• Korean Journal of Environmental Agriculture
• /
• v.19 no.1
• /
• pp.6-12
• /
• 2000

This study was carried out to determine the adsorption characteristics of eight pesticides on thirty citrus orchard soil so soil samples were taken from nineteen soil series containing different fractions of organic carbon(Foc). The adsorption characteristics for eight pesticides fitted to Freundlich isotherms. The adsorption isotherms showed C-type for alachlor and chlorpyrifos, L-type for linuron and diniconazole. and S, C, and L-types for metribuzin, metolachlor, and alachlor with increasing Foc, respectively. In particular, the adsorption of chlorothalonil showed S, C, L, and H-types with increasing Foc. Distribution coefficient(Kd) values of metribuzin, metolachlor, and alachlor were below $10\;Lkg^{-1}$ and increased linearly with Foc. Kd values of linuron, diuron and chlorothalonil increased exponentially to 60, 200, and $400\;Lkg^{-1}$, respectively and those of diniconazole and chlorpyrifos increased logarithmically. Kf value. Freundlich adsorption coefficiient, increased with Kd in the same manner with Kd. Furthermore, the linearity of Kf value was larger than that of Kd value.

• Korean Journal of Environmental Agriculture
• /
• v.11 no.2
• /
• pp.101-108
• /
• 1992

In order to illustrate adsorption phenomena of herbicides(alachlor and paraquat) on soils, absorption equation of herbicides and the relationships between soil properties and adsorption constants were investigated with 22 soils. The results were as follows : 1. The shaking time for approaching equillibrium reaction of herbicides(alachlor and paraquat) with woils were about 30 minutes for paraquat and 4 hours for alachlor, respectively. 2. The distribution coefficients of alachlor were inbetween 0.81-33.83 in 5 ppm and 0.09-15.52 in 50 ppm, respectively. 3. The adsorption of alachlor was positively correlated with organic matter and paraquat was with clay content of soils. 4. Both paraquat and alachlor were highly adsorbed in Chunpo series soil containing low contents of organic matter and clay on account of different mechanism from other soils, 5. Freundlich's adsorption constant(K) was greater than distribution coefficient(Kd), and the differences between K and Kd's were to be increased with increasing equillibrium concentrations.

• Analytical Science and Technology
• /
• v.21 no.4
• /
• pp.326-331
• /
• 2008

Distribution coefficients (Kd) of uranyl ion onto divinylbenzene amidoxime resins were measured in sodium carbonate solution and the Kd values were increased up to about 70 as the resin bead size was decreased. At a condition of 0.0044 M $Na_2CO_3$, the adsorption capacity for uranium was $3.4{\mu}mole$ U/g-resin. The Kd values in the 0.5 M $Na_2CO_3-NaHCO_3$ solution, ranging from pH 9 to pH 11, revealed that they were increased as the pH increased and revealed lower values than those in the pure sodium carbonate solution. The amidoxime resins were characterized by FTIR-ATR showing the absorption bands of the amidoxime functional groups. A species of the uranyltricarbonate complex, $UO_2(CO_3)_3^{-4}$, was confirmed by UV-Vis spectroscopy, revealing four absorption peaks between 400 and 500 nm. Uranium was separated from some fission products by a column operation. However, most of the uranium and fission products were eluted before an adsorption and only a small amount of uranium was adsorbed onto the resin due to the low capacity of the resin.

• Korean Journal of Weed Science
• /
• v.18 no.3
• /
• pp.257-261
• /
• 1998

This study was carried out to investigate the adsorption and the degradation of herbicide napropamide in soils tinder laboratory conditions. The adsorption distribution coefficients(Kd) of napropamide in 3 soils varied from 5.38 to 11.39. With higher content of organic matter in soils, the extent of adsorption was high. The rapid degradation of napropamide took place after a lag period. The time to 50% loss of napropamide was approximately 65, 45 and 30 days in soil incubated at 10, 20 and $30^{\circ}C$, respectively. The time to the 90% loss varied from about 90 days at $10^{\circ}C$ to about 45 days at $30^{\circ}C$. In the soil pre-incubated with napropamide, the herbicide degraded without a lag time, and the rate of degradation was also accelerated. This should be a evidence on enhanced biodegradation of napropamide in soil with the repeat-application.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.5
• /
• pp.47-56
• /
• 2008

Temporal changes of metal solubility have been repeatedly observed in soils equilibrated with metal salt solutions. This phenomenon is known as aging, yet factors that affect the degree of metal aging remain largely unexamined. In this study, we compared the extent of aging on metal partitioning depending on soil, metal, and metal loading. Five soils spiked with four levels of Cd (2.5-20 mg ${kg}^{-1}$), Cu, and Zn (50-400 mg ${kg}^{-1}$) salt solutions were aged in the laboratory up to 1 year. The partitioning coefficient ($K_d$) of each metal was calculated from the ratio of total to dissolved metal concentration in samples collected at times ranging from 1 day to 1 year. The highest $K_d$ values for Cd, Cu and Zn were recorded in a Histosol, Andisol, and fine-textured Alfisol, respectively, whereas the lowest $K_d$ was recorded for an Oxisol and coarsetextured Alfisol. For all soils, a pattern of increasing Kd with aging was evident for Cd and Zn, but not Cu. Rapid Cu sorption was limited when dissolved organic matter was high in soils. In highly-retentive soils, $K_d$ values seemed to be insensitive to metal loading, although a longer period was required for the higher metal loadings to reach the same degree of metal aging as the lower loadings. In soils with low sorption capacity, the $K_d$ values were determined more by metal loading than by aging. Therefore, marked differences can be expected in the degree of metal aging in spiked soils by the soil type, metal and amount of metal added.

