• The Korean Journal of Pesticide Science
• /
• v.2 no.1
• /
• pp.59-64
• /
• 1998

In order to elucidate the leaching behaviour of the herbicide bentazon in soil, soil columns(5cm ID ${\times}$ 34 cm L) were packed with three different soils up to 30 cm height, followed by the treatment of [$^{14}C$]bentazon, and rice plants(Oryza sativa L.) were grown for 9 weeks on these columns, with the columns without growing rice plants as the control for comparison. The amounts of $^{14}C$ activities percolated were about 92% of the originally applied $^{14}C$ irrespective of the physicochemical properties of the soils in the absence of rice plants, whereas $21{\sim}50%$ of the originally applied $^{14}C$ was percolated in the presence of rice plants, suggesting that the amounts of $^{14}C$ leached decreased remarkably in rice-cultivating soils. Bentazon leached faster in soil with higher pH and with lower organic matter content in the presence of growing rice plants. The amounts of $^{14}CO_{2}$ evolved from the soil columns were less than 0.2% of the originally applied $^{14}C$. Smaller amounts of $^{14}C$ were translocated into shoots via roots in soils with higher organic matter content. $^{14}C$ activities distributed into the aqueous phase of the leachate collected from the soil columns increased with leaching period and by rice cultivation, whereas the physico-chemical properties of soils did not exhibit any effect. The amounts of soil-bound residues increased remarkably by cultivating rice plants.

• Applied Chemistry for Engineering
• /
• v.17 no.5
• /
• pp.517-520
• /
• 2006

The leaching behaviors of zinc and manganese oxides of spent alkaline manganeses battery in sulfuric acid solution by using $H_{2}O_{2}$ as a reducing agent were investigated according to the concentration of $H_{2}SO_{4}$, temperature, reaction time, and the amount of $H_{2}O_{2}$. The experimental results of zinc and manganeses dissolution rates obtained without a reducing agent at 100 g/L solid/liquid ratio, 3.0 M $H_{2}SO_{4}$, $60^{\circ}C$ and 200 r.p.m. were 97.7% and 43.5%, respectively. On the other hand, zinc and manganeses dissolution rates obtained by adding 30 mL reducing agent at $60^{\circ}C$ were 99.6% and 97.1%, respectively. The addition of the reducing agent increased the leaching of manganese by two-fold compared to the absence of a reducing agent. In case of adding over 30 mL $H_{2}O_{2}$, however, the leaching rates of zinc and manganeses were independent of reducing agent amounts.

• Korean Journal of Soil Science and Fertilizer
• /
• v.27 no.1
• /
• pp.15-20
• /
• 1994

Lysimeter experiments were conducted to elucidate the behavior of $NO_3-N$ derived from urea applied at different rates and accompanying cations in soils and to further provide fundamental information of rational nitrogen-fertilizer management. Urea was applied at rates of 0, 7, 14, 21, 28 and 35kg N/10a to sandy loam pakced into PVC cylindrical lysimeter(vol. : $0.187m^2$, area $0.43m^2$). Leachates from the lysimeter with or without grass grown were collected periodically and analyzed for $NO_3$ and cations. Grass growth and yield responses to N fertilization were also examined. Dry matter yield and nitrogen uptake increased with the urea application rate. The amount of leachate from the lysimeter was negatively correlated with urea application ratesl($r=-0.95^{**}$). The nitrate leaching loss with grass grown was 230 g N/10a at the maximum rate of 35kg N/10a, but the highest leaching loss was observed as 1,607 g N/10a from the bare plot. Increase in urea application rates decreased significantly leaching losses of Ca, Mg, K and Na(>0.01). The highest leaching loss from the bare plot was observed for Ca but only 6.5% of exchangeable form and 14.0% for K from the grass plot respectively. Equivalent ratio of cations to nitrate leached were 3.2 % for the bare plot and the ratio for the grass plot increased with the urea application rate, ranging from 18.6 to 32.7%.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.3
• /
• pp.345-349
• /
• 2003

