• Korean Journal of Remote Sensing
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• v.38 no.5_3
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• pp.835-850
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• 2022

Microplastics have arisen as a worldwide environmental concern, becoming ubiquitous in all marine compartments, and various researches on monitoring marine microplastics are being actively conducted worldwide. Recently, application of a remote detection technology that enables large-scale real-time observation to marine plastic monitoring has been conducted overseas. However, in South Korea, there is little information linking remote detection to marine microplastics and some field studies have demonstrated remote detection of medium- and large-sized marine plastics. This study introduces research cases with remote detection of marine plastics in South Korea and overseas, investigates potential feasibility of using the remote detection technology to marine microplastic monitoring, and suggests some future works to monitor marine microplastics with the remote detection.

• Journal of Marine Life Science
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• v.8 no.1
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• pp.68-77
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• 2023

In this study, we investigated the quantitative distribution of microplastics in the surface seawater at 8 points near the Taean Peninsula using fluorescence staining. The study revealed a detection range of microplastics from 0 to 360.5 particles/l, with an average of 149.7 ± 46.0 particles/l. When classifying the microplastics by size, it was found that particles smaller than 50 ㎛ were dominant, although there were differences at Site 3. Moreover, it was not possible to identify clear correlations when comparing the number of microplastics based on collection area and particle size. Various physical and chemical factors, including plastic material, dynamic ocean conditions (such as currents, wind, waves, tides), geological characteristics (topography, slope), sediment materials including coastal organisms, human activities (fishing, development, tourism), and weather conditions (floods, rainfall), affect the behavior of microplastics. Therefore, future efforts should focus on standardizing quantitative analysis methods and conducting fundamental research on microplastic monitoring, including the analysis of environmental factors.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.701-716
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• 2023

Microplastics (<5 mm diameter) in aquatic environments adsorb heavy metals, potentially exposing humans to their toxic effects via food chains. We investigated factors influencing the adsorption of heavy metals on microplastics in aquatic environments, examining their adsorption processes and mechanisms. Adsorption characteristics vary with polymer type, crystallinity, particle size, and environmental conditions (pH, temperature, weathering), and the adsorption capacity for heavy metals increases with weathering and reduction in polymer particle size. However, correlations between environment temperature, polymer crystallinity, and adsorption capacity for heavy metals could not be confirmed. The adsorption behavior of heavy metals can be explained in terms of physicochemical adsorption processes and evaluated through adsorption kinetics and isothermal studies, with multiple mechanisms usually being involved. An understanding of the adsorption of heavy metals by microplastics should aid evaluation of the potential risks of microplastics in aquatic environments.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.461-475
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• 2020

This study was conducted in the southwestern area of Korea using a neuston net in September (14 stations) 2017 to understand the environmental factors affecting neustonic zooplankton. Temperature, salinity, chlorophyll a concentration, suspended solids, and microplastics were included as environmental factors. Based on the density of the copepods, the study area was divided into three regions: the Seomjin River water influence area, the frontal mixing area, and the warm water affected area (Jeju warm current and Tsushima warm current). In the latter two areas, the major species were Pontella chierchiae, Canthocalanus pauper, and Oncaea spp. Also, neustonic zooplankton showed a significant relationship between the density of phytoplankton and microplastics in the frontal mixing area, and temperature and suspended solids in the warm water affected area, respectively (p<0.05). This indicates that microplastics can affect the offshore zooplankton community.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.72-81
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• 2022

Numerous studies have investigated the occurrence and fate of microplastics in the environment; however, only limited effort has been devoted to exploring the characteristics of dissolved organic matter (DOM) leached from microplastics. In microplastic (MP)-contaminated environment, MPs are typically mixed with naturally-occurring particles, which interferes with their detection in the environment. Thus, it is necessary to distinguish between the DOM leached from MPs and those leached from natural particles and also to characterize their properties. This study investigated DOM leaching behavior from MPs (polystyrene: PS, polyvinylchloride: PVC) and natural particulates (forest soil: FS, litter leaves: LL) under light, which is considered one of the main weathering processes that affect MPs in the environment. The leached DOM concentrations and fluorescence characteristics were compared under dark versus light conditions. Regardless of the origins, UV light promoted DOM release from all the particulates. More DOM was released from natural particles than from MPs under both conditions. However, the effect of promoting DOM release by UV was more pronounced for MPs than for natural particles. It was observed from fluorescence spectra that the intensity of the humic-like region was substantially reduced when MP-derived DOM was exposed to UV light, whereas the change of intensity was very little for natural particles. Under light conditions, the ratio of protein-like to humic-like fluorescence of MP-derived DOM was higher than that of DOM from natural particles. This study implies that a substantial amount of DOM could be leached from MPs even in MP-polluted environment under UV irradiation. Protein/humic fluorescence ratio could be utilized as a fast probing indicator to separate the two sources of particles under light.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.83-92
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• 2022

