Adsorption of ^(134)Cs from aqueous solution by zinc fcrrocyanide,and the effect of experimental conditions on the adsorption were investigated.Preliminary results showed that zinc ferrocyanide was very efficient as a...Adsorption of ^(134)Cs from aqueous solution by zinc fcrrocyanide,and the effect of experimental conditions on the adsorption were investigated.Preliminary results showed that zinc ferrocyanide was very efficient as an absorbent.Over 98% of ^(134)Cs could be removed by zinc ferrocyanide of 0.33 g·L^(-1) from ^(134)Cs solution (Co) of 3.2～160.0 kBq·L^(-1),with adsorption capacities (Q) of 9.6～463.0 kBq·g^(-1).The adsorption equilibrium time was within one hour and the suitable pH ranged 1～10.No significant differences on ^(134)Cs adsorption were observed at 0～50℃,or in solutions containing Ca^(2+),Fe^(3+),Mg^(2+),HCO_3^-,CO_3^(2-),Cl and SO_4^(2-),even though they are 1000 times higher than the anions or cations in groundwater.However,the adsorption rates decreased when solutions contained K^+ or Na^+.The adsorption process could be described by Frcundlich and Langmuir adsorption equations.展开更多
For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the...For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the zeroth-order hyperfine constants are evaluated with Dirac-Fock wave function. The finite basis sets of dirac equation are constructed by B-splines. With the finite basis sets the core polarization and the correlation diagrams are calculated. The hyperfine structure constants of the 5S1/2 and 6S<sub>1/2 states of 85Rb as well as the 6S1/2 and 7S<sub>1/2 states of 133Cs are evaluated.展开更多
The collision of alkali-metal atoms at ultralow temperatures have been studied, The Scattering lengths and the effective range are calculated for 7Li, 23Na, 39K, 87Rb, and 133Cs.
Due to its inert reaction in soil system and distinctive vertical distribution in soil profile, caesium-137 (137Cs) has been used as a tracer to assess wind erosion. In this study, 62 soil samples were collected from ...Due to its inert reaction in soil system and distinctive vertical distribution in soil profile, caesium-137 (137Cs) has been used as a tracer to assess wind erosion. In this study, 62 soil samples were collected from 4 sampling sites in Taipusi County, Inner Mongolia; Caesium-137 activities for those soil samples were measured using a gamma-ray spectrometry in Sichuan University, Chengdu. Distribution pattern of 137Cs in vertical soil profile was different for different land use and land cover types. Caesium-137 was distributed homogeneously in plow layer of cropland, and negatively exponential in low to medium cover grassland. Distribution pattern in high covered grassland was represented by a peak at 2-4 cm soil depth followed by a negative exponential curve. Based on those findings, simplified mass balance model was chosen to estimate the rate of wind erosion for cropland, while profile distribution model was used for grassland. Estimated wind erosion rates were 7990,4270 and 1808 Mg·km-2·a-1 for cropland, low cover grassland and medium cover grassland, respectively. Wind erosion intensity correlated negatively with plant cover.展开更多
Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and aband...Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km?2·a?1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm·a?1, and wind erosion rates up to 6723.06 t·km?2·a?1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not in- duce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.展开更多
The bacterium Thermus sp. TibetanG7, isolated from hot springs in Tibet, China, was examined for the ability to accumulate cesium from solutions. Environmental conditions were simulated and the effects of pH, K+, Na+ ...The bacterium Thermus sp. TibetanG7, isolated from hot springs in Tibet, China, was examined for the ability to accumulate cesium from solutions. Environmental conditions were simulated and the effects of pH, K+, Na+ and K+-regimes were then studied to determine the possible role of the bacterium in the formation of cesium-bearing geyserite around these hot springs. In despite of the inhibition of K+ and Na+, the bacterium Thermus sp. TibetanG7 revealed noticeable accumulation of cesium from solutions, with maximum accumulations of 53.49 and 40.41 μmol Cesium/g cell dry weight in Na+ and K+ inhibition experiments, respectively. The accumulation of cesium by this microorganism is rapid, with 40%―50% accumulated within the first 5 min. K+-deficient cells showed a much higher capacity of cesium accu- mulation compared with K+-sufficient cells. It is evident that the bacteria within the genus thermus play a significant role in the cesium assembly. The formation of cesium-bearing geyserite is also considered.展开更多
文摘Adsorption of ^(134)Cs from aqueous solution by zinc fcrrocyanide,and the effect of experimental conditions on the adsorption were investigated.Preliminary results showed that zinc ferrocyanide was very efficient as an absorbent.Over 98% of ^(134)Cs could be removed by zinc ferrocyanide of 0.33 g·L^(-1) from ^(134)Cs solution (Co) of 3.2～160.0 kBq·L^(-1),with adsorption capacities (Q) of 9.6～463.0 kBq·g^(-1).The adsorption equilibrium time was within one hour and the suitable pH ranged 1～10.No significant differences on ^(134)Cs adsorption were observed at 0～50℃,or in solutions containing Ca^(2+),Fe^(3+),Mg^(2+),HCO_3^-,CO_3^(2-),Cl and SO_4^(2-),even though they are 1000 times higher than the anions or cations in groundwater.However,the adsorption rates decreased when solutions contained K^+ or Na^+.The adsorption process could be described by Frcundlich and Langmuir adsorption equations.
