Development of an analytical method for accurate and precise determination of rare earth element concentrations in geological materials using an MC-ICP-MS and group separation.

The concentration of rare earth elements (REEs) in geological materials including SLRS-6 (natural water certified reference material) and JB1b, JA1, and JG2 (Standard Rock Materials of Geological Survey of Japan) can be used as a tracer to characterize various geochemical processes in earth systems. Particularly, accurate and precise determination of rare earth element concentration in natural waters is difficult due to their extremely low concentration and the interference of polyatomic oxides. In this study, we developed a method for accurate and precise determination of the REE (particularly heavy rare earth elements) concentrations in geological materials including natural waters using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) and group separation by 2-hydroxyisobutyric acid (HIBA).

Analysis of Natural Organic Matter in Water from Cold and Hot Mineral Springs in South Korea Using 15T FT-ICR-MS.

The natural organic matter (NOM) properties in water from cold and hot mineral springs in South Korea are not well documented. We analyzed the characteristics of NOM in water from 25 cold and hot mineral springs located across South Korea. The NOM of each sample was concentrated using solid-phase extraction and analyzed using 15T Fourier-transform ion cyclotron resonance mass spectrometry.

Tracing microplastic (MP)-derived dissolved organic matter in the infiltration of MP-contaminated sand system and its disinfection byproducts formation.

Microplastic (MP) pollution in soil/subsurface environments has been increasingly researched, given the uncertainties associated with the heterogeneous matrix of these systems. In this study, we tracked the spectroscopic signatures of MP-derived dissolved organic matter (MP-DOM) in infiltrated water from MP contaminated sandy subsurface systems and examined their potential to form trihalomethanes (THMs) and haloacetic acids (HAAs) by chlorination. Sand-packed columns with commercial MPs (expanded polystyrene and polyvinylchloride) on the upper layer were used as the model systems.

Exposure of Metal Oxide Nanoparticles on the Bioluminescence Process of and Recombinant Strains.

Comparison of the effects of metal oxide nanoparticles (NPs; CuO, NiO, ZnO, TiO, and AlO) on different bioluminescence processes was evaluated using two recombinant ( and ) strains of with same inducer exposure. Different sensitivities and responses were observed according to the type of NPs and recombinant strains. EC values were determined.

Spatial distributions of oxygen and hydrogen isotopes in multi-level groundwater across South Korea: A case study of mountainous regions.

This study presents the spatial distributions of stable isotopes for groundwater according to well depth and spring water across South Korea, using an interpolation model to provide baseline information for hydrological studies. In total, 888 groundwater and 108 spring water samples were collected across South Korea; their oxygen and hydrogen isotopic compositions (δO and δH) were analyzed. δO and δH values biased toward the summer local meteoric water line and low d-excess values indicate that summer precipitation is important for groundwater recharge.

Measurement of radium and radon in water using a combination technique of radon-emanation and pair-measurements methods.

Since Rn is continuously generated by the decay of Ra, it is difficult to analyze Rn in water containing Ra. To analyze Ra, a large amount of water is passed through a manganese fiber column to adsorb radium, and then radium delayed coincidence counting or gamma-ray spectroscopy is performed approximately four weeks later. A combination technique of radon-emanation and pair-measurement was tested to analyze Ra and Rn in water.

Comparisons of the Effect of Different Metal Oxide Nanoparticles on the Root and Shoot Growth under Shaking and Non-Shaking Incubation, Different Plants, and Binary Mixture Conditions.

We evaluated the toxicity of five metal oxide nanoparticles (NPs) in single or binary mixtures based on root and shoot growth of two plant species under non-shaking and shaking conditions. The effects of NPs on root and shoot growth differed depending on the NP type, incubation condition, and plant type. The half maximal effective concentration (EC) of NPs based on root growth were significantly lower, by 2.

Delineation of groundwater quality locations suitable for target end-use purposes through deep neural network models.

