• Environmental Engineering Research
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• v.14 no.3
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• pp.170-173
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• 2009

This study examined the special technique of photocatalytic degradation (RPODisk) for removal of taste and odor causing materials, algae, and algal toxin. The RPODisk was effective for removal of these troublesome contaminants. It outperformed the fixed media and the UV irradiation for geosmin removal. The RPODisk performance was comparable to the combination of the UV irradiation with TiO2. The RPODisk performance was affected by the rotating speed. The faster the speed was, the better the performance. The RPODisk was also effective for removal of algae and algal toxin. The algal activity reduced by 80% after 30 mins of the treatment. More toxic microcystin (MC)-LR was more difficult to remove than MC-RR. The times for 50% removal were 23.7 mins for MC-LR and 14.1 mins for MC-RR. Almost 100 mins of the contact time was required to completely remove MC-LR at the rotating speed of 260 rpm.

• Journal of Korean Society on Water Environment
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• v.40 no.1
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• pp.1-10
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• 2024

Algal blooms occur seasonally in the eutrophicated rivers or reservoirs, and some harmful cyanobacteria species produce toxic substances, which are directly or indirectly harmful to the ecosystem and terrestrial animals. So, the monitoring and control of harmful cyanobacteria occurrence and toxins residual in the aquasystem are important to preserve the water environment and secure public health. In this study, the four harmful cyanobacteria occurrences and toxic substance concentrations of two agricultural reservoirs in the southern part of Gyeonggi Province were investigated from August to October 2022. Among four harmful cyanobacteria (Microcystis sp., Anabaena sp., Oscillatoria sp., Aphanizomenon sp.), three kinds of cyanobacteria except Oscillatoria sp. were observed, and Microcystis sp. was the dominant cyanobacteria except for Anabaena sp. dominant result of a sample collected on October at reservoir B. The cell density of cyanobacteria was influenced by season and weather due to the length of daytime and concentrations of organic carbon and nitrogen. Three kinds of microcystin and anatoxin-a were quantitatively analyzed as total (in the cell body and water) and extracellular (in water) concentrations. The maximum total concentrations of anatoxin-a, microcystin-LR, microcystin-RR, and microcystin-YR were 0.1291 ㎍/L, 0.2776 ㎍/L, 0.3721 ㎍/L, and 0.0306 ㎍/L, respectively, in reservoir A and 0.3274 ㎍/L, 0.1495 ㎍/L, 0.2037 ㎍/L, and 0.0153 ㎍/L, respectively, in reservoir B.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.5
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• pp.249-260
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• 2022

The effect of permanganate oxidation was investigated as water treatment strategy with a focus on comparing the reaction characteristics of NaOCl and sodium permanganate (NaMnO₄) in algae (Monoraphidium sp., Micractinium inermum, Microcystis aeruginosa)-contained water. Flow cytometry explained that chlorine exposure easily damaged algae cells. Damaged algae cells release intracellular organic matter, which increases the concentration of organic matter in the water, which is higher than by NaMnO₄. The oxidation reaction resulted in the release of toxin (microcystin-LR, MC-LR) in water, and the reaction of algal organic matter with NaOCl resulted in trihalomethanes (THMs) concentration increase. The oxidation results by NaMnO₄ significantly improved the concentration reduction of THMs and MC-LR. Therefore, this study suggests that NaMnO₄ is effective as a pre-oxidant for reducing algae damage and byproducts in water treatment process.

• Journal of Environmental Science International
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• v.11 no.11
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• pp.1157-1163
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• 2002

The effective removal of microcystins by chlorination was investigated on a laboratory scale. With an initial chl.a concentration of more than 1,000 $\mu\textrm{g}$/ℓ, the required chlorine dose for the effective removal of microcystins from the raw water was more than 8.0 mg/ℓ. Whereas, a chlorine dose of 3.0 mg/ℓcould effectively remove microcystins from raw water containing a chl.a concentration of less than 1,000 $\mu\textrm{g}$/ℓ. The microcystin removal was more effective below pH 8.0, plus the optimum pH range was unrelated to the concentration of toxic algal material. Although chlorination is one of the most effective methods for reducing the toxin from blue-green algae, it causes cell lysis and toxin release. However, it was demonstrated that the released cell lysates and toxins could be effectively removed by a higher dose of the oxidant. The highest removal efficiency of dissolved microcystins(initial concentration: 280 $\mu\textrm{g}$ L$\^$-1/) was with a chlorine dose of 5.0 mg/ℓ.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.843-850
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• 2012

