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Kang M, Le VV, Ko SR, Chun SJ, Choi DY, Shin Y, Kim K, Baek SH, Ahn CY. Effect of rainfall in shaping microbial community during Microcystis bloom in Nakdong River, Korea. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 928:172482. [PMID: 38621529 DOI: 10.1016/j.scitotenv.2024.172482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/20/2024] [Accepted: 04/12/2024] [Indexed: 04/17/2024]
Abstract
Various environmental factors play a role in the formation and collapse of Microcystis blooms. This study investigates the impact of heavy rainfall on cyanobacterial abundance, microbial community composition, and functional dynamics in the Nakdong River, South Korea, during typical and exceptionally rainy years. The results reveal distinct responses to rainfall variations, particularly in cyanobacterial dominance and physicochemical characteristics. In 2020, characterized by unprecedented rainfall from mid-July to August, Microcystis blooms were interrupted significantly, exhibiting lower cell densities and decreased water temperature, compared to normal bloom patterns in 2019. Moreover, microbial community composition varied, with increases in Gammaproteobacteria and notably in genera of Limnohabitans and Fluviicola. These alterations in environmental conditions and bacterial community were similar to those of the post-bloom period in late September 2019. It shows that heavy rainfall during summer leads to changes in environmental factors, consequently causing shifts in bacterial communities akin to those observed during the autumn-specific post-bloom period in typical years. These changes also accompany shifts in bacterial functions, primarily involved in the degradation of organic matter such as amino acids, fatty acids, and terpenoids, which are assumed to have been released due to the significant collapse of cyanobacteria. Our results demonstrate that heavy rainfall in early summer induces changes in the environmental factors and subsequently microbial communities and their functions, similar to those of the post-bloom period in autumn, leading to the earlier breakdown of Microcystis blooms.
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Affiliation(s)
- Mingyeong Kang
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Ve Van Le
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - So-Ra Ko
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Seong-Jun Chun
- LMO Research Team, National Institute of Ecology, 1210 Geumgang-ro, Maseo-myeon, Seocheon 33657, Republic of Korea
| | - Dong-Yun Choi
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Yuna Shin
- Water Quality Assessment Research Division, National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Kyunghyun Kim
- Water Quality Assessment Research Division, National Institute of Environmental Research, Incheon 22689, Republic of Korea
| | - Seung Ho Baek
- Ecological Risk Research Department, Korea Institute of Ocean Science and Technology (KIOST), Geoje 53201, Republic of Korea; Department of Ocean Science, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Chi-Yong Ahn
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
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Nam SH, Kwon S, Kim YD. Development of a basin-scale total nitrogen prediction model by integrating clustering and regression methods. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 920:170765. [PMID: 38340839 DOI: 10.1016/j.scitotenv.2024.170765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/15/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024]
Abstract
Nutrient runoff into rivers caused by human activity has led to global eutrophication issues. The Nakdong River in South Korea is currently facing significant challenges related to eutrophication and harmful algal blooms, underscoring the critical importance of managing total nitrogen (T-N) levels. However, traditional methods of indoor analysis, which depend on sampling, are labor-intensive and face limitations in collecting high-frequency data. Despite advancements in sensor allowing for the measurement of various parameters, sensors still cannot directly measure T-N, necessitating surrogate regression methods. Therefore, we conducted T-N predictions using a water quality dataset collected from 2018 to 2022 at 157 observatories within the Nakdong River basin. To account for the water quality characteristics of each location, we employed a clustering technique to divide the basin and compared a Gaussian mixture model with K-means clustering. Moreover, optimal regressor for each cluster was selected by comparing multiple linear regression (MLR), random forest, and XGBoost. The results showed that forming four clusters via K-means clustering was the most suitable approach and MLR was reasonably accurate for all clusters. Subsequently, recursive feature elimination cross-validation was used to identify suitable parameters for T-N prediction, thus leading to the construction of high-accuracy T-N prediction models. Clustering was useful not only for improving the regressors but also for spatially analyzing the water quality characteristics of the Nakdong River. The MLR model can reveal causal relationships and thus is useful for decision-making. The results of this study revealed that the combination of a simple linear regression model and clustering method can be applied to a wide watershed. The clustering-based regression model showed potential for accurately predicting T-N at the basin level and is expected to contribute to nationwide water quality management through future applications in various fields.
