• Fisheries and Aquatic Sciences
• /
• v.1 no.2
• /
• pp.159-167
• /
• 1998

The environmental characteristics in shellfish farms were investigated in the western part of Jinhae Bay, 1996. During summer, anoxia and high nutrient concentrations were found in the bottom waters of shellfish farms. The concentrations of particulate organic species in seawaters were enriched, showing an average 57.44 uM for POC, an average 5.45 uM for PON, and an average 0.42uM for PP. The sediments environment in the farms was very polluted. The concentrations of COD and AVS were more than 20 mg/g.dry and 0.5 mg/g.dry, respectively. The total sedimentation rate was high as an average $7.81g/m^2/day$ with organic matter contents of $26\%$. Oxygen consumption rate was similar to polluted area as an average of $439mg/m^2/day$. Nutrient release rates were an average of $8.25mg/m^2/day$ for nitrogen and an average of $1.38mg/m^2/day$ for phosphorous. The cluster analysis through environmental data in summer indicated that DO, nutrient in the bottom water, and AVS in the sediment were important factors to characterize the polluted environmental site.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.2
• /
• pp.212-218
• /
• 2006

Three out of fourteen Microcystis-dominant cyanobacterial blooms in Central India were found to be toxic to mice ($LD_{50}$ ranging from 35-450 mg bloom dry mass/kg body weight). The liver architecture of the treated mice showed characteristic symptoms of hepatotoxicity relative to the untreated controls, with increased enzyme activities of serum lactate dehydrogenase (LDH), serum glutamate oxaloacetate transaminase (SGOT), alkaline phosphatase (ALP), and serum glutamate pyruvate transaminase (SGPT). RP-HPLC revealed the presence of microcystin-LR, microcystin-RR, and desmethyl microcystin-RR in the given region to maximum amounts of 390, 1,030, and $860{\mu}g/g$ bloom dry weight, respectively, corresponding to a maximum of 2.8 mg/l microcystin-LR in the lake water. Further confirmation of the microcystin variants was conducted using a MALDI-TOF MS analysis.

• Journal of Korea Water Resources Association
• /
• v.53 no.5
• /
• pp.369-381
• /
• 2020

In this paper, observed water quality, algal blooms and flow rates in the Yeongsan River and its boundaries including 8 tributaries and 2 wastewater treatment plants for two years of 2018-2019 were analyzed. It seems effects of non-point source load inputs from basin areas to the river may be significant though the field data availability was limited. The EFDC model was calibrated against data collected from 6 water level monitoring stations and 6 water quality monitoring stations, respectively, in the study area. Water quality improvement scenarios were developed assuming 50% and 75% reductions of major pollution sources including treatment plants and tributaries. The developed scenarios were applied to the EFDC model to estimate effects on algal bloom occurrences in the Seungchon weir and Juksan weir. Improvement of the effluent of Gwangju 1 WWTP by 75% did not show any effect on algal blooms for two weir locations. The major tributary affecting algal blooms in the Seungchon weir was the Hwangryong River. The Jisuk stream was found as the most important tributary for the Juksan weir followed by the effect of the Hwangryong River. Though it seems other scattered small nonpoint source load input to the Yeongsan river also seem to be important, it was not possible to reflect their effects appropriately due to field data availability.

• Korean Journal of Ecology and Environment
• /
• v.46 no.1
• /
• pp.1-9
• /
• 2013

Algal blooms in potable water supplies are becoming an increasingly prevalent and serious water quality problem around the world. In addition to precipitating taste and odor problems, blooms damage the environment, and some classes like cyanobacteria (blue-green algae) release toxins that can threaten human health, even causing death. There is a recognized need in the water industry for models that can accurately forecast in real-time algal bloom events for planning and mitigation purposes. In this study, using data for an interconnected system of rivers and reservoirs operated by a New Jersey water utility, various ANN models, including both discrete prediction and classification models, were developed and tested for forecasting counts of three different algal classes for one-week and two-weeks ahead periods. Predictor model inputs included physical, meteorological, chemical, and biological variables, and two different temporal schemes for processing inputs relative to the prediction event were used. Despite relatively limited historical data, the discrete prediction ANN models generally performed well during validation, achieving relatively high correlation coefficients, and often predicting the formation and dissipation of high algae count periods. The ANN classification models also performed well, with average classification percentages averaging 94 percent accuracy. Despite relatively limited data events, this study demonstrates that with adequate data collection, both in terms of the number of historical events and availability of important predictor variables, ANNs can provide accurate real-time forecasts of algal population counts, as well as foster increased understanding of important cause and effect relationships, which can be used to both improve monitoring programs and forecasting efforts.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.168-168
• /
• 2023

The frequent occurrence of cyanobacterial harmful algal blooms (CHABs) in inland waters under climate change seriously damages the ecosystem and human health and is becoming a big problem in South Korea. Satellite remote sensing is suggested for effective monitoring CHABs at a larger scale of water bodies since the traditional method based on sparse in-situ networks is limited in space. However, utilizing a standalone variable of satellite reflectances in common CHABs dual-models, which relies on both chlorophyll-a (Chl-a) and phycocyanin or cyanobacteria cells (Cyano-cell), is not fully beneficial because their seasonal variation is highly impacted by surrounding meteorological and bio-environmental factors. Along with the development of Artificial Intelligence (AI), monitoring CHABs from space with analyzing the effects of environmental factors is accessible. This study aimed to investigate the potential application of AI in the dual-model strategy (Chl-a and Cyano-cell are output parameters) for monitoring seasonal dynamics of CHABs from satellites over Korean inland waters. The Sentinel-3 satellite was selected in this study due to the variety of spectral bands and its unique band (620 nm), which is sensitive to cyanobacteria. Via the AI-based feature selection, we analyzed the relationships between two output parameters and major parameters (satellite water-leaving reflectances at different spectral bands), together with auxiliary (meteorological and bio-environmental) parameters, to select the most important ones. Several AI models were then employed for modelling Chl-a and Cyano-cell concentration from those selected important parameters. Performance evaluation of the AI models and their comparison to traditional semi-analytical models were conducted to demonstrate whether AI models (using water-leaving reflectances and environmental variables) outperform traditional models (using water-leaving reflectances only) and which AI models are superior for monitoring CHABs from Sentinel-3 satellite over a Korean inland water body.