Due to the fast response to algae bloom issue in drinking water treatment plant, very fast determination methodology for algal toxin is required. In this study, column switching technique based online preconcentration method was combined with high resolution full scan mass spectrometer to save sample preparation time and to obtain fast and accurate result. After parameter optimization of online preconcentration, 1mL filtered sample was directly injected to trap column with switching valve system. Next, target toxins are eluted by 98% acetonitrile and analysed with 150 - 1,100 amu scan range at 50,000 resolving power. Method detection limit (MDL) for microcystin-LR, the most toxic isomer, was 0.1 ng/mL and others such as microcystin-YR, microcystin-RR and nodularin were 0.08, 0.03 and 0.04 ng/mL, respectively. This is the best improved sensitivities with 1mL volume in the literature. Furthermore, due to the use of ultra pressure HPLC (UPLC), the whole method run was completed in 4 min. Real sample applications for 173 sample including 55 surface water and 118 treatment plant samples for raw and treated water could be done within 16 hours. In our calculation, this methodology is roughly 80% faster than the previous manual solid-phase extraction with LC-MS/MS method.

• Analytical Science and Technology
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• v.13 no.3
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• pp.399-402
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• 2000

To determine the concentrations of microcystins present in lake water or in tap water using high performance liquid chromatography, it is necessary to concentrate a large volume of water samples (about 20 L) into very small volume (0.1-0.3 mL). Concentration can be conveniently done when disc type solid phase extraction (SPE) apparatus is used. Using this apparatus we have investigated the recovery rates of three kinds of microcystins, RR, YR, LR. The recovery rates were relatively low and the reproducibilities were not good either. It is expected, however, that the appropriate selection of the disc conditioning and eluting solvents and reproducible reconcentration process after SPE will improve both the recovery rates and the reproducibilities.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.50-56
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• 2003

A freshwater bloom-forming cyanobacterium, Microcystis aeruginosa, and local soil isolate Scytonema sp. strain BT 23 were demonstrated to contain biotoxic secondary metabolites with pesticidal and mosquito larvicidal activities. A purified toxic constituent from M aeruginosa showed an absorption maximum at 230 nm and its toxicity symptoms, Rf value on TLC, and retention time observed ill an HPLC analysis were similar to those of the hepatotoxic heptapeptide microcystin-LR. The bioactive constituent of the Scytonema sp. was less polar in nature and exhibited two peaks at 240 and 285 m. When applied to two cruciffrous pests, Pieris brassicae and Plutella flostella, the crude extracts and toxic principles from the two cyanobacteria showed significant antifeedant activity in a no-choice bioassay, and at higher concenuations exhibited contact toxicity to the insect larvae. The purified toxin from M. aeruginosa was found to be more effective and produced 97.5 and $92.8\%$ larval mortality in the two pests, fo11owing 2 h of toxin treatment at a concentration of $25{\mu}g$ Per leaf disc (2.5 cm dia.). Meanwhile, similar treatment with the purified toxin from Sytonema sp. stain BT 23 only produced 73 and $78\%$ mortality in the two pests. The cyanobacterial constituents also showed significant activity against Culex and Anopheles larvae. The M. aeruginosa toxin ($20{\mu}g\;ml^-1$) caused 98.2 and $88.1\%$ mortality in the Culex and Anopheles larvae, respectively, while the purified toxin from the Sytonema sp. was less toxic and only produced a 96.3 and $91.2\%$ mortality, respectively, at a much higher concentration ($40{\mu}g\;ml^-1$). Accordingly, the current results point to certain hitherto unknown biological properties of cyanobacterial biotoxins.