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Affiliation(s)
- Su Han Nam
- Department of Civil and Environmental Engineering, Myongji University, Yongin, South Korea
| | - Siyoon Kwon
- Center for Water and the Environment, Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Young Do Kim
- Department of Civil and Environmental Engineering, Myongji University, Yongin, South Korea.
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Kim J, Lee G, Han S, Kim MJ, Shin JH, Lee S. Microbial communities in aerosol generated from cyanobacterial bloom-affected freshwater bodies: an exploratory study in Nakdong River, South Korea. Front Microbiol 2023; 14:1203317. [PMID: 37520352 PMCID: PMC10374321 DOI: 10.3389/fmicb.2023.1203317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/20/2023] [Indexed: 08/01/2023] Open
Abstract
Toxic blooms of cyanobacteria, which can produce cyanotoxins, are prevalent in freshwater, especially in South Korea. Exposure to cyanotoxins via ingestion, inhalation, and dermal contact may cause severe diseases. Particularly, toxic cyanobacteria and their cyanotoxins can be aerosolized by a bubble-bursting process associated with a wind-driven wave mechanism. A fundamental question remains regarding the aerosolization of toxic cyanobacteria and cyanotoxins emitted from freshwater bodies during bloom seasons. To evaluate the potential health risk of the aerosolization of toxic cyanobacteria and cyanotoxins, the objectives of this study were as follows: 1) to quantify levels of microcystin in the water and air samples, and 2) to monitor microbial communities, including toxic cyanobacteria in the water and air samples. Water samples were collected from five sites in the Nakdong River, South Korea, from August to September 2022. Air samples were collected using an air pump with a mixed cellulose ester membrane filter. Concentrations of total microcystins were measured using enzyme-linked immunosorbent assay. Shotgun metagenomic sequencing was used to investigate microbial communities, including toxic cyanobacteria. Mean concentrations of microcystins were 960 μg/L ranging from 0.73 to 5,337 μg/L in the water samples and 2.48 ng/m3 ranging from 0.1 to 6.8 ng/m3 in the air samples. In addition, in both the water and air samples, predominant bacteria were Microcystis (PCC7914), which has a microcystin-producing gene, and Cyanobium. Particularly, abundance of Microcystis (PCC7914) comprised more than 1.5% of all bacteria in the air samples. This study demonstrates microbial communities with genes related with microcystin synthesis, antibiotic resistance gene, and virulence factors in aerosols generated from cyanobacterial bloom-affected freshwater body. In summary, aerosolization of toxic cyanobacteria and cyanotoxins is a critical concern as an emerging exposure route for potential risk to environmental and human health.
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Affiliation(s)
- Jinnam Kim
- Major of Food Science & Nutrition, Division of Food Science, College of Fisheries Science, Pukyong National University, Busan, Republic of Korea
| | - GyuDae Lee
- Department of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea
| | - Soyeong Han
- Major of Food Science & Nutrition, Division of Food Science, College of Fisheries Science, Pukyong National University, Busan, Republic of Korea
| | - Min-Ji Kim
- Department of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea
| | - Jae-Ho Shin
- Department of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea
- NGS Core Facility, Kyungpook National University, Daegu, Republic of Korea
| | - Seungjun Lee
- Major of Food Science & Nutrition, Division of Food Science, College of Fisheries Science, Pukyong National University, Busan, Republic of Korea
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Park JH, Lee H, Zhumabieke M, Kim SH, Shin KH, Khim BK. Basin-specific pollution and impoundment effects on greenhouse gas distributions in three rivers and estuaries. WATER RESEARCH 2023; 236:119982. [PMID: 37087919 DOI: 10.1016/j.watres.2023.119982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/12/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023]
Abstract
Large uncertainties exist regarding the combined effects of pollution and impoundment on riverine greenhouse gas (GHG) emissions. It has also been debated whether river eutrophication can transform downstream estuaries into carbon sinks. To assess human impacts on the riverine and estuarine distributions of CO2, CH4, and N2O, two source-to-estuary surveys along three impounded rivers in Korea were combined with multiple samplings at five or six estuarine sites. The basin-wide surveys revealed predominant pollution effects generating localized hotspots of riverine GHGs along metropolitan areas. The localized pollution effect was pronounced in the lower Han River and estuary adjacent to Seoul, while the highest GHG levels in the upper Yeongsan traversing Gwangju were not carried over into the faraway estuary. CH4 levels were elevated across the eutrophic middle Nakdong reaches regulated by eight cascade weirs in contrast to undersaturated CO2 indicating enhanced phytoplankton production. The levels of all three GHGs tended to be higher in the Han estuary across seasons. Higher summer-time δ13C-CH4 values at some Nakdong and Yeongsan estuarine sites implied that temperature-enhanced CH4 production may have been dampened by increased CH4 oxidation. Our results suggest that the location and magnitude of pollution sources and impoundments control basin-specific longitudinal GHG distributions and estuarine carryover effects, warning against simple generalizations of eutrophic rivers and estuaries as carbon sinks.
