Hee Sun Moon

Korea Institute of Geoscience and Mineral Resources | KIGAM

Widely used conservative approaches for risk-based assessments of the subsurface transport processes have been calculated using simple analytical equations or general default values. Higher-tier risk assessment of contaminated sites requires the numerical models or additional site-specific values for input parameters. Previous studies have focused...

Study region Noseong Stream watershed in Nonsan, Chuncheongnam-do, South Korea. Study focus This study aims to identify and quantify groundwater inflow to a stream based on the spatial and temporal distributions of ²²⁰Rn and ²²²Rn activities in stream water and groundwater. Groundwater–stream water exchange fluxes were estimated on the basis of ²²...

Studying groundwater inflow and quantifying its flux into aquatic systems remain challenging because of geological and topographical heterogeneities. In this study, we measured the ²²²Rn activities in the surface water and porewater of a shallow wetland, the Baekseok Reservoir Wetland, to investigate the groundwater flow system and quantify the gro...

The feasibility of the lumped approach for reactive transport of 12 organic compounds in mixtures through simulated aquifer sands with different organic carbon content (foc) within soil columns was evaluated. From direct measurements of effluent samples and temporal and spatial pore-water concentration profiles within soil columns, 12 organic compo...

We developed and applied a multidisciplinary approach to the impact of an accidentally spilled acid on the underlying geomedia and subsurface environment, based on the concept of geoecosystem. We used mineralogical, geochemical, microbiological, and ecotoxicological techniques to identify and assess the multiple aspects involved. First, we construc...

Recent increases in the frequency of extreme floods and droughts associated with climate change can affect fluctuating groundwater or wetland water levels and wetland plant growth, and consequently cause redox condition changes in nitrogen dynamics in wetland sediments. Here, we studied the fate of nitrate (NO3-), dissolved organic carbon (DOC), an...

Groundwater discharge delivering anthropogenic N from surrounding watersheds can impact lake nutrient budgets. However, upgradient groundwater processes and changing dynamics in N biogeochemistry at the groundwater‐lake interface are complex. In this study, seasonal water‐level variations in a groundwater flow‐through lake altered discharge pattern...

We reviewed the chemical/physical properties, toxicity, environmental fate, and ecotoxicity of strong acids in soil and groundwater environments. We recommend that sulfuric acid and hydrofluoric acid be classified as chemicals of priority control based on volumes used, toxicity, carcinogenicity, and past significant spill events. Understanding the...

Changes in microbial community induced by acid shock were studied in the context of potential release of acids to the environment due to chemical accidents. The responses of microbial communities in three different soils to the exposure to sulfuric or hydrofluoric acid and to the subsequent neutralization treatment were investigated as functions of...

Although abiotic process of competitive sorption between phosphate (P) and arsenate (As(V)), especially onto iron oxides, are well understood, P-mediated biotic processes of Fe and As redox transformation contributing to As mobilization and speciation in wetlands remain poorly defined. To gain new insights into the effects of P on As mobility, spec...

Impacts of land use changes and groundwater management actions on groundwater quality were evaluated at the island scale with spatiotemporal trends of NO3-N and Cl concentrations in groundwater of Jeju Island, Korea. The temporal trends from 1993 to 2012 in the concentrations of NO3-N and Cl from more than 3900 wells were estimated using the Mann–K...

Arsenic (As) biogeochemistry coupled with iron (Fe) and sulfur (S) was studied using columns packed with As(V)-contaminated sediments under two phases: a reduction phase followed by an oxidation phase. During the reduction phase, four identical columns inoculated with G. sulfurreducens were stimulated with 3 mM acetate for 60 days. The As(III) in t...

Coastal areas where submarine groundwater discharge (SGD) occurs are active mixing zones with characteristic biogeochemical and ecological functions. In this study, we investigated the microbial community associated with the changes in groundwater discharge flux at a coastal beach site on Jeju Island, South Korea. We performed water chemistry analy...

The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, M...

