Characterizing land use effect on shallow groundwater contamination by using self-organizing map and buffer zone.

Nitrate-nitrogen (NO3-N) contamination in groundwater is a major problem of drinking and domestic waters in rural areas. This study revealed the influence of land use type on shallow alluvial groundwaters in a typical rural area in South Korea by applying a self-organizing map (SOM), principal component analysis (PCA), and hierarchical cluster analysis (HCA). The uncertainty of spatial information on land use was improved by using a buffer zone of the average influence radius of 32.65 m surrounding wells. Two major land-use types, forests (44.9%) and rice fields (28.8%), occupied a total of 73.7% of the rural area. The higher concentrations of NO3-N in public facilities and livestock areas were demonstrated to directly recharge groundwater pollutants. NO3-N contamination in rice paddies, which also contained chlorine (Cl) and sulfate (SO4), was assessed according to the nutrients and residual salt in the soil. In addition, different NO3-N concentrations for the same land use indicate various biochemical reactions and NO3-N recharge types into the groundwater system. The shallow groundwaters in the study area were classified into three clusters according to their chemical constituents and land-use properties, especially NO3-N concentration, including pH, Cl, and SO4, using a SOM, PCA, and HCA. Unlike existing studies, we applied a buffer zone based on the Cooper-Jacob equation to obtain an improved SOM model prediction accuracy approximately 10% greater than that using the original dataset.

Effective time- and frequency-domain techniques for interpreting seismic precursors in groundwater level fluctuations on Jeju Island, Korea.

An effective method, involving time and frequency domains was developed to interpret seismic precursors by comparing groundwater-level fluctuations recorded immediately and long before the occurrence of a known earthquake. The proposed method, consisting of the pre-processing (3-point filtering, band-pass filtering, and spectrum analysis) and post-processing (weighted moving average method and histogram and spectrum analyses) stages, was applied to the groundwater-level time series measured at three monitoring wells on Jeju Island, South Korea, from 00:00 on 8 September 2016 to 00:00 on 22 September 2016. The Gyeongju earthquake (Mw 5.4) occurred at 20:32 on 12 September2016. The histogram analysis exhibited an accentuating bellshape as the total number of waveforms, including those caused by the earthquake, of the groundwater-level fluctuations increased. The weighted moving average analysis indicated that various abnormal waveforms with different periods occurred in the fluctuations approaching the occurrence of the earthquake. The periods of seismic precursors in the groundwater-level fluctuations were determined by spectrum analysis and varied among the monitoring wells. Seismic precursor responses attributable to the Gyeongju earthquake were identified at least 8 hours before the earthquake, and the method used in this study indicates its good potential to predict an impending earthquake.

Contribution of nitrate-nitrogen concentration in groundwater to stream water in an agricultural head watershed.

This study characterized nitrate-nitrogen (NO3-N) concentrations in groundwater and stream water in an agricultural head watershed in South Korea and identified the pollution load of NO3-N as a result of the groundwater entering streams using field surveys, analyses of chemical constituents, and numerical modeling. The mean NO3-N concentration in groundwater was 7.373 mg/L, which is approximately 1.9 times higher than concentrations found in stream water. The groundwater and stream water samples belonged to the Ca-HCO3 type. The concentration of NO3-N in groundwater tended to increase in the lowland areas downstream. There was seasonal variations of NO3-N in both the groundwater and stream water samples, with increases in concentration during the dry season (January-April) and decreases during the wet season (June-October). The NO3-N load in stream water to that in groundwater (R) was higher during the wet season (September) than the dry season (March), with R distinctly increasing in upstream areas relative to downstream areas, indicating that during the wet season, a large amount of NO3-N is introduced into stream water from groundwater. By analyzing the relationship between groundwater and stream water and through NO3-N transport modeling, it was revealed that in the watershed, the nitrate-N load in stream water is greatly augmented by inputs from groundwater, particularly in the middle and downstream areas.

Performance of composite mineral adsorbents for removing Cu, Cd, and Pb ions from polluted water.