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Affiliation(s)
- Ji-Hyung Park
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea.
| | - Hyunji Lee
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Maidina Zhumabieke
- Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Seung-Hee Kim
- Department of Marine Science and Convergence Engineering, Hanyang University ERICA, Ansan 15588, Republic of Korea
| | - Kyung-Hoon Shin
- Department of Marine Science and Convergence Engineering, Hanyang University ERICA, Ansan 15588, Republic of Korea
| | - Boo-Keun Khim
- Department of Oceanography and Marine Research Institute, Pusan National University, Busan 46241, Republic of Korea
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Key factors determining water quality, fish community dynamics, and ecological health in an Asian temperate lotic system. ECOL INFORM 2022. [DOI: 10.1016/j.ecoinf.2022.101890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Anam GB, Govarthanan M, Ahn YH. Assessment of nitrogen interaction with temperature on the growth and toxin production of mat-forming toxin-producing Anagnostidinema carotinosum. J Appl Microbiol 2022; 133:2851-2863. [PMID: 35983987 DOI: 10.1111/jam.15784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/25/2022] [Accepted: 08/14/2022] [Indexed: 11/29/2022]
Abstract
AIMS Global warming and eutrophication contribute to the severity of cyanobacteria blooms. However, it is unclear how these factors influence the growth and toxin production of Anagnostidinema carotinosum. METHODS AND RESULTS Based on morphological and molecular analysis, this is the first time A. carotinosum was identified in South Korea. The interactive effect of temperature (25, 30 or 34 °C) and nitrogen (2.5, 3.5 or 4.5 mg NO3 -N l-1 ) on A. carotinosum growth and toxin production were studied. Increasing nitrogen limitation reflects reduced growth and chlorophyll-a content at all temperatures. However, the growth was effective under nitrogen limitation when temperatures exceeded 25 °C. The maximum growth was found at 30 °C, followed by 34 °C under higher nitrate levels (3.5 and 4.5 mg l-1 ). In addition, the cell microcystin and anatoxin-a quota increased significantly at 25 °C with increasing nitrate limitation, decreasing considerably at 30 °C in the same nitrate gradient. CONCLUSION These results suggested temperatures stimulate A. carotinosum growth at 30 and 34 °C and cellular toxin quota at 25 and 34 °C with increasing NO3 -N levels. SIGNIFICANCE AND IMPACT OF THE STUDY These findings imply that limiting nitrogen input alone can effectively reduce biomass; however, controlling A. carotinosum and its toxins at higher temperatures under nitrate limitation is necessary for water quality.