• Korean Journal of Weed Science
• /
• v.18 no.4
• /
• pp.325-332
• /
• 1998

This study was carried out to investigate the adsorption and the movement of herbicide fenoxaprop-P-ethyl in the silty clay soil(SiC) and the sandy loam soil(SL). Fifteen percent of the added herbicide was adsorbed within 30 min after shaking, and a quasi-equilibrium was reached after 8 to 14 h. The time required for 50% adsorption was 15.8 h in the SiC and 19.3 h in the SL. The equilibrium adsorption isotherm was followed by the Freundlich equation and the Kd was 3.86 in the SiC and 2.32 in the SL. The herbicide in the soil columns flooded with 3 cm water depth and eluted at 0.8 cm/day was leached to 6 cm and 8 cm depth at 7 and 21 days after the treatment, respectively. However, the movement was widened with increased amount of leaching water. The herbicide in the field soils was moved up to 6 cm and 8 cm depth at 14 and 56 days after the treatment, respectively. However, the large amount of the applied herbicide was distributed in 0~2 cm profile in all of the soils examined. Half-life of the chemical in soils was shorter than 7 days and the time to 90% degradation was about 4 weeks. The results indicate that the herbicide has relatively small mobility and short persistence.

• Korean Journal of Weed Science
• /
• v.7 no.2
• /
• pp.165-170
• /
• 1987

This study was undertaken to elucidate the behavior of herbicide bensulfuron-methyl[methyl-2-[[[[[(4,6-dimethoxy pyrimidine-2yl)amino]carbonyl]amino]sulfonyl]methyl]benzoate]in soils. Adsorption of the herbicide in soils was mainly correlated with content of organic matter and clay, and canon exchange capacity. Adsorption distribution coefficient(Kd value) in clay loam soil was greater than those in loam and sandy loam soils. The Kd value decreased in the order of zeolite, bentonite, halloysite and laziolite clay minerals. Bensulfuron-methyl moved to 3cm deep in clay loam soil and 4cm deep in sandy loam and herbicide treated layer was 0 to 2cm profile in the two soils. The decomposition rate of bensulfuron methyl varied with the soil properties. The rate was slower in sterilized soil than in nonsterilized. Addition of organic matters to the soils accelerated the decomposotion. The degradation was more rapid in 30$^{\circ}C$ soil temperature than in 20$^{\circ}C$.

• Korean Journal of Environmental Agriculture
• /
• v.12 no.3
• /
• pp.209-218
• /
• 1993

The behaviour of insectcide ethoprophos (O-ethyl S,S-propyl phosphorodithioate) in soil was investigated. In a laboratory study, the degradation of ethoprophos in soil followed first-order reaction kinetics. The half-life of the insecticide in the soil incubated with 10, 18 and $25^{\circ}C$ was 12.4, 5.5 and 2.5 days, respectively. Arrhenius activation energy was 73.8 KJ/mole. The half-life was 46.4, 17.6 and 6.9 day in the soil with 7, 14 and 19% of soil water content, respectively. The moisture dependence B value in empirical equation was 1.67. The adsorption isotherm for ethoprophos in the soil agreed with freundlich equation. The adsorption distribution coefficient (Kd) was 0.27. In a field study prepared in autumn with undisturbed soil column in a mini-lysimeter system, ethoprophos residues were largely distributed in the top $0{\sim}2cm$ soil layer and moved down to the top 6cm soil layer. Persistence of ethoprophos in field soil was correlated with variation in weather pattern during the period of experiments. The half-life of ethoprophos treated at March and October was about 17 and 5 days, respectively. The ethoprophos woil was degraded up to 90% at 37day after the both treatment. In persistence and mobility of ethoprophos in field soil, the observed data were reasonably corresponded with predicted data by some computer model of pesticide behaviour.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.2
• /
• pp.123-131
• /
• 2005

This study was focused on adsorption, leaching, photolysis, and hydrolysis of the fungicide procymidone in soils. Adsorption type of procymidone on three different soil were well fitted to Linear and Freundlich isotherm. Distribution coefficients (Kd) were ranged from 2.75 to 12.18 and Freundlich isotherm Kf value $1.99{\sim}9.98$, 1/n value $0.74{\sim}0.89$. Desorption rates were $20.1{\sim}34.0%$ (Namgye), $26.3{\sim}44.6%$ (Jigog) and $31.6{\sim}50.9%$ (Baegsan series) and desorption hysteresis were $0.65{\sim}0.79,\;0.55{\sim}0.73\;and\;0.49{\sim}0.68$. Procymidone seemed to be stable to photolysis in acidic and neutral solutions but hydrolyzed rapidly in alkaline solution. Considering leaching properties procymidone mobility low in soils.

• Korean Journal of Environmental Agriculture
• /
• v.20 no.3
• /
• pp.162-168
• /
• 2001

This study was conducted to evaluate the degradation, adsorption and desorption and leaching of acetamiprid in soils. The half-life of acetamiprid in field condition was $1.7{\sim}3.3$ days in Bokhyun soil and, in case of laboratory condition, 15.5 days. Adsorption of acetamiprid was equilibrated in 12 hours incubation. In adsorption experiment using modified soils, such as oxidized soil, oxidized soil added humic acid, fulvic acid, kaolinite or montmorillinite, adsorption rate of acetamiprid was the highest in the oxidized soil added fulvic acid. The desorption rate was the lowest in the oxidized soil added fulvic acid. The adsorption and desorption results should be suggested that acetamiprid could be strongly adsorbed with soil humic materials, especially fulvic acid. When the mobility of acetamiprid in soil was calculated according to GUS (Groundwater Ubiquity Score) equation, it was prove to non-leacher, and it was confirmed in the leaching experiment with soil column. Most of acetamiprid was remained in the upper 30 cm of the soil column after eluting with water and it was not even detected in leachate.