Publications by authors named "Kongtae Ra"

Copper (Cu) and zinc (Zn) are common trace metal contaminants in marine environments that, despite their importance for the health of marine organisms, can be toxic. Recently, the stable isotopes of these elements have emerged as powerful tracers for studying their cycles. Thus, this review aims to connect urban and marine interfaces under a "land-sea continuum" framework to understand the complex sources, pathways, and transformations of Cu and Zn in urbanized coastal environments, a perspective currently lacking in the literature.

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This study investigated the distribution and composition of 28 per- and polyfluoroalkyl substances (PFASs) in surface and core sediments from the regional seas of South Korea. Surface sediments were collected from the Yellow Sea (YS, n = 10), East China Sea (ECS, n = 6), South Sea (SS, n = 5), and East Sea (ES, n = 12), and core sediments were obtained from the ES (n = 3, 0-30 cm). Sediment samples were extracted with methanol by shaking, followed by purification using solid-phase extraction cartridges.

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This study investigated metal organotropism and ZnCu isotopic compositions in hydrothermal vent mussels (Bathymodiolus sp.) and sea snails (Ifremeria sp. and Alviniconcha sp.

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Impacts of dam construction on mercury (Hg) sources, biogeochemical cycling, and bioaccumulation were investigated along the west coast of Korea, where large-scale national projects were initiated between 1978 and 1990 to build dam or weir at the interface between rivers and estuaries. Total Hg (THg) and methylmercury (MeHg) concentrations and Hg stable isotopes in estuarine sediment cores sampled downstream of dam/weir reveal 74 ± 3% reduction in THg, 536 ± 158% increase in MeHg, and shifts in Hg sources from riverine export to wet deposition (precipitation) as revealed by increases in ΔHg (by 0.13 ± 0.

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Mercury (Hg) is a contaminant that poses health risks for human populations relying on seafood consumption. To mitigate its impact, identifying and monitoring Hg sources have become priorities, notably under the Minamata Convention. Bivalves are commonly used as sentinels in contaminant biomonitoring but can accumulate Hg from diverse environmental media.

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This study investigated the spatial distribution and chemical characteristics of potentially toxic elements (PTEs) in road-deposited sediments (RDS) at the Port of Busan by size fraction. Enrichment factor (EF) values for Zn, Cd, and Sb in fine RDS <250 μm were 52-69, 49-78, and 46-44, respectively, indicating 'extremely high enrichment'. Various statistical analyses, including PCA and PMF models, revealed a strong correlation between pollution levels in RDS <250 μm and vehicle type, identifying non-exhaust emissions (NEE) of vehicles as a primary source of PTEs in RDS from the port.

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Article Synopsis
  • - Polymetallic nodules on the seafloor contain valuable metals, but their leachates can harm marine ecosystems during mining operations by affecting marine organisms.
  • - The study focused on the marine copepod Tigriopus koreanus, examining how exposure to these leachates influences mortality, development, fecundity, and specific gene expressions related to detoxification and reproduction.
  • - While there were no significant changes in mortality, the leachates shortened developmental time and increased fecundity, with certain metals like manganese and iron showing a positive impact on copepod development when combined with others.
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This study investigates the applicability of elemental and Cu isotope compositions in sediments and bivalves from the Korean coast to monitor anthropogenic Cu contamination. Sediments with high Cu (>64.4 mg/kg) and/or moderate enrichment levels (EF) exhibit homogenous δCu values (-0.

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Deep-sea mining can remobilize large amounts of inert metals from hydrothermal seafloor massive sulfides (SMSs) into bioavailable toxic forms that are dissolved in the water column, potentially impacting marine ecosystems. It is thus critical to assess the impacts of deep-sea mining on the reactivities and behaviors of crucial elements (e.g.

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Estuaries, vital coastal ecosystems, face growing threats from industrialization. To understand the pace of sedimentary changes and heavy metal pollution at the anthropogenically altered and industrialized Nakdong River Estuary in South Korea, we used sediment coring to reconstruct environmental change. Estuarine dam construction in 1934 shifted the sedimentary system from sand to mud, coinciding with a post-1930s mercury increase due to coal burning.

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This study investigated the large-scale distributions of persistent toxic substances (PTSs) and heavy metals in sediments of the Yellow Sea, collected from six transects between latitudes 32 and 37 degrees north (n = 35). Elevated concentrations of polychlorinated biphenyls (PCBs) were detected near the mainland, with a predominance of low-chlorinated congeners (di to tetra, ∼60%), indicative of atmospheric deposition. Analysis of traditional and emerging polycyclic aromatic hydrocarbons (t-PAHs and e-PAHs) revealed notable enrichment in the Central Yellow Sea Mud Zone (CYSM), attributing fossil fuel combustion as the significant source.