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Affiliation(s)
- Giridhar Babu Anam
- Department of Civil Engineering, Yeungnam University, Gyeongsan, Gyeongbuk, Republic of Korea
| | - Muthusamy Govarthanan
- Department of Environmental Engineering, Kyungpook National University, Deagu, South Korea.,Department of Biomaterials, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai, India
| | - Young-Ho Ahn
- Department of Civil Engineering, Yeungnam University, Gyeongsan, Gyeongbuk, Republic of Korea
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Yadav S, Anam GB, Ahn YH. Comparative growth characteristics and interspecific competitive interaction of two cyanobacteria, Phormidium autumnale and Nostoc sp. . JOURNAL OF ENVIRONMENTAL QUALITY 2022; 51:78-89. [PMID: 34786721 DOI: 10.1002/jeq2.20305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/25/2021] [Indexed: 06/13/2023]
Abstract
This study examined the growth characteristics and competitive interaction of two cyanobacteria, Phormidium autumnale GJ_2B_I1 and Nostoc sp. DS_2B_I1, which were newly isolated from a southeast river (Nakdong) during the cyanobacterial harmful algal bloom (CyanoHAB) season in Korea. As major environmental parameters, water temperature (25 and 30 °C) and alkalinity (19-78 mg CaCO3 L-1 ) and nitrate concentration (1.5-3.5 mg NO3 -N L-1 ) were selected based on the water environmental monitoring data during the CyanoHAB season. Unlike P. autumnale, Nostoc sp. has a relatively high growth rate under both monoculture and co-culture and prefers the maximum environmental conditions (30 °C and 78 mg CaCO3 L-1 ; pH 9) during the CyanoHAB season. In addition, the growth of P. autumnale is relatively unaffected by alkalinity. Nitrogen (N) stress also has a limiting effect in the interspecific interactions of both cyanobacterial strains. All other cases except for Nostoc sp. in a co-culture showed a considerable increase in growth rate with increasing N content (1.5-3.5 mg NO3 -N L-1 ), showing 20-64% under the minimum field conditions (25 °C and 19 mg CaCO3 L-1 ; pH 7) and 18-140% under the maximum field conditions. The results show that the growth of P. autumnale can be stimulated by enhanced N stress. On the other hand, Nostoc sp. is less affected by N stress compared with P. autumnale. Therefore, it has excellent potential to be a major group of CyanoHABs because of their relatively high growth rate, particularly in the range of N tested.
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Affiliation(s)
- Seema Yadav
- Dep. of Civil Engineering, Yeungnam Univ., Gyeongsan, Gyeongbuk, 38541, Republic of Korea
| | - Giridhar Babu Anam
- Dep. of Civil Engineering, Yeungnam Univ., Gyeongsan, Gyeongbuk, 38541, Republic of Korea
| | - Young-Ho Ahn
- Dep. of Civil Engineering, Yeungnam Univ., Gyeongsan, Gyeongbuk, 38541, Republic of Korea
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Marion GS, Jupiter SD, Radice VZ, Albert S, Hoegh-Guldberg O. Linking isotopic signatures of nitrogen in nearshore coral skeletons with sources in catchment runoff. MARINE POLLUTION BULLETIN 2021; 173:113054. [PMID: 34744009 DOI: 10.1016/j.marpolbul.2021.113054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 09/20/2021] [Accepted: 10/10/2021] [Indexed: 06/13/2023]
Abstract
We use a multi-tracer approach to identify catchment sources of nitrogen (N) in the skeletons of nearshore Porites corals within the Great Barrier Reef. We measured δ15N, δ13C and C:N ratios of particulate organic matter (POM) sampled from the Pioneer River catchment and identified five distinct end-members: (1) marine planktonic and algal-dominated matter with higher δ15N values from the river mouth and coastal waters; (2) estuarine planktonic and algal matter with lower δ15N values associated with estuarine mixing; (3) lower river freshwater phytoplankton and algal-dominated matter in stratified reservoirs adjacent to catchment weirs, with the 15N-enriched source likely caused by microbial remineralization and denitrification; (4) upper river low δ15N terrigenous soil matter eroded from cane fields bordering waterways; and (5) terrestrial plant detrital matter in forest streams, representing a low δ15N fixed atmospheric nitrogen source. The δ15N values of adjacent, nearshore Porites coral skeletons is reflective of POM composition in coastal waters, with 15N-enriched values reflective of transformed N during flood pulses from the Pioneer River.
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Affiliation(s)
- Guy S Marion
- ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Stacy D Jupiter
- ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, QLD 4072, Australia; ARC Centre of Excellence for Coral Reef Studies, Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia; Wildlife Conservation Society, Melanesia Program, 11 Ma'afu St, Suva, Fiji.