A siderophore-producing bacterium (i.e., Pseudomonas aeruginosa) capable of chelating Fe?? from its mineral form (i.e., iron oxides) was used to enhance As uptake by plants. Since As in soil is mainly associated with iron oxides, siderophore can play an important role in As mobilization through the dissolution of As-bearing iron oxides. A series of...

Pollutants such as heavy metals and explosives originating from the military operational ranges can be migrated to adjacent surface water body or offsite soil, and can affect to local residents and aquatic ecosystem. Therefore, Korea Ministry of the National Defense has established various guidelines for environmental management including the insta...

Operation of underground oil (gas) storage cavern in coastal area can induce seawater intrusion because excavation of underground storage cavern causes the groundwater level decrease of coastal aquifer. Seawater intrusion has the potential to cause the corrosion of underground cavern facility and leakage of gas and oil from the storage caverns, the...

We reviewed literature focusing on the amounts of domestic production, distribution, and consumption of strong acids and their spill cases. In particular, we investigated the chemistry and toxicity of four strong acids classified as "accident preparedness substances," including hydrochloric, nitric, sulfuric, and hydrofluoric acid. We recommend sul...

Ecological risk due to the hyperaccumulation of As in Pteris cretica during phytoremediation was evaluated at an abandoned As-contaminated site. Five receptor groups representing terrestrial invertebrates, avian insectivores, small mammals, herbivores, and omnivores were selected as potentially affected ecological receptors. Soil and food ingestion...

Siderophores, produced by Pseudomonas aeruginosa, released slightly more Fe (53.6μmol) than that chelated by ethylenediaminetetraacetic acid (EDTA; i.e. 43.7μmol) in batch experiment using As-adsorbed ferrihydrite. More importantly, about 1.79μmol of As was found to be associated with siderophores in the aqueous phase due to siderophore-As complex...

During the Korean foot-and-mouth disease outbreak in 2010–2011, about 3.38 million pigs and cattle were slaughtered and disposed into 4,600 burial pits around the country. In this study, the hydrogeochemical characteristics of landfill leachate and its impact on microbial communities in soils and groundwater were investigated at two hydrogeological...

This study was conducted to investigate whether or not phosphate-solubilizing bacteria (PSB) as a kind of plant growth promoting rhizobacteria enhance the uptake of Cd by plants. In addition, the effect of PSB augmentation during phytoextraction on the microbial community of indigenous soil bacteria was also studied. In the initial Cd-contaminated...

River bank filtration has been considered as a promising alternative water management scheme, in which groundwater is extracted from an aquifer near a river after infiltration of the river water into the aquifer, thereby improving and maintaining the quality of water recovered. Iron (Fe) associated with sediment in contact with groundwater and infi...

Chemical forms of arsenic (As) present in a former smelter site were determined. A five-step sequential extraction showed that about 94.8 to 99.2% of total As concentration was found to be present as residual form, and interestingly some of the residual As seemed to be still bioaccessible, when determined with an in vitro bioaccessibility test. How...

In this study, three dimensional and two dimensional laboratory experiments were conducted to investigate the effect of water table rising on DNAPL migration, contaminants mass discharge (), and residual NAPL distribution. The accumulation of TCE in unsaturated zone was observed in both two and three dimensional experiments. This implies DNAPL sour...

The groundwater of Jeju Island (Republic of Korea) is vulnerable to contamination because its aquifers are mainly composed of highly permeable geological units and its agricultural fields are often exposed to excessive use of predominantly synthetic fertilizers. In the Gosan area of Jeju Island, we investigated nitrate contamination in both a perch...

A study was conducted to investigate the effect of waste composition change on the methane production in landfills. An empirical equation for the methane potential of the mixed waste is derived based on the methane potential values of individual waste components and the compositional ratio of waste components. A correction factor was introduced in...

In this study, phosphate-solubilizing bacteria (PSB), Bacillus megaterium, were used to enhance Cd bioavailability and phytoextractability of Cd from contaminated soils. This strain showed a potential for directly solubilizing phosphorous from soils more than 10 folds greater than the control without inoculation. The results of pot experiments reve...