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As human society has advanced, nuclear energy has provided energy security while also offering low carbon emissions and reduced dependence on fossil fuels, whereas nuclear power plants have produced large amounts of radioactive wastewater, which threatens human health and the sustainability of water resources. Here, we demonstrate a hydrate-based desalination (HBD) technology that uses methane as a hydrate former for freshwater recovery and for the removal of radioactive chemicals from wastewater, specifically from Cs- and Sr-containing wastewater. The complete exclusion of radioactive ions from solid methane hydrates was confirmed by a close examination using phase equilibria, spectroscopic investigations, thermal analyses, and theoretical calculations, enabling simultaneous freshwater recovery and the removal of radioactive chemicals from wastewater by the methane hydrate formation process described in this study.

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Here, we introduce CO hydrate-based desalination (CHBD) technology for freshwater recovery from radioactive wastewater, for water particularly containing Cs and Sr. The hydrate equilibrium curves of CO hydrates shift towards lower temperature and higher pressure regions as the concentrations of CsCl and SrCl increase. X-ray diffraction and Raman spectroscopy measurements found that neither CsCl nor SrCl can affect the structure of CO hydrates.

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The concentrations and isotopic compositions of carbon (C), copper (Cu), zinc (Zn), and lead (Pb) in coastal sediments were analyzed to identify potential pollution sources. High concentrations of total organic carbon (TOC) and metals were found close to cities and industrial areas. The isotopic compositions of C, Cu, Zn, and Pb tended to decrease as their concentrations increased.

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Antifouling paints (APs) are one of the important sources of Cu and Zn contamination in coastal environments. This study applied for the first-time a multi-isotope (Cu, Zn, and Pb) and multi-elemental characterization of different AP brands to improve their tracking in marine environments. The Cu and Zn contents of APs were shown to be remarkably high ∼35% and ∼8%, respectively.

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This study was the first to investigate the pollution and ecological risks of heavy metals in coastal, river/stream and road-deposited sediments (RDS) from Apia in Samoa. Cr and Ni concentrations in sediment samples were higher than those of other metals. River sediments and RDS had relatively high EF values around the intensive commercial areas, with a moderate to significant enrichment of Cu, Zn, Cd, and Pb.

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Fine road dust is a major source of potentially toxic elements (PTEs) pollution in urban environments, which adversely affects the atmospheric environment and public health. Two different sizes (10−63 and <10 μm) were separated from road dust collected from Apia City, Samoa, and 10 PTEs were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Fine road dust (<10 μm) had 1.

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Potentially toxic elements' (PTEs; V, Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Pb, and Hg) pollution level was investigated in size-fractionated road dust in Busan Metropolitan City. Health risks to humans (adult and children) were also evaluated in fine particle fraction (< 63 μm) of road dust. PTE concentrations in the fine particles (< 63 μm) were ranked as follows (unit: mg/kg): Zn (2511) > Cu (559) > Cr (531) > Pb (385) > Ni (139) > V (83.

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In this study, we evaluated metal accumulation in different species and tissues of seagrasses and green macroalgae Halimeda and assessed metal pollution levels in Chuuk, Micronesia. In seagrass, the concentrations of Ni, Cu, Zn, Cd, Pb, and Hg were higher in leaves than in roots, whereas Cr and As concentrations were higher in roots. Halimeda had higher concentrations of Ni than of the other metals, and the mean Ni concentration was approximately 2.

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The central-eastern Yellow Sea is an important region for transporting organic matter (OM) to the Pacific Ocean, however, there is limited information available regarding the characteristics and sources of OM in this area. The present study investigated the concentrations and stable isotopic compositions of carbon (δC) and nitrogen (δN) for particulate matter and sediment in the central-eastern Yellow Sea during April 2019. The physicochemical properties (i.

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Thirteen trace metals and Zn isotopic signatures were investigated in mussels and oysters collected from the coast of South Korea to evaluate their bioavailability in bivalve mollusks. The average Cu, Zn, and Cd concentrations were 2.6-17.

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Non-exhaust emissions (e.g., particles from brake pads, asphalt, curb, road paint, tire) are important sources of potentially toxic elements (PTEs) pollution in urban environments and are potential causes of PTEs pollution in road dust.

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Novel halogenated flame retardants (HFRs) were introduced to industrial markets as alternatives to legacy brominated FRs (BFRs), such as polybrominated diphenyl ethers (PBDEs). In the present study, PBDEs and their brominated and chlorinated alternatives, novel BFRs (NBFRs) and dechlorane plus (DP), were measured in multiple environmental matrices in a highly industrialized lake in Korea. Legacy and novel HFRs were detected in multiple samples, indicating ubiquitous contamination.

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Potentially toxic elements (PTEs) were investigated in the different sizes of road deposited sediments (RDS) around the active smelting industry to understand their sources and to assess the pollution and ecological risk levels. The highest PTEs concentrations was shown near the raw materials import port and the smelting facilities. The fine particles of RDS showed extremely high PTEs concentrations.

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Heavy metals in coastal sediments and seagrass (Enhalus acoroides) were studied to assess the pollution level and to understand the bioaccumulation of metals on different organs. The mean of metal concentrations in sediments were in the following order: Cr > Ni > As>Zn > Cu > Co > Pb > Cd > Hg. The results of principal component analysis indicate that Cr, Ni, Cu, Zn, As and Hg are derived from natural sources but Cd and Pb seems to be of anthropogenic sources.

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