Physicochemical Forms Research Articles

Speciation of Mercury in Coal-Fired Power Station Flue Gas†

Mercury is a potentially toxic trace metal. Mercury exists naturally in coal in very low concentrations, having been incorporated during the coalification process. Consequently, coal-fired power stations are a major anthropogenic source of mercury because of the large quantity of coal used for electricity generation. In the environment, mercury transforms into methylmercury, a potential neurotoxin, bioaccumulates in aquatic biota, and subsequently, enters the food chain. The subsequent environmental fate and ability to capture mercury prior to emission are dependent upon its different physicochemical forms and oxidation states, known as speciation. In this work, speciation of mercury was conducted at five different coal power stations across Australia (one in New South Wales, three in Western Australia, and one in Queensland) by the Ontario Hydro sampling and analysis method. The total Hg concentrations in the emissions of these plants were found to be in the range of 1.9−5.6 μg Nm−3. Particle-bound mercury HgP occurred in very low proportions of 0.3−3.7%, while variable proportions of Hg0 and HgII were observed. Kinetic calculations were performed assuming a homogeneous system to understand role of the chlorine/mercury ratio of feed coal in the oxidation of mercury during power station combustion. Results from this study are compared to previous work published in the literature and discussed with respect to operating parameters of the power station.

Plutonium isotopes in ecosystem of a running shallow lake

The aim of the present work is to get information on the possibilities of the shallow lake self-cleaning from plutonium isotopes using Lake Žuvintas as an object of study. A choice of the object is mainly related to the peculiarity of hydrology and hydrodynamics of Lake Žuvintas located in the southern part of Lithuania that was affected by radioactive fallouts after the nuclear events. During the period of study the bottom sediments of Lake Žuvintas behaved mainly as an accumulator of Pu isotopes. The main part of plutonium of the Chernobyl origin in surface sediments is present in exchangeable and potentially mobile physico-chemical forms. Processes of Pu migration are especially active during winter season when under anaerobic conditions the most important role in the Pu isotopes transfer belongs to reduced plutonium ions. Keywords: lake, plutonium isotopes, water, sediments, physico-chemical forms

Variability of Mercury in Urine Among Mexican Women Residing in a Mining Area

To know the variability of the creatinine-adjusted inorganic mercury (HgUCr) levels in women aged >or=12 years to evaluate the impact of residing at a site contaminated by mercury in soil. A cross-sectional epidemiologic study was conducted, in which 122 women participated, in whom, HgUCr was determined. Simultaneously, a questionnaire was applied for evaluate the different factors of mercury exposure, sociodemographic characteristics, and dietary hygiene measures. The environmental exposures were evaluated by measure Hg in soil and mining dumps. Women aged >30 years residing in areas contaminated by Hg in soil (>625 ppb) had 212% more HgUCr than the women who living in areas least contaminated, while women with amalgam dental fillings had 120% more HgUCr than women without these. In conclusion, exposure to different physicochemical forms of Hg by environmental mechanisms and factors intrinsic to the women are probably responsible for HgUCr-level variability in the women.

Behavioral and electrophysiological changes in rats after 3 to 6 weeks nasal exposure by two physicochemical forms of manganese

