• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.29-37
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• 2007

Shallow alluvial groundwaters in Korea of tell exceed the Korean Drinking Water Standard for dissolved iron (0.3 mg/L), which is one of the important water quality problems, especially in the use of bank infiltration technique. Using the reactive transport modeling, in this study we simulated the effectiveness of injection-and-pumping technique to remove dissolved iron in groundwater. The results of simulation showed that pumping of groundwater after injection of oxygenated water into aquifers is very effective to acquire the permissible water quality level. Groundwater withdrawal up to several times of irjected water in volume can be applicable to yield drinkable water. Potential problems such as clogging and permeability lowering due to in-situ precipitation of iron hydroxides may be insignificant. We also discuss on the mechanism and spatial extent of iron removal in aquifer.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.217-234
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• 2009

This study characterized groundwater quality and the influence of agrochemicals in a part of Ilgwang-Myeon agricultural area in Gijang-Gun, Busan Metropolitan City, using factor analyses. From the 1st, 2nd, and 3rd analyses of groundwater samples, the mean concentrations of $Ca^{2+}$, $Na^+$, $Mg^{2+}$, $K^+$, $Zn^{2+}$, $Cu^{2+}$, $Fe^{2+}$, $Al^{3+}$, $NO_3\;^-$, $Cl^-$, $SO_4\;^{2-}$, $F^-$, and $SiO_2$ were higher in the 2nd analysis than the other analyses. Pesticide carbofuran and herbicide alachlor were detected at the wells more than a half of all the wells in the 2nd analysis but not in the 4th analysis. This fact may be explained by that a higher precipitation induced higher infiltration rate of contaminants into groundwater during the 2nd survey. According to R- and Q-mode factor analyses, and chemical composition, inorganic constituents excepting $SiO_2$, $HC0_3\;^-$-, and $F^-$ may be influenced by anthropogenic sources (manures, synthetic fertilizers, and domestic wastes), seawater as well as water-mineral interaction. A typical indicator of groundwater contamination, nitrate, exceeds around 4-5 times over the Korean standard for drinking water. Additionally, the influence of seawater diminishes from the seaside to inland.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.547-561
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• 2005

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a ffw previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about $28\%$ of the shallow groundwaters exceeded the Bangladesh drinking water standard, $50{\mu}g/L$, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of $SO_4^{2-}$ and $NO_3^-$, and high contents of dissolved organic carbon (DOC) and $NH_4^+$ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciatiion during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about $1\%$ of grounwaters have concentrations higher than $10{\mu}g/:L.$ However, it was revealed that $19.3\%$ of mineral waters, and $7\%$ of tube-well waters from Nonsan and Geumsan areas contained As concentrations above $10{\mu}g/:L.$. Also, percentages exceeding this value during detailed groundwater quality surveys were $36\%\;and\;22\%$ from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.

• The Journal of Engineering Geology
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• v.2 no.2
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• pp.173-200
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• 1992

The quality of groundwater in the central part of Taegu City is influenced by upstreams of Sin-stream and Beomeo-stream because the stream waters are main source of the groundwater, and chemical composition of the upstream waters has close relationship with andesite and monzonite in the igneous rock terrain. The pH of upstreams are weak acid ~ neutral in the igneous rock area and weak alkaline in the sedimentary rock area. Contents of $Ca^{2+}$ and $Mg^{2+}$ in the streams are apparently high, and $Na^{+}$ content is only slightly high in the sedimentary rock area. But $K^{+}$ content is lower in the Panyaweol formation area than in the monzonite area. The contents of heavy metals and $N0_3^{-}$ are also higher in the sedimentary rock area of residential sections and industrial complexes than those in the igneous rock area. The groundwater is contaminated in comparison to the upstream water of the igneous rock areas, and there are some differences in pollution level between the Panyaweol formation area of residential sections and the Haman formation area of industrial complexes. K, Na, Ca, Mg, Cl, $SO_4$ and $NO_3$ contents in the Haman formation area are relatively higher than those in the Panyaweol formation area. But pH is nearly equal in the two areas. The content of heavy metal ions is still lower than the drinking water standard of Korea and only slightly differs in the two sedimentary rock areas. But the groundwater in the Haman formation area is considerably contaminated by Kongdanstream and Dalseo-stream.

• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.599-606
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• 2005

Arsenic is a significantly toxic contaminant in groundwater in many countries. Numerous treatment technologies have been developed to remove arsenic from groundwater. The USEPA recommends several technologies as the best available technology (BAT) candidates for the removal of arsenic. Based on the USEPA classification, arsenic treatment technologies can be divided into four technologies such as precipitation, membrane, ion exchange, and adsorption technology. The recent amendment of arsenic drinking water standard from 50 to $10{\mu}g/L$ in the United States have impacted technology selection and application for arsenic removal from arsenic contaminated groundwater. Precipitation technology is most widely used to treat arsenic contaminated groundwater and can be applied to large water treatment facility. In contrast, membrane, ion exchange, and adsorption technologies are used to be applied to small water treatment system. Recently, the arsenic treatment technology in the United States and Europe move towards adsorption technology to be applied to small water treatment system since capital and maintenance costs are relatively low and operation is simple. The principals of treatment technologies, effect factors on arsenic removal, arsenic treatment efficiencies of real treatment systems are reviewed in this paper.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.461-470
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• 2001

The Shihung mine was restored in the early 90's after abandonment for 20 yews since 1973. Although disposed mine tailings were removed and the site was replaced by an incineration plant, still some residual mine tailings remain in the places including the old mine tailing ditposal area and the adjacent agricultural area. These residual mine tailings are prone to impose an adverse impact on the soil and groundwater and needs investigation for the potential contamination. Mine tailing samples were collected from the old tailing disposal area and the iii paddy. The porewater from the mine tailing were extracted and analysed to investigate chemical changes along the reaction path. Batch leaching tests were also carried out in the laboratory to find any supporting evidence found in the field analysis. Evidence of elemental leaching was confirmed both by the mine tailing and the porewater chemistry in them. The element concentrations of Cu, Cd, Pb, Zn in the porewater exceed the standard for drinking water of Korean government and US EPA. Leaching of heavy metals from the mine tailing seem to be responsible for the contamination. In batch leaching test. heavy metals were either continuous1y released or declined rapidly. Combining the information with porewater variation with depths and the geochemical meodeling results, most of elements are controlled by dissolution and/or precipitation processes, with some solubility controlling solid phases (Cu, Pb, Fe and Zn). Batch leaching test conducted at fixed pH 4 showed much higher releases for the heavy metals up to 400 times (Zn) and this area is becoming more vulnerable to soil and groundwater pollution as precipitation pH shifts to acidic condition.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.689-697
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• 2006

Distribution and speciation of arsenic in water resources was investigated in the Ulsan mine area. In 62% of uoundwater samples from the mine area, total As concentrations exceeded 0.05 mg/l, the Korean Drinking Water Standard. As(V) was the major type in groundwater with minor As(III). Arsenic species appeared to be in transition stages following redox changes after exposure to the air through the monitoring wells. In areas around the mine, the mine and Cheongog spring appeared to be the sources of arsenic contamination of water resources. The spring showed 0.345 mg/1-As, as much as seven times of the Korean standard. Groundwater and stream samples showed As-concentrations greater than 0.05 mg/l in 30% and 33% samples, respectively, and 60 and 67% of samples exceeded 0.01 mg/l of WHO guideline, respectively. Again, As(V) was a dominant species, however, several samples had As(III) in appreciable levels. In one stream sample, organic species including DMA and AsB were detected in low levels, probably resulted from transformation or related biogeochemical processes.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.395-404
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• 2002