Groundwater is the main source of water for beverages, and its quality varies depending on extraction location; this is particularly the case in regions with complex geology, topography, and multiple forms of land use. Thus, it is important to determine a suitable groundwater extraction location based on intended water use and the related water quality standards. In this study, deep neural network (DNN) models and GIS data relating to groundwater quality were applied to estimate potential maps of Gangwon Province in South Korea, where groundwater is frequently extracted for drinking purposes.

Evaluation of the Effects of Particle Sizes of Silver Nanoparticles on Various Biological Systems.

Seven biological methods were adopted (three bacterial activities of bioluminescence, enzyme, enzyme biosynthetic, algal growth, seed germination, and root and shoot growth) to compare the toxic effects of two different sizes of silver nanoparticles (AgNPs). AgNPs showed a different sensitivity in each bioassay. Overall, the order of inhibitory effects was roughly observed as follows; bacterial bioluminescence activity ≈ root growth > biosynthetic activity of enzymes ≈ algal growth > seed germination ≈ enzymatic activity > shoot growth.

Comparative Effects of Particle Sizes of Cobalt Nanoparticles to Nine Biological Activities.

The differences in the toxicity of cobalt oxide nanoparticles (Co-NPs) of two different sizes were evaluated in the contexts of the activities of bacterial bioluminescence, - gene, enzyme function and biosynthesis of β-galactosidase, bacterial gene mutation, algal growth, and plant seed germination and root/shoot growth. Each size of Co-NP exhibited a different level of toxicity (sensitivity) in each biological activity. No revertant mutagenic ratio (greater than 2.

Application of stable isotopes and dissolved ions for monitoring landfill leachate contamination.

We evaluated groundwater contamination by landfill leachate at a municipal landfill and characterized isotopic and hydrogeochemical evidence of the degradation and natural attenuation of buried organic matter at the study site. Dissolved ion content was generally much higher in the leachate than in the surrounding groundwater. The leachate was characterized by highly elevated bicarbonate and ammonium levels and a lack of nitrate and sulfate, indicating generation under anoxic conditions.

Toxic Effects of Metal Oxide Nanoparticles Based on the Enzymatic Activity and Biosynthesis of -Galactosidase Using a Mutant Strain of .

The effects of six metal oxide nanoparticles (MO-NPs) on the activity and biosynthesis of an enzyme (-galactosidase) were examined using a mutant strain of . Different sensitivities were observed according to the type of NP and metabolic process. The toxic effects on enzyme activity were significantly greater than on biosynthesis (p < 0.

Occurrence of metal-rich acidic groundwaters around the Mekong Delta (Vietnam): A phenomenon linked to well installation.

Acidic groundwaters enriched with heavy metals are frequently observed in the coastal plain aquifers. The acidic pHs are observed even in the deep confined aquifers in southern Vietnam. This study geochemically explores the causes of these acidic groundwaters by investigating 41 groundwater samples, 4 soil samples and a 54 m long sediment core and the long-term monitoring data (4189 observations) obtained from 178 wells of the National Groundwater Monitoring Network for the South of Vietnam (NGMNS).

Ecotoxicity evaluation of Cu- and Fe-CNT complexes based on the activity of bacterial bioluminescence and seed germination.

The toxic effects of the composites of Fe and Cu with different percentages of CNTs were examined based on the activity of bacterial bioluminescence and seed germination. In terms of the EC values, the toxic effects of Cu on bacterial bioluminescence and seed germination were approximately 2 and 180 times greater than that of Fe, respectively. The toxicity increased with increasing CNT content in the Cu-CNT mixtures for both organisms, whereas opposite results were observed with Fe-CNT mixtures.

Influence of Incubation Conditions on the Nanoparticles Toxicity Based on Seed Germination and Bacterial Bioluminescence.

The effects of the modified incubation conditions of a conventional bioassay on the toxicity of partially soluble nanoparticles (NPs) were evaluated based on the activity of seed germination and bacterial bioluminescence. Different levels of toxicity were observed for seed germination (CuO > ZnO > NiO) and bacterial bioluminescence (ZnO > CuO > NiO). The NP inhibition of seed germination increased strongly under modified incubation conditions: sample volume from 5 mL to 10 mL, shaking from none to 70 rpm, and working vessel from a Petri dish (+/− filter paper) to an Erlenmeyer flask (no filter paper).

