[en] The sorption of cesium onto γ-Al₂O₃ was studied by using batch technique and ultra-filtration method at room temperature, at pH 4.0, 6.0 and 8.0 and ionic strength ranged from 0.001M to 0.1M NaClO₄. The pore size of the filter 1000K was used to separate the liquid from the solid phase. UV vis spectrophotometer was used to determine the concentration of humic acid in the solution at wavelength of 254 nm. The sorption of humic acid and Cs on the γ-Al₂O₃ was studied in the pH range from 2 to 12. The sorption of humic acid on the γ-Al₂O₃ was strong (∼98% HA was sorbed on the surface of γ-Al₂O₃ below pH 9) and strongly depended on the pH values (above pH_zpc the sorption of HA decreased markedly with the increasing of pH), humic acid has a little negative effect on the sorption of cesium. This may be attributed to the formation of HA-Cs complexation in the solution. The sorption of Cs onto γ-Al₂O₃ was weak depending on the pH and independent on the ionic strength. The sorption of Cs onto γ-Al₂O₃ may be contributed to cation exchange and surface complexation mechanism. (author)

[en] The distribution coefficients of 47 elements from Na to Bi on untreated calcareous soil, treated soil to remove CaCO₃ and treated soil to remove both CaCO₃ and organic matter, respectively, were determined by using a multitracer technique. The variation of the distribution coefficients of 47 elements was explained in terms of chemical bond formation and hydration. The effect of different solid components of the calcareous soil on the adsorption was investigated. (author)

[en] The effect of pH and fulvic acid on the sorption of Sr on bentonite was investigated by using batch experiments. The sorption and desorption isotherms of Sr on bentonite were determined at room temperature, at pH 6.0±0.2 and in presence of 0.1M NaCl. It was found that the sorption of Sr is independent at pH<8, and then increases slightly with increasing pH. Fulvic acid increases the sorption of Sr significantly on bentonite at low pH, but decreases the sorption of Sr at pH>8. The sorption of Sr on bentonite can be described by a reversible sorption process and the sorption mechanism consists mainly of ion exchange. (author)

[en] The migration of radionuclides ⁸⁵⁺⁸⁹Sr²⁺, ¹³⁴Cs⁺, ¹²⁵I^- and ⁷⁵SeO₃^2- in calcareous soil from Yuzhong county of Gansu Province (China) at pH 7.8±0.2 and ^152+154Eu(III) in red earth from Yingtan county of Jiangxi Province (China) at pH 4.6±0.2, in presence of CaCl₂ was studied using column experiments. Results indicate that the negative anions, iodide and selenide are mobile nuclides while the migration of positive cations is related to the sorption capacity for the element. Iodide can be assumed to be non-reactive in calcareous soil. The breakthrough curves (BTCs) were fitted to the analytical solution or numerical solution of one-dimensional convection-dispersion transport models. Good agreements were obtained between the measured and predicted concentration profiles. (author)

[en] The effect of various solid soil components on the retention of Cs was investigated by using batch technique and selective extraction method. The sorption and desorption isotherms of Cs on the untreated, calcareous soil and the three treated soils were determined at 20 deg C, pH 7.8 ± 0.2 and in the presence of 0.001 M CaCl₂. It was found that all isotherms are nonlinear, and that the sorption-desorption hysteresis on the calcareous soil actually occurs on the same time scale. (author)

[en] Objective: To investigate the incidence of HGV infection in patients with HBV hepatitis and any possible adverse effect of the superinfection. Methods: Serum HGV-RNA expression was examined with PCR in 1104 patients with HBV hepatitis and 251 controls. Results: The positive rate of HGV-RNA in HBV hepatitis patients was not significantly different from that in controls (3.17% vs 2.79%, P>0.05). Among the patients with HBV hepatitis, HGV-RNA positive rate in patients with chronic hepatitis was significantly higher than that in patients with acute hepatitis (4.78% vs 0.96, P<0.05). Conclusion: HGV infection might be presented as non-symptomatic carriers or other mild form of hepatitis. The incidence of HGV infection was not especially high in HBV hepatitis patients, however, concomitant HGV and HBV infection might predispose to development of chronicity. (authors)

