계절적 유량과 1차 생산성 영양염류 인자에 따른 우리나라 저수지 수질의 장기적 변동

블랜디나제네스카코레 ( Blandina Genes Kakore ),이상재 ( Sang-jae Lee ),안광국 ( Kwang-guk An ) 한국환경생태학회 2021 한국환경생태학회 학술대회지 Vol.2021 No.2

In the recent few decades, a lot of environmental ecological pollution and public health issues seem to be connected to poor water quality. The deterioration of water quality is a major concern in the world currently. The Seomjingan River Dam is one of the biggest dams in South korea and it was built for the purpose of preserving the water and reducing floood damages in the areas downstream. The main goal of this research was to decribe the changes in water quality that occur within and after the dam for over a long period, the dataset used was of 10 years (2011-2020). Seasonal analysis of 9 physico chemical water quality variables showed that during the monsoon rain season there was great changes in the water quality variables of which Total Nitrogen (TN), Total Phosphate (TP) and Total Suspended Solids (TSS) were largely influenced to change especially in the inflow site. Inter-annual analysis of 9 water quality variables showed that in between the 10 years indicated that there was decrease of BOD before the reservoir and after the reservoir but it increased within the reservoir. There was high values of TSS, BOD, TP, TN, and TOC in the inlet river site which clarified that the presence of great agricultural and industrial runoff into the river entering the reservoir. This analysis also showed showed that there was decrease of Chl-a throughout the years in the reservoir but there was increase in the washout from the reservoir which indicated that the water that there is primary productivity within the reservoir which affected the water quality. An Empirical analysis also deduced that this reservoir was a P-limited reservoir, and TP had a positive relationship to Chlorophyll-a which means that the TP coming in the reservoir was used for production as it reduced after the reservoir. The trophic State Index analysis for the reservoir indicated that Seomjin dam gets into a eutrophic state during the monsoon perios and this clarifies that there is high nutient runoff into the dam during the monsoon and hence productivity which was indicated by the high CHL-a that is dictated after the dam. In general, from this analysis it can be said that despite the water quality going into the reservoir being bad and that it influenced primary reproduction and sedimentation within the reservoir but due to these processes the water released from the dam seem to be in a better quality than when it entered the reservoir. It is therefore safe to think due to the results found in this study that the reservoir is in a high probability of facing degradation within the next few years.

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.

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.

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.