The absence of standardized, biology-based assessment criteria for lake ecosystems at the national level underscores the need for developing systematic and integrative phytoplankton-based evaluation tools. Phytoplankton are primary producers that regulate energy flow and nutrient cycling in lake ecosystems, and their rapid responses to environmental changes such as eutrophication, altered hydrodynamics, and seasonal fluctuations make them highly effective biological indicators. Multimetric indices (MMIs) offer a structured and integrative approach for capturing complex community level responses to environmental stressors, thereby enhancing the ecological relevance and management utility of biological assessment tools for lentic systems. This study presents the Lake Phytoplankton Assessment Index (LPAI), developed using long term ecological and water quality data from 90 lakes and reservoirs across South Korea. The LPAI comprises six ecologically meaningful metrics: total cell density (M2), cell density of flagellated algae (M10), cell density of harmful cyanobacteria (M17), cell density of eutrophic Chlorophyta (M18), relative abundance of saprophilous diatoms (M23), and relative abundance of eutraphentic diatoms (M25). Application of the LPAI demonstrated that lake health grades exhibited a broad and near-normal distribution across seasons, while summer assessments showed a marked increase in lower grade (C~E) lakes associated with elevated temperatures and cyanobacterial blooms. Conversely, winter assessments showed improved conditions due to reduced phytoplankton biomass and the dominance of low eutrophic diatom assemblages. Correlation analyses confirmed that the selected metrics captured distinct ecological gradients, particularly nutrient enrichment and organic matter driven turbidity, while PCA results indicated that the LPAI performed consistently across lake types without structural bias. Overall, the LPAI reliably reflects trophic conditions, harmful algal risks, and structural changes in phytoplankton communities, offering a scientifically grounded and management-relevant tool for evaluating the ecological health of Korean lakes and reservoirs.

This study aims to advance Korea’s aquatic ecosystem assessment framework by developing and validating an Integrated Assessment Index (IAI) that synthesizes three biological indicators: the Diatom Assessment Index (DAI), the Benthic Macroinvertebrate Assessment Index (BAI), and the Fish Assessment Index (FAI). Using biomonitoring data collected from 2019 to 2021, three integration methods: the minimum grade method, most frequent grade method, and arithmetic mean method, were compared. The arithmetic mean method demonstrated the highest suitability and was adopted as the final integration approach. The resulting IAI showed stronger correlations with major water quality factors (BOD, TN, TP) than individual biological indices, indicating its enhanced capacity to capture both water quality gradients and ecological response patterns across biological assemblages. Application of the IAI to aquatic ecosystem assessment data from 2016 to 2023 revealed that the overall ecological condition of Korean rivers remained at a “fair (C)” level. Approximately half of the sites were classified as good to very good (A~B), while around 20% were rated as poor to very poor (D~E). Annual cycle analysis further indicated that first-year surveys within each monitoring phase exhibited higher proportions of good conditions, whereas second- and third-year surveys showed increasing frequencies of fair conditions, suggesting cumulative environmental stressors or progressive habitat alteration. Mid-sized basin target standards achievement analysis showed a clear discrepancy between waterquality and biological outcomes. While BOD and TP targets were met at relatively high rates, IAI achievement rates were the lowest across all major river basins (18~33%). This indicates that current water quality centered management goals insufficiently reflect actual ecological conditions. The results highlight that improvements in physico-chemical factors alone are insufficient for biological recovery and that habitat structure, flow regime, and substrate conditions are critical drivers of ecological integrity. Overall, the IAI effectively integrates biological and physico-chemical information, offering a more comprehensive quantification of river aquatic ecosystem health than single metric approaches. The index demonstrates strong potential as a practical tool for future policy applications, including mid-sized basin target management, ecological restoration prioritization, and integrated water resource planning.

Current assessments of stream ecosystem health in Korea using benthic diatoms rely primarily on the Trophic Diatom Index (TDI), which is highly sensitive to phosphorus concentrations but has limited ability to capture complex environmental stressors such as organic pollution and physical habitat degradation. To address these limitations and enhance the ecological diagnostic capacity of diatom-based assessments, we developed a Korean-type multimetric diatom index, the Diatom Assessment Index (DAI). Using benthic diatom assemblage data and environmental variables collected from 3,029 sites nationwide between 2019 and 2021, we screened candidate metrics based on variability, redundancy, discriminatory power, and sensitivity analyses. Five metrics-TDI, proportion of motile diatoms, proportion of sensitive diatoms, proportion of saprophilous diatoms, and the [Achnanthes / (Achnanthes+Navicula)] ratio-were ultimately selected and integrated to calculate the DAI score. Applying the DAI to an independent dataset from 3,005 sites (2022~2024) demonstrated that the index exhibited a near-normal distribution across assessment classes, in contrast to the TDI, which tended to be skewed toward specific ranges. The DAI showed strong correlations not only with physicochemical parameters such as BOD and TP but also with physical habitat indicators, including flow velocity and the proportion of fine substrates. In addition, the DAI was significantly correlated with other biological indices, such as the Benthic Macroinvertebrate Index (BMI) and the Fish Assessment Index (FAI). These results indicate that the DAI provides a more comprehensive and ecologically meaningful measure of stream health in Korea and can serve as an effective tool for national aquatic ecosystem assessment and management.

