Acute and chronic effects of polymetallic nodule leachate in the marine copepod Tigriopus koreanus.

Polymetallic nodules containing manganese, iron, and other metals are found in the seafloor. Leachates of polymetallic nodules can be discharged into seawater during ocean mining, disrupting marine ecosystems and causing adverse effects on marine organisms. Here, we investigate the acute and chronic effects of two polymetallic nodule leachates on the life-history parameters (mortality, development, and fecundity) and transcriptional differences of detoxification, antioxidant, and reproduction-related genes for cytochrome P450, glutathione S-transferase, and vitellogenin in the marine copepod Tigriopus koreanus. We also examine single and combined effects for six metals whose concentrations differ between the two leachates. No significant changes in mortality were observed, but developmental time was significantly shortened and fecundity increased in T. koreanus in response to exposure to the leachates. No adverse effects on physiological parameters were seen, but transcriptional differences by leachates were evident. In addition, manganese and iron in the leachates improved copepod development when they were combined with other metals. The findings of this study elucidate the potential impact of polymetallic nodule leachates on marine copepods.

Combined copper isotope and elemental signatures in bivalves and sediments from the Korean coast: Applicability for monitoring anthropogenic contamination.

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 (EFCu) exhibit homogenous δ65CuAE647 values (-0.12 to +0.16 ‰), suggesting similar anthropogenic Cu fingerprints along the Korean coast. Sediments with Cu concentrations near natural background levels (< 20.6 mg/kg) display large isotopic variability (Δ65Cumax-mim: ~0.8 ‰), encompassing those from sediments under anthropic influences. We hypothesize that Cu isotopic compositions of Korean geology are heterogeneous, therefore, natural end-members of source mixing models should be established locally at small scales. Cu concentrations in Oysters correlate with sediments, and their isotopic compositions are more suitable for monitoring Cu contamination, while mussel's regulatory mechanisms seem to affect source records. The current Cu isotope data will help to detect shifts attributable to anthropic contamination in future biomonitoring.

Pace of heavy metal pollution in the anthropogenically altered and industrialized Nakdong River Estuary, South Korea: Implications for the Anthropocene.

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. Mercury concentrations in other South Korean regions surged in the 1970s, indicating proximity to emission sources matters. However, most heavy metal levels (Cu, Cd, Zn, Ag) sharply rose in the 1960s and 1970s with regional industrialization. Modern heavy metal concentrations doubled pre-industrial levels, underscoring human activities as the primary driver of Nakdong Estuary environmental changes. This emphasizes the need for a balanced approach to development and environmental preservation.

Zinc and copper isotope fractionation in metal leaching from hydrothermal ore deposits: Environmental implications for deep-sea mining.

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., Zn and Cu) and their isotopes during mineral leaching processes. To this end, we conducted leaching experiments using different SMS mineral types (CuFe rich, Fe rich, and ZnFe rich) to assess metal releases and the isotope fractionations of Zn and Cu. Significant correlations were observed between Ni, Cu, Zn, Cd, and Pb concentrations in leachates and the SMSs, suggesting that metal leaching into seawater depended on individual SMS metal content. The Zn and Cu concentrations in leachates varied greatly by both SMS type and the leaching time. Zn concentrations from ZnFe rich SMSs exceeded the recommended effluent limits set by the IFC World Bank and the USEPA. SMS ore leachates exhibited Cu and Zn isotope ratios distinct from those of Indian Ocean deep seawater. The isotope fractionation magnitude (Δore-seawater) of Cu was more pronounced than that of Zn, likely due to the redox process involved in the leaching processes. In contrast, the Zn isotope signatures in leachates conserve those of minerals, although slight isotope fractionations occurred in solution following the adsorption and precipitation processes of Fe-oxyhydroxides. Our findings confirm that leveraging the chemical and isotope signatures of toxic metals offers a valuable approach for assessing the extent of metal contamination of leachates and mine tailings stemming from deep-sea mining operations, concerning their influence on the surrounding water columns.

Compound- and element-specific accumulation characteristics of persistent toxic substances and metals in sediments of the Yellow Sea.

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. Styrene oligomers and alkylphenols exhibited notable accumulation near the Han River Estuary in South Korea and the Yangtze River Estuary in China, respectively. The accumulation of heavy metals was predominantly observed in the CYSM, with element-specific distribution patterns. Cluster analysis revealed distinct distribution patterns for PTSs and metals, highlighting their source-dependent and grain size-dependent behaviors. In addition, the distribution and accumulation of PTSs tended to depend on their partitioning coefficients, such as the octanol-air partition coefficient (log KOA) and octanol-water partition coefficient (log KOW). This study offers valuable insights into the sources, transport, and fate of hazardous substances in the Yellow Sea, emphasizing the necessity for targeted environmental management strategies.