Toxicity Evaluation of Individual and Mixtures of Nanoparticles Based on Algal Chlorophyll Content and Cell Count.

The toxic effects of individual and binary mixtures of five metal oxide nanoparticles (NPs) were evaluated based on changes in two endpoints of algal growth: the cell count and chlorophyll content. Various effects were observed according to the concentration tested and type of NPs, and there were no significant differences in findings for the two endpoints. In general, ZnO NPs caused the greatest inhibition of algal growth, and Fe₂O₃ NPs the least.

Evaluation of the Effects of Nanoparticle Mixtures on Brassica Seed Germination and Bacterial Bioluminescence Activity Based on the Theory of Probability.

Effects of binary mixtures of six metal oxide nanoparticles (NPs; 54 combinations) on the activities of seed germination and bacterial bioluminescence were investigated using the theory of probability. The observed toxicities of various NPs combinations were compared with the theoretically expected toxicities, calculated based on individual NPs toxicities. Different sensitivities were observed depending on the concentrations and the types of NPs.

Enrichment and geochemical mobility of heavy metals in bottom sediment of the Hoedong reservoir, Korea and their source apportionment.

Physicochemical characteristics of bottom sediment in the Hoedong reservoir were studied to evaluate the effectiveness of the reservoir as traps for trace metals. Roadside soil, stream sediment and background soil were also studied for comparison. Sequential extractions were carried out, and lead isotopic compositions of each extraction were determined to apportion Pb sources.

Application of the freeze-dried bioluminescent bioreporter Pseudomonas putida mt-2 KG1206 to the biomonitoring of groundwater samples from monitoring wells near gasoline leakage sites.

This study examined the applicability of a freeze-dried bioluminescent bioreporter, Pseudomonas putida mt-2 KG1206 (called KG1206), to the biomonitoring of groundwater samples. Samples were collected from the monitoring wells of gas station tanks or old pipeline leakage sites in Korea. In general, the freeze-dried strain in the presence of pure inducer chemicals showed low bioluminescence activity and a different activity order compared with that of the subcultured strain.

Determination of recharge fraction of injection water in combined abstraction-injection wells using continuous radon monitoring.

The recharge fractions of injection water in combined abstraction-injection wells (AIW) were determined using continuous radon monitoring and radon mass balance model. The recharge system consists of three combined abstraction-injection wells, an observation well, a collection tank, an injection tank, and tubing for heating and transferring used groundwater. Groundwater was abstracted from an AIW and sprayed on the water-curtain heating facility and then the used groundwater was injected into the same AIW well by the recharge system.

Interactive Effects of Metal Mixtures on Seed Germination and Bioluminescence Activities based on the Theory of Probabilities.

The interactive effects of metal mixtures on seed germination (36 combinations) and bacterial bioluminescence (60 combinations) activities were investigated based on the theory of probabilities. Observed effects were compared with expected effects, which were calculated based on single metal activities. Different responses and sensitivities were observed depending on the types and concentrations of mixture metals as well as the organisms tested.

Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites.

The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co₃O₄ and TiO₂) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change.

Toxic effects of nanoparticles on bioluminescence activity, seed germination, and gene mutation.

The potential environmental toxicities of several metal oxide nanoparticles (NPs; CuO, TiO2, NiO, Fe2O3, ZnO, and Co3O4) were evaluated in the context of bioluminescence activity, seed germination, and bacterial gene mutation. The bioassays exhibited different sensitivities, i.e.

Molecular analysis of spatial variation of iron-reducing bacteria in riverine alluvial aquifers of the Mankyeong River.

Alluvial aquifers are one of the mainwater resources in many countries. Iron reduction in alluvial aquifers is often a major anaerobic process involved in bioremediation or causing problems, including the release of As trapped in Fe(III) oxide. We investigated the distribution of potential iron-reducing bacteria (IRB) in riverine alluvial aquifers (B1, B3, and B6 sites) at the Mankyeong River, Republic of Korea.