• Journal of Environmental Health Sciences
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• v.42 no.1
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• pp.10-18
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• 2016

Objectives: Microcystin (MC) produced during cyanobacterial blooms is a worldwide problem presenting a serious health threats to humans and ecosystems. During July through October of 2013, the Ilwol Reservoir experienced a high biomass of phytoplankton (maximum $211.7mg/m^3$ of Chlorophyll-a) containing the toxigenic cyanobacterium Oscillatoria sp. The aim of this study is to analyze MC concentration in the reservoir water, as well as in representative fish species (Carassius cuvieri, Carassius auratus, Channa argus). We also evaluated the human health risk of exposure to MCs accumulated in the fish. Methods: Concentrations of MCs in the water and fish samples were analyzed by liquid chromatography with a triple quadrupole tandem mass spectrometer (LC/MS/MS) and enzyme-linked immunosorbent assay (ELISA). Results: The total levels of four MC variants, including MC-LR, MC-RR, MC-YR and MC-LA were below the WHO drinking water guideline limit (1 ug MC-LR per liter) both for the dissolved and particulate fraction present in the water samples. The mean MC concentrations in the livers of all species were significantly higher than in the gills (p < 0.01) and muscles (p < 0.05). The values of estimated daily intake of MCs in muscles, the edible part of the fish, would be only $0.005-0.015{\mu}g/kg{\cdot}day$, much lower than WHO's provisional tolerable daily intake of $0.04{\mu}g/kg{\cdot}day$. Conclusion: This study suggests that, owing to the spatial distribution or temporal variation of MC, there is a need for careful monitoring of cyanotoxin in reservoir water and aquatic animals to protect public health.

• Ecology and Resilient Infrastructure
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• v.8 no.3
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• pp.143-153
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• 2021

The growth inhibition effects of M. aeruginosa were verified using large volume (7.2 L) of algae samples and ultrasonication (high frequency of 1.6 MHz vs. low frequency of 23 kHz) in lab-scale experiment. The chlorophyll-a (chl-a) and cell number decreased gradually after 6 hr sonication with high frequency of 1.6 MHz whereas both decreased sharply after 6 hr sonication with low frequency of 23 kHz. Additionally, the first order degradation coefficient (k) values after sonication were greater than those during sonication. These results indicate that relatively low sonication energy per volume may affect the cell membrane and internal organs of M. aeruginosa in a slow and retarded manner and resulted in gradual decrease of cell numbers of M. aeruginosa. Based on the comparison of chl-a and cell number of M. aeruginosa after sonication, low frequency of 23 kHz is superior for growth inhibition of M. aeruginosa, since low frequency of 23 kHz easily penetrates the cell membrane and ruptures the internal organs including gas vesicles. As is evident in SEM and TEM images, ruptured cell membranes were clearly observed for low frequency of 23 kHz. Finally, the microcystin-LR in water is not detected and considered to be harmless in aquaculture systems.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.22-30
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• 2011

This study was purposed to develop an effective LC/MS/MS method for simultaneously determining five pre-treated cyanotoxins (anatoxin-a, microcystins-RR, -YR, -LR and -LA) of cyanobacteria blooms. Cyanobacterial bloom samples were collected from 11 major lakes and three downstream areas of river around Korea during 2005~2009. Cyanotoxins were identified in 38 samples from the lakes. The validity of the method was evaluated and the recovery rates were found ranging from 83~87%. The MDL turned out to be $0.046\;{\mu}g\;L^{-1}$ for anatoxin-a and $0.066\;{\mu}g\;L^{-1}$ for microcystins (RR, YR, LR and LA), which indicates that the method has high sensitivity and accuracy. The most dominant genus of the cyanobacterial blooms was Microcystis, which accounted for 71% of the analysed samples. Microcystis also contained the largest amount of microcystins ($398.5\;{\mu}g\;gDW^{-1}$) among the analyzed cyanobacteria. The analysis of the five cyanotoxins showed that anatoxin-a ranged between $0{\sim}41.833\;{\mu}g\;gDW^{-1}$ and microcystins ranged between $6.311{\sim}2,148.786\;{\mu}g\;gDW^{-1}$. Among the microcystins, micocystin-RR took up 58.3%, the largest portion. Anatoxin-a was found to account for 77.8% of the samples. This study has its significance in that it allowed the establishment of toxin criteria appropriate for the Korean water systems. Further studies may be necessary to conduct for improving water treatment methods.