Freshwater Recovery and Removal of Cesium and Strontium from Radioactive Wastewater by Methane Hydrate Formation.

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. More importantly, the proposed HBD technology is applicable to radioactive wastewater containing Cs+ and Sr2+ across a broad concentration range of low percentages to hundreds of parts per million (ppm) and even subppm levels, with high removal efficiency of radioactive chemicals. This study highlights the potential of environmentally sustainable technologies to address the challenges posed by radioactive wastewater generated by nuclear technology, providing new insights for future research and development efforts.

Isotopic (Cu, Zn, and Pb) and elemental fingerprints of antifouling paints and their potential use for environmental forensic investigations.

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. The δ65CuAE647, δ66ZnIRMM3702, and 206Pb/207Pb of the APs differed depending on the manufacturers and color (-0.16 to +0.36‰, -0.34 to +0.03‰, and 1.1158 to 1.2140, respectively). A PCA analysis indicates that APs, tires, and brake pads have also distinct elemental fingerprints. Combining isotopic and elemental ratios (e.g., Zn/Cu) allows to distinguish the environmental samples. Nevertheless, a first attempt to apply this approach in highly urbanized harbor areas demonstrates difficulties in source apportionments, because the sediment was chemically and isotopically homogeneous. The similarity of isotope ranges between the harbor and non-exhaust traffic emission sources suggests that most metals are highly affected by urban runoff, and that APs are not the main contributors of these metals. It is suspected that AP-borne contamination should be punctual rather than dispersed, because of APs low solubility properties. Nevertheless, this study shows that the common coastal anthropogenic sources display different elemental and isotopic fingerprints, hence the potential for isotope source tracking applications in marine environments. Further study cases, combined with laboratory experiments to investigate isotope fractionation during releasing the metal sources are necessary to improve non-traditional isotope applications in environmental forensics.

Characteristics of metal pollution and multi-isotopic signatures for C, Cu, Zn, and Pb in coastal sediments from special management areas in Korea.

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. Bi-plots between δ65Cu and δ66Zn showed that the isotopic compositions in most coastal sediments, except sediments around a smelter, were similar to the isotopic compositions of road dust in urban and industrial areas of Korea. Our results suggest that heavy metal pollution in coastal sediments is greatly influenced by the pollution source, such that most metals originate from traffic and industrial activities in the urban environment. This analysis of multiple isotopes provides insights concerning the transport mechanisms and clarifies potential sources of metal contamination in coastal environments.

Pollution and ecological risk assessments for heavy metals in coastal, river, and road-deposited sediments from Apia City in Upolu Island, Samoa.

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. The results indicate that Cr and Ni have a natural origin from volcanic parent materials, while Cu, Zn, Cd, and Pb originated from anthropogenic activities, such as traffic emissions and the discharge of municipal wastewater. The assessments of pollution and ecological risk revealed that coastal sediments adjacent to the river are anthropogenically contaminated and present a moderate ecological risk. This study demonstrates that metals that have accumulated in the urban impermeable layer and river/stream bed have flowed into the coastal environment through runoff.

Pollution and Health Risk Assessments of Potentially Toxic Elements in the Fine-Grained Particles (10−63 µm and <10 µm) in Road Dust from Apia City, Samoa

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 1.2−2.3 times higher levels of copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), antimony (Sb), lead (Pb), and mercury (Hg) than 10−63 µm particles. The enrichment factor (EF) value of Sb was the highest among PTEs, and reflected significant contamination. Cu, Zn, and Pb in road dust were also present at moderate to significant levels. Chromium (Cr), cobalt (Co), and nickel (Ni) in road dust were mainly of natural origins, while Cu, Zn, Sb, and Pb were due to traffic activity. The levels of PTEs in road dust in Samoa are lower than in highly urbanized cities, and the exposure of residents in Samoa to PTEs in road dust does not pose a noncarcinogenic health risk. Further studies of the effects of PTEs contamination in road dust on the atmosphere and living organisms are needed.

Seagrass and green macroalgae Halimeda as biomonitoring tools for metal contamination in Chuuk, Micronesia: Pollution assessment and bioaccumulation.

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 2.1 times higher in Halimeda than in seagrass leaves. The concentrations of Cr, As, Cu, Pb, and Hg in Halimeda were similar to those in seagrasses, whereas the Zn and Cd concentrations in Halimeda were very low. Significant correlations in metal concentrations between sediment and both seagrasses and Halimeda were observed for Cr, Ni, Cu, Zn, and Pb. This study suggests that seagrasses and Halimeda are useful indicators for monitoring metal pollution in coastal environments.

Source apportionment and health risk assessment for potentially toxic elements in size-fractionated road dust in Busan Metropolitan City, Korea.