[en] The fate and transport of toxic metal ions and radionuclides in the environment is generally controlled by sorption reactions. The extent of sorption of divalent metal cations is controlled by a number of factors including cosorbing or complexing. In this work, the effects of pH, humic acid HA/Co(II) addition orders, ionic strength, concentration of HA, and foreign cations on the Co(II) sorption on γ-Al₂O₃ in the presence of HA were investigated. The sorption isotherms of Co(II) on γ-Al₂O₃ in the absence and presence HA were also studied and described by using S-type sorption model. The experimental results showed that the Co(II) sorption is strongly dependent on the pH values, concentration of HA, but independent of HA/Co(II) addition orders, ionic strength, and foreign cations in the presence of HA under our experimental conditions. The results also indicated that HA enhanced the Co(II) sorption at low pH, but reduced the Co(II) sorption at high pH. It was hypothesized that the significantly positive influence of HA at low pH on the Co(II) sorption on γ-Al₂O₃ was attributed to strong surface binding of HA on γ-Al₂O₃ and subsequently the formation of ternary surface complexes such as ≡S-OOC-R-(COO^-)_xCo^2-x. Chemi-complexation may be the main mechanism of the Co(II) sorption on γ-Al₂O₃ in the presence of HA. (author)

[en] The effects of pH, ionic strength, competing ions and initial metal concentrations on the uptake behavior and mechanism of radioactive Ni(II) onto MnO₂ was investigated using a combination of classical macroscopic methods and the extended X-ray absorption fine structure (EXAFS) spectroscopy technique. The results indicated that the uptake of Ni(II) on MnO₂ is obviously dependent on pH but independent of ionic strength, which suggested that the uptake of Ni(II) onto MnO₂ is attributed to an inner-sphere surface complex rather than an outer-sphere surface complex. EXAFS analysis shows that the hydrated Ni(II) is adsorbed through six-fold coordination with an average Ni-O interatomic distance of 2.04 ± 0.01 A. It can be inferred from the EXAFS analysis that the inner-sphere surface complex of Ni(II) onto MnO₂ is involved in both edge-sharing and corner-sharing linkages. Both the macroscopic uptake data and the molecular level evidence of Ni(II) surface speciation at the MnO₂-water interfaces should be factored into better prediction of the bioavailability and mobility of Ni(II) in soil and water environment. (author)

[en] The distribution coefficient of Eu(III) derived from batch experiments is used to predict the migration of Eu(III) in compacted bentonite with time. The effect of the dispersion coefficient and the pore water velocity on the migration of Eu(III) are also taken into account. It was found that the dispersion coefficient does not influence the migration, while the variation of the distribution coefficient and the water velocity affected the behavior of Eu(III) in compacted bentonite. Most of the europium is retained in the first several meters. So, 30 m of backfill bentonite may be sufficient to prevent the release of Eu(III) to the environment. (author)

[en] The effects of pH, ionic strength and FA (fulvic acid) on the sorption and desorption of Eu(III) and Yb(III) on alumina were respectively investigated by using batch technique and radiotracers ^152+154Eu and ¹⁶⁹Yb. The distribution coefficients for sorption and desorption of Eu on alumina at pH 4.4, 4.6 and 5.7 in 1 mol/l NaCl solutions as a function of solid phase concentration were determined in the presence or absence of FA. The effects of pH, FA and ionic strength on the distribution coefficients for sorption and desorption of Yb on alumina were determined in 0.01–2.0 mol/l NaNO₃. It was found that pH and FA influenced the sorption of Eu(III) and Yb(III) on alumina greatly. A surface hydrolysis model can satisfactorily and qualitatively explain the observations on bare alumina. The competition among the complexations of surface free hydroxyl groups, soluble and sorbed fulvic acids can satisfactorily and qualitatively explain the observations on the coated alumina.