The amount of the plastic waste has been increasing according to global demand for plastic. Microplastics are the most hazardous among all plastic pollutants due to their toxicity and unknown physicochemical properties. This study investigates the optimal methodology that can be applied to sewage samples for detecting microplastics before discussing reducing microplastics in MWTPs. In this study, the effect of different pretreatment methods while detecting microplastic analysis of MWTP influent samples was investigated; the samples were collected from the J sewage treatment plant. There are many pretreatment methods but two of them are widely used: Fenton digestion and hydrogen peroxide oxidation. Although there are many pretreatment methods that can be applied to investigate microplastics, the most widely used methods for sewage treatment plant samples are Fenton digestion and H₂O₂ oxidation. For each pretreatment method, there were factors that could cause an error in the measurement. To overcome this, in the case of the Fenton digestion pretreatment, it is recommended to proceed with the analysis by filtration instead of the density separation method. In the case of the H₂O₂ oxidation method, the process of washing with distilled water after the reaction is recommended. As a result of the analysis, the concentration of microplastics was measured to be 2.75ea/L for the sample using the H₂O₂ oxidation method and 3.2ea/L for the sample using the Fenton oxidation method, and most of them were present in the form of fibers. In addition, it is difficult to guarantee the reliability of measurement results from quantitative analysis performed via microscope with eyes. A calibration curve was created for prove the reliability. A total of three calibration curves were drawn, and as a result of analysis of the calibration curves, all R² values were more than 0.9. This ensures high reliability for quantitative analysis. The qualitative analysis could determine the series of microplastics flowing into the MWTP, but could not confirm the chemical composition of each microplastic. This study can be used to confirm the chemical composition of microplastics introduced into MWTP in the future research.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.337-348
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• 2018

As the issue of microplastics (MPs) detection in tap water was raised in other countries in 2017, monitoring of MPs in drinking and source water, and sewage treatment plant (STP) effluents was initiated. This study intends to look into other studies on MPs in STPs at home and abroad, and review the characteristics of MPs and their removal efficiencies in the STPs, the risk and effect of MPs on watersheds, and management practices in order to help better understand MPs in STPs. To manage MPs effectively in STPs, it is necessary to investigate the detection of MPs discharged from STPs, do research on human health risk and control measures, and build a monitoring system including standardized analytical methods.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.316-325
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• 2021

Human-made plastics takes more than 500 years to break down and have been introduced into the ecosystem, threatening terrestrial and aquatic organisms. By 2025, there will be more than 250 million tons of plastics in the ocean. Although studies regarding microplastics have been exponentially increasing since 2015, international standards for defining the size classification for microplastics, as well as methods for qualitative/quantitative analysis have not been concluded yet. Thus, in this study, the latest trends in analytical methodologies have been reviewed. Further, the study suggests directions for future research approaches can be taken to analyze aquatic microplastics, which could be as useful information for establishing effective microplastic management policy via standardization in microplastic analysis.

• Membrane and Water Treatment
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• v.14 no.1
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• pp.19-25
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• 2023

The studies on the effect of different plastic properties (e.g., types, shapes, presence of additivies) on the sorption of contaminants in the agricultural environment are limited. In this study, Cu and Pb, the commonly found heavy metals in the environment, were used to investigate the sorption capacities of microplastics (MPs). The Pb sorption capacity increased in the order of polystyrene (PS)<polyethylene (PE)<polyvinyl chloride (PVC). The estimated Cu sorption capacity was greater for the PE films than the PE fragments, while the sorption strength was greater for the PE fragments. This suggests that the shapes of MPs can affect the contaminant sorption capacities. With the PE fragments, the Pb sorption capacity was greater than the Cu sorption capacity by 10-12 times. Also, the Pb and Cu sorption capacities were greater for the PE fragments with additives than the PE fragment without additives. After the sorption of Pb or Cu on MPs, the toxic effects of the Pb or Cu solutions were decreased, suggesting that the toxic effects of contaminants can be affected by the co-presence of MPs in the environment. Overall, the results show that different types and shapes of MPs and the presence of additives can affect the heavy metal sorption capacities of MPs.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.386-399
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• 2023

Microplastics and nanoplastics (NMPs) are considered one of hazardous contaminants in marine ecosystems due to their toxic effects, such as reproduction disorder and oxidative stress, on marine organisms. Although water temperature is rising due to global climate change, little information on the toxicological interaction between NMPs and temperature is available. Therefore, in this study, we confirmed the toxicity of NMPs (polystyrene [PS] beads; 0.05- and 6-㎛) on brackish water fleas (Diaphanosoma celebensis) depending on increased temperature (30℃ and 35℃) at individual and molecular levels. In the chronic toxicity test, the group exposed to high temperatures showed an earlier first reproduction time compared to the normal temperatures group, but it was delayed by co-exposure to NMPs at 35℃. Notably, the total reproduction decreased significantly only after 0.05-㎛ PS beads exposure at 30℃. Interaction analysis showed that first reproduction time, modulation of the antioxidant-related gene (GSTS1), heat shock gene (Hsp70), and ecdysteroid pathway-related genes (EcR_A, EcR_B, and CYP314A1) were closely related to temperature and PS beads size. These results indicate that microplastics have size-dependent toxicity, and their toxicity can be enhanced at high temperatures. In addition, higher temperatures and PS beads exposure may have negative effects on reproduction. This study suggests that various factors such as water temperature should be considered when evaluating the toxicity of microplastics in marine ecosystems, and provides an understanding of the complex toxic interaction between water temperature and microplastics for marine zooplankton.