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.2017.33.5.511 Vol.33(No.5) 511-524, 2017

This study was carried out for the purpose of creationg a restoration plan to improve ecological quality of Changwon and Nam streams. Based upon the results of comprehensive diagnostic assessment, restoration priority was given in the upstream reach, where conservation status is relatively superior. Restoration level was usually determined to practice active restoration as conservation, and the states of both Changwon and Nam streams were not so good. Restoration plans, by reach, were classified into “upstream”, “midstream”, and “downstream” were suggested in both terms of horizontal section frame and vegetation based on the result of diagnostic assessment and the reference information. “Upstream”, “mid-stream”, and “downstream” of Changwon and Nam streams were classified into “small-gravel- mountainous”, “small-sand-plain”, and “small-clay-plain streams”, respectively (based on scale, and substrate and slope of river bed). The spatial arrangement of vegetation was laid out in diagram form by reflecting micro-topography and the water level of the horizontal section of river. Information regarding species composition was recommended as dominant species, which appear frequently in three vegetation zones composed of herbaceous plant, shrubs and tree and sub-tree dominated zones divided by reflecting disturbance regime, depending on position on the horizontal section of river. Moreover, there have been prepared not only plans to improve the terrestrial ecosystems around the streams but also plans to create ecological networks, which can serve to improve ecological quality of the whole regional environment by serving to connect streams and terrestrial ecosystems, a process probably necessary and definitely recommended to realize true (genuine) restoration. Plans for ecological park and networks were prepared by mimicking species composition of Alnus japanica community, Zelkova serrata community, Carpinus laxiflora community, Quercus aliena community, and Q. serrata community.

Diagnostic assessment, Ecological network, Reference information, Restoration priority, Restoration plan

이재호 Jaeho Lee , 이승현 Seunghyun Lee , 이수형 Soohyung Lee , 이재관 Jaekwan Lee

DOI:10.15681/KSWE.2017.33.5.525 Vol.33(No.5) 525-530, 2017

The attainment ratios of the water quality goals of the 114 mid-watershed representative stations, examined during the period2011 to 2015, were evaluated in the study. Of the four major river basins, the attainment ratio on water quality goal of the Geum River basin turned out to be the lowest. As a result of formal evaluation of the attainment ratios of BOD, COD and TOC, it was found that the attainment ratio of COD was much lower than that of BOD and TOC (I a circumstance thought to be caused by the higher COD/BOD and COD/TOC ratios of the water quality of the river than those of the environmental water quality standard). As well, higher COD/BOD and COD/TOC of wastewater discharged from point and non-point sources (other than those of the environmental water quality standards) might possibly represent one of the reasons. We also compared attainment ratio between the main stream and tributaries, which indicated that the higher attainment ratio was present in the main stream. The attainment ratio is also documented as more significant in the winter season than the summer season, possibly due to the contribution of non-point pollutants swept in by rain during the summer season during documented periods of high precipitation. Thus, water quality management in summer season and improvement of water quality of the tributaries might be important as a means of increasing attainment ratio on water quality goal.

Attainment ratio, Mid-watershed representative station, River basin, Total organic carbon (TOC), Water quality goal

최동호 Dongho Choi , 조소현 Sohyun Cho , 황태희 Taehee Hwang , 김영석 Youngsuk Kim , 정재운 Jaewoon Jung , 최우정 Woojung Choi , 박현규 Hyunkyu Park , 윤광식 Kwangsik Yoon

