• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.322-327
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• 2007

This study was conducted to analysis the chemical properties of Peunggang river and investigate the effect of irrigation sources on the growth of tomato and cucumber. The salt concentration in Peunggang river was high by $3.22{\sim}3.62dS{\cdot}m^{-1}s$ from March to May and lower gradually from April to February of next year, which was also lower in upper stream than in middle or low stream of Peunggang river. The growth such as plant height, fresh weight and dry weight in tomato and cucumber was better in drain water and tap water irrigation than in PR water (Peunggang river) irrigation. Mean fruit weight was highest in the tap water, and that of cucumber was no significance in the treatments. The number of setting fruit was lower in the PR water than in the treatments, and which was no significance between rain water and tap water. The yield of tomato and cucumber was found to be highest by 10,594 and 11,826 kg/10a in tap water, respectively and also lowest in the PR water among the three treatments. The fruit quality, soluble solids of tomato shows a tendency to increase in the PR water as compared with the other treatment, and the rate of blossom-end rote was higher by 13.6% in the PR water. T-N and P content of tomato and cucumber were no significance in the treatments. Ca content was lowest, but Na content highest in the PR water. It was thought that a rain water and tap water as alternative irrigation source of a PR water were proper.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.89-97
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• 2007

This study analyzed the lpcd of 25 districts in Seoul using random samples of residents in Seoul selected by computer selecting system. By classifying these samples according to the type of houses(tenement houses, apartment houses and detached houses), the type of districts, the effects of the number of residents in a house and the type of the houses on tap water use are analyzed. From these samples, the consumption of tap water per capita day(lpcd) in Seoul can be estimated statistically. It is also observed that the lpcd decreases as the flat-dwellers increase. As the dwellers increase from 1 to 2, from 2 to 3, from 3 to 4 and from 4 to 5, lpcd has decreased by 47.6%, 20.8%, 16.9%, and 9.0%, respectively. The regression curve, which fits the tendency of decrease well, is represented by an power function. And the estimated linear regression equation shows that the average decreasing rate of lpcd as flat dwellers increasing is 12%.

• Journal of agricultural medicine and community health
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• v.21 no.2
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• pp.159-171
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• 1996

It is investigated to determine the removal efficiency of organic - phosphorus insecticide residues in lettuce by washing processes, the 5 washing solution (stagnant tap water, flowing tap water, alkaline solution, acidic solution) were used with the washing time(10, 30, 50sec) and frequencies(1, 2, 3 washing, 2 rinsing). The removal efficiency of residual pesticides by 5 washing methods was increased on the more washing time and frequency, and also was the highest on the 3 times washing for each 50 sec. The removal rate with stagnant tap water was 33.7% of Diazinon, 45.7% of Dimethoate and 24.6% of Fenitrothion, but 29.4% of Diazinon, 37.7% of Dimethoate and 24.5% of Fenitrothion with flowing tap water. Therefore, the former was significantly higher effective than the latter one. The removal rate of residual pesticides with alkaline solution showed 32.1% of Diazinon, 49.5% of Dimethoate and 29.9% of Fenitrothion, and 30.4% of Diazinon, 36.4% of Dimethoate and 21.0% of Fenitrothion with acidic solution. The washing efficiency of neutral detergent showed the most effective result than others with 47.1% of Diazinon, 58.0% of Dimethoate and 39.5% of Fenitrothion. Consequently, it's appeared that the neural detergent washing was the most effective method on the 3 times washing for each 50 sec.

• Journal of Soil and Groundwater Environment
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• v.16 no.1
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• pp.12-18
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• 2011

