• Journal of Environmental Science International
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• v.28 no.8
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• pp.689-700
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• 2019

The adsorption and leaching characteristics of five ionic pesticides including four acidic pesticides (2,4-D, dicamba, MCPA, and MCPP) and one amphoteric pesticide (imazaquin) in agricultural soils were investigated. Soils around spring waters that were heavily affected by pesticide run-off and soils around wells considering the regional characteristics in Jeju Island were collected at 24 stations. The Freundlich constant, $K_F$ value, which is a measure of the adsorption capacity, decreased in the order of 2,4-D > MCPA > MCPP > dicamba > imazaquin. The adsorption capacity of these ionic pesticides decreased with increasing pH owing to the effects of ionization of pesticides and different ionizable functional groups of soils. The leaching of ionic pesticides in the soil column showed a reverse relationship with their adsorption in soils, namely, the ionic pesticides were leached more quickly for the pesticides with lower adsorption capacity. The groundwater contamination potential of the ionic pesticides was evaluated in the order of imazaquin > MCPA > MCPP > dicamba > 2.4-D according to the groundwater ubiquity score based on soil Koc and the half-life of the pesticide.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.295-298
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• 2004

It was revealed that leaching of elements were partly inhibited because seawater contains plenty of dissolved ions than fresh water. On the other hands, the low activity coefficient and the formation of complex with chloride and sulfate play roles in enhancing element leachability. However, the pH buffaring capacity of seawater is the most important factor that makes the leaching of elements and its chemical behavior in the seawater system different from those in the fresh water environments. In general, the leaching from the weathered ash was smaller than that from the fresh ash. However, it was revealed that the leaching of Si, Fe, Al, Mn, phosphate, and some other elements were independent of ash weathering. They were dependant only on the pH of the solutions.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.372-378
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• 2003

This study investigates the fractional composition and the leaching characteristics of heavy metals in polluted soils due to mining activities. The fractionated composition of heavy metals is classified into five fractions, adsorbed, carbonate, reducible, organic and residual fraction. The status of humic substances in mine wastes of most sites are polyhumic except tailing from Sangdong mine. According to the sequential extraction procedures (SEPs), leaching probabilities of Cd in coal wastes and tailing are relatively low due to high percentage of residual fraction. 46.4% of Ni in tailings from Sangdong mine is probably leached under oxidized environment, and 39.4% of Cu in these tailings is readily extracted under strongly oxidized environment by organic fraction. According to leaching condition of pH 3.0 and pH 5.6, the amount of heavy metals leached out of coal wastes and tailing increases to 1/2 hours. At pH 3.0 and pH 5.6, concentration of Ni in tailing increases up three times of the initial value. Heavy metals released from coal wastes and tailing were not influenced significantly by leaching time.

• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.349-358
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• 1996

The leaching behavior of uranium from unirradiated CANDU UO$_2$ fuel pellet in the spent fuel wet storage and disposal conditions has been investigated. A modified IAEA leach test method was used, and then the extent of leaching was monitored by analysis for uranium in the leachant. The leach test has been performed in various leachants(demineralized water and boric acid solution at pH=6, synthetic granite groundwater) for a long-term period of 5.4 years, and the effect of temperature on the leach rate of uranium has been analyzed. The leach rates of uranium at $25^{\circ}C$ were dependent on the leachants. Over initial 100 days of leach periods, the leach rate in groundwater was the highest in three leachants and no significant differences of leach rates ore observed in the demineralized oater and boric acid solution. But these leach rates in three leachants around 2,000 days at $25^{\circ}C$ appeared to be reached the steady rates in the range of 1~5$\times$10$^{-8}$ g/$\textrm{cm}^2$ day. The leach rate of uranium in groundwater shooed to be independent of the temperature, but those in both demineralized water and boric acid solution increased with temperature. These results show that the leaching behavior of uranium from UO$_2$ fuel in both the demineralized water ann boric acid may be controlled tv the surface oxidative.dissolution reaction of UO$_2$ and the leach rate of uranium in groundwater at room temperature could mainly be controlled by the complex reaction of dissolved uranyl ions with carbonate ions and no variation of leach rate of UO$_2$ in groundwater with temperature may be due to the local deposition of passivating uranyl phases on the surface.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1541-1554
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• 2016