文摘For heavy atoms or ions, such as, Rb and Cs et al., relativistic effect must be considered in the calculation. In this paper, the relativistic many-body perturbation theory is used to solve the Dirac equation. And the zeroth-order hyperfine constants are evaluated with Dirac-Fock wave function. The finite basis sets of dirac equation are constructed by B-splines. With the finite basis sets the core polarization and the correlation diagrams are calculated. The hyperfine structure constants of the 5S1/2 and 6S<sub>1/2 states of 85Rb as well as the 6S1/2 and 7S<sub>1/2 states of 133Cs are evaluated.
文摘The collision of alkali-metal atoms at ultralow temperatures have been studied, The Scattering lengths and the effective range are calculated for 7Li, 23Na, 39K, 87Rb, and 133Cs.
基金the Chinese National Key Basic Research Promotion Program(Grant No.2002CB412500) the Chinese Acad-emy of Sciences Knowledge Innovation Project(Grant No.KZCX-2-308).
文摘Due to its inert reaction in soil system and distinctive vertical distribution in soil profile, caesium-137 (137Cs) has been used as a tracer to assess wind erosion. In this study, 62 soil samples were collected from 4 sampling sites in Taipusi County, Inner Mongolia; Caesium-137 activities for those soil samples were measured using a gamma-ray spectrometry in Sichuan University, Chengdu. Distribution pattern of 137Cs in vertical soil profile was different for different land use and land cover types. Caesium-137 was distributed homogeneously in plow layer of cropland, and negatively exponential in low to medium cover grassland. Distribution pattern in high covered grassland was represented by a peak at 2-4 cm soil depth followed by a negative exponential curve. Based on those findings, simplified mass balance model was chosen to estimate the rate of wind erosion for cropland, while profile distribution model was used for grassland. Estimated wind erosion rates were 7990,4270 and 1808 Mg·km-2·a-1 for cropland, low cover grassland and medium cover grassland, respectively. Wind erosion intensity correlated negatively with plant cover.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40571130 and 40701150)the Key Project of International Cooperation, CAS (Grant No. GJHZ06)+3 种基金the Scientific Database of CAS (Grant No. INF105-SDB-A3)the Director Foundation of Institute of Geographic Sciences and Resources Research, CAS (Grant Nos. 06W60000SZ and 06W60001SZ)the Open Foundation of Key Laboratory of Water Cycle & Related Land Surface Processes, CAS (Grant No. WL2005001)the Key Project of Natural Science Foundation of Inner Mongolia of China (Grant Nos. 200608010602)
文摘Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km?2·a?1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm·a?1, and wind erosion rates up to 6723.06 t·km?2·a?1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not in- duce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.
基金the China Geological Survey (contract No. 200313000065) the State Plan for Development of Basic Research in Key Areas (contract No. 2002CG412610)
文摘The bacterium Thermus sp. TibetanG7, isolated from hot springs in Tibet, China, was examined for the ability to accumulate cesium from solutions. Environmental conditions were simulated and the effects of pH, K+, Na+ and K+-regimes were then studied to determine the possible role of the bacterium in the formation of cesium-bearing geyserite around these hot springs. In despite of the inhibition of K+ and Na+, the bacterium Thermus sp. TibetanG7 revealed noticeable accumulation of cesium from solutions, with maximum accumulations of 53.49 and 40.41 μmol Cesium/g cell dry weight in Na+ and K+ inhibition experiments, respectively. The accumulation of cesium by this microorganism is rapid, with 40%―50% accumulated within the first 5 min. K+-deficient cells showed a much higher capacity of cesium accu- mulation compared with K+-sufficient cells. It is evident that the bacteria within the genus thermus play a significant role in the cesium assembly. The formation of cesium-bearing geyserite is also considered.