Event Abstract Back to Event Behavioral and electrophysiological changes in rats after 3 to 6 weeks nasal exposure by two physicochemical forms of manganese Gábor Oszlánczi1*, András Papp1, Edina Horváth1 and Tünde Vezér1 1 Szeged University, Medical School, Department of Public Health Medicine, Hungary Airborne manganese represents a major risk of nervous system damage first of all in industrial settings. The resulting effects may depend on the dose and physicochemical form of Mn. To compare the effect of soluble and nanoparticulate Mn, adult male rats received daily instillation of MnCl2 solution or MnO2 nanoparticle (diameter ca. 23 nm) suspension into the nasal cavity for 3 and 6 weeks (dose: 2.53 mg Mn per rat). At the end of treatment, spontaneous open field motility was tested, electrophysiological recording was done in urethane anesthesia, and brain tissue Mn level was determined. Decrease of open field motility, reduction of body weight gain and metal level increase in the brain samples was significant in the MnCl2 treated but slight in the nano-Mn treated rats. The latency of cortical evoked potentials was significantly altered in both groups, but the band spectrum of spontaneous cortical activity only in the rats receiving MnCl2. The time of local activity and rearing in the open field test, as well as the latency of somatosensory evoked potential, showed fair correlation with brain Mn levels what underlined causal relationship. The physicochemical form of Mn had substantial effect on the resulting neuro-functional alterations. Electrophysiological tests might be more sensitive to the effects of Mn than general toxicological or neurobehavioral tests. Conference: IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010. Presentation Type: Poster Presentation Topic: Disorders of the nervous system Citation: Oszlánczi G, Papp A, Horváth E and Vezér T (2010). Behavioral and electrophysiological changes in rats after 3 to 6 weeks nasal exposure by two physicochemical forms of manganese. Front. Neurosci. Conference Abstract: IBRO International Workshop 2010. doi: 10.3389/conf.fnins.2010.10.00054 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 20 Apr 2010; Published Online: 20 Apr 2010. * Correspondence: Gábor Oszlánczi, Szeged University, Medical School, Department of Public Health Medicine, Szeged, Hungary, octbintw@freemail.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Gábor Oszlánczi András Papp Edina Horváth Tünde Vezér Google Gábor Oszlánczi András Papp Edina Horváth Tünde Vezér Google Scholar Gábor Oszlánczi András Papp Edina Horváth Tünde Vezér PubMed Gábor Oszlánczi András Papp Edina Horváth Tünde Vezér Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Fractionation of metal complexes with dissolved organic matter in a rhizosphere soil solution of a humus-rich Andosol using size exclusion chromatography with inductively coupled plasma-mass spectrometry

To better understand the behavior of metals in soil–plant systems, their physicochemical forms in rhizosphere soil should be elucidated. The dissolved organic matter (DOM) in a soil solution influences the mobility and bioavailability of metals in soil. The present study examined the effects of plant growth on DOM–metal complexes in a rhizosphere soil solution using size exclusion chromatography combined with an inductively coupled plasma-mass spectrometer system (SEC–ICP-MS) and an ultrafiltration technique. Humus-rich volcanic ash soil from the surface of an agricultural field was used in a pot cultivation experiment. Brassica rapa nothovar. was cultivated in a pot in which rhizosphere soil (R) was separated by a nylon net screen from non-rhizosphere soil (NR). Soil solutions were collected using a high-speed centrifugation method 3 weeks after sowing and analyzed using SEC–ICP-MS. Some peaks of DOM with a high molecular size were detected in the ultraviolet-absorbing chromatograph (280 nm) of the soil solution samples. Their concentrations were much higher in the R solution than in the NR solution. Metals including Al, Fe, Cu, Zn, Pb, Y, La and U were detected at the ultraviolet peak positions of the DOM. The ultrafiltration experiment showed that the size distributions of the organic materials to which the metals were combined differed between the R and NR soil solutions. These results suggest that plant growth enhanced the dissolution of metals adsorbed with organic matter from the solid phase in rhizosphere soil.

A new method for quantitative analysis of metal content in heterogeneous catalysts: Laser ablation–ICP–AES

Abstract Analysis of catalysts by XRF, ICP–AES or AAS requires sample preparation, which is time consuming and a source of contaminations. Analytical performances of direct analysis of catalysts by LA–ICP–AES are evaluated and compared to usual methods. The coupling allows direct and simultaneous analysis of elements from the support and the catalytic phase. The analytical criteria obtained: LODs below 50 ppm, precision better than 5%, linearity from 0.01 to several weight percents and an analysis time less than 5 min, demonstrated that this method represents an interesting alternative to classical methods. Accuracy was evaluated according to different criteria: alumina phase, physico-chemical form of the supported metals, and presence of concomitant metals. Results showed no influence of the alumina phase on Pt–Sn determination in catalysts. Nevertheless, for the analysis of catalysts with high metal loading, matrix effects were observed. As an example, the use of matrix matching was found to give a mean accuracy in the 10% range for Ni determination.