The quantity, process and kinetics of di-(2-ethylhexyl)phthalate (DEHP) migration in the 30/70 and 40/60 poly(vinylchloride) (PVC)/DEHP blends were investigated using gas chromatograph. A thin and flexible PVC sheet was soaked in surrounding medium (SM) of water/ethanol mixture and acetonitrile with constant stirring to release DEHP. By observed concentration of DEHP in the SM, it is found that acetonitrile is more intense in DEHP migration than water/ethanol mixture. In addition the amount of extracted DEHP is proportional to the leaching temperature and added ratio of DEHP. The behavior of DEHP migration from flexible PVC sheets was described by the Ficks's law with $2.72-10.1\;{times}\;10^{-10}$ cm²/s of the diffusion coefficients.

• Economic and Environmental Geology
• /
• v.35 no.3
• /
• pp.257-271
• /
• 2002

One of the main interests in relation to heavily contaminated gully-pot sediment in urban area is the short term mobility of heavy metals, which depends on the pH of acidic rainwater and on the buffering effects of carbonate minerals. The buffering effects of carbonates are determined by titration (acid addition). Leaching experiments are carried out in solutions with variable initial HN03 contents for 24h. The gully-pot sediment appears to be predominantly buffered by calcite and dolomite. In case of sediment samples, which highly contain carbonates, pH decreases more slowly with increasing acidity. On the other hand, for the sediment samples, which less contain carbonate minerals, pH rapidly drops until it reaches about 2 then it decreases slowly. The leaching reactions are delayed until more acid is added to compensate for the buffering effects of carbonates. The Zn, Cu, Pb and Mn concentrations of leachate rapidly increase with decreased pH, while Cd, Co, Ni, Cr and Fe dissolutions are very slow and limited. The solubility of heavy metals depends not only on thc pH values of leachatc but also on the speciation in which metals are associated with sediment particles. In slightly to moderately acid conditions, Zn, Cd, Co, Ni and Cu dissolutions become increasingly important. As deduced from leaching runs, the relative mobility of heavy metals at pH of 5 is found to be: Zn > Cd > Co > Ni > Cu » Pb > Cr, suggesting that moderately acid rainwater leach Zn, Cd, Co, Ni and Cu from thc contaminated gully-pot sediment, while Pb and Cr would remain fixed. The buffering effects of Ca- and Mg-carbonates play an important role in delaying as well as limiting the leaching reactions of heavy metals from highly contaminated gully-pot sediment. The extent of such a secondary environmental pollution will thus depends on how well the metals in sediment can be leached by somewhat acidic rain water. Changes in the physicochemical environments may result in the severe environmental pollution of heavy metals. These results are to be taken into account in the management of contaminated sediments during rainstorms.

• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.4
• /
• pp.353-359
• /
• 1996

Micro plot study was conducted to elucidate the behavior of nitrogen derived from animal manure in soil and to obtain the fundamental information on animal waste management. Soils used in this experiment were sandy loam and loam. Soil water samplers (1m length ceramic cup tube) were installed at 90cm depth of soil to collect the percolate. Fresh and fermented pig manure were applied at the rate of 0, 50, 100 ton per ha. Maize was grown to evaluate the effect of crop on nitrogen behavior through soil profile. Concentration of nitrate nitrogen in percolate increased by application of pig manure. This trend was more obvious at the loam with fermented pig manure than sandy loam with fresh pig manure treatment. The concentration of nitrate nitrogen was lower under the maize cultivation than bare soil condition by 64.6-68.9%. Concentration of Ca, Mg and Na of soil and percolate increased as nitrate nitrogen concentration increased. The equivalent ratio of cation to nitrate nitrogen of percolate was increased by application of pig manure. This result showed that canon leaching was accompanied by nitrate nitrogen. Concentration of nitrate nitrogen of subsurface soil was increased by pig manure application.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.23 no.3
• /
• pp.31-46
• /
• 1978

