New insights into U(VI) sorption onto montmorillonite from batch sorption and spectroscopic studies at increased ionic strength.

The influence of ionic strength up to 3 mol kg-1 (background electrolytes NaCl or CaCl2) on U(VI) sorption onto montmorillonite was investigated as function of pHc in absence and presence of CO2. A multi-method approach combined batch sorption experiments with spectroscopic methods (time-resolved laser-induced fluorescence spectroscopy (TRLFS) and in situ attenuated total reflection Fourier-transform infrared spectroscopy (ATR FT-IR)). In the absence of atmospheric carbonate, U(VI) sorption was nearly 99% above pHc 6 in both NaCl and CaCl2 and no significant effect of ionic strength was found. At lower pH, cation exchange was strongly reduced with increasing ionic strength. In the presence of carbonate, U(VI) sorption was reduced above pHc 7.5 in NaCl and pHc 6 in CaCl2 system due to formation of aqueous UO2(CO3)x(2-2x) and Ca2UO2(CO3)3 complexes, respectively, as verified by TRLFS. A significant ionic strength effect was observed due to the formation of Ca2UO2(CO3)3(aq), which strongly decreases U(VI) sorption with increasing ionic strength. The joint analysis of determined sorption data together with literature data (giving a total of 213 experimental data points) allowed to derive a consistent set of surface complexation reactions and constants based on the 2SPNE SC/CE approach, yielding log K°≡SSOUO2+ = 2.42 ± 0.04, log K°≡SSOUO2OH = -4.49 ± 0.7, and log K°≡SSOUO2(OH)32- = -20.5 ± 0.4. Ternary uranyl carbonate surface complexes were not required to describe the data. With this reduced set of surface complexes, an improved robust sorption model was obtained covering a broad variety of geochemical settings over wide ranges of ionic strengths and groundwater compositions, which subsequently was validated by an independent original dataset. This model improves the understanding of U(VI) retention by clay minerals and enables now predictive modeling of U(VI) sorption processes in complex clay rich natural environments.

[Everyday life and solidarity in north-east German rural communities - first qualitative results of the Rural Health Study]. / Alltägliche Lebensführung und Solidarität in nordostdeutschen Landgemeinden - Erste qualitative Ergebnisse der Landgesundheitsstudie.

There have been increasing discussions in the health sciences in recent years about socio-spatial influences on health activities. The starting point has been the growing territorial inequality in spatial development resources, which has an effect on the participatory chances of people in structurally weak regions. The concept of "peripherisation" is used to describe this change. Empirical investigations of socio-spatial resources at the local level are rare, because the theoretical preconditions have not been elaborated sufficiently for the theoretical modelling to be recognised for hypothesis-based empirical investigations. At the centre of this theorisation are analyses of the "social capital" of every-day actions. As part of the Rural Health Study 2008 at the University of Applied Science Neubrandenburg (involving a longitudinal analysis with quantitative surveys in 14 rural communities in north-eastern Germany 1973, 1994, 2008), a qualitative approach was also adopted with case and community studies. The first results are compared with the state of the literature. Case studies are presented showing strategies for adaptation and improvement of the individual's situation, and also the daily solidarity of people in villages. Development potentials are outlined.