• Membrane Journal
• /
• v.31 no.2
• /
• pp.101-119
• /
• 2021

The demand for clean water is virtually present in all modern human societies even as our society has developed increasingly more advanced and sophisticated technologies to improve human life. However, as global climate change begins to show more dramatic effects in many regions in the world, the demand for a cheap, effective way to treat wastewater or to remove harmful bacteria, microbes, viruses, and other solvents detrimental to human health has continued to remain present and remains as important as ever. Well-established synthetic membranes composed of polyaniline (PANI), polyvinylidene fluoride (PVDF), and others have been extensively studied to gather information regarding the characteristics and performance of the membrane, but recent studies have shown that making these synthetic membranes conductive to electrical current by doping the membrane with another material or incorporating conductive materials onto the surface of the membrane, such as allotropes of carbon, have shown to increase the performance of these membranes by allowing the adjustability of pore size, improving antifouling and making the antibacterial property better. In this review, modern electrically conductive membranes are compared to conventional membranes and their performance improvements under electric fields are discussed, as well as their potential in water filtration and wastewater treatment applications.

• Applied Chemistry for Engineering
• /
• v.23 no.1
• /
• pp.71-76
• /
• 2012

Biofouling by marine organisms such as algae and barnacles causes lots of significant problems in marine systems such as a rise of the maintenance-repair cost for the ship and the marine structures. In this work, a fluoropolymer, perfluoropolyether (PFPE), was applied as an anti-biofouling coating material that prevents the adhesion of marine organisms and facilitates the removal of them. Water contact angles of various surfaces were tested to examine the hydrophobicity of the PFPE-modified surface. The PFPE-modified surface showed the water contact angle of $64.5^{\circ}$ which is a remarkable rise from $46.7^{\circ}$ of amine-treated surface. When the substrate was treated with PFPE, the adhesion on the of the barnacle and other marine organisms were repressed around 15% by the enhanced hydrophobicity. In addition, the removal the of the adhered marine organisms were better comparing to that of the surface prepared by PDMS. Surfaces of the substrate treated by PFPE were characterized through physical and chemical methods to analyze the biofouling results. Degree of biomolecular adhesion to the substrate was quantified by the measurement the fluorescence intensity of marine organisms dyed with green fluorescence. PFPE is expected to be applicable not only to anti-biofouling systems but also to medical devices where the prevention of protein adhesion is required.

• Journal of Life Science
• /
• v.23 no.3
• /
• pp.341-346
• /
• 2013

The disappearance of seaweed flora in some rocky areas, which is known as algal whitening, barren ground, coralline flats, or deforested areas, is associated with some species of coralline algae. To determine the biological characteristics of a representative species of crustose coralline alga, the 18S rDNA gene was sequenced to identify the genus Lithophyllum. According to its morphological and distributional characteristics, it was deduced to be L. yessoense. Viability was measured using triphenyl tetrazolium chloride and showed high viability from December to February. Culture conditions of $16^{\circ}C$, a 16 hr light, 8 hr dark cycle, and 30 ${\mu}E/m^2/s$ light intensity were optimal for maintaining the viability of the alga for up to five days. Included in the fatty acids was 9.7% ${\omega}$-3 eicosapentaenoic acid. An electron microscopy scan of the surface structure revealed round craters about 3.6 ${\mu}m$ in diameter, which were covered with rough, irregular, and angular polygon-shaped structures about 1.0 to 3.7 ${\mu}m$ in size. Based on the composition and structure found in our study, biomimetic coralline alga might become an environmentally friendly antifouling material against the attachment of soft foulants.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.2
• /
• pp.68-74
• /
• 2009

Polycyclic aromatic hydrocarbons (PAHs), one of ubiquitous organic pollutants in marine environments, are major toxic components of petroleum and are produced during the incomplete combustion of organic materials. As shipyards are located inside of natural or artificial semi-enclosed bay, even a relatively weak environmental disturbance by ship-building activity can cause severe damage to marine ecosystem in the bay. Many studies of pollution in shipyard area have been focused on the antifouling agent, like tributyltin. This study aimed to investigate the effect of ship-building activity on PAH contamination. Total PAHs concentration was higher nearby and inside shipyard area than outside, implying that shipyard could be one of major source area of PAH contamination to pose harmful effects to surrounding environments. Through PAH profile and source recognition index, the source of PAHs inputs in this area was estimated to originate from both petrogenic and pyrogenic origin. PAH levels showed a significant correlation with total butyltins, indicating that ship-building activity influenced PAH concentration and distribution. Vertical distribution of PAHs historically confirmed the correlation between shipbuilding activity and PAHs contamination.