This study examines the current framework for diagnosing the causes of stream ecosystem impairment in South Korea and proposes strategies to improve the effectiveness of aquatic ecosystem restoration policies. While technical guidelines and manuals for impairment diagnosis have been developed, they remain limited in practice due to weak legal enforceability, lack of integration with restoration planning, and insufficient coordination between related laws such as the Water Environment Conservation Act and the River Act. To address these issues, this study highlights the need for institutional reforms, including the legal establishment of a national inventory of impaired streams, the development of a comprehensive management plan, and the incorporation of diagnosis results into river planning processes. It also proposes clarifying the roles of central and local agencies to enhance administrative efficiency and reduce project fragmentation. Furthermore, the study emphasizes the potential of Nature-based Solutions (NbS) as a paradigm shift in stream restoration. The application of NbS should be linked to the results of scientific diagnosis and tailored to the specific characteristics and impairment mechanisms of each stream. By strengthening the link between diagnosis, planning, and implementation, and adopting ecosystem-based approaches such as NbS, this study aims to inform integrated policy and institutional directions for sustainable stream restoration in South Korea.

Water environment management in Korea has long been driven by chemical water quality standards; however, such an approach does not adequately reflect the structural and functional integrity of aquatic ecosystems. Accordingly, the introduction of biological water quality criteria (biocriteria) has emerged as a key task for establishing ecosystem-centered water environmental policies. This study reviewed the scientific and legal foundations necessary for developing biocriteria suited to Korean aquatic ecosystems and proposed practical approaches for institutionalizing them as environmental standards. To this end, we conducted a comparative analysis of biocriteria implementation cases in major countries, including the United States, the European Union (EU), and Canada, and examined both the applicability and limitations of domestic multi-metric index (MMI)-based biological indicators. In addition, we evaluated the potential linkage with national legislation, including the Framework Act on Environmental Policy and the Water Environment Conservation Act, and proposed an institutionalization roadmap. This study emphasizes the necessity of establishing biocriteria as a policy turning point for securing the ecological health of Korean freshwater ecosystems and building an integrated water environment management framework.

This study investigated seasonal variations in phytoplankton community composition and physicochemical water quality across 90 lakes in South Korea surveyed 2022 to 2024, and examined their relationships with environmental factors. Over the course of four seasons, a total of 952 phytoplankton taxa were identified, with Bacillariophyta (diatoms) and Chlorophyta (green algae) accounting for 64.2% of the total species richness. Diatom species such as Aulacoseira granulata, Fragilaria crotonensis, and Cyclotella meneghiniana were frequently observed regardless of season. In terms of cell density, Cyanophyta were dominant, comprising 85.1% on average, with particularly high summer densities driven by blooms of Microcystis aeruginosa and Aphanizomenon sp. In contrast, diatoms accounted for the highest relative abundance in winter (54.1%). Canonical correspondence analysis (CCA) revealed that Cyanophyta and Chlorophyta were positively correlated with water temperature, TP, COD, and Chl-a, whereas Bacillariophyta and Cryptophyta showed negative correlations with these variables. These results indicate that phytoplankton communities in Korean lakes are highly responsive to variations in temperature and nutrient concentrations, and that summer rainfall-driven nutrient inflow plays a critical role in triggering cyanobacterial blooms. This study provides a scientific basis for understanding seasonal ecosystem dynamics in Korean lakes and offers foundational data for eutrophication management and the development of biological water quality assessment indices.