| | - Veronica Z Radice
- ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, QLD 4072, Australia; Old Dominion University, Norfolk, VA, USA
| | - Simon Albert
- School of Civil Engineering, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ove Hoegh-Guldberg
- ARC Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, QLD 4072, Australia; School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; Global Change Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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Long-Term Water Quality Patterns in an Estuarine Reservoir and the Functional Changes in Relations of Trophic State Variables Depending on the Construction of Serial Weirs in Upstream Reaches. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182312568. [PMID: 34886296 PMCID: PMC8656708 DOI: 10.3390/ijerph182312568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/14/2021] [Accepted: 11/24/2021] [Indexed: 01/05/2023]
Abstract
Water quality degradation is one of the major problems with artificial lakes in estuaries. Long-term spatiotemporal patterns of water quality in a South Korean estuarine reservoir were analyzed using seasonal datasets from 2002 to 2020, and some functional changes in relations of trophic state variables due to the construction of serial weirs in the upper river were also investigated. A total of 19 water quality parameters were used for the study, including indicators of organic matter, nutrients, suspended solids, water clarity, and fecal pollution. In addition, chlorophyll-a (CHL-a) was used to assess algal biomass. An empirical regression model, trophic state index deviation (TSID), and principal component analysis (PCA) were applied. Longitudinal fluctuations in nutrients, organic matter, sestonic CHL-a, and suspended solids were found along the axis of the riverine (Rz), transition (Tz), and lacustrine zones (Lz). The degradation of water quality was seasonally caused by resuspension of sediments, monsoon input due to rainfall inflow, and intensity of Asian monsoon, and was also related to intensive anthropic activities within the catchment. The empirical model and PCA showed that light availability was directly controlled by non-algal turbidity, which was a more important regulator of CHL-a than total nitrogen (TN) and total phosphorus (TP). The TSID supported our hypothesis on the non-algal turbidity. We also found that the construction of serial upper weirs influenced nutrient regime, TSS, CHL-a level, and trophic state in the estuarine reservoir, resulting in lower TP and TN but high CHL-a and high TN/TP ratios. The proportions of both dissolved color clay particles and blue-green algae in the TSID additionally increased. Overall, the long-term patterns of nutrients, suspended solids, and algal biomass changed due to seasonal runoff, turnover time, and reservoir zones along with anthropic impacts of the upper weir constructions, resulting in changes in trophic state variables and their mutual relations in the estuarine reservoir.
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Growth characteristics of lytic cyanophages newly isolated from the Nakdong River, Korea. Virus Res 2021; 306:198600. [PMID: 34648883 DOI: 10.1016/j.virusres.2021.198600] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/03/2021] [Accepted: 10/04/2021] [Indexed: 11/20/2022]
Abstract
Cyanophages are primary regulators of cyanobacterial harmful algal blooms (CyanoHABs), and they control host cyanobacterial dynamics, frequency, and diversity in the aquatic environment. This study deals with growth characteristics of three lytic cyanophages, Myoviridae AGM-1, Myoviridae NGM-1, and Podoviridae NDP-1, newly isolated from the Nakdong River in South Korea. These isolates are capable of infecting Amazoninema brasiliense, Nododsilinea nodulosa, and Nostoc sp. The results showed that abiotic parameters such as water temperature and pH balance significantly affect the growth of a cyanophage and the interaction with its host in the aquatic environment. The optimal growth conditions of the newly isolated cyanophages are less than 37 °C and pH 9, whereas optimal conditions are 25-30 °C and pH 7 for the cyanobacteria used as hosts. However, each cyanophage was found to have significantly different growth characteristics in phage titer, latent period, and burst size, depending on the characteristics of the species. Among the three cyanophages, Podoviridae NDP-1 showed the highest burst size and infection activity. The lower the designed multiplicity of infection (MOI) ratio (0.01 to 10), the longer it takes to lyse the host cells. The minimum MOI value for sustainable biocontrol of CyanoHABs is proposed as MOI=1. These results can be used as basic information in further studies, such as pyophage control of CyanoHABs and enrichment of cyanophages with high activity.