• Korean Journal of Environmental Biology
• /
• v.41 no.4
• /
• pp.427-438
• /
• 2023

Biocide dichlofluanid breaks down quickly and accumulates easily in sediment, potentially causing a persistent impact on various marine organisms. We analyzed the potential toxicity of dichlofluanid on major aquaculture species in Korea, Undaria pinnatifida. Female gametophytes of U. pinnatifida were exposed to dichlofluanid at concentrations of 0, 1, 2, 4, 8, 16, and 32 mg L^-1, and their survival and relative growth rate were analyzed. The no observed effect concentration(NOEC), lowest observed effect concentration (LOEC), and median lethal concentration (LC₅₀) for female gametophyte survival were determined as 1, 2, and 10.82 (95% CI: 8.87-13.23) mg L^-1, respectively. The NOEC, LOEC, and median effective concentration (EC₅₀) for relative growth rate were 1, 2, and 6.58 (95% CI: 6.03-7.17) mg L^-1, respectively. Female gametophytes of U. pinnatifida were expected to experience toxic effects at concentrations above 2 mg L^-1 of dichlofluanid. These research findings are expected to serve as important reference data for evaluating the toxicity effects of U. pinnatifida in its early life stages when exposed to dichlofluanid.

• Environmental Analysis Health and Toxicology
• /
• v.18 no.2
• /
• pp.89-94
• /
• 2003

Tributyltin (TBT) used world-wide in antifouling paints for ships is a widespread environmental pollutant and cause reproductive organs atrophy in rodents. At low doses, antiproliferative modes of action have been shown to be involved, whereas at higher doses apoptosis seems to be the mechanism of toxicity in reproductive organs by TBT. In this study, we investigated that the mechanisms underlying DNA fragmentation induced by TBT in the rat leyding cell line, R2C. Effects of TBT on intracellular Ca$\^$2+/ level and reactive oxygen species (ROS) were investigated in R2C cells by fluorescence detector. TBT significantly induced intracellular Ca$\^$2+/ level in a time-dependent manner. The rise in intracellular Ca$\^$2+/ level was followed by a time-dependent generation of reactive oxygen species (ROS) at the cytosol level. Simultaneously, TBT induced the release of cytochrome c from the mitochondrial membrane into the cytosol. Furthermore, ROS production and the release of cytochrome c were reduced by BAPTA, an intracellular Ca$\^$2+/ chelator, indicating the important role of Ca$\^$2+/ in R2C during these early intracellular events. In addition, Z-DEVD FMK, a caspase-3 inhibitor, decreased apoptosis by TBT. Taken together, the present results indicated that the apoptotic pathway by TBT might start with an increase in intracellular Ca$\^$2+/ level, continues with release of ROS and cytochrome c from mitochondria, activation of caspases,and finally results in DNA fragmentation.

• Korean Journal of Environmental Biology
• /
• v.36 no.3
• /
• pp.392-399
• /
• 2018

Toxicity assessment of antifouling agent, zinc undecylenate (ZU) has been investigated using the rate of survival and population growth in marine rotifer, Brachionus plicatilis. The survival rate of Brachionus plicatilis was determined after 24 h of exposure to ZU and was not affected up to the maximum level of $100.0mg\;L^{-1}$ of ZU. The population growth rate (r) was determined after 72 h of exposure to ZU. It was observed that r in the controls (absence ZU) was greater than 0.5 but exhibited a sudden decrease with an increase in the concentration of ZU. ZU reduced r in a dose-dependent manner and a significant reduction occurred at a concentration greater than $12.5mg\;L^{-1}$. The 50% effective concentration ($EC_{50}$) value of r during ZU exposure was $26.4mg\;L^{-1}$, No-observed-effect-concentration (NOEC) was $6.3mg\;L^{-1}$ and Lowest-observed-effect-concentration (LOEC) was $12.5mg\;L^{-1}$, respectively. Based on the results, it is apparent that ZU concentration greater than $12.5mg\;L^{-1}$ exhibited a toxic effect on the r of zooplankton, B. plicatilis in natural ecosystems.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.36 no.5
• /
• pp.407-428
• /
• 1991