Physicochemical modeling of the behavior of microelements (As, V, Cr, Co, and Hg) under the mixing of riverine and marine waters (the Razdol’naya River-Amur Bay System)

By means of physicochemical modeling with the Selector software package, a model for the mixing of riverine water (pH = 7.02) and seawater was compiled and calculated. The Razdol’naya River-Amur Bay (Sea of Japan) system was assessed as an example. By means of the MINTEQA2/PRODEFA2 software package, the role of the sorption processes in riverine and marine waters, as well as in the zone of their mixing, was ascertained. The physicochemical migration forms of microelements (arsenic, vanadium, chromium, cobalt, and mercury) in the waters of the geochemical system considered and their behavior in passing through the geochemical barrier were established.

Fractionation of radionuclide species in the environment

Naturally occurring and artificially produced radionuclides in the environment may be present in different physico-chemical forms (i.e., radionuclide species) varying in size (nominal molecular mass), charge properties and valence, oxidation state, structure and morphology, density, degree of complexation, etc. Low molecular mass (LMM) species are believed to be mobile and potentially bioavailable, while high molecular mass (HMM) species such as colloids, polymers, pseudocolloids and particles are considered inert. Due to time-dependent transformation processes such as mobilisation of radionuclide species from solid phases or interactions of mobile and reactive radionuclide species with components in soils and sediments, the original distribution of radionuclides deposited in ecosystems will change over time. To assess the environmental impact from radionuclide contamination, information on radionuclide species deposited, interactions within affected ecosystems and the time-dependent distribution of radionuclide species influencing mobility and biological uptake is essential. The development of speciation techniques to characterize radionuclide species in waters, soils and sediments should therefore be essential for improving the prediction power of impact and risk assessment models. The present paper reviews available fractionation techniques which can be utilised for radionuclide speciation purposes.

Efficient Reduction of Prions by the Manufacturing Process of a VWF/FVIII Product

Variant Creutzfeldt-Jakob disease (vCJD) is a fatal neurodegenerative disease acquired through infection with prions which cause bovine spongiform encephalopathy (BSE) by consumption of beef products from infected cattle. Presumptive transfusion transmitted cases of vCJD have been reported in the UK increasing the concern that medicinal products manufactured from plasma might also pose a risk of vCJD transmission. Therefore, investigational studies were performed to assess the prion reduction capacity of the manufacturing process of a VWF/FVIII product (Haemate® P / Humate-P®). In these studies hamster brain derived prion material in the form of a microsomal preparation were used to spike plasma product intermediates. As the purification process of a desired plasma protein may impact the physico-chemical form of the spiked prion protein, the addition of reduction factors from single step studies possibly might not reflect the true prion reduction of the full process; in particular where the spike material is heterogeneous, one fraction, i.e. gross aggregates of prion material could be preferentially removed by one step and the same subfraction by a subsequent step. Therefore, we employed a combined step study approach and not a single spike step approach to address that issue of the impact of heterogeneous spike fractions regarding the overall reduction factor. The manufacturing process of the VWF/FVIII product was divided in two parts which were studied independently twice: Pooled plasma donations (4,500 ml) were spiked and processed covering cryoprecipitation, Al(OH)3 adsorption and subsequent precipitations by glycine and NaCl. The second part of the VWF/FVIII manufacturing process was studied starting with spiked dissolved NaCl precipitate (154 ml) and processed further by pasteurization, second NaCl precipitation, dialysis, ultracentrifugation and sterile filtration. The prion spiked starting material and product intermediate were processed according to the manufacturing conditions based on a valid down-scale model. The prion reduction factors were determined as the difference of the prion load in the spiked starting materials and in the respective final samples using a biochemical assay (Conformation-Dependent Immunoassay (CDI)) or a bioassay in hamsters for quantification of PrPSc (dose dependent incubation period measurement). The results of these investigational studies for the two prion quantification methods are shown belowPrionReduction Factors [log10] demonstrated byManufacturing stepsbiochemical methods (CDI)bioassay (incubation time)Cryo precipitation / Al(OH)3adsorption / Glycine precipitation3.2 ± 0.12.8 ± 0.3Pasteurization / NaCl precipitation / Dialysis / Ultracentrifugation / Sterile filtration2.9 ± 0.23.1 ± 0.1Filling / Lyophilizationn.d.n.d.Overall Prion Reduction Factor6.1 ± 0.25.9 ± 0.3These results demonstrate (i) comparable prion reduction factors quantified either by biochemical methods or by a bioassay and (ii) an appropriate overall prion reduction capacity of the manufacturing process of Haemate® P / Humate-P®. Based on complementary safety procedures, i.e., collection of plasma by stringent donor selection due to geographic donor deferral policy and the overall prion reduction factor of approximately 6 log10, which clearly exceeds a potential prion load in the manufacturing pool, a risk assessment results in an extremely remote risk of prion transmission by the VWF / FVIII product Haemate® P / Humate-P®.

