• Geomechanics and Engineering
• /
• v.15 no.6
• /
• pp.1135-1141
• /
• 2018

Volume changes of soils induced by inorganic acids cause severe foundation and superstructure failures in industrial buildings. This study aimed to assess the potential of fly ash to control volume changes in soils under acidic environment. Two soils such as black cotton soil predominant with montmorillonite and kaolin clay predominant with kaolinite were used for the present investigation. Both soils exhibited an increase in swelling subjected to phosphoric acid contamination. Ion exchange reactions and mineralogical transformations lead to an increase in swelling and a decrease in compressibility in black cotton soil, whereas phosphate adsorption and mineral dissolution lead to an increase in swelling and compressibility in case of kaolin clay. Different percentages of Class F fly ash obtained from Ramagundam national thermal power station were used for soil treatment. Fly ash treatment leads to significant reduction in swelling and compressibility, which is attributed to the formation of aluminum phosphate cements in the presence of phosphoric acid.

• Journal of Food Hygiene and Safety
• /
• v.1 no.1
• /
• pp.51-56
• /
• 1986

In the particular area the heavy metal concentrations in the soil were determined and compared to the contents in vegetables which were grown on the soil. Simultaneously the degree of contamination was examined. Samples were collected from Chinese cabbage, radish and Altari-mu, together with the soil on which the three kinds of vegetables have grown. The sites of samples collection were Jinguan-sa(non-polluted area) and Sangaedong(polluted area). The contents of cadimium, copper, lead and zinc were determined by means of atomic absorption spectro-photometer. The results obtained were as follows; 1. In soils, the average contents of heavy metal in Jinguan-sa area (Cd; 0.15ppm, Cu; 0.15ppm, Zn; 11.5ppm) were lower than those in sangye-dong(Cd; 0.26ppm, Cu; 13.0ppm, Zn; 17.1ppm). 2. In vegetables, the average have metal contents in Jinguan-sa were cadmium; 0.11ppm, copper; 5.29ppm, zinc; 18.75ppm and the average contents in Sangye-dong were cadmium; 0.16ppm, copper; 6.64ppm, lead; 0.14ppm, zinc; 15.01ppm. 3. The contents of lead showed zero ppm in Jinguan-sa area(soil and vegetables). In vegetables difference in concentration of heavy metals was not observed between reclaimed area and non reclaimed area. Statistical analysis showed that no correlation in the heavy metal concentrations between those in soils and in vegetables.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.4
• /
• pp.208-213
• /
• 2017

In this study, four inorganic pollutants (cadmium, chromium, manganese, lead), that could cause contamination events in drinking water distribution system, were selected and batch tests were carried out to determine the "minimum response concentration (MRC)", a part of Korean Contamination Warning system establishment. As the results, the minimum response concentration of cadmium was found to be 0.05 to 0.08 mg/L (0.005 mg/L : water quality standard) and that of chrome was 0.03 mg/L (0.05 mg/L). And the minimum reaction concentration was 0.005 mg/L for manganese (0.05 mg / L for water quality) and 0.02~0.08 mg/L for lead (0.01 mg/L).

• Journal of Plant Biology
• /
• v.17 no.4
• /
• pp.158-162
• /
• 1974

Some ecological attributes of perennial plants and Pb contamination were analyzed for study plots near an entrance of Nevade Test Site at Mercury Valley, Nye County, Nevada. The surface of the desert pavement soil was composed of stones (1 to 4cm diameter). The underside of each stone was coated with coarse and fine sand (about 90%). The profiles of soil were constituted with the A-horizon and C-horizon only. The soil pH at the plots ranges from 7.6 to 8.5, C/N was 13 and cation exchange capacity showed 15me/100g. Nine species and 42 number of individuals were found in all plots. Franseria dumosa and Larrea divaricata were dominant species. The discrete clumps of vegetation were consisted of 9 species of common perennials and these were covered about 25% on desert pavement, on the other words, bare area without vegetation was about 75%. The size and spacing of the plants was irregular. Community coefficient as comparison between shrub species in these study area and those in near the low elevation desert indicated a low degree of similarity. Density, cover and productivity in the study plots as compared with those in the nearest study areas in Mercury Valley showed a higher value. The soils in the studied area involved high heavy metal contents in the plant tissue was higher than those of its soil. The leavds of Lycium andersonii tended to accumulate more Zn and Mo than those of the other species. Larrea divaricata leaves accumulated very high leaves of Fe and Ephedra nevadensis were generally high in Mn. Lead contamination was apparent in foliage of desert vegetation collected alongside the roadway, reflecting the variation in traffic volume. Lead contents greater than fifteen-fold of normal (low traffic) were found in plant foliage alongside the heavily traveled roadway. Lead content of old foliage by the heavily traveled roadway was as much as 129 ppm but that of new foliage 17 ppm only.

