Se-Yeong Hamm

Monitoring of environmental phenolic endocrine disrupting compounds in treatment effluents and river waters, Korea

The last two decades have witnessed growing scientific and public concerns over endocrine disrupting compounds (EDCs) that have the potential to alter the normal structure or functions of the endocrine system in wildlife and humans. In this study, the phenolic EDCs such as alkylphenol, chlorinated phenol and bisphenol A were considered. They are commonly found in wastewater discharges and in sewage treatment plant. In order to monitor the levels and seasonal variations of phenolic EDCs in various aquatic environments, a total of 15 water samples from the discharged effluent from sewage and wastewater treatment plants and river water were collected for 3 years. Ten environmental phenolic EDCs were determined by GC-MS and laser-induced fluorescence (LIF). GC-MS analysis revealed that most abundant phenolic EDCs were 4-n-heptylphenol, followed by nonlyphenol and bisphenol A during 2002-2003, while 4-t-butylphenol and 4-t-octylphenol were newly detected in aquatic environments in 2004. The category of phenolic EDCs showed similar fluorescence spectra and nearly equal fluorescence decay time. This makes it hard to distinguish each phenolic EDC from the EDCs mixture by LIF. Therefore, the results obtained from LIF analysis were expressed in terms of the fluorescence intensity of the total phenolic EDCs rather than that of the individual EDC. However, LIF monitoring and GC-MS analysis showed consistent result in that the river water samples had lower phenolic EDCs concentration compared to the effluent sample. This revealed a lower fluorescence intensity and the phenolic EDCs concentration in summer was lower than that in winter. For the validation of LIF monitoring for the phenolic EDCs, the correlation between EDCs concentration acquired from GC-MS and fluorescence intensity from LIF was obtained (R=0.7379). This study supports the feasibility of the application of LIF into EDCs monitoring in aquatic systems.

Combined analyses of chemometrics and kriging for identifying groundwater contamination sources and origins at the Masan coastal area in Korea

Hydrogeochemical analyses including the basic statistics of chemical components, Piper’s trilinear diagram, and Mazor’s compositional bivariate diagram revealed that the main source and origin of groundwater contamination was seawater intrusion in the study area. However, the other sources and origins of groundwater contamination could be found by the combined analyses of chemometrics and kriging. Cluster analysis was helpful for the classification on the basis of the contamination characteristics of groundwater quality; however, it was not sufficient for the apportionment of groundwater contamination sources. Factor analysis (FA) determined three factors with 81.07% in total variance: Factor 1 for seawater contamination, Factor 2 for nitrate contamination, and Factor 3 for iron contamination. Factor analysis determined the sources of groundwater contamination; however, it could not discover the origins of contaminants except Factor 1. In backward stepwise mode, discriminant analysis decreased the number of parameters from 18 to 6 in discriminating the contaminant type with 96.2% correctness. TDS, Ca, NO3, Mn, Fe, and Br were the most significant parameters for the discrimination of contaminants. Kriging analysis was very useful for the understanding of correlation and similarity between contaminants and factors of FA, and for the investigation of contaminant origins. It also showed that the similarity between factor scores and contaminant concentrations was proportional to the magnitudes of factor loadings for contaminants. This study represented that the combined analyses of chemometrics and kriging were very indispensable to the identification of groundwater contamination sources and origins, as well as for the spatial classification and assessment of groundwater quality.

Relationship between groundwater and climate change in South Korea

Climate change has resulted in a gradual increase in the surface temperature and significantly variable precipitation in different regions of the world. Linear regression of the groundwater levels in Korea between 2000 and 2010 revealed a decreasing trend with a slope of −29.2 mm/yr; −29.6 mm/yr in the wet season and −32.0 mm/yr in the dry season. Mann-Kendall and Sen’s tests were carried out using the groundwater levels and groundwater temperatures at 78 locations in South Korea between 2000 and 2010. The groundwater levels showed a trend in ~50% of the 78 groundwater level datasets, of which ~70% exhibited a decreasing trend at the 95% confidence level. This decreasing trend in the groundwater levels appears to be related to a change in the precipitation in South Korea because more abundant rainfall in the wet season each year does not contribute significantly to groundwater recharge, whereas less rainfall that occurs in the dry season can cause a decrease in the groundwater level. Linear regression of the groundwater temperatures revealed a slope of 0.1006 °C/yr between 2000 and 2010 with a gentler slope (0.08 °C/yr) in summer (June–September), showing that the increase in surface temperature has an impact on increasing the groundwater temperature. In this situation of climate change in Korea, the paradigm of groundwater management strategy needs to be altered properly.

Spectroscopic Interpretation of PAH-Spectra in Minerals and Its Possible Application to Soil Monitoring

In order to properly assess the feasibility of using Laser-Induced Fluorescence (LIF) spectroscopy for soil monitoring, the variation of fluorescence intensity due to the heterogeneity and complexity of soil media was investigated. Different soil minerals showed fluorescence spectral structures distinguishable from the contaminants, implying dissimilar interactions or the binding of contaminants on mineral surfaces. More interestingly, solvent and water addition showed different responses in the fluorescence spectral structure showing their effect on the interactions between contaminants and minerals. These results support the claim that the spectral structure contains information on contaminant-mineral interactions; therefore contaminants can be used as a fluorescence probe for these interactions.

