reach indicated the requirement for active restoration, such as transformation of the channelized stream into a meandering one and a step-type cross section into a pool-type one, introduction of vegetation suitable to the region and site, and creation of an ecological network between the stream and the surrounding terrestrial ecosystems.

Diagnostic evaluation, Ecological network, Restoration plan, Riparian vegetation