The eastern coastal area having variability of climate is located within Taebaek mountain range and the east coast of Korea. It is therefore ease to cause the wind damages in paddy field during rice growing season. The wind damages to rice plant in this area were mainly caused by the Fohn wind (dry and hot wind) blowing over the Taebaek mountain range and the cold humid wind from the coast. The dry wind cause such as the white head, broken leaves, cut-leaves, dried leaves, shattering of grain, glume discolouration and lodging, On the other hand the cold humid wind derived from Ootsuku air mass in summer cause such symptom as the poor rice growth, degeneration of rachis brenches and poor ripening. To minimize the wind damages and utilize as a preparatory data for wind injury of rice in future, several experiments such as the selection of wind resistant variety to wind damage, determination of optimum transplanting date, improvement of fertilizer application methods, improvement of soils and effect of wind break net were carried out for 8 years from 1982 to 1989 in the eastern coastal area. The results obtained are summarized as follows. 1. According to available statisical data from Korean meteorological services (1954-1989) it is apperent that cold humid winds frequently cause damage to rice fields from August 10th to September 10th, it is therefore advisable to plan rice cultivation in such a way that the heading date should not be later than August 10th. 2. During the rice production season, two winds cause severe damage to the rice fields in eastern coastal area of Korea. One is the Fohn winds blowing over the Taebaek mountain range and the other is the cold humid wind form the coast. The frequency of occurrence of each wind was 25%. 3. To avoid damage caused by typhoon winds three different varieties of rice were planted at various areas. 4. In the eastern coastal area of Korea, the optimum ripening temperature for rice was about 22.2$^{\circ}C$ and the optimum heading date wad August 10th. The optimum transplanting time for the earily maturity variety was June 10th., medium maturity variety was May 20th and that of late maturity was May 10th by means of growing days degree (GDD) from transplanting date to heading date. 5.38% of this coastal area is sandy loamy soil while 28% is high humus soil. These soil types are very poor for rice cultivation. In this coastal area, the water table is high, the drainage is poor and the water temperature is low. The low water temperature makes it difficult for urea to dissolve, as a result rice growth was delayed, and the rice plant became sterile. But over application of urea resulted in blast disease in rice plants. It is therefore advise that Ammonium sulphate is used in this area instead of urea. 6. The low temperature of the soil inhibits activities of microorganism for phosphorus utilization so the rice plant could not easily absorb the phosphorus in the soil. Therefore phosphorus should be applied in splits from transplanting to panicle initiation rather than based application. 7. Wind damage was severe in the sandy loamy soil as compared to clay soils. With the application of silicate. compost and soil from mointain area. the sand loamy soil was improved for rice grain colour and ripening. 8. The use of wind break nets created a mocro-climate such as increased air. soil and water temperature as well as the reduction of wind velocity by 30%. This hastened rice growth, reduced white head and glume discolouration. improved rice quality and increased yield. 9. Two meter high wind break net was used around the rice experimental fields and the top of it. The material was polyethylene sheets. The optimum spacing was 0.5Cm x 0.5Cm. and that of setting up the wind break net was before panicle initiation. With this set up, the field was avoided off th cold humid wind and the Fohn. The yield in the treatment was 20% higher than the control. 10. After typhoon, paddy field was irrigated deeply and water was sprayed to reduce white head, glume discolouration, so rice yield was increased because of increasing ripening ratio and 1, 000 grain weight.

• Korean Journal of Environmental Biology
• /
• v.39 no.3
• /
• pp.390-398
• /
• 2021

In this study, the toxicity of chlorothalonil was investigated using survival rate and population growth rate of a marine rotifer, Brachionus plicatilis, typically used in live food in marine aquaculture systems. The survival rate of B. plicatilis was determined after 24 h of exposure to chlorothalonil (0.010-0.156 mg L^-1). Population growth rate of B. plicatilis was calculated after 72 h of exposure to chlorothalonil (0.078-1.250 mg L^-1). The survival rate and population growth rate of B. plicatilis exposed to chlorothalonil in single-dose toxicity assessment showed concentration-dependent reductions. Survival rates of B. plicatilis exposed to chlorothalonil had the following values: NOEC, 0.020mg L^-1; LOEC, 0.039 mg L^-1; and EC₅₀, 0.057 mg L^-1. Population growth rate of B. plicatilis exposed to chlorothalonil had the following values: NOEC, 0.156 mg L^-1; LOEC, 0.313 mg L^-1; and EC₅₀, 0.506 mg L^-1. When the residual concentration of chlorothalonil in the marine coastal area was more than 0.039 mg L^-1, it had a toxic effect on B. plicatilis, a zooplankton. This paper provides toxicity values that can be used as baseline data for organizing environmental standards of chlorothalonil. It also provides insight into toxic effects of chlorothalonil on other non-target organisms.

• Korean Journal of Environmental Biology
• /
• v.38 no.4
• /
• pp.518-527
• /
• 2020

The aim of this study was to define the toxic effects of diuron and irgarol, which are new-antifouling agents, on the fertilization rate and normal embryogenesis rate in the sea urchin, Hemicentrotus pulcherrimus. In addition, the study was intended to confirm the hindrance of development in sea urchins. The fertilization rate of H. pulcherrimus was not decreased by the tested concentrations. However, the normal embryogenesis rate was decreased in a concentration-dependent manner. The 50% effective concentrations (EC₅₀) of normal embryogenesis rate were 7.12 mg L^-1 and 2.31 mg L^-1, respectively. As the embryos developed into pluteus larvae, after 18 h of exposure to diuron and irgarol at EC₅₀, development of the early gastrula stage was delayed, and significant developmental delays were observed after 24 h. After this, continuous developmental delays were observed in the process leading to the early gastrular, gastrular, early pluteus, and pluteus stages. Therefore, the toxic effects of diuron and irgarol on sea urchins were attributed to the delay in the developmental processes in the early life stages. Diuron and irgarol are highly persistent in the environment and have known-well toxic effects on various marine organisms including invertebrates, as shown in this study. Therefore, it is urgent to establish an environmental protection strategy to prevent the pollution of and preserve the marine environment.