Eun-Joung Ko

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.

Remediation process monitoring of PAH-contaminated soils using laser-induced fluorescence.

In order to investigate the feasibility of Laser-Induced Fluorescence(LIF) for soil remediation process monitoring, the variation in the LIF intensity was studied, in relation to the moisture content and soil particle size distribution for different soil conditions. For each set of conditions, significant correlation was shown between the level of Polycyclic Aromatic Hydrocarbon (PAH) and the LIF intensity (R2 > 0.97). Higher fluorescence intensities were measured for PAH contaminated soils with higher sand and moisture contents. The resultsof the LIF monitoring for the remediation process were compared with the traditional High Pressure Liquid Chromatography (HPLC) results, after applying a surfactant-enhanced electrokinetic process for the remediation of PAH-contaminated soils. In the electrokinetic (EK) process cell, the PAH concentration, and the normalized LIF intensity near the anode and cathode, showed somewhat contrary trends with respect to the degree of the remediation, even though significantly similar trends were observed in the middle of the soil cell. This may be interpreted as the EK remediation advances, as the electro osmotic flow induce a different moisture and silt/clay, or sand, distribution throughout the soil media, which in turn influences the LIF intensity of the soils. Therefore, in order to overcome these differences, the corrected LIF intensity, using the diffuse reflectance, was applied, which showed a similar remediation trend for the soil specimens in the electrokinetic process cell.

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.

Monitoring pah‐contaminated soil using laser‐induced fluorescence (LIF)

Abstract The heterogeneity and opacity of soil matrices pose considerable challenges for the quantification of soil contaminants. In order to investigate the feasibility of applying the Laser‐Induced Fluorescence technique to measure contamination levels of soils, statistical analyses of contaminant levels and intensity of fluorescence were investigated in relation to soil properties. A significant correlation (R2> 0.97) between contaminant levels and intensity of fluorescence was shown under different matrix conditions, such as moisture content and particle size distribution. Higher fluorescence intensities were obtained from soils with higher sand and moisture content. The statistical results in relation to the interaction between fluorescence intensity and matrix properties rejected the hypothesis that all properties of the matrices and contaminants had an equal influence on fluorescence. This implied that the concentrations of contaminants had the greatest contribution to the fluorescence intensity, but other variables also showed a considerable influence.

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.