다목적 음용수 시설에서의 다변량 기법에 의한 시공간적 계절 수질 평가

우스만아티크 ( Usman Atique ),마문MD ( Md Mamun ),안광국 ( Kwang-guk An ) 한국환경생태학회 2021 한국환경생태학회 학술대회지 Vol.2021 No.2

A long-term water quality evaluation of critical water quality determinants was planned to explore a sustainable water quality supply and management suitability. We analyzed the spatio-seasonal variabilities of ambient nutrients and their enrichment, sestonic chlorophyll-a (CHL-a), the influence of flow regime, and monsoon precipitation through multivariate techniques (PCA, DA) in the second-largest reservoir in South Korea during 2010 -2020. The outcomes sharply defined the maneuvering role of monsoon-mediated flow regime effects on reservoir water chemistry. The reservoir showed a poor to average nutrient condition. An occasional emergence of total coliform bacteria (TCB) of 16000 MPNmL-100 at S3 may break out the waterborne diseases among the children. The Mann-Kendal test exhibited a consistent increase in water temperature (WT), conductivity, and chemical oxygen demand (COD), which may critically endanger a safer drinking water supply. Drought and flood dynamics showed seasonal heterogeneities in CHL-a, TCB, total suspended solids (TSS), and nutrients (N, P). The N:P ambient ratios are a more reliable predictor of sestonic CHL-a productivity, while the reservoir is P-limited. Total phosphorus (TP) showed a strong negative (R2 = 0.59), while TSS (R2 = 0.50) and CHL-a (R2 = 0.32) displayed a strong positive association with reservoir outflow, indicating flow regime impact on enhancing water quality and clarity. Seasonal trophic state index revealed oligo-mesotrophic nutrient enrichment, a good sign for long-term water quality management with limited risk of eutrophication. In conclusion, monsoon arbitrated the flood and drought conditions and disturbed the flow regime influencing the seasonal water quality. Furthermore, increasing intensive crop farming may threaten oligotrophic nutrient enrichment.

토지이용도, 유기물, Chl-a의 영양염류간의 상호작용 및 장마철 강우 시 영양염류 상태에 따른 농업용 저수지의 분류

우스만아티크 ( Usman Atique ),블랜디나제네스카코레 ( Blandina Genes Kakore ),안광국 ( Kwang-guk An ) 한국환경생태학회 2021 한국환경생태학회 학술대회지 Vol.2021 No.2

This study explored a range of agricultural reservoirs characterized according to their land-use patterns. The classifications included cropland, forest, urban and estuarine regions in the South Korean peninsula during 2008-2017. We analyzed the inter-annual and seasonal water quality deviation with monsoon precipitation intensity, and empirical models were developed on nutrients, their ambient ratios, and chlorophyll-a (Chl-a), total organic carbon (TOC), and ratios of chlorophyll-a with nutrient contributing factors. The multi-metric water pollution index (WPIKR) reflected the chemical health of reservoirs in relation to monsoon and land use patterns. The results indicated the intensity of monsoon rainfall tremendously influenced nutrients, Chl-a, and TOC levels in the cropland and urban reservoirs. However, TOC disclosed highest relationship with Chl-a in cropland (R2 = 0.66) and forest (R2 = 0.71) regions. Secchi disk depth (SDD) negatively correlated with the solids regime, TP and Chl-a in the cropland and estuarine regions. On the other hand, the trophic state index specified the majority of reservoirs in zooplankton grazing state except a few in the estuarine region showing the propensity of blue-green algae presence. Further principal component analysis (PCA) designated cropland region characterized by higher TP and Chl-a level within increasing Carlson’s trophic state index (CTSI), the urban region receiving higher sediments and chemical oxygen demand. On the contrary, the forest region tended to have higher organic matter (TOC), while estuarine was characterized by higher electrical conductivity (EC). Hierarchical cluster analysis (HCA) showed that cropland region reservoirs are nearer to urban reservoirs in deteriorating water quality. Based on WPIKR results, cropland and urban region reservoirs reflected as ‘poor’, estuarine as ‘fair’ condition while forest region indicated ‘excellent to good’ chemical health status. According to CTSI, forest and estuarine reservoirs were in the oligotrophic state, urban in mesotrophic and cropland region reservoirs from mesotrophic to eutrophic state. This study advocates a reduction in phosphorus yielding fertilizers in the Korean Peninsula that could help to mitigate the impending eutrophication events in lentic ecosystems in the future.