To investigate the natural reduction characteristics of radon with a short half-life (3.82 day) in drinking Qgroundwater, we analyzed the changes of radon concentrations of groundwater, waters in storage tanks, and tap waters from the small-scale groundwater-supply systems (N = 301) by LSC (Liquid Scintillation Counter). We also analyzed the concentrations of uranium (half-life 4.5 billion years) in the waters by ICP/MS to compare with natural reduction of radon concentration. The radon concentrations of 68 groundwater-supply systems occupying 22.6% of the total samples exceeded the US EPA's Alternative Maximum Contaminant Level (AMCL : 4,000 pCi/L), with the average radon concentration of 7,316 pCi/L (groundwaters), 3,833 pCi/L (tank waters) and 3,407 pCi/L (tap waters). Compared to the radon levels of pumped groundwaters, those of tank and tap waters naturally reduced significantly down to about 50%. Especially, in case of 29 groundwater-supply systems with the groundwater radon concentrations of 4,000~6,000 pCi/L, average radon concentrations of the tank and tap waters naturally decreased down to the AMCL. Therefore this study implies that radon concentrations of drinking groundwater can be effectively reduced by sufficient storage and residence in tanks.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.313-320
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• 2004

In this study, variable characteristics of drinking water and the influences on underground water reservoirs, rooftop water tanks, and service water pipes in the building were assessed. The influence of underground water reservoir material and water capacity on water quality also were assessed. The results are the following as; First of all, the drinking water passing through underground water reservoirs or service water pipes in the building, averagely metal component concentration more increased from percent of 41.3 to percent of 74.2 totally than other items of water quality. On the other hand, both residual chlorine and total solid highly decreased 65.6 percent and 35.3 percent, respectively. Therefore, it was thought that water quality could be getting worse for microorganism re-growth by residual chlorine reduction, and total solid also could be a cause for extraneous matters accumulated in water reservoir. Secondly, the variations on water quality of each stage for water supply system in the building were higher in water service pipes connected from rooftop water tanks to the tap than in underground water reservoirs. In addition to, among of twelve items on water quality, ten items on water quality except dissolved oxygen and residual chlorine increased. Therefore, it was thought that the influence of water service pipes connected from rooftop water tanks to the tap on water quality were higher than other stages of water supply system in the building. Thirdly, in case of materials of underground water reservoir, it was likely that the variation on water quality by stainless steel and concrete materials got some similar. In case of water capacity, the variations on water quality of underground water reservoirs over $1,000m^3$ higher than those under $1,000m^3$. That reasons was likely that the retention time(49.72 hours averagely) of underground water reservoirs over $1,000m^3$ was two times longer than it of those under $1,000m^3$(23.37 hours). Therefore, it was thought that the influence on water quality by materials were some similar, but in case of water capacity, the influence of underground water reservoirs were higher.

• Applied Biological Chemistry
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• v.48 no.4
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• pp.388-393
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• 2005

This study was conducted to experiment the removal efficiency of 6 pesticides in fruits and vegetables using various washing solutions. As results, the average removal efficiencies of pesticides washed with tap-water were 68.3%, whereas those washed by ultrasonic cleaning for 2 and 5 minutes were 73.7% and 82.5%, respectively. Using different washing solutions with various additional materials such as 0.5% detergent, 5% vinegar, 5% salt and flour, the removal rates were 82.9%, 76.9%, 75.8% and 75.7%, respectively. With 0.5% detergent, pesticides were 20% more removed when washed by ultrasonic cleaning than tap-water washing; moreover, Chlorthalonil in cherry tomato showed the highest removal efficiency while EPN in grape washed with tap-water showed the lowest. The order of removal efficiencies of pesticides were Chlorthalonil (90.0%)>Procymidone (81.3%)>Chlorpyrifos (76.6 %)>Endosulfan (75.7%)>Fenitrothion (75.5%)>EPN (73.8%).

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.29-35
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• 2013

The objective of this research was to investigate the effect of various clay materials on the growth and change in mineral composition of soybean sprout. Further effect of sericite concentration on growth of soybean sprout was optimized. The experiments were carried by using three different viz., loess supernatant, tap water and sericite supernatant. From the obtained results it was found that a significant growth in soybean sprouts was observed while using sericite supernatant this growth was 14.71% and 50% more total growth than that of loess supernatant and tap water. In addition, using sericite supernatant the length of root of soybean sprouts was reached 17.30% and 36.50% longer than that of tap water and loess supernatant. The plausible reason for this growth using sericite supernatant may be due to the presence of various mineral($K^+$, $Ca^+$) in sericite. Further the mineral contents of sericite supernatant were 11.56% and 13.48% more than that for loess supernatant and tap water. Among the various sericite concentration used it was found that 100g/L sericite supernatant showed significant growth rate compared with other fractions. From the obtained results comparing with all materials 100g/L sericite concentration was economic for the cultivation of soybean sprout.