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Yadav S, Anam GB, Ahn YH. Influence of Abiotic Factors on the Growth of Cyanobacteria Isolated from Nakdong River, South Korea 1. JOURNAL OF PHYCOLOGY 2021; 57:874-885. [PMID: 33556185 DOI: 10.1111/jpy.13143] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/15/2020] [Accepted: 12/02/2020] [Indexed: 06/12/2023]
Abstract
Changes in physico-chemical factors due to natural climate variability and eutrophication could affect the cyanobacterial growth patterns in aquatic systems that may cause environmental health problems. Based on morphological and 16S rRNA gene analysis, three cyanobacterial species isolated for the first time from the Nakdong River water sample in South Korea were identified as Amazoninema brasiliense, Microcystis elabens, and Nododsilinea nodulosa. The variations in temperature, pH, nitrogen, or phosphorus levels significantly impacted the cyanobacterial growth patterns. The optimal temperature range for the growth of isolates was from 25-30°C. A neutral or weak alkaline environment favored growth; however, A. brasiliense resulted in 44.2-87.5% higher biomass (0.75 g · L-1 as dry solids, DS) and growth rate (0.24 · d-1 ) at pH 7 than the other isolates (0.4-0.52 g DS · L-1 , 0.16-0.19 · d-1 ). The increased nitrate-nitrogen (NO3 -N) concentrations significantly (P < 0.05) favored biomass production and growth rate for A. brasiliense and M. elabens, respectively, and the maximum growth rate was observed for A. brasiliense at 3.5 mg NO3 -N · L-1 . The orthophosphate concentration (PO4 -P) from 0.1 to 0.5 mg PO4 -P · L-1 increased the growth of the isolates. These observations suggest that isolate growth rates in water bodies can vary depending on different physico-chemical parameters. This study contributes to the further understanding of the growth of microalgae in natural freshwater bodies under fluctuating environmental conditions and aquatic ecosystem stability.
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Affiliation(s)
- Seema Yadav
- Department of Civil Engineering, Yeungnam University, Gyeongsan, 38541, Gyeongbuk, Korea
| | - Giridhar Babu Anam
- Department of Civil Engineering, Yeungnam University, Gyeongsan, 38541, Gyeongbuk, Korea
| | - Young-Ho Ahn
- Department of Civil Engineering, Yeungnam University, Gyeongsan, 38541, Gyeongbuk, Korea
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12
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Park HK, Lee HJ, Heo J, Yun JH, Kim YJ, Kim HM, Hong DG, Lee IJ. Deciphering the key factors determining spatio-temporal heterogeneity of cyanobacterial bloom dynamics in the Nakdong River with consecutive large weirs. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:143079. [PMID: 33127129 DOI: 10.1016/j.scitotenv.2020.143079] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/12/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Following the construction of eight large weirs in a 200-km section of the Nakdong River, which is a major water source for the region, harmful cyanobacterial blooms have been occurring annually, causing severe problems with water quality. The present study investigated the community structure of harmful cyanobacteria and identified temporal and spatial patterns in harmful cyanobacterial blooms and their dynamic relationships with physicochemical, hydrological, and meteorological variables in the eight weir sections for 6 years from 2013 to 2018. The dominant harmful cyanobacteria in the eight weir sections were Aphanizomenon and Microcystis spp. There was a successional phenomenon wherein Aphanizomenon spp. first bloomed in spring, and then Microcystis spp. bloomed as water temperatures increased. Additionally, the initiation and duration of the blooms of both genera were affected by the timing and volume of heavy rainfall that caused flushing of cyanobacterial biomass, resulting in direct reduction of cyanobacterial growth in all sections. The harmful cyanobacteria of upstream weirs did not affect the biomass of downstream weirs in terms of either growth initiation or time taken to reach peak biomass, despite being physically connected. Owing to the long retention time during the dry season, similar to what occurs in separate reservoirs, the water quality of each weir section, particularly regarding nutrient characteristics and retention time, were the major factors determining the harmful cyanobacterial abundance, resulting in heterogeneous spatial distribution of harmful cyanobacterial blooms in the Nakdong River.
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Affiliation(s)
- Hae-Kyung Park
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea.