하천 어류군집에 기반한 생태학적 건강도 악화를 초래하는 대규모 보 건설의 영향

우스만아티크 ( Usman Atique ),마문MD ( Md Mamun ),남스라이자갈 ( Namsrai Jargal ),안광국 ( Kwang-guk An ) 한국환경생태학회 2021 한국환경생태학회 학술대회지 Vol.2021 No.2

Massive weirs installations in larger rivers could be strongly detrimental to the ecosystem services, water chemistry, and fish assemblages due to unpredicted hydrological modifications and new microhabitat features. This study highlighted the impact of three gigantic weirs erected in Geum River during 2010-2017 compared to the riverine zones from upstream to downstream. Nineteen water quality parameters were studied at 21 sites, while fish assemblages were investigated at 26 sites. The data evaluations included the application of index of biotic integrity (IBI), water pollution index (WPI), and principal component analysis (PCA). The results disclosed seasonal and spatial heterogeneities indicating gradual water quality degradation. TOC, ambient ratios (N:P), Chl-a, and conductivity are dissimilar, while BOD, COD, TSS, TP, and fecal coliforms are directly influenced by seasonal precipitation. Nutrients (N, P) exhibited week relationships in weirs (GW: R2 = 0.21, SW: R2 = 0.12, BW: R2 = 0.25), but stronger in the upstream zone (R2 = 0.74) of the river. WPI, however, designated the weirs and river zones into ‘fair to very poor’ water quality status. Likewise, the ecological health based on IBI specified sites into ‘fair to poor’ health. Overall, 60 fish species and 64637 fish individuals were observed, with 81.24% individuals observed at the weir sites, while Squalidus japonicus coreanus (18.47 % RA) and Hemibarbus labeo (9.25 % RA) were relatively the most abundant fish species sampled. The number of fish species and the total number of individuals gradually declined along the river gradient. PCA grouped the dominant factors in the different zones of the river with a percent cumulative variance 81.80%. The tolerant and omnivorous fish species confirmed aggregations at the downstream zone accompanied by increased insectivorous species. In conclusion, the impacts of weir installation manifested assiduously and indicted increasingly deteriorating water chemistry, gradually declining fish assemblages with jumbled distribution, perturbed microhabitat conditions, and inclusively deteriorating ecological health status.

낙동강 인공구조물에 의한 자연하천 연속성의 단절 이론 증명

블랜디나제네스카코레 ( Blandina Genes Kakore ),우스만아티크 ( Usman Atique ),안광국 ( Kwang-guk An ) 한국환경생태학회 2021 한국환경생태학회 학술대회지 Vol.2021 No.2

The primary goals of this research were to demonstrate the Serial Discontinuity Concept in a regulated natural river and to see how weirs alter physicochemical water quality going down the river and within different seasons. Monsoon rains control river runoff and chemical water component concentrations in the river as it flows downstream. The Nakdong River contains eight weirs that were built with the purpose of securing the water resource to solve the problems of water scarcity and improving the water quality in the Nakdong basin. Despite these positive objectives, the constructed weirs have mainly caused changes in the river lotic system making it to have the characteristics of a lentic system. The increase and decrease in Chl-a amounts in the midstream and downstream weirs show that there is a discontinuity in nutrient resources (Total Phosphorus) in the river from an upper weir to the next one. Other water physicochemical factors such as COD, EC and TSS were also analyzed and showed to have fluctuations going down the river, mostly increasing. The effect of weirs can also be seen in the residence time differences between all the weirs, which also support different chemical processes to happen. From the statistical correlation analysis in this study, Chl-a showed to have an average positive relationship with residence time. The correlation analysis showed there was high correlation of water quality factors down the river and Chl-a was positively correlated with Inflow in each weir from the weir before it. With the results that were found in this study it is clear that due to presence of weirs in this natural river, the continuity of the water chemistry is distorted and therefore there is Serial discontinuity.

다목적 저수지 유입 영양염류, Chl-a 상태에 대한 장마기간의 장기적 및 계절 영향 평가

남스라이자갈 ( Namsrai Jargal ),우스만아티크 ( Usman Atique ),마문MD ( Md Mamun ),블랜디나제네스카코레 ( Blandina Genes Kakore ),안광국 ( Kwang-guk An ) 한국환경생태학회 2021 한국환경생태학회 학술대회지 Vol.2021 No.2

Due to rapid eutrophication, sustainable water quality management and supply are essential in drinking water sources and aquatic biota in large reservoirs. We evaluated the potentially crucial factors influencing the algal chlorophyll (Chl-a), nutrients, and the links between the rainfall and other vital elements in a large multipurpose reservoir (Yongdam Reservoir) during 2013-2019. We developed the empirical models on algal Chl-a, total phosphorus (TP), total nitrogen (TN), and TN:TP’s ambient ratios considering the maneuvering influence of Asian monsoons. The intensive rainfall during the monsoon months strongly impacted the nutrient regime and other vital factors. The seasonal patterns of algal Chl-a varied in response to the nutrient contents (TN, TP), suspended solids, and ambient N:P ratios along the longitudinal gradient. The conditional plot analysis, empirical modeling, and observations supported an overall P-limitation scenario, as was evident from the magnitude of N:P ratios (R2 = 0.36, F = 24.9, p < 0.001). Furthermore, the reservoir’s trophic status alluded to the larger particles and blue-green algae during the monsoon and postmonsoon months. The correlation analysis, Mann- Kendall trend test, and principal component analysis illustrated compelling links between CHL-a, TP, and rainfall regime. The outcomes suggested the reservoir was primarily controlled by phosphorus limitation, with an increasing CHL-a tendency along with nitrogen dilution. However, a slight decline in phosphorus was also detected. The Yongdam Reservoir is under the threat of recurrent eutrophication events that could jeopardize this vital drinking water facility due to increasing agricultural and anthropic activities.