Physicochemical modeling of the behavior of microelements under the mixing of acid riverine water (the Yur’ev River) with seawater

By means of physicochemical modeling with the Selektor software package, models were created and calculated for acid riverine water (pH = 2.19), for seawater, and for the mixing of these types of waters. The Yur’ev River-Sea of Okhotsk system was assessed as an example. The physicochemical migration forms of microelements (aluminum, zinc, lead, iron, manganese, and silicon) and their behavior in the water-mixing zone were established. The formation of solid hydrogenous phases under the mixing of acid riverine waters with seawater was shown. By means of the MINTEQA2/PRODEFA2 software package, the influence of the sorption processes on the behavior of the elements considered in the mixing zone was revealed.

Influence of tidal regime on the distribution of trace metals in a contaminated tidal freshwater marsh soil colonized with common reed (Phragmites australis)

A historical input of trace metals into tidal marshes fringing the river Scheldt may be a cause for concern. Nevertheless, the specific physicochemical form, rather than the total concentration, determines the ecotoxicological risk of metals in the soil. In this study the effect of tidal regime on the distribution of trace metals in different compartments of the soil was investigated. As, Cd, Cu and Zn concentrations in sediment, pore water and in roots were determined along a depth profile. Total sediment metal concentrations were similar at different sites, reflecting pollution history. Pore water metal concentrations were generally higher under less flooded conditions (mean is (2.32+/-0.08)x10(-3) mg Cd L(-1) and (1.53+/-0.03) x 10(-3) mg Cd L(-1)). Metal concentrations associated with roots (mean is 202.47+/-2.83 mg Cd kg(-1) and 69.39+/-0.99 mg Cd kg(-1)) were up to 10 times higher than sediment (mean is 20.48+/-0.19 mg Cd kg(-1) and 20.42+/-0.21 mg Cd kg(-1)) metal concentrations and higher under dryer conditions. Despite high metal concentrations associated with roots, the major part of the metals in the marsh soil is still associated with the sediment as the overall biomass of roots is small compared to the sediment.

Strong Colloidal and Dissolved Organic Ligands Binding Copper and Zinc in Rivers

The speciation or physicochemical form of copper and zinc in freshwater plays an important role in reactivity, bioavailability, and toxicity. Strong metal-binding ligands, which determine speciation, were detected by voltammetric methods, both anodic stripping voltammetry (ASV) and competitive ligand equilibration adsorptive stripping voltammetry (CLE-AdSV); the latter technique can detect nanomolar levels of extremely strong (log K' > 13) ligands. Through careful field site selection and the investigation of ultrafiltration permeate samples, natural organic ligands were measured with limited interferences of colloidal inorganic iron- and aluminum-based trace metal-binding phases. Furthermore, ultrafiltration allowed measurement of colloidal and dissolved ligands independently, and differences of ligand abundance and strength in different size classes are reported. For copper, ultrafilterable (<3 kDa) organic ligand site concentrations (expressed normalized to dissolved organic carbon) were on average 33% of the colloidal level, but ultrafilterable ligand log K' values were 0.5 log units stronger than those of the 0.4 microm filterable concentration. The ultrafilterable copper-binding ligand concentration showed a smaller variation across the rivers (25% rsd) than zinc-binding ligands (90% rsd). For all field sites and size fractions, strong ligand sites greatly exceeded metal concentrations; subsequently, equilibrium speciation modeling predict picomolar levels of free metal. Modeling also indicated that the very strong ligands (detected by CLE-AdSV) predominate, so modeling based solely on ASV data in freshwater may be inadequate. Competition experiments indicated that the very strong ligand sites are metal specific for copper and zinc.