Predicting long-term change of groundwater level with regional climate model in South Korea

Global climate change causes a high variability in precipitation and surface temperature increase in the world. Global climate models (GCMs) are effectively used to predict climate change at a global scale. In contrast, regional climate models (RCMs) can more efficiently predict climate change scenarios for a small territory such as South Korea. We estimated the groundwater level change in four drainage basins (the Han River, Nakdong River, Geum River, and Yeongsan-Sumjin River basins) in South Korea over the period 2000–2012, and then predicted the groundwater level change from 2000 to 2100 using a water budget model, considering RCMs with RCP 4.5 and RCP 8.5 scenarios. A distinct trend in the groundwater levels of each drainage basin was detected via the inversely close relationship with precipitation patterns of the drainage basin, showing a decrease in the groundwater level in relation to the increasing precipitation trend of the RCM scenarios. It is also proposed that the precipitation amount during the dry season more dominantly affects groundwater recharge than during the wet season.

Analysis of Groundwater Level Changes Due to Earthquake in Jeju Island (For the Indonesian Earthquake with Magnitude 7.7 in 2010)

This study was conducted to investigate the relationship between groundwater level change and a large earthquake using the data of groundwater and seawater intrusion monitoring wells in Jeju Island. Groundwater level data from 13 observation wells were analyzed with a large earthquake. The Earthquake occurred at Sumatra, Indonesia (Mw

Application of Laser Based Spectroscopic Monitoring into Soil Remediation Process of PAH-Contaminated Soil

ABSTRACT The application of Laser-Induced Fluorescence (LIF) into soil remediation process is not popular due to the difficulties of the interpretation of remediation process. The monitoring for the lab-scale surfactant enhanced electrokinetic remediation process using the LIF was performed. The variation of the fluorescence intensity and the change of the fluorescence spectral signature reflecting the nature of the surrounding environment were investigated. The diffuse reflectance correction method for the soil matrix properties on fluorescence, and the time resolution for isolation of surfactant which can be overlapped with PAHs spectra of interest were considered to provide the information of contaminants taking place during the remediation process. Eletrokinetic (EK) remediation process as control experiment was also performed and this result was compared with the surfactant-enhanced EK process especially in terms of the spectral signature of PAHs. The LIF monitoring for soil remediation process showed that the relative quantities and the state of contaminant in soil media which can be an important key to assess the feasibility of remediation process.

Time Series and Groundwater Recharge Analyses Using Water Fluctuation Data in Mountain Geumjeong Area

Groundwater recharge characteristics in a fractured granite area, Mt. Geumjeong, Korea. was interpreted using bedrock groundwater and wet-land water data. Time series analysis using autocorreclation, cross-correlation and spectral density was conducted for characterizing water level variation and recharge rate in low water and high water seasons. Autocorrelation analysis using water levels resulted in short delay time with weak linearity and memory. Cross-correlation function from cross-correlation analysis was lower in the low water season than the high water season for the bedrock groundwater. The result of water level decline analysis identified groundwater recharge rate of about 11% in the study area.

Fifty years of groundwater science in Korea: a review and perspective

We present a review of groundwater studies over the past 50 years (1968–2017) in Korea. With economic and agricultural growth, water demand has been expanding, and groundwater development is gradually increasing. Initially, groundwater studies were largely focused on using pumping and slug tests to understand aquifers in Korea. However, the interest has expanded to groundwater monitoring and data analyses, as many national and local networks for monitoring groundwater quantity and quality have been implemented. Frequent severe droughts in recent decades have led to research on the design and pilot tests for managed aquifer recharge, especially on the volcanic island of Jeju and agricultural areas. As groundwater development and its use has increased, groundwater contamination is becoming a public grievance. Thus, effective investigation of contaminated groundwater and its efficient remediation are big issues in the Research and Development (R & D) sector. The recent Gyeongju earthquake posed an additional challenge for Korean groundwater scientists to develop a method to predict earthquakes using groundwater monitoring. Furthermore, changes in precipitation patterns caused by the changing climate aggravate groundwater recharge conditions. The country has seen many academic and technical achievements in groundwater science, but many issues remain to be resolved in the near future.

Analysis of Groundwater Discharge into the Geumjeong Tunnel and Baseflow Using Groundwater Modeling and Long-term Monitoring

When constructing tunnels, it is important to understand structural, geological and hydrogeological conditions. Geumgeong tunnel that has been constructed in Mt. Geumjeong for the Gyeongbu express railway induced rapid drawdown of groundwater in the tunnel construction area and surroundings. This study aimed to analyze groundwater flow system and baseflow using long-term monitoring and groundwater flow modeling around Geumgeong tunnel. Field hydraulic tests were carried out in order to estimate hydraulic conductivity, transmissivity, and storativity in the study area. Following the formula of Turc and groundwater flow modeling, the annual evapotranspiration and recharge rate including baseflow were estimated as 48% and 23% compared to annual precipitation, respectively. According to the transient modeling for 12 years after tunnel excavation, baseflow was estimated as with a decreasing tendency.