This study evaluated the efficiency of the removal of heavy metals from contaminated water via adsorption isotherm and kinetic experiments on two composite mineral adsorbents, CMA1 and CMA2. The developed CMA1 (zeolite with clinoptilolite of over 20 weight percent and feldspar of ~10 percent, with Portland cement) and CMA2 (zeolite with feldspar of over 15 weight percent and ~9 percent clinoptilolite, with Portland cement) were applied to remove Cu, Cd, and Pb ions. Based on the adsorption isotherm and kinetic experiments, the adsorbents CMA1 and CMA2 exhibited high removal efficiency for Cu, Cd, and Pb ions in solution compared to other adsorbents. In the adsorption kinetic experiment, CMA2 demonstrated better adsorption than CMA1 with the same initial concentration and reaction time, and Cu, Cd, and Pb ions almost reached equilibrium within 180 min for both CMA1 and CMA2. The results of the adsorption kinetic experiments with pseudo-first-order (PFO) and pseudo-second-order (PSO) models indicated that the PSO model was more suitable than the PFO model. Comparing the Langmuir and Freundlich adsorption isotherm models, the former showed a very slightly higher correlation coefficient (r2) than the latter, indicating that the two models can both be applied to heavy metal solutions on a spherical monolayer surface with a weak heterogeneity of the surface. Additionally, the adsorbents CMA1 and CMA2 demonstrated different removal abilities depending on which heavy metals were used.

Occurrence and distribution of pharmaceutical and personal care products, artificial sweeteners, and pesticides in groundwater from an agricultural area in Korea.

This study investigated the occurrence and distribution of 33 pharmaceutical and personal care products (PPCPs), five artificial sweeteners (ASs), and six pesticides in groundwater in rural agricultural and rural non-agricultural area in South Korea. A total of 31 target compounds (15 antibiotics, four anthelmintics, seven other PPCPs, four ASs, and one pesticide) were detected in agricultural groundwater at concentrations from not detected (ND) to 49.3 ng/L for PPCPs, ND to 1340 ng/L for ASs, and ND to 116 ng/L for pesticides. Four target compounds (two PPCPs and two ASs) were detected in rural non-agricultural groundwater in the range of 0.085-5.74 ng/L for PPCPs and 5.64-1330 ng/L for ASs. Among the target compounds, ASs, especially acesulfame (detection frequency 69% in rural agricultural areas and 100% in the rural non-agricultural area) were predominantly detected in both agricultural (mean: 32.9 ng/L) and non-agricultural (mean: 536 ng/L) groundwater, but different occurrence patterns were observed according to the sources of contamination. Known markers of sewage leakage were detected in both agricultural and non-agricultural groundwater samples (e.g., acesulfame (69% and 100%), caffeine (88% and 100%), and crotamiton (62% and 100%)), while compounds related to agricultural activities were only observed in agricultural groundwater (e.g., sulfathiazole (38%), sulfamethoxazole (31%), oxfendazole (69%), and carbofuran (42%)).

Immunomodulatory Effects of Deokgu Thermomineral Water Balneotherapy on Oxazolone-Induced Atopic Dermatitis Murine Model.

BACKGROUND: Although the therapeutic mechanism of balneotherapy for atopic dermatitis has not been clarified, many atopic patients who visit thermomineral springs have shown clinical improvements. OBJECTIVE: This study was aimed to evaluate the immunomodulatory effect of thermomineral water balneotherapy on the atopic dermatitis murine model. METHODS: The oxazolone-induced atopic dermatitis murine model was used to evaluate the therapeutic effect of balneotherapy with Deokgu thermomineral water compared with distilled water. Histologic evaluation and confocal microscopic imaging were performed to analyze the lesional expression of cluster-of-differentiation (CD)4 and forkhead box p3 (Foxp3). Lesional mRNA expression of interleukin (IL) 33, thymic stromal lymphopoietin (TSLP), and Foxp3 was evaluated by real-time reverse transcription polymerase chain reaction. RESULTS: Compared with the distilled water bath group, confocal microscopic evaluation of CD4 and Foxp3 merged images showed increased expression of regulatory T cells in the thermomineral balneotherapy group. The lesional mRNA level of IL-33 showed a reduced trend in the thermomineral balneotherapy group, whereas the level of mRNA of Foxp3 was increased. TSLP showed a decreased trend in both distilled water and thermomineral water bath groups. There was a trend of reduced expression in lesional IL-33 mRNA but increased cell count of CD4(+) Foxp3(+) regulatory T cells in thermomineral balneotherapy compared with distilled water bath. CONCLUSION: Therefore, thermomineral balneotherapy can be an effective and safe adjuvant therapeutic option for atopic dermatitis.

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 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.