DOI:10.15681/KSWE.2017.33.5.531 Vol.33(No.5) 531-537, 2017

The biologic Oxygen Demand (BOD) is a reliable and generally accepted indicator of water pollution by organic pollutants. Accordingly, estimation of BOD export from paddies carries important implications fwith regard to water management in rural areas. In this study, hydrology and BOD concentration were monitored during the period 2008 through 2012, in an effort to understand the characteristics of BOD export from paddy fields. The findings demonstrated that BOD load by rainfall above 50 mm. occupied about 50 % of total load, whereas the load by less than ten mm. rainfall occupied about 29 % of the total load during periods of stormy activity. It therefore seems that it could be possible to reduce the BOD load up to 29 % during storm periods, when drainage control conducted for rainfall less than ten mm.(an amount which is relatively easy to manage). The documented mean loads of storm and non-storm were 17.1 kg ha^-1 yr^-1 and 11.2 kg ha^-1 yr^-1, respectively. The BOD load during the significant rainfall period was similar to the renewed unit load by NIER (2014). However, there were substantial differences between unit load and actual load when the non-storm load was incorporated into the BOD load estimation from paddy fields. In view of the foregoing, it is felt that, the non-storm load needs to be further considered and managed for the successful implementation of Total Maximum Daily Load (TMDL) program.

BOD, TMDL, Unit load, Water management

류희성 Hui-seong Ryu , 신라영 Ra-young Shin , 이정호 Jung-ho Lee

DOI:10.15681/KSWE.2017.33.5.538 Vol.33(No.5) 538-545, 2017

The purpose of this study is to investigate growth response and toxigenicity under various temperature and nutritional conditions, in order to understand the physioecological characteristics of Aphanizomenon flos-aquae, which is a bloom-forming cyanobacterium in the Nakdong River. The strain was inoculated into media under combinations of four temperatures (4, 12, 21, 30°C) and three nutrients (modified CB medium, P-depleted CB medium, N-depleted CB medium) for 28 days. The algae-inhibition tests were performed to assess the potential allelopathic effects of the strains' filtrates on the growth of four algae strains (Microcystis aeruginosa, Aulacoseria ambigua f. spiralis, Aphanizomenon flos-aquae, Scenedesmus obliquus). Toxin production of a strain was measured by Enzyme-Linked ImmunoSolbent Assay (ELISA). The optimal growth temperature (Topt) of strains was 19.9°C (18.3-21.2°C), and the temperature range for growth was from -0.3°C to 34.3°C. Specific growth rate (μ) in modified CB medium varied from 0.10 to 0.16 day^-1, and the maximum growth rate (μmax) was 0.17 day^-1. Although growth curves under N-existed and N-depleted conditions were almost the same, growth under N-depleted condition was relatively slowed (μ = 0.09 to 0.14 day^-1), with a decreased maximum cell density. However, growth under the P-depleted condition was restricted for all temperatures, Two stains of Aphanizomenon flos-aquae were confirmed as not producing toxins, because saxitoxin and cylindrospermopsin were not detected by ELISA. The exudates or filtrates from the Aphanizomenon flos-aquae (DGUC003) resulted in significant inhibition of algal growth on the Aulacoseira ambigua f. spiralis (DGUD001) and Aphanizomenon flos-aquae (DGUC001) (p < 0.01).

Cyanobacteria, Cylindrospermopsin, ELISA, Harmful algae, Saxitoxin

임도영 Do Young Lim , 류홍덕 Hong-duck Ryu , 정유진 Eu Gene Chung , 김용석 Yongseok Kim , 이재관 Jae Kwan Lee

DOI:10.15681/KSWE.2017.33.5.546 Vol.33(No.5) 546-555, 2017

The Nutrient budget is one of the agricultural-environment indicators of OECD. A nutrient budget measures the surplus as the differential between the inputs and the outputs of within a certain boundary and within a specified period of time (i.e. one year). According to OECD, the annual nitrogen budget for Korea was 245 kg N ha^-1 in 2014, which corresponds to the first position among OECD countries. In Korea in 2014, about 90 % of livestock excreta was composted as solid and liquid manure, which are usually and customarily spread on agricultural land. The objectives of this study are intended to suggest methodology of the regional nitrogen budget as a nitrogen management tool, which considers conversion from raw excreta to composted manures based on the methodology of OECD/Eurostat, and application of the new method in an agricultural region of Korea. As a result, the calculated excess rate of hydrospheric nitrogen surplus was 251 kg N ha^-1 (in the region in 2014), which indicates the presence of potential risks emanating from excessive nitrogen, with regard to both export water and soil environments. The findings also assert that this was shown to be one of the most important elements in the nitrogen budget, which translates to the actual amounts of nitrogen lost during the solid composting process. To better understand the process and the reliability of the method, it is necessary to analyze the sensitivity of the relevant co-efficients used in the method in the near future.