Benthic attached diatoms (BADs), a major primary producer in lotic stream and river ecosystems are micro-sized organisms and require a highly magnified microscopic technique in the observation work. Thus, it is often not easy to ensure accuracy and precision in both qualitative and quantitative analyses. This study proposed a new technique applicable to improve quality control of aquatic ecosystem monitoring and assessment using BADs. In order to meet the purpose of quality control, we developed a permanent mounting slide technique which can be used for both qualitative and quantitative analyses simultaneously. We designed specimens with the combination of grid on both cover and slide glasses and compared their efficiency. As a result of observation and counting of BADs, the slide glass designed with the color-lined grid showed the highest efficiency compared to other test conditions. We expect that the method developed in this study could be effectively used to analyze BADs and contributed to improve the quality control in aquatic ecosystem health monitoring and assessment.

루이보스티에서 5종의 phenolic acid (gallic acid, chlorogenic acid, caffeic acid, p-coumaric acid, trans-ferulic acid) 와 9종의 flavonoid (procyanidin b1, aspalathin, rutin, vitexin, hyperoside, isoquercitrin, luteolin, quercetin, chrysoeriol)를 UPLC-MSMS를 이용하여 동시 분석하였다. 14종 페놀릭 류를 동시 분석하기 위하여 기기조건과 유효성을 검증하였고 확립된 분석방법을 이용하여 시중에 유통중인 루이보스티 30건을 채취하여 페놀릭류를 분석하였다. 루이보스티 1 g 혹은 1티백에 뜨거운 물 100 mL을 가하여 3분, 6분, 30분이 경과 후 그리고 차가운 물 (25-30oC)에 30분 우려낸 루이보스티의 페놀릭류 함량을 구하였다. 루이보스티에서 전체 실험대상 페놀릭류 중 rutin과 aspalathin이 가장 많이 추출되어 나왔으며 각각 물질의 함량은 제품별로 달랐다. 페놀릭류 성분의 추출효율은 14종 페놀릭류의 총 합 기준으로 뜨거운 물 30분 > 6분 > 3분 > 차가운 물 30분 순으로 높았다.

Cyanobacteria Aphanizomenon population is widely distributed in the world, and well known as harmful algae by producing toxins and off-flavor materials, thus belonging to one of the taxa that became more interested in the field of limnoecology. In this study, the frequency, intensity, and duration of Aphanizomenon occurrence were increased with the abnormal drawdown of water level in the winter in Boryeong Reservoir, and the spatial and temporal characteristics of them are compared with each other in the perspective of hydrometeorology (1998 to 2017) and limnology (2010 to 2017). In Korea, Aphanizomenon flourished mainly in high temperature, and the appearance in the low temperature was rare in total five times. The harmful cyanobacteria Aphanizomenon was observed in the low temperature (December to February) in Boryeong Reservoir from 2014, and then reached a maximum value of 2,160 cells mL-1 in January 2017. In addition, the period exceeding 1,000 cells mL-1 at this time was more than 3 months. This was simultaneously associated with abnormal water level fluctuation in the low temperature (<10℃). The large drawdown of water level in the winter season has the potential to promote or amplify the germination and development of harmful algae. Also, subsequent water quality and ecological impacts (e.g., algal toxins and off-flavor substances) need to be considered carefully.

The sewage and wastewater (SAW) are a well-known major source of eutrophication and greentide in freshwaters and also a potential source of thermal pollution; however, there were few approaches to thermal effluent of SAW in Korea. This study was performed to understand the behavioral dynamics of the thermal effluents and their effects on the water quality of the connected streams during winter season, considering domestic sewage, industrial wastewater and hot spring wastewater from December 2015 to February 2016. Sampling stations were selected the upstream, the outlet of SAW, and the downstream in each connected stream, and the water temperature change was monitored toward the downstream from the discharging point of SAW. The temperature effect and its range of SAW on the stream were dependent not only on the effluent temperature and quantity but also on the local air temperature, water temperature and stream discharge. The SAW effects on the stream water temperature were observed with temperature increase by 2.1~5.8℃ in the range of 1.0 to 5.5 km downstream. Temperature effect was the greatest in the hot spring wastewater despite of small amount of effluent. The SAW was not only related to temperature but also to the increase of organic matter and nutrients in the connected stream. The industrial wastewater effluent was discharged with high concentration of nitrogen, while the hot spring wastewater was high in both phosphorus and nitrogen. The difference between these cases was due to with and without chemical T-P treatment in the industrial and the hot spring wastewater, respectively. The chlorophyll-a content of the attached algae was high at the outlet of SAW and the downstream reach, mostly in eutrophic level. These ecological results were presumably due to the high water temperature and phosphorus concentration in the stream brought by the thermal effluents of SAW. These results suggest that high temperature of the SAW needs to be emphasized when evaluating its effects on the stream water quality (water temperature, fertility) through a systematized spatial and temporal investigation.