• Journal of radiological science and technology
• /
• v.22 no.2
• /
• pp.47-51
• /
• 1999

We calculated the energy distribution and the percentage depth-dose at 10 cm in a $10{\times}10\;cm^2$ with a photon beam at SSD of 100 cm by using a Monte Carlo Simulation. PDD is used as a beam-quality specifier for radiotherapy beams. It is better than the commonly used values of TPR or nominal accelerating potential. The presence of electron contamination affects the measurement of PDD, but can be removed by the use of a 0.1 cm lead filter. It reduces surface dose from contaminant electrons from the accelerator by more than 90% for radiotherapy beams. The filter performs best when it is placed immediately below the head. An electron-contamination correction factor is introduced to correct for electron contamination from the filter and air. It converts PDD which includes the electron contamination with the filter in place into PDD for the photons in the filtered beam. The correction factor can be used to determine stopping-power ratio. Calculations show that the values of water-to-air slopping power ratio in the unfiltered beam are related to PDD.

• Proceedings of the SCSK Conference
• /
• 2003.09b
• /
• pp.524-526
• /
• 2003

Lipsticks are cosmetics which do not contain water and are usually preserved with parabens. When submitted to the Challenge Test, theses products did not reach the CTFA criteria, which means that microbiological contamination could occur before the end of its shelf life. The aim of this study was to evaluate the contamination level of 130 lipsticks after its use. Microorganisms were isolated from 14,6 % of the samples. However, only in two samples (1,5%) the contamination level exceeded the 100 CFU/g level, which means that, although the preservative system was not efficient to eliminate bacteria, the lack of free water was enough to prevent the microbial development. Total bacteria and fungi were determined by conventional methodology, according to CTFA Microbiological Guidelines. The microbes were then isolated and characterized as normal skin flora microorganisms. This suggest that products were contaminated by the constant application of lipsticks by consumers. This could lead to cross contamination when the same product is shared by several people. Extra care should be taken into account when this type of products are available to be tested by several consumers in demonstration displays.

• Progress in Superconductivity and Cryogenics
• /
• v.25 no.1
• /
• pp.6-10
• /
• 2023

2 K superfluid helium cryogenic system is the crucial component of many large accelerators. When the cryogenic system is operating at 2K@3129Pa, many room-temperature parts are connected to superfluid helium via tubes. Air Leakage in these connections may lead to air contamination of the cryogenic system. Air contamination may cause equipment failure in cryogenic systems and, in extreme cases, render the entire accelerator system inoperable. Helium guard is a technique that guards against air contamination of these sub-atmospheric pressure connections in 2 K superfluid helium cryogenic system. This paper introduces a typical 2 K cryogenic distribution design for large accelerators, and make risk analysis of air contamination. Finally, the analysis of specific leakage points and detailed engineering design are presented, which may be used as a reference when designing of a 2 K superfluid helium cryogenic distribution system.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.4
• /
• pp.377-389
• /
• 2020

In this study, pollution characteristics were investigated for the Andong Dam sediments in the Nakdong River. Sediment samples were collected from the middle, left, and right points of the lake up to 40km upstream of the Andong Dam at intervals of about 5km by stratification and turnover period. In the case of nutrients and total organics such as loss of ignition, total nitrogen, and phosphorus, the degree of contamination is low, but heavy metals of arsenic and cadmium is very high. The contamination level of sediments in the dam area is higher than that of the branch of river and the control group, and concentration of chromium, copper, and lead are higher in the stratification period, and that of zinc is higher in turnover period. Arsenic, cadmium, manganese, and zinc showed contamination variation between upstream and downstream but chromium, copper, mercury, iron and lead didn't show the variation.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.241-246
• /
• 1999

In this research, electrokinetic remediation test was experimented with contaminated kaoline specimen at below, above the cation-exchange capacity of the mineral. The changes of the flow in electro-osmosis with open electrodes and current were presented, and lead removal results were evaluated through the extraction test. As a result, it was showed that removal efficiency was 20-30%, 67-87% In the anode As lead transport continues, the lead precipitation within a narrow zone very close to the cathode can go significantly high. This high lead precipitation near the cathode could block the flow path, decrease the conductivity, and thus the electroosmotic flow. The net effect will cause a decrease in the efficiency of electrokinetic processing. Therefore, in this study, citric acid and surfactant solution was used at the cathode as enhancement techniques.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.04a
• /
• pp.38-43
• /
• 2002

A series of tests were performed to investigate the effects of pH and contamination level on cation exchange capacity and zeta potential in kaolinite loaded with lead. Test results show that cation exchange capacity of kaolinite is found to be in the range from 4 to 20meq/100g and it increased with increasing pH up to the converged number about 20meq/100g over pH 8. And then CEC has a tendency to reduce and converge to zero with increasing the concentration of Pb in the kaolinite surface. Moreover, zeta potential of kaolinite contaminated with lead is found to be in the range from -10 to 5mV, and zero point of charge is measured at about pH 3.5. Zeta potential of kaolinite contaminated with lead decreases with increasing pH values and decreasing Pb concentration of kaolinite.