Composting, Nitrogen (N), Nitrogen Budget, OECD

윤성호 Sung Ho Yoon , 하홍주 Hong Joo Ha , 이성종 Sung Jong Lee , 조은혜 Eun Hea Jho

DOI:10.15681/KSWE.2017.33.5.556 Vol.33(No.5) 556-562, 2017

Heavy metals in water systems are being managed on the concentration-based guidelines in Korea. However, various chemicals present in water can interact with heavy metals affecting their toxicity. Such interactions are not considered in the concentration-based guidelines. This study investigated the effect of hardness and coexisting heavy metals on heavy metal toxicity to emphasize the importance of having the effect-based guidelines together with the concentration-based guidelines in water management. The toxic effects of Cd, Zn, or mixtures of Cd and Zn were studied with Daphnia magna as a test species following the standard test method at different hardness conditions (100, 200, and 300 mg L^-1 as CaCO3). The toxicities of single metal solutions and mixtures showed a decreasing trend with increasing hardness, and this can be attributed to the competition between heavy metals and cations such as calcium ions (Ca²⁺) that cause hardness. The predicted toxicities of the heavy metal mixtures from the single metal toxicity deviated from the measured toxicities, and the predicted toxic effects tend to be greater than the measured toxic effects suggesting that Cd and Zn are in competition. This shows the limitations of using predicted toxic effects and the needs for further studies on mixture toxicities. Overall, this study shows that the management of heavy metals in waters needs to employ the effect-based guidelines together with the concentration-based guidelines.

Cadmium, Daphnia magna, Hardness, Toxicity, Zinc

최정현 Choi Jeonghyeon , 이옥정 Lee Okjeong , 김상단 Kim Sangdan

DOI:10.15681/KSWE.2017.33.5.563 Vol.33(No.5) 563-571, 2017

Because of the rapid progress of urbanization in recent decades, the proportion of impervious areas in cities has increased. As a result, the hydrological properties of urban streams have changed and non-point pollution sources have increased, that have had considerable influence on human life and ecosystem. To manage these situations, the application of non-point pollution reduction facilities and LID facilities are expanding recently. In this study, it is investigated if rainfall interception rate used in design of non-point pollution reduction facilities can be applied to design of LID facilities. For this purpose, EPA SWMM is constructed for part of Noksan National Industrial Complex area wherein long-term observed storm water data can be obtained and storm water interception rates for various design capacities of a bio-retention LID facility reservoirs are estimated. While sensitivity of storm water interception rate according to design specifications of bio-retention facility is not large, the sensitivity of storm water interception rate according to regional rainfall characteristics is relatively large. As a result of comparing present rainfall interception rate estimation method with the one proposed in this study, the present method is highly likely to overestimate performance of the bio-retention facility. Finally, a new storm water interception rate formula for bio-retention LID facility is proposed.

Bio-retention, EPA SWMM, Low impact development, Stormwater interception rate

김태윤 Taeyoon Kim , 이준배 Junebae Lee , 이동우 Dongwoo Lee , 신현석 Hyunsuk Shin , 김현철 Hyunchul Kim , 권순철 Soonchul Kwon

DOI:10.15681/KSWE.2017.33.5.572 Vol.33(No.5) 572-579, 2017

Increased impervious surface caused by rapid urbanization serves to produce the discharge of non-point source pollutants such as total suspended solid (TSS). There exist various methods of removing TSS, including a filtration process using granular media (a well-known method to be practically used after the consideration of removal efficiency, clogging, and backwashing efficiency). To determine the TSS removal capability of the filter, we initially performed lab-scale experiments which assessed flow rates, influent concentrations, permeability co-efficients, the particular shapes of suspended solids and potential clogging, and also evaluated TSS removal efficiency when applied to filtration facility in a pilot-scale. In low filtration flux condition, the removal efficiency of suspended solids was more than 95 %, while decreased to 83% in high filtration flux. Regarding the clogging aspect of the experiment, total cumulative solids were loaded up to 19.15 kg/m², and TSS removal efficiency was noted to commence to decrease when the loaded solids exceeded 9.0 kg/m². It was also noted, however, that superior efficiency was maintained for six hours. In addition, for pilot-scale experiment, the removal efficiency was still high enough (83.4 %) for the solid concentration of 140~343 mg SS/L and after backwashing, head loss was recovered to 92~95 % during two hour filtration. With these results, It was confirmed that lifetime of the filter applied to the test was prolonged due to the high treatment efficiency and good backwashing efficiency for the cumulative solids load.