Biotic ligand-based models to predict site-specific toxicity of Cd and Pb contaminated soil were developed by using a Vibrio fischeri toxicity test. Firstly, competition effect by cations (i.e., Ca, Mg, K) commonly found in soil solution was incorporated into the models. For this purpose, biotic ligand-based model parameters including conditional b...

Stimulating microbial reduction of soluble U(VI) to less soluble U(IV) shows promise as an in situ bioremediation strategy for uranium contaminated groundwater, but the optimal electron donors for promoting this process have yet to be identified. The purpose of this study was to better understand how the addition of various electron donors to urani...

This study investigated the effect of long chain fatty acids (LCFAs) removal as a pretreatment prior to anaerobic digestion on the production of methane from food waste. The results showed that the anaerobic digestion of food waste containing 1.6 g COD/L of LCFAs was not inhibited (4 days lag-time, 78.3 % methane recovery in 35 days) compared to th...

Risk based pollution level of Pb and Cd in metal contaminated soils depending on physicochemical properties of soil in a target site was assessed using biotic ligand model. Heavy metal activity in soil solution defined as exposure activity (EA) was assumed to be toxic to Vibrio fischeri and soil organisms. Predicted effective activity (PEA) determi...

The biodegradability and the biodegradation rate of two kinds biodegradable polymers; poly(caprolactone) (PCL)-starch blend and poly(butylene succinate) (PBS), were investigated under both aerobic and anaerobic conditions. PCL-starch blend was easily degraded, with 88% biodegradability in 44 days under aerobic conditions, and showed a biodegradatio...

A phenanthrene-degrading bacterium, Sphingomonas paucimobilis EPA505 was used to construct two fluorescence-based reporter strains. Strain D harboring gfp gene was constructed to generate green fluorescence when the strain started to biodegrade phenanthrene. Strain S possessing gef gene was designed to die once phenanthrene biodegradation was initi...

This work presents a new framework for describing biologically mediated reduction of thin layers of poorly crystalline iron oxides. The research here explores the nature of the biomass to surface area relationship and the role of biogenic ferrous iron during Geobacter sulfurreducens-mediated ferrihydrite reduction, with and without an electron shut...

Flow-through sediment column experiments were conducted to determine the stability of biogenic U(IV) after biostimulation has been discontinued, and to isolate the key biogeochemical processes that affect the post-biostimulation U(IV) stability. Columns, packed with sediments from an UMTRA site (Rifle Colorado) were biostimulated for two months by...

The bioavailability of field-aged Cd and Cu was calculated, and compared to the total concentrations determined by acid digestion. Only 0.60–4.15% for Cd and 0.59–9.43% for Cu were found to be bioavailable when determined by stomach-phase extraction. The incorporation of bioavailability reduced more than 90% of the calculated risk of the metals at...

This study evaluated the influence of changes in the microbial community structure on reoxidation of reduced uranium during a postbiostimulation period. Effluent groundwater from acetate-stimulated sediment flow-through columns was analyzed over 60 days after acetate amendment was discontinued. Only a small reoxidation of iron or uranium (17%) occu...

There is a growing need for a better understanding of the biogeochemical dynamics involved in microbial U(VI) reduction due to an increasing interest in using biostimulation via electron donor addition as a means to remediate uranium contaminated sites. U(VI) reduction has been observed to be maximized during iron-reducing conditions and to decreas...

Phytoextraction, one type of phytoremediation processes, has been widely used in the removal of heavy metals from polluted soil. This paper reviewed literature on metal uptake by plants and characterized the metal uptake by types of metals (Zn, Cu, Pb, Cd, and As), plant species, initial metal concentrations in soil and the distribution of metals i...

Substrate-dependent evolution of a bacterial community capable of transforming nitrate was examined in sulfur-based autotrophic denitrification columns. The 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE) analysis revealed that the initial bacterial consortium was well adapted to column operation time and distribution of nitrate c...