In order to secure the proper use of herbicides that are frequently used in Korea, the behavior of herbicides in various type of soil were studied. This study includes the variation of phytotoxicity, leaching and movement, and residual activity period of herbicides depending upon the type of soil etc. Experiments were also conducted to establish a guideline for the selection of herbicides according to the type of soil and the proper use of each herbicide in various type of soil in Korea. Experimental results showed that the behavior of herbicides could be characterized based on the series or kind of herbicides and devided into two major groups. One group (nitrofen. CNP, benthiocarb and butachlor) of herbicides showed relatively little crop injury and was very dependable. The action of this group was not remarkably influenced by soil components, rainfall and the quantity of herbicide used with the type of soil that had small adsorption capacity such as most of soil in Korea. The other group(simazine, 2, 4-D. linuron, alachlor and simetryne) showed a wide variation in it's action and retained potentially injurious effect. This group was very susceptable to using condition as well as the type of soil itself. Based on the results of various experiments the disappearance of the residual activity period of major herbicides used in upland and paddy field and the related factors were explained. It is believed that the results of this study can be used as a base for the establishment of a guideline for the proper use of each herbicide and can suggest a direction of developing new herbicides.

• Resources Recycling
• /
• v.6 no.1
• /
• pp.35-39
• /
• 1997

This study was carried out to find the existing forms of chlorlnc in EM dust and to understand the valaliliratian behavior and the removal of chlorine from EAF dust with lemperalure and heating almosphere The chemical compositions of dust A are 27.3%Fe. 21.8%3Zn, 3 15%Pb, 3 51%C1 and that of dust B BE 33.92%Fe, 15.94%Zn, 2.73% Pb, 3.98%Cl. The XRD analysis and water leaching test shows that chlorlne in EM dust exist mainly as NaCI, KCI, Pb (0H)Cl. Above 99% of chlorine was volatilized when dust was hentcd in alr atmosphere at 1100$^{\circ}$C h r 1 hour and that was 96% when heated in reduction atmosnherc at 1100$^{\circ}$C for 1 hour.

• Journal of Korean Society on Water Environment
• /
• v.38 no.2
• /
• pp.72-81
• /
• 2022

Numerous studies have investigated the occurrence and fate of microplastics in the environment; however, only limited effort has been devoted to exploring the characteristics of dissolved organic matter (DOM) leached from microplastics. In microplastic (MP)-contaminated environment, MPs are typically mixed with naturally-occurring particles, which interferes with their detection in the environment. Thus, it is necessary to distinguish between the DOM leached from MPs and those leached from natural particles and also to characterize their properties. This study investigated DOM leaching behavior from MPs (polystyrene: PS, polyvinylchloride: PVC) and natural particulates (forest soil: FS, litter leaves: LL) under light, which is considered one of the main weathering processes that affect MPs in the environment. The leached DOM concentrations and fluorescence characteristics were compared under dark versus light conditions. Regardless of the origins, UV light promoted DOM release from all the particulates. More DOM was released from natural particles than from MPs under both conditions. However, the effect of promoting DOM release by UV was more pronounced for MPs than for natural particles. It was observed from fluorescence spectra that the intensity of the humic-like region was substantially reduced when MP-derived DOM was exposed to UV light, whereas the change of intensity was very little for natural particles. Under light conditions, the ratio of protein-like to humic-like fluorescence of MP-derived DOM was higher than that of DOM from natural particles. This study implies that a substantial amount of DOM could be leached from MPs even in MP-polluted environment under UV irradiation. Protein/humic fluorescence ratio could be utilized as a fast probing indicator to separate the two sources of particles under light.

• Resources Recycling
• /
• v.10 no.1
• /
• pp.42-48
• /
• 2001

The dissolution behavior of gold and silver from gold-silver alloys in aerated cyanide solutions has been investigated by an electrochemical means as well as a direct measurement of gold and silver ions reported in the bulk solution as a function of time using rotating disc electrodes. The variables studied included oxygen partial pressure, rotating speed of the disc, concentration of cyanide, temperature and composition of the allyos. The dissolution potential and the rate of dissolution were obtained in view of the anodic and cathodic current-potential relationships. The results were discussed in terms of the mixed potential theory. The results showed that the dissolution rate of gold and silver from the alloys was controlled partially by chemical reaction. but largely by transport of either oxygen or cyanide, depending on their relative concentration under the experimental conditions employed in this study.