| | - Hae-Jin Lee
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea; Water Environmental Engineering Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
| | - Jun Heo
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea
| | - Ji-Hyeun Yun
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea
| | - Yong-Jin Kim
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea
| | - Hyun-Mac Kim
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea
| | - Dong-Gyun Hong
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea
| | - In-Jung Lee
- Nakdong River Environment Research Center, National Institute of Environmental Research, Daegu, Republic of Korea; Water Quality Assessment Research Division, Chilgok, National Institute of Environmental Research, Republic of Korea
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Kim YJ, Park HK, Kim IS. Invasion and toxin production by exotic nostocalean cyanobacteria (Cuspidothrix, Cylindrospermopsis, and Sphaerospermopsis) in the Nakdong River, Korea. HARMFUL ALGAE 2020; 100:101954. [PMID: 33298363 DOI: 10.1016/j.hal.2020.101954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/09/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
The extent and frequency of harmful cyanobacterial blooms are increasing, owing to the climate change caused by global warming, and some harmful filamentous cyanobacteria that were first reported in the tropics are spreading to temperate regions, such as North America, Europe, and Northeast Asia. Although these exotic invasive cyanobacteria have a high toxigenic potential, they are not targeted in management plans in many countries. This study analyzed the occurrence of and potential toxin and off-flavor secondary metabolite production by invasive nostocalean cyanobacteria in the Nakdong River in Korea, which is a temperate region. The occurrence of four species belonging to three genera of cyanobacteria was confirmed in the Nakdong River. The quantities of cyanobacteria in the Nakdong River were mostly low, fewer than 1,000 cells mL-1. Twenty-four strains belonging to four species in three genera of cyanobacteria were isolated from the Nakdong River. Analysis revealed no off-flavor secondary metabolite production by any of the isolates, and those belonging to Cylindrospermopsis raciborskii, Sphaerospermopsis aphanizomenoides, and S. reniformis were identified as nontoxic strains. However, anatoxin-a production was observed in two of the eleven isolates of Cuspidothrix issatschenkoi. Given the sites and the timing of its occurrence, C. issatschenkoi had the highest potential for toxin production among the invasive nostocalean cyanobacteria appearing in the Nakdong River.
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Affiliation(s)
- Yong-Jin Kim
- Nakdong River Environment Research Center, National Institute of Environmental Research, Dalseong-gun, Daegu, Korea
| | - Hae-Kyung Park
- Nakdong River Environment Research Center, National Institute of Environmental Research, Dalseong-gun, Daegu, Korea.
| | - In-Soo Kim
- Nakdong River Environment Research Center, National Institute of Environmental Research, Dalseong-gun, Daegu, Korea
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14
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Effects of Baekje Weir Operation on the Stream–Aquifer Interaction in the Geum River Basin, South Korea. WATER 2020. [DOI: 10.3390/w12112984] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hydraulic structures have a significant impact on riverine environment, leading to changes in stream–aquifer interactions. In South Korea, 16 weirs were constructed in four major rivers, in 2012, to secure sufficient water resources, and some weirs operated periodically for natural ecosystem recovery from 2017. The changed groundwater flow system due to weir operation affected the groundwater level and quality, which also affected groundwater use. In this study, we analyzed the changes in the groundwater flow system near the Geum River during the Baekje weir operation using Visual MODFLOW Classic. Groundwater data from 34 observational wells were evaluated to analyze the impact of weir operation on stream–aquifer interactions. Accordingly, the groundwater discharge rates increased from 0.23 to 0.45 cm/day following the decrease in river levels owing to weir opening, while the hydrological condition changed from gaining to losing streams following weir closure. The variation in groundwater flow affected the groundwater quality during weir operation, changing the groundwater temperature and electrical conductivity (EC). Our results suggest that stream–aquifer interactions are significantly affected by weir operation, consequently, these repeated phenomena could influence the groundwater quality and groundwater use.
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The Response of Dissolved Organic Matter during Monsoon and Post-Monsoon Periods in the Regulated River for Sustainable Water Supply. SUSTAINABILITY 2020. [DOI: 10.3390/su12135310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dissolved organic matter (DOM) in rivers are an important factor in pollution management due to the abundance of stored carbon. Using fluorescent spectroscopy, we investigated the temporal and spatial dynamics of DOM compositions, as well as their properties, for two of the major four regulated rivers—Han River (HR) and Geum River (GR) in South Korea. We collected eight sampling sites, four from each of the two rivers (from close to the weirs) in order to observe the integrated effects of different land use (terrestrial input) during the monsoon (July) and post-monsoon periods (September). High integral values of DOM compositions (July: 30.81 ± 9.71 × 103 vs. September: 1.78 ± 0.66 × 103) were present in all eight sites after heavy rainfall during the monsoon period, which indicated that Asian monsoon climates occupy a potent role in the DOM compositions of the rivers. Regarding DOM compositions, tryptophan-like and fulvic acid-like components were predominant in HR and GR, especially in GR with high integral values of protein-like and humus components. However, the properties of terrestrial DOM between HR and GR are markedly different. These results considered due to the different land use, where the terrestrial DOM shows a low degree of humification due to a high percentage of agriculture and urban land use in GR. Furthermore, these two rivers are typical regulated rivers, due to their weir constructions. High values of DOM components were present in the downstream of the weirs; however, increasingly high patterns appeared in the HR because of heavy rainfall (511.01 mm in HR; 376.33 mm in GR). In addition, a lower increasing trend of humic-like component was present in the GR due to a low percentage of forest land use/cover. These results suggest that the effect of the weir on rivers can be highlighted by the different percentages of land use/cover under the conditions of the monsoon period. Hence, DOM fluorescence can serve as an effective indicator for providing an early signal for the complex impacts of the different land use and rainfall in the regulated river systems.