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 (83.8) > Sb (31.6) > Co (21.6) > As (17.2) > Cd (4.1) > Hg (0.38). The PTE concentrations in fine particles (< 63 µm) were significantly higher than those in coarse particles except for V, Co, and As. The mean PTE loadings of fine particle fraction (< 63 µm; 233 mg/m2) in road dust were up to 4.5 times higher than other particle fractions. Igeo values of Sb were higher than 5 except for > 1000-µm fraction, indicating extremely polluted status. PCA results and elemental ratios indicated that most of the PTEs in road dust were derived from non-exhaust traffic-related sources such as brake pads and tires. Cr, Pb, and Sb had higher HI values than other metals for both adults and children. Sampling sites of heavy traffic and industrial areas showed that the carcinogenic risk exceeded the maximum threshold level (10 - 4). Especially in children, the mean carcinogenic risk (ingestion pathway) of As (6.8 × 10 - 4) Cd (2.0 × 10 - 4), and Ni (4.1 × 10 - 4) exceeded the maximum threshold level, indicating that continuous exposure to road dust may pose a high cancer risk to children. Therefore, continuous monitoring and management of these metals are needed to protect human health and the urban environment.

Changes in the characteristics of organic matter associated with hydrodynamics and phytoplankton size structure in the central-eastern Yellow Sea.

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 (δ13C) and nitrogen (δ15N) for particulate matter and sediment in the central-eastern Yellow Sea during April 2019. The physicochemical properties (i.e., salinity, temperature, fluorescence, and nutrients), size-fractionated phytoplankton biomass (Chl-a), and concentration and fluorescence characteristics of dissolved organic matter (DOM) were also determined. The satellite SST and Chl-a data indicated that mixing cold and warm water masses were observed. Phytoplankton blooms occurred a few days before our sampling campaign. Considering the high concentration of suspended solids in the bottom layer, resuspended sediment caused by tidal currents could be a major source of OM in coastal areas. The δ13C values of particulate organic matter (POM) in the coastal area were higher (-23 to -22‰) than those of OM from terrestrial sources (approximately -28 to -27‰). Instead, the lowest δ13C values were observed in the central part of our study area, where the relative abundance of picophytoplankton was high. These results indicated that phytoplankton-derived OM after phytoplankton spring blooms in the coastal area could be the primary source of OM rather than terrestrial origins. In addition, the source of OM that presented low δ13C values could be picophytoplankton-derived OM. The characteristics of DOM were related to biological processes (mediated by phytoplankton and bacteria) and resuspension of sedimentary organic matter. We did not detect an influx of large amounts of terrestrial OM in coastal sediments. Overall, the source and characteristics of OM appeared to be influenced by the hydrodynamics and the distribution properties of lower trophic-level organisms in the central-eastern Yellow Sea during the spring season.

Characteristics of potentially toxic elements and multi-isotope signatures (Cu, Zn, Pb) in non-exhaust traffic emission sources.

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. We present the PTEs concentrations (Cr, Ni, Cu, Zn, As, Cd, Sn, Sb, Pb) of non-exhaust emission sources and pollution degree of PTEs. Isotopic signatures of Cu, Zn, and Pb were also analyzed to distinguish these sources. Among PTEs, the Cu concentration in all brake pads was significantly high and brake pads from Korea showed remarkably high Sb concentrations. Asphalt had a higher Pb concentration than other non-exhaust emission sources. Mean of δ65CuAE647, δ66ZnIRMM3702, and 206Pb/207Pb values of non-exhaust emission sources in this study ranged from -0.49‰ to +0.19‰, -0.24‰ to +0.16‰, and 1.1535 to 1.4471, respectively. Non-exhaust emission sources could be discriminated by plotting the concentration and isotopic composition of Cu. Cu isotopic compositions (δ65CuAE647) were clearly distinguished between brake pads including domestic and imported products and tires. Zn isotope values (δ66ZnIRMM3702) of brake pads, tires, and asphalt overlapped, but discriminated from road paint and curb. Our results indicate that the combination of Cu and Zn isotopic signatures can distinguish various non-exhaust traffic emissions, especially brake pads and tires.

A nationwide survey of trace metals and Zn isotopic signatures in mussels (Mytilus edulis) and oysters (Crassostrea gigas) from the coast of South Korea.

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 2.6-17.7 times higher in oysters than mussels, and high biota sediment accumulation factors (>30) were observed for these metals in oysters. Except for Pb in mussels, most metals had no correlation with total sediment concentrations. In oysters, Fe, V, Cu, Zn, Sn, and Pb concentrations were significantly correlated with sediments. The average values of δ66ZnIRMM3702 in mussels, oyster, and sediments were +0.09‰, +0.12‰, and -0.06‰, respectively. Soft tissues of mussels and oysters with high Zn concentrations tended to contain lighter Zn isotopes. The results indicate that oysters are a better biomonitoring organism for metal contamination than mussels and can be used in the monitoring and management of coastal environments and ecosystems.