Contents of the specific components in the natural mineral water was discussed in relation to the well depth and geology. According to water quality data during the last five years(1998~2002), the nitrate and fluoride concentrations, and pH averaged 0.89~ 1.09 mg/L, 0.37~0.45 mg/L, and 7.30~7.59, respectively. These values are the similar range to those of generalized groundwater having same well depths, implying that shallow groundwaters flow into the production wells. In general, no clear relationships between the water quality, well depth, and geology were found. The average arsenic concentration of the natural mineral water increased from 0.0024 mg/L in 1999 to 0.0066 mg/L in 2002. The percentage of production well with arsenic level higher than 0.001 mg/L also increased from 20.1% in 1999 to 64.9% in 2002. In 2002, 11 out of 57 production wells exceed 0.001 mg/L which will be announced as a new arsenic standard for drinking water by USEPA.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.57-73
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• 2008

Nitrate concentrations were measured up to 49 mg/L (as $NO_3$-N) and 22% of the samples exceeded drinking water standard in shallow and bedrock groundwater of the northern Nonsan area. Nitrate concentrations showed a significant difference among land use groups. To predict nitrate concentration in groundwater, multiple regression analysis was carried out using hydrogeologic parameters of soil media, topography and land use which were categorized as several groups, well depth and altitude, and field parameters of temperature, pH, DO and EC. Hydrogeologic parameters were quantified as area proportions of each category within circular buffers centering at wells. Regression was performed to all the combination of variables and the most relevant model was selected based on adjusted coefficient of determination (Adj. $R^2$). Regression using hydrogelogic parameters with varying buffer radii show highest Adj. $R^2$ at 50m and 300m for shallow and bedrock groundwater, respectively. Shallow groundwater has higher Adj. $R^2$ than bedrock groundwater indicating higher susceptibility to hydrogeologic properties of surface environment near the well. Land use and soil media was major explanatory variables for shallow and bedrock groundwater, respectively and residential area was a major variable in both shallow and bedrock groundwater. Regression involving hydrogeologic parameters and field parameters showed that EC, paddy and pH were major variables in shallow groundwater whereas DO, EC and natural area were in bedrock groundwater. Field parameters have much higher explanatory power over the hydrogeologic parameters suggesting field parameters which are routinely measured can provide important information on each well in assessment of nitrate contamination. The most relevant buffer radii can be applied to estimation of travel time of contaminants in surface environment to wells.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.469-483
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• 2020

The results of long-term groundwater level and quality monitoring can be used not only as the basic data for evaluating the impact of various disasters including climate change and establishing responses, but also as key data for predicting and managing geological disasters such as earthquakes. Some countries use groundwater level and quality monitoring for researches to predict earthquakes and to assess the impacts of the earthquake disaster. However, a few cases in Korea report on individual groundwater quality factors (i.e., dissolved ions) observed before and after the earthquakes, being different from other countries. To establish the abnormality criteria for groundwater quality in Pohang, groundwater samples were collected and analyzed five times from 14 agricultural or private wells existing in Shingwang-myeon and Heunghae-eup. As a result of the analysis, it was found that Ca2+ was the dominant cation in Shingwang-myeon, while Na+ was the dominant cation in Heunghae-eup. The elevated NO3- concentration in Shingwang-myeon is contributed to the agricultural activity in the area. A high concentration of Fe was detected in a well on Heunghae-eup; the concentration exceeded the drinking water standard by nearly 100 times. Relatively higher dissolved ions were observed in the groundwater of Heunghae-eup, and it is considered as the result of the flow velocity difference and water-rock reaction accompanying the difference in bedrock and sediment characteristics. The groundwater of Shingwang-myeon appeared to be most affected by the weathering of granite and silicates, while that of Heunghae-eup was mainly affected by the weathering of silicates and carbonate. The background concentrations (baselines) of groundwater Shingwang-myeon and Heunghae-eup was identified through the survey; however, the continuous monitoring is required to monitor the possible changes and the repeatability of seasonal variation.