Bacterial community succession related to 1,4-dioxane exposure was investigated in two different activated sludge-inoculated reactors (municipal wastewater and dye industrial wastewater sludge), with or without additional carbon source, for 7 weeks. The denaturing gradient gel electrophoresis (DGGE) analysis revealed that microbial succession varie...

Due to an increasing interest in microbial biostimulation for the purpose of U(VI) bioreduction, which proceeds via iron reduction, there is a growing need for a better understanding of the associated biogeochemical dynamics. This includes Fe(III) availability as well as the microbial community changes, including the activity of iron-reducers durin...

Sediment column experiments were performed to quantify the effect of biogenic iron sulfide precipitates on the stability of bioreduced uranium during and after a simulated bioremediation scenario. In particular, this study examined the effect of different oxidants (dissolved oxygen and nitrate) on biogenic U(IV) oxidation in sediment that experienc...

During biostimulation of microbial iron reduction for the purpose of U(VI) removal at the Rifle Integrated Field Challenge (IFC) site, the onset of sulfate reduction is usually observed within 20 to 30 days of biostimulation. A series of flow-through sediment column experiments were performed to determine if the onset of sulfate reducing conditions...

The biogeochemistry related to iron- and sulfate-reducing conditions influences the fate of contaminants such as petroleum hydrocarbons, trace metals, and radionuclides (i.e., uranium) released into the subsurface. An understanding of these processes is imperative to successfully predict the fate of contaminants during bioremediation scenarios. A s...

The long-term performance of a sulfur-based reactive barrier system was evaluated using autotrophic denitrification in a large-scale column. A bacterial consortium, containing autotrophic denitrifiers attached on sulfur particles, serving as an electron donor, was able to transform 60 mg N L(-1) of nitrate into dinitrogen. In the absence of phospha...

Urban streams play a significant role in the transport of dissolved inorganic nitrogen (DIN) from uplands to sensitive coastal receiving waters. In this study, we investigate the timing of DIN export through monitoring conducted during several storm events of different magnitude and with different antecedent conditions in an urban catchment. Our mo...

During the biostimulation of iron reducers for the purpose of concurrent biological reduction of U(VI), it has been postulated that iron reduction proceeds while bioavailable iron is present, after which the system switches to sulfate reduction if sulfate is present. Field experiments from the Rifle Integrated Field Challenge (IFC) site in Colorado...

Microbially mediated reduction of poorly crystalline iron oxides in the subsurface controls the fate and transport of many organic and inorganic contaminants and plays a role in biogeochemical nutrient cycling. Despite recent advances in understanding this important process, much remains undiscovered. In particular, the influence of biomass on iron...

Flow-through sediment column experiments examined the reoxidation of microbially reduced uranium with either oxygen or nitrate supplied as the oxidant. The uranium was reduced and immobilized via long-term (70 days) acetate biostimulation resulting in 62-92% removal efficiency of the 20 microM influent uranium concentration. Uranium reduction occur...

As a part of a study developing a biological reactive barrier system to treat nitrate-contaminated groundwater, the effects of reactive media composition and co-contaminants on sulfur-oxidizing autotrophic denitrification were investigated. The size of sulfur granules affected the denitrification rates; kinetic constants of 2.883, 2.949, and 0.677...

The present study describes the effects of initial alkalinity and various solid alkalinity sources such as calcite, dolomite, and oyster shell on nitrate removal in a sulfur-oxidizing autotrophic denitrification process. The results showed that denitrification rate increased as the initial alkalinity present in the system increased. Denitrification...

Biodegradation potentials of polycyclic aromatic hydrocarbons (PAHs) were determined with soil samples collected from various depths of a PAH-contaminated site and of a site nearby where PAHs were not found. Putative dioxygenase genes were amplified by a primer set specific for initial dioxygenases and identified by web-based database homology sear...

This study was conducted to evaluate the potential applicability of an in situ biological reactive barrier system to treat nitrate-contaminated bank filtrate. The reactive barrier consisted of sulfur granules as an electron donor and autotrophic sulfur-oxidizing bacteria as a biological component. Limestone was also used to provide alkalinity. The...