Severe contamination and time trends of legacy and novel halogenated flame retardants in multiple environmental media from Lake Shihwa, Korea: Effectiveness of regulatory action.

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. Concentrations of HFRs in water and sediment observed in creeks running through machine, textiles, and automobile industrial complexes were significantly higher than those observed in inside and outside of the lake. Higher bioaccumulation levels of HFRs were observed in inshore compared with offshore waters. Results suggest that multi-matrix distribution of legacy and novel HFRs was dependent on the geographical proximity to industrial sources. Compared with previous studies, the highest levels of PBDEs and NBFRs were recorded in water samples on a global scale, implying on-going emissions from industrial activities. Decabromodiphenyl ethane (DBDPE) was a dominant compound in water samples, whereas the concentrations of PBDEs, NBFRs, and DP in sediment were similar to each other. This suggests a shift in consumption from legacy to novel HFRs, preferentially in water environments. A significant declining trend in PBDEs was observed in water and sediment collected between 2008 and 2015, indicating the effectiveness of regulatory actions. Based on their environmental occurrence and bioaccumulation potential, pentabromoethylbenzene and bis(2-ethylhexyl) tetrabromophthalate may pose emerging concerns regarding contamination of aquatic environments.

Potentially toxic elements pollution in road deposited sediments around the active smelting industry of Korea.

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. Zn has the highest mean concentration in the < 63 µm particle size of RDS, followed by Pb > Cu > As > Cr > Ni > Cd > Hg. The PTEs concentrations of this study were the highest values compared to the soils around the smelter and the RDS in urban and industrial areas in the world. This indicates that these PTEs pollution in RDS were mainly attributed to the transportation of raw materials for the smelting industry. According to nemerow pollution index calculation, RDS at all sampling sites with particles of less than 250 mm was seriously polluted with PTEs. The ecological risk was also found to be very high in all RDS fractions and highly toxic elements such as Cd, Pb and Hg pose extremely risk. Given the total amounts PTEs in the road surface, it is necessary to apply RDS removal management plan to reduce the PTEs pollution.

Heavy metal pollution assessment in coastal sediments and bioaccumulation on seagrass (Enhalus acoroides) of Palau.

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. Cr, Ni, Cu, Zn, Cd and Pb in the coastal sediments were at low ecological risk level. As and Hg presented the highest ecological risk among all metals. The mean concentrations of Cr, Ni, Cu, Zn, Cd, and Hg were higher in leaves of E. acoroides than in roots. Significant correlations (p < 0.05) for Cr, Ni, Cu, Zn, and Pb in between sediments and in E. acoroides both leaves and roots. High bioconcentration factor (BCF) were calculated for Zn, Cd, and Hg.

Source identification and implications of heavy metals in urban roads for the coastal pollution in a beach town, Busan, Korea.

Heavy metals in the sediments of urban roads (RDS), storm drains (SDS), and marine areas (MS) were investigated to assess road pollution in a beach town adjacent to the coast in Busan and identify their relationships with the marine environment. RDS were considerably polluted with Zn, Cu, Cr, and Pb, with mean concentrations of 1090, 178, 171, and 199 mg/kg, respectively. MS were severely contaminated with Zn and Cu, exceeding the effects range median (ERM; Cu = 270, Zn = 410 mg/kg). PCA and HCA identified tire and brake wear in RDS as the major sources of Zn, Pb, Cu, and Cd, and that high levels of Zn, Cu, and Pb in RDS originating from traffic activities contaminated MS through the urban storm drain system. The results suggested that traffic-originated metals in RDS are potential pollutants in coastal environments, and further studies on their fate and management should be conducted.

Characterization of the contribution of road deposited sediments to the contamination of the close marine environment with trace metals: Case of the port city of Busan (South Korea).

We examined the concentrations of 12 trace metals in road-deposited sediments (RDS) and their contributions to the pollution of harbor/marine sediments in the port city of Busan, South Korea. The concentrations of Cr, Cu, Zn, Cd, Sn, Sb, and Pb in RDS affected by industrial and traffic activities were 6.7-25.7 times higher than those in marine sediments. The enrichment factors indicate that RDS are extremely polluted with Sb and moderately to strongly polluted with Cr, Cu, As, Sn, Pb, Zn, and Cd. The mean modified pollution index distinguished between unpolluted marine sediments, moderately to heavily polluted harbor sediments, and severely polluted RDS. Furthermore, harbor/marine sediments close to shipyards and the mouths of streams and rivers were found to be moderately polluted with Cu, Zn, Cd, Sb, and Pb. RDS containing trace metals accumulate on impervious surfaces and flow into the marine environment via untreated stormwater runoff.