To understand the characteristics of vanadium leaching from soils formed by the weathering of basalts, paleo soil at Gosan, Jeju Island, Korea, and several present-day soils from neighboring areas were collected. Leaching experiments were carried out by two approaches: 1) batch experiments under various geochemical conditions (redox potential (Eh) and pH) and 2) continuous leaching experiments under conditions similar to those of natural environments. From the batch experiments, leached vanadium concentrations were highest under alkaline (NaOH) conditions, with a maximum value of $2,870{\mu}g/L$, and were meaningful (maximum value, $114{\mu}g/L$) under oxidizing ($H_2O_2$) conditions, whereas concentrations under other conditions (acidic-HCl, $neutral-NaHCO_3$, and $reducing-Na_2S_2O_3$) were negligible. This indicated that the geochemical conditions, in which soil-water reactions occurred to form groundwater with high vanadium concentrations, were under alkaline-oxidizing conditions. From the continuous leaching experiments, the pH and leached vanadium concentrations of the solution were in the ranges of 5.45~5.58 and $6{\sim}9{\mu}g/L$, respectively, under $CO_2$ supersaturation conditions for the first 15 days, whereas values under $O_2$ aeration conditions after the next 15 days increased to 8.48~8.62 and $9.7{\sim}12.2{\mu}g/L$, respectively. Vanadium concentrations from the latter continuous leaching experiments were similar to the average concentration of groundwater in Jeju Island ($11.2{\mu}g/L$). Furthermore leached vanadium concentrations in continuous leaching experiments were highly correlated with pH and Al, Cr, Fe, Mn and Zn concentrations. The results of this study showed that 1) alkaline-oxidizing conditions of water-rock (soil) interactions were essential to form vanadium-rich groundwater and 2) volcanic soils can be a potential source of vanadium in Jeju Island groundwater.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.451-454
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• 2003

Nonpoint source pollution of groundwater and subsurface water from irrigated agriculture is a major concern in many areas. In this study we aimed to investigate the effect of the water applied by irrigation in agricultural area on the transport of nitrogen and phosphorus originated from fertilizers applied to the surface of soil in agricultural activities. We first conducted investigation on the resdual concentrations of soil N and P in a selected agricultural area. And simulating the target area by column studies in the laboratory leaching extent of various components from the composite and urea fertilizers applied on the soil surface during irrigation was studied. Infiltration of water enhanced the leaching of nitrogen and phosphorus in both the rice paddy field soil and the patch soil. The downward N and P transport with infiltrating water was more pronounced in the patch soil column and the increased residual concentrations of N and P in the lower sections in the patch soil column was found with time.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.327-329
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• 2002

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.30-33
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• 2001

Melting is one of the most effective treatments for stabilizing heavy metals and also creates high value by-products. In this study, authors evaluated the leaching characteristics of heavy metals in melting slag obtained from incinerator ashes. In order to evaluate the environmental compatibility of the recycled melting slag, the samples analysed various leaching tests of heavy metals were raw incinerator ashes, melting slag and the construction materials recycled from melting slag. As the results: (1) The leaching concentrations of tile melting slag were lower than those of the raw incinerator ashes in the experiment performed in accordance with Korea Standard Leaching Test (KSLT). (2) The result of leaching test with the method of RG Min-StB 93. FGSV Forschungsgesellschaft fur Stra $\beta$ en- und Verkehrswesen) met the requirements in German. (3) The compressive strengths of mortar samples used for evaluating the feasibility of recycling the melting slag as construction materials also showed the suitable range for recycling (4) Melting slag was considered the stable materials with respect to the chemical stability against chemical solutions with various pH conditions.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.37-43
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• 2015

Ground characteristics is important in tunnel structure utilizing the strength of underground. In the case of the fault fracture zone such as weak soil conditions exists in the tunnel section and groundwater leaching occurs at the same time, it happens to occur to excessive displacement or collapse of tunnel frequently. Fault fracture zone is an important factor that determines the direction of displacement and the collapse of the tunnel under construction. Behavior of fault fracture zone is determined depending on the size and orientation of the surface portion of the tunnel. If the groundwater occurs in the face of tunnel, groundwater causes displacement and collapse. And the collapse characteristics of tunnel is a major factor in determining that the time-dependent behavior. It is difficult to accurately predict groundwater leaching from the fault fracture zone in the numerical analysis method and analyze the interaction behavior of groundwater and fault fracture zone. Therefore numerical analysis method has limitations the analysis of ground water in the ground which the fault fracture zone and groundwater occurs at the same time. It is required to comprehensively predict the behavior of tunnel and case studies of tunnel construction. Thus, the location of fault fracture zone is an important factor that determines the direction of displacement and the collapse of the tunnel. In this study, behavior characteristics of the tunnel according to the location of the fault fracture was analyzed.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.23-31
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• 2001

Melting is one of the most effective treatments for stabilizing heavy metals and also creates high value by-products. In this study, authors evaluated the leaching characteristics of heavy metals in melting slag obtained by incinerator ashes. In order to evaluate the environmental compatibility of the recycled melting slag, the samples were analysed various leaching tests of heavy metals with raw incinerator ashes, melting slag and the construction materials recycled from melting slag. As the results : (1) The leaching concentrations of the melting slag were lower than those of the raw incinerator ashes in the experiment performed in accordance with Korea Standard Leaching Test (KSLT). (2) The heavy metal concentration of long term leaching test, which was conducted in various pH conditions, were under the standard level of regulation in KSLT. (3) The leaching concentration of mortar samples used for evaluating the feasibility of recycling the melting slag as construction materials also shows the suitable range for recycling. (4) The result of leaching test with the method of RG Min-StB 93, FGSV (Forschungsgesellschaft fur Stra$\beta$en- und Verkehrswesen) met the requirements in German.