• Journal of the Korean Ceramic Society
• /
• v.53 no.1
• /
• pp.1-6
• /
• 2016

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating ($1000^{\circ}C$ for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and carbonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. $CO_2$ implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

• Journal of Korea Water Resources Association
• /
• v.49 no.9
• /
• pp.789-798
• /
• 2016

Frequent algal blooms at major river systems in Korea have been serious social and environmental problems. Especially, the appearance of cyanobacteria with toxic materials is a threat to secure a safe drinking water. In order to model the behaviour of cyanobacteria cell number, an exclusive causality analysis using prewhitening technique was introduced to delineate effective parameters to predict the cell numbers of cyanobacteria in Seungchon Weir and Juksan Weir along Youngsan river system. Both input and output transfer function models were obtained to explain temporal variation of cyanobacteria cell number. A threshold behaviour of water temperature was implemented into the model development to consider winter characteristic of cyanobacteria. The implementation of water temperature threshold into the model structure improves the predictability in simulation. Even though the input output transfer model cannot completely explained all blooms of cyanobacteria, the simple structure of model provide a feasibility in application which can be important in practical aspect.

• Journal of Energy Engineering
• /
• v.26 no.1
• /
• pp.68-75
• /
• 2017

Global warming affects water supply and water resources throughout the world. In many countries, climate change affects significantly on the fresh water resources. Vietnam is exposed mainly, to landslides and floods triggered by tropical storms and monsoon rains, although storm surge, whirlwind, river bank and coastal line erosion, hail rain. In addition to the prevalent drought, there are many major water challenges, including water availability, stress, scarcity and accessibility, because of poor resource management. Fast growth of urbanization, industrialization and population growth, agricultural activities and climate change cause heavy pressure on water quality. Both domestic and industrial wastewater, as well as storm water shares the same drainage. The common facilities for wastewater treatment are not available. Therefore, wastewater is treated only superficially and then discharged directly into rivers and lakes causing serious pollution of surface water environment. In this paper, we reported the severe water crisis and massive green algal blooms formation in Vietnam rivers and lakes. This is the biggest evidence of climate change variations in Vietnam.

• ALGAE
• /
• v.26 no.2
• /
• pp.181-192
• /
• 2011

Ballasting and deballasting of shipping vessels in foreign ports have been reported worldwide as a vector of introduction of non-native aquatic plants and animals. Recently, attention has turned to ballast water as a factor in the global increase of harmful algal blooms (HABs). Many species of microalgae, including harmful dinoflagellate species, can remain viable for months in dormant benthic stages (cysts) in ballast sediments. Over a period of four years, we surveyed ballast water and sediment of ships docked in two ports of Tampa Bay, Florida, USA. Sampling conditions encountered while sampling ballast water and sediments were vastly different between vessels. Since no single sample collection protocol could be applied, existing methods for sampling ballast were modified and new methods created to reduce time and labor necessary for the collection of high-quality, qualitative samples. Five methods were refined or developed, including one that allowed for a directed intake of water and sediments. From 63 samples, 1,633 dinoflagellate cysts and cyst-like cells were recovered. A native, cyst-forming, harmful dinoflagellate, Alexandrium balechii (Steidinger) F. J. R. Taylor, was collected, isolated, and cultured from the same vessel six months apart, indicating that ships exchanging ballast water in Tampa Bay have the potential to transport HAB species to other ports with similar ecologies, exposing them to non-native, potentially toxic blooms.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.5
• /
• pp.523-530
• /
• 2020

Based on the results of harmful algal blooms (HABs) monitoring by the National Institute of Fisheries Science and local governments, the effects of changes in the marine environment on HABs are described. Since the beginning of HABs monitoring in 1972, they continued to increase from the 1980s to the 1990s. After the largest number of HAB incidents (109) in 1998; the trend declined until the 2010s. Most HABs in the 1970s were caused by diatoms. In the 1980s, coastal dinoflagellates caused HABs; Cochlodinium polykrikoides blooms have been occurring continuously since 1993. There are three HAB species that cause damage to fisheries in Korea. The high-density bloom of Karenia mikimotoi caused mass mortality in shellfish in Jinhae Bay in 1981. Karenia sp. blooms occurring around Tongyeong in 1992 killed aquaculture fish. Since the occurrence of the largest fisheries damage of KRW 76.6 billion in 1995 caused by C. polykrikoides blooms, they have been occurring continuously. The concentration of nutrients in coastal waters was the highest in the 1980s and has declined since the mid-1990s. This reduction in nutrient concentration is a good explanation for the decreasing number of HABs. Since 2016, a summer high water temperature of 30℃ or more has appeared, and the range and scale of C. polykrikoides blooms have been greatly reduced. In 2016, K. mikimotoi blooms occurred around Wando, Jangheung and Goheung and small scale blooms of C. polykrikoides occurred around Yeosu. There were no C. polykrikoides blooms in 2017; however, Alexandrium affine blooms occurred from Yeosu to Tongyeong. There was a small-scale blooms of C. polykrikoides in 2018 compared to those in the previous years. Our results show that reduction in nutrients and the high water temperature owing to climate change are a good explanation for variation in HABs in Korean coastal waters.