Thermal effluent of the hot spring has long been a field of interest in the relationship between temperature gradient and freshwater algae in geology, limnology and aquatic ecology throughout the world. On the other hand, many artificial hot springs have been developed in Korea, but the research on them has not been still active. This study was performed every month from December 2015 to September 2016, to elucidate the spatiotemporal effects of thermal wastewater effluent (TWE) on the ecosystem of benthic algal assemblage in four stations (BSU (upstream), HSW (hot spring wastewater outlet), BSD1~2 (downstream)) of the upstream reach of the Buso Stream, a tributary located in the Hantan River basin. During the survey, the influencing distance of temperature on TWE was <1.0 km, and it was the main source of N·P nutrients at the same time. The effects of TWE were dominant at low temperature and dry season (December~March), but it was weak at high temperature and wet season (July~September), reflecting some seasonal characteristics. Under these circumstances, the attached algal communities were identified to 59 genera and 143 species. Of these, the major phylum included 21 genera 83 species of diatoms (58.0%), 9 genera 21 species of blue-green algae (14.7%) and 25 genera 32 species of green algae (22.4%), respectively. The spatiotemporal distribution of them was closely related to water temperature (5℃ and 15℃) and current (0.2 m s-1 and 0.8 m s-1). In the basic environment maintaining a high water temperature throughout the year round, the flora favoring high affinity to PO4 in the water body or preferring stream habitat of abundant NO3-PO4 was dominant. As a result, when compared with the outcomes of previous algal ecology studies conducted in Korea, the Buso Stream was evaluated as a serious polluted state due to persistent excess nutrient supply and high thermal pollution throughout the year round by TWE. It can be regarded as a dynamic ecosystem in which homogeneity (Summer~Autumn) and heterogeneity (Winter~Spring) are repeated between upstream and downstream.

유해조류의 생물학적 제어를 위하여 여과능이 입증된 패류와 동물플랑크톤을 혼합적용하고, 현장적용 가능성을 검토하였다. 실험수는 매년 남조 Microcystis aeruginosa가 대발생하는 일감호 (서울)의 현장수, sediment, 배지를 대형 수조에 일정량 넣고 인위적으로 조류대발생을 일으켜 유지하고 있는 실험수를 이용하였다. 실험은 동물플랑크톤만 처리한 Z군 (40 individuals L-1), 패류만 처리한 M군 (2 individuals L-1), 동물플랑크톤과 패류를 모두 첨가한 ZM군 (Z, M군의 밀도를 합한 것)으로 설계하였다. 수심별 조류제어 효과를 확인하기 위하여 표층, 중층에서 각각 일정량의 실험수를 꺼내 엽록소량의 경시적 변화를 측정하였다. 결과, 중층의 모든 처리구에서 Chl-a의 감소를 보였으며 24시간째 Z군은 63.2%의 제어율을 보인 반면, M군과 ZM군은 각각 79.8%, 90.8%의 제어율을 나타내 뚜렷한 억제효과를 보였다. 표층의 경우, Z군과 ZM군은 각각 51.9%, 63.4% 등으로 50% 이상의 억제효과를 보인 반면, M군의 경우 대조군의 27.4%로서 가장 낮은 제어율을 보였다. 결과를 종합하면, 두 생물제재의 혼합이 수층에 상관없이 그 효과는 입증되었으나 남조 M. aeruginosa의 부유성을 감안한다면, 패류의 적용수심이 조류제어에 매우 중요한 인자임을 알 수 있었다. 따라서 생물제재의 혼합적용이 보다 높은 효과를 보였으며 조류의 생리적 특성과 생물 제재간의 상호관계에 대한 세밀한 연구가 요구되었다.