Clogging, Filtration system, Media, Prmeability coefficients

김호섭 Ho-sub Kim , 김상용 Sang-yong Kim , 박지형 Jihyung Park , 한미덕 Mideok Han

DOI:10.15681/KSWE.2017.33.5.580 Vol.33(No.5) 580-586, 2017

The fractionation characteristics of organic matter were investigated in inflow and effluent of each other pollution sources and river. While the DOC/TOC ratio in the influent of public sewage treatment plant and livestock disposal facilities was above 0.58, the POC/TOC ratio of human livestock Night soil treatment plant and stormwater runoff was more than 0.7. The TOC removal efficiency of public sewage treatment plant and human livestock Night soil treatment plant were 88.5 % and 99.6 %, respectively. Although the concentration distribution of organic matter pollution most of total organic carbon (TOC) in effluent of pollution sources accounted for dissolved organic carbon (DOC) type (DOC/TOC ratio >0.89) and Refractory- DOC (RDOC)/TOC ratio was higher (>0.65). The fractionation characteristics of organic matter in river were similar with that of sewage treatment plant and TOC concentration showed the positive correlation with DOC (r² = 0.93) and RDOC (r² = 0.89) concentration. The decay rate of Labile DOC (LDOC) (avg. 0.128 day^-1) was higher than labile particulate organic carbon (LPOC) (0.082 day^-1), while that of DOC (0.008 day^-1) was lower than POC (0.039 day^-1) (paired t-test, p < 0.001, n = 5). These study results suggested that it should consider important both TOC and DOC as the target indicator to control refractory organic matter in pollution sources.

Fractionation, Pollution sources, Refractory organic matter, Target indicator, Total organic carbon

공동수 Dongsoo Kong , 손세환 Se-hwan Son , 김진영 Jin-young Kim , 김아름 Ah Reum Kim , 권용주 Yongju Kwon , 김정우 Jungwoo Kim , 김예지 Ye Ji Kim , 민정기 Jeong Ki Min , 김필재 Piljae Kim

DOI:10.15681/KSWE.2017.33.5.587 Vol.33(No.5) 587-599, 2017

Physical environmental factors (water depth, current velocity and substrate) and fish community were surveyed in the Gapyeong stream, Korea. The fish group of Gapyeong Stream was divided into three types. Lithophilic fish, Koreocobitis rotundicaudata and Pseudopungtungia tenuicorpa preferred shallow depth, low-velocity current, and coarse bed condition, whereas Coreoleuciscus splendidus and Microphysogobio longidorsalis were adapted to high-velocity current and bed materials. Nektonic fish, Zacco koreanus and Zacco platypus appeared in a wide range of physical conditions. Intermediate fish, Hemibarbus longirostris, Pungtungia herzi and Coreoperca herzi adapted to moderate water depths and current velocities. Among them, H. longirostris and C. herzi were adapt to various bed materials. C. splendidus, M. longidorsalis and P. herzi showed high niche overlap for current velocity, water depth and substrate with Z. koreanus and Z. platypus. The occurrence of M. longidorsalis in a relatively low-velocity current compared to Z. koreanus and Z. platypus suggests that the current velocity act as a isolation factor for these species. The competition, isolation and character displacement among these species investigated detail in the future. Based on canonical correspondence analysis, the relative importance of each environmental factor was determined as substrate > water depth > current velocity.

Aquatic Habitat, Cluster Analysis, Fish Community, Gapyeong stream, Niche Overlap, Physical Environmental Factors