Prediction of monitoring data for 239Pu accidentally injected via wound site based on the proposed NCRP wound model

In response to the consultation from the National Council on Radiation Protection and Measurements (NCRP) to the International Commission on Radiological Protection (ICRP) committee 2, retention and excretion of 239Pu deposited at wound site were calculated by coupling together the proposed NCRP wound model and the current ICRP systemic model of Pu. The physicochemical forms considered were the soluble form categorized into 'Strong Retention', and the colloidal, particulate and fragmentary forms. The results are summarized as follows. If in soluble form, immediate medical intervention is needed to prevent uptake of radionuclides to body tissues, and prompt wound monitoring is essential for an accurate estimation of the initially deposited radioactivity. If in particulate form, a multi-component exponential equation leads to an overestimation of the absorption rate to blood because of significant lymph node drainage. The committed doses in the organs for direct transfer of 239Pu to the blood may be applied to every cases of accidental injection except for fragments.

Percutaneous penetration of uranium in rats after a contamination on intact or wounded skin

The aim of this work is to assess in vivo in a hairless rat model, the percutaneous diffusion of uranium through intact or wounded rat skin. Six types of wounds were simulated by excoriation and burns with 10 N HF, 2, 5 and 14 N HNO3 and 10 N NaOH on anaesthetised hairless rats. Percutaneous penetration through wounded skin towards blood and subsequent urinary excretion of uranium was followed in vivo during 24 h. The influence of the physicochemical form (solution or powder) of uranyl nitrate (UN) on its percutaneous diffusion was also investigated. UN, even as a powder, can diffuse through intact skin. The presence of uranium in blood is more persistent and its urinary elimination is slower after an HF burn than after an HNO3 burn. Excoriation increases dramatically percutaneous absorption of UN. Thus, percutaneous diffusion of UN is largely dependent on skin barrier integrity with a particular importance of stratum corneum.

The NCRP wound model: development and application

The US National Council on Radiation Protection and Measurements, in collaboration with the International Commission on Radiological Protection, has been developing a biokinetic and dosimetric model for radionuclide-contaminated wounds. The finalised model is described briefly in this paper, together with the scientific basis and application. The multicompartment model uses first-order linear biokinetics to describe the retention and clearance of a radionuclide deposited in a wound site using seven default retention categories. Examples using plutonium nitrate in colloidal form and uranium in metal fragments show the behaviour of the less soluble forms of radionuclides in wounds, in which long-term retention is predicted. Using uranium as an example, the wound model is coupled to a uranium International Commission on Radiological Protection systemic model to predict urinary excretion patterns for different physicochemical forms of uranium. The latter application is needed for bioassay interpretation.

Speciation of radionuclides – analytical challenges within environmental impact and risk assessments

The mobility, biological uptake and accumulation of radionuclides are essentially dependent on the physico-chemical form of the nuclides. As a major fraction of refractory radionuclides released during historical nuclear events is associated with particles, a key analytical challenge within environmental impact and risk assessments is to characterise radioactive particles with respect to properties influencing particle weathering, remobilisation and the subsequent ecosystem transfer of associated radionuclides. Preanalysis techniques are needed to fractionate, identify and localize individual particles in contaminated samples. To obtain information on particle characteristics such as particle size distributions, structures, elemental and radionuclide particle composition as well as oxidation state of matrix elements, solid-state speciation techniques are needed. Electron microscopy as well as X-ray microscopic techniques utilising synchrotron X-ray radiation have proved most useful in providing such information. The present paper summarises the present status on advanced techniques and presents historical sources that have contributed to radioactive particle contamination.