어린이집 유아들이 공용으로 사용하는 수건의 미생물 오염도와 분리된 식중독 미생물의 장독소 유전자 및 장독소 생산 특성을 분석하여 어린이집 유아 사용 수건의 위생 안전성을 확보하고자 어린이가 손 씻은 후 공용으로 사용 하는 수건 22개 (사용 전 7개, 사용 중 15개)를 연구대상으로 하였다. 일반세균수는 평균 6.2 log CFU/100 cm2로 검출되었고 진균수는 평균 4.1 log CFU/100 cm2로 검출되었 으며 대장균군은 사용 전 수건의 경우 7건 중 4건 (57.1%), 사용 중인 수건의 경우 15건 모두에서 (100%) 검출되었 다. 어린이 사용 수건의 미생물 오염도가 높게 나타나 수 건의 위생적인 살균 세탁 및 상대습도가 낮은 곳에 보관하는 등의 보관 방법 개선이 필요한 것으로 판단되었다. Salmonella spp.의 경우 실험에 사용된 모든 수건에서 검출되지 않았으나, Staph. aureus는 22건 중 5건 (22.7%), B. cereus는 11건 (50.0%)에서 검출되어 B. cereus 오염이 가장 심각한 것으로 나타났다. Staph. aureus 장독소 유전 자와 독소 단백질은 모두 불검출 되었으나 분리 동정된 11균주의 B. cereus 장독소 유전자 실험 결과 hblC, hblD, hblA 유전자가 각각 72.7, 72.7, 54.5% 검출되고 nheA, nheB, nheC 유전자가 각각 81.8, 72.7, 54.5% 검출되었으며 cytK, entFM 장독소 유전자는 각각 45.5, 90.0% 검출 되었다. B. cereus 장독소 실험결과 HBL 장독소는 11균주 중 8균주 (72.7%), NHE 장독소는 5균주 (45.5%) 검출되었고 HBL과 NHE 장독소 중 하나 이상을 생산하는 B. cereus 균주는 10균주 (90.9%)로 나타났다. 수건에 오염된 B. cereus 균주의 교차오염에 따른 식중독 위험성이 상존 하는 것으로 나타나 개인별 수건 또는 종이 타올 사용을 고려하여야 할 것으로 판단되었다.

본 연구는 섬강 수계 하천에서 하천의 형태복잡도와 부착규조류 군집 분포와의 관계를 자연지리, 토지이용도, 수리, 수질요인들과의 관계를 통해 분석하였다. 하천의 형태복잡도는 하천의 입지(고도)와 하폭 그리고 주변의 토지이용도와 밀접한 관계를 나타냈으며, 동시에 하천의 수질과도 유의한 관계를 보여주었다. 즉, 형태복잡도가 높 은 하천은 숲과 농경지의 이용도가 높았으며, 반면 형태 복잡도가 낮은 하천에서는 도시 이용도가 높게 나타났다. 한편, 형태복잡도가 높을수록 하천의 영양염의 농도가 낮 은 결과를 나타냈다. 섬강 수계에서 출현한 부착규조는 총 145 분류군(2목 3아목 8과 26속 125종 15변종 2품종 3아종)이 출현하였다. 하천의 형태복잡도 차이에 관계없 하천 형태복잡도와 부착규조류 군집 분포 119 이 부착규조류 군집의 종조성과 우점종의 차이는 크지 않 았으나 밀도와 지표종의 차이는 뚜렷하게 나타났다. 부착 규조류 지표종은 낮은 형태복잡도를 가진 지점들에서 호 오탁성종의 상대밀도가 높았던 반면, 복잡도가 높은 지점 들에서는 호청수성종의 종수와 상대밀도가 더욱 높았다. 부착규조류 생물지수(TDI, DAIpo)를 이용해 생물학적 수 질을 평가한 결과 형태복잡도가 낮은 지점들에서의 수질 이 상대적으로 불량하게 나타났다. 특히, BOD, TP, PO4-P 농도는 DAIpo와 높은 상관관계를 나타냈다. 결론적으로, 섬강 수계 하천의 형태복잡도는 부착조류 군집의 분포와 밀접한 관계를 보여주었으며, 보다 직접적으로 이들의 관 계는 형태복잡도의 차이를 결정짓는 주변 토지이용의 형 태가 하천수질에 영향을 미쳐 나타난 것으로 이해되었다.

현재 미국 및 유럽에서 공정시험법중 하나로 인정되고 있는 표면시험법을 사용하여 유기물과 함께 또는 유기물없이 세균만 건조된 식품접촉 표면에 서의 살균소독제 유효성에 대한 정보를 제공하고자 식품접촉표면으로 사용되는 스테인리스, 폴리프로필렌 및 실리콘에 Escherochia coli ATCC 10536 또는 Staphylococcus aureus ATCC 6538을 접종하고 살균소독제로서 염화벤잘코늄, 차아염소산나트륨 또는 에탄올을 20 ℃에서 5분간 처리하였다. 그 결과, 각 표면의 종류는 살균소독제의 유효성에 큰 영향을 미치지 않았으며, 200 ppm 농도의 염화벤잘코늄 및 차아염소산나트륨은 유기물질이 존재할 경우 생균수를 4 cfu log10/carrier 이상 감소시키지 못하였으나, 40% 에탄올은 생균수를 4 cfu log10/carrier 이상 감소시키는 것으로 나타났다.