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Kang S, Kim JH, Ryu JS, Shin KH. Dual carbon isotope (δ 13C and Δ 14C) characterization of particulate organic carbon in the Geum and Seomjin estuaries, South Korea. MARINE POLLUTION BULLETIN 2020; 150:110719. [PMID: 31732177 DOI: 10.1016/j.marpolbul.2019.110719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 06/10/2023]
Abstract
We investigated the source, composition, and reactivity of particulate organic carbon (POC) in two contrasting Korean estuary systems, a closed estuary (Geum) (i.e., with an estuary dam at the river mouth) and an open (Seomjin) estuary. A dual isotope (δ13CPOC and Δ14CPOC) approach was applied to surface water samples collected along a salinity gradient in August 2016. Our results indicate that phytoplankton-derived POC was the main contributor to the total POC pool in the reservoir of the Geum estuary, while terrestrial-derived POC predominated the upper Seomjin estuary. A simple binary mixing model using Δ14CPOC revealed a higher modern POC contribution (87-90%) in the Geum estuary reservoir than that (77%) of the upper Seomjin estuary. Accordingly, it appears that an estuary dam can alter the source and reactivity of POC in a reservoir, which can be transferred to the adjacent coastal ecosystem.
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Affiliation(s)
- Sujin Kang
- Hanyang University ERICA, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan-si, Gyeonggi-do 415588, South Korea
| | - Jung-Hyun Kim
- KOPRI Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea.
| | - Jong-Sik Ryu
- Department of Earth and Environmental Sciences, Pukyong National University, Busan 48513, South Korea
| | - Kyung-Hoon Shin
- Hanyang University ERICA, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan-si, Gyeonggi-do 415588, South Korea.
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Choi J, Min JO, Choi B, Kang JJ, Choi K, Lee SH, Shin KH. Variation of Primary Productivity and Phytoplankton Community in the Weirs of Mid and Downstream of the Nakdong River during Fall and Early Winter: Application of Phytoplankton Pigments and CHEMTAX. ACTA ACUST UNITED AC 2019. [DOI: 10.11614/ksl.2019.52.2.081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Relationship between Coliform Bacteria and Water Quality Factors at Weir Stations in the Nakdong River, South Korea. WATER 2019. [DOI: 10.3390/w11061171] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Artificial structures installed in rivers can change the natural physical, physiochemical, and biological characteristics of the rivers. Coliform bacteria are important water quality indicators, related to human health. This study investigated the relationship between coliform bacteria and water quality factors at eight weir stations constructed in the Nakdong River, a major river in South Korea. Fifteen water quality factors were analyzed at these sites from 2012 to 2016 using correlation and multiple regression analyses. The results for all stations confirmed the analytical validity, with high adjusted R2 values of approximately 0.6 and 0.8 on average for total and fecal coliforms, respectively. The results showed influential water quality factors affecting the concentration of coliform bacteria at weir stations. Specifically, total coliforms were mostly affected by organic matter and fecal coliforms were mostly affected by phosphate phosphorus and suspended solids. Rainfall was the most influential factor affecting both coliforms. Further, both coliforms were negatively affected by organic matter below the Dalseong weir in the mid- to downstream area of the Nakdong River. A positive relationship with phosphate phosphorus was indicated at all weir stations. To the authors’ knowledge, this kind of study has never been attempted so far. Thus, the study results can provide important information on influential water quality factors related to coliform bacteria, especially in the Nakdong River, creating a foundation for future water quality management.
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