INCORPORATION AND DISTRIBUTION OF URANIUM IN RATS AFTER A CONTAMINATION ON INTACT OR WOUNDED SKIN

Uranium uptake can occur accidentally by inhalation, ingestion, injection, or absorption through intact or wounded skin. Intact or wounded skin routes of absorption of uranium have received little attention. The aims of our work were (1) to evaluate the influence of the type of wound contamination on the short term distribution and excretion of uranium in rats and (2) to generate data to assess the time available to treat contamination of intact or wounded skin before significant uptake of uranium occurs. Biokinetic data presented in the present paper are based on an in vivo rat model. This study shows that a significant uptake of a uranyl nitrate solution through intact skin can occur within the first 6 h of exposure. Absorption of a uranyl nitrate solution through excoriated skin is significant after only 30 min of exposure. After a 24-h exposure, uranium uptake through intact skin and excoriated skin represents about 0.4% and 38% of the initial deposit of uranium, respectively. Contaminated serious chemical skin burns induced by HNO3 or NaOH are paradoxically less important in terms of uranium uptake risk because 99% of the incorporated uranium remains trapped at the wound site and its incorporation is delayed for at least 6 h after the beginning of contamination. These results confirm that the biokinetics of a given physicochemical form of uranium incorporated after wound contamination depend largely on the physiological evolution of the considered wound. Each type of wound, with its corresponding biokinetics of a uranium species, is a particular case.

Beryllium: A Modern Industrial Hazard

Beryllium exposure can cause a granulomatous lung disease in workers who develop a lymphocyte-mediated sensitization to the metal. Workers in diverse industries are at risk because beryllium's properties are critical to nuclear, aerospace, telecommunications, electronic, metal alloy, biomedical, and semiconductor industries. The occupational air concentration standard's failure to protect beryllium workers is driving many scientific and occupational health advances. These developments include study of bioavailability of different physicochemical forms of beryllium, medical surveillance to show effectiveness of skin protection in preventing sensitization in high-risk processes, gene-environment interaction, transgenic mice for use in experimental research, and risk-based management of industrial exposures in the absence of effective exposure-response information. Beryllium sensitization and disease prevention are paradigms for much broader public health action in both occupational and general population settings.

Release Behavior of Copper and Zinc from Sandy Soils

Copper (Cu) and zinc (Zn) transport after agricultural applications have accumulated in the sediments and are suspected to affect fish health in the Indian River Lagoon and St. Lucie Estuary, South Florida. Minimal information is available on the release of soil Cu and Zn to water and its relation to their concentrations and physicochemical forms in the soils. Sandy soil samples (n = 13) with a wide range of total Cu and Zn content were collected from forestland and commercial citrus groves in the Indian River area, Florida. The soils were subjected to column leaching and batch extractions to understand the release behavior of Cu and Zn as affected by soil‐water contact time, soil/water ratio, pH, and electrolyte concentration and cations. Copper released in batch extractions that simulated long‐term leaching was primarily from exchangeable and carbonate‐bound fractions, whereas Zn was primarily from the carbonate‐bound fraction. The Cu and Zn released from the column represented short‐term leaching and were primarily from their exchangeable fractions. Leached Zn decreased linearly as the solution pH was raised from 3.0 to 9.0. Leached Cu was at a minimum at pH 5 to 7 and increased at higher or lower pH beyond that range. These results indicate that long‐term saturated conditions after precipitation enhanced Cu and Zn release to water from the sandy soils. The released Cu decreased with increasing Ca concentration but increased with sodium (Na) concentration in the soil solution because of their differential effects on soil colloids, especially organic matter (flocculated by Ca2+ and dispersed by Na+) because organically bound Cu is the dominant fraction in the soils. Increasing Ca, K, Na, or NH4+ concentration generally increased Zn release through cation exchange. These findings merit attention in the development of best management practices to reduce transport of heavy metals from land to water.

Vertical distribution of rhenium in seawater samples collected at three locations off the coast of Aomori, Japan

Summary The behavior rhenium in surface seawater (0-30 m) was studied using the samples collected at three locations off the coast of Aomori Prefecture, Japan. The physico-chemical forms of Re in seawater from other locations were also studied to verify the Aomori findings. It was found that almost 100% of Re was in dissolved forms, mainly ReO4-, therefore, the Re concentration was constant from the surface to 30 m depth and ranged from 6.1-7.4 ng. kg-1. The Re concentration in the Sea of Japan side was slightly lower than those in the Pacific Ocean side. Possibly, low Re concentration was added by river waters from Japan and/or the Asian continent to the Sea of Japan side.