• Journal of Korean Society on Water Environment
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• v.38 no.6
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• pp.275-281
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• 2022

To maintain water quality after water treatment, monitoring whether the quality of treated tap water quality changes is essential. However, current investigations are insufficient to prevent secondary contamination in drinking water supply systems. This study investigated Gyeonggi's e apartment where a red water problem occurred and monitored the water quality and corrosiveness of the overall water supply system to the apartment from June 2021 to April 2022. In a comparison of drinking water quality after water treatment and the influent of the reservoir, turbidity and heavy metal concentrations were increased and residual chlorine was decreased due to increases in temperature. Correlation analysis and principal component analysis (PCA) indicated that a low level of residual chlorine may cause the abscission of Mn²⁺ and Fe²⁺ through microorganism activation, which also causes a high level of turbidity. The corrosion index (LI) in the influent of the reservoir tank was increased due to Ca²⁺ and temperature. These results indicate that the corrosiveness of drinking water and the deterioration of drinking water quality were mainly increased between the drinking water treatment plant and the reservoir tank's influent. The findings provide clear evidence that it is essential to manage water supply systems and reservoir tanks to prevent the secondary contamination of drinking water.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.615-623
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• 2012

In this study, we evaluate the corrosion indexes (CI) such as Langelier Index (LI), Larson ratio (LR), Ryznar saturation index (RSI), Aggressiveness index (AI) of water quality for raw water, treated water and water in distribution reservoir at major eight drinking water treatment plants (DWTPs) in Korea. By analyzing secondary contamination of tap water, the variation of secondary contaminants was investigated with regard to pipe materials, aging and corrosion index (CI). In addition, we suggested an appropriate CI applicable water quality and the management plan for CI monitoriing. All CI showed corrosive water quality, and they did not change significantly in the distribution network. However, Copper (Cu), iron (Fe) and zinc (Zn) concentrations as secondary contaminants increased through the distribution network. Among CI, LI was most sensitive to changes in raw water quality and drinking water treatment. Also, it has high correlations with other indexes such as RSI, AI. Therefore, LI is considered as an appropriate CI to the domestic water quality. Based on these result, we propose LI as a drinking water quality standard to control the pipe corrosion from DWTPs.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.12a
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• pp.103-114
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• 2005

Chlorine disinfection has been used in drinking water supply to disinfect the water-borne microbial disease which may cause to serious human disease. As Chlorination is still the least costly, relatively easy to use, chlorination is the primary means to disinfect portable water supplies and control bacterial growth in the distribution system. However, chlorine also reacts with natural organic matter (NOM), which presents in nearly all water sources, and then produces disinfection by-product (DBps), which may have adverse health effects. Although the existent DBPs have been reported in drinking water supplies, it is not feasible to predict the levels of the various DBPs due to the complex chemistry reaction involved. The objectives of this study were to investigate seasonal variation of DBPs formation and difference of DBPs concentration in the plant to tap water. The average concentration of THMs was 20.04 ${\mu}g/{\ell}$, HAAs 8-15 ${\mu}g/{\ell}$, HANs 2-4.5 ${\mu}g/{\ell}$ respectively. Distant variation of DBPs formation is that THMs concentration increase by 17% at 2 km point from the plant and by 28% at 7 km and HAAs, HANs also increase each by 16%, 32%, at 2 km from the plant and 35%, 56%, at 7 km. DBPs increase in water supply pipe continually. The seasonal occurrence of DBPs is that in May and August DBPs concentration is very high then in March, in May DBPs concentration is highest. The temperature is main factor of DBPs formation, precursor also. Precursor which was accumulated for winter flowed into the raw water by flooding in spring and summer and produced DBPs. Therefore for the supply of secure drinking water, it is required to protect precursor of flowing into raw water and to add to BCAA and DBAA to drinking water standards.