Authors:Zsuzsanna Szabó, Nóra Edit Gál, Éva Kun, Teodóra Szőcs and György Falus
In worst-case leakage scenarios of CO2 geological storage, CO2 or brine may contaminate shallower drinking water aquifers. This work applies an advanced geochemical modeling methodology to predict and understand the effects of the aforementioned contamination scenarios. Several possibilities, such as equilibrium batch, kinetic batch, and 1D kinetic reactive transport simulations, were tested. These have all been implemented in the widely applied PHREEQC code. The production of figures and animations has been automated by R programming. The different modeling levels provide complementary information to each other. Both scenarios (CO2 or brine leakage) indicate the increase of ion concentrations in the freshwater, which might exceed drinking water limit values. The dissolution of CO2 changes the pH and induces mineral dissolution and precipitation in the aquifer and therefore changes in solution composition. Brine replacement of freshwater due to the pressure increase in the geological system induces mineral reactions as well.
Humic acids (HA) can influence the speciation of metal ions, e.g., actinide ions, and thus their migration in the environment.
Therefore, knowledge of the impact of HA on the actinide migration is required to assess their transport in natural systems.
However, due to the complex and heterogeneous nature of HA, there are a lot of difficulties in the thermodynamic description
of their geochemical interaction behavior. A more basic understanding of the interaction processes of HA can be obtained by
investigations applying HA model substances with more specific and tailored properties. This work gives a review of selected
types of HA model substances (HA-alike melanoidins, synthetic HA with pronounced redox functionality, modified HA with blocked
phenolic/acidic OH groups, synthetic humic substance-clay-associates), their synthesis, isotopic labeling, and characterization
in comparison to isolated natural HA. Examples for their application in various geochemical studies, such as complexation,
redox, sorption and migration studies with uranium as representative for actinides are presented.
Authors:Y. Sakai, K. Ohshita, S. Koshimizu and K. Tomura
By preconcentrational neutron activation analysis, trace vanadium was determined in natural water samples such as ground water, river water, lake water and so on. Preconcentration was accomplished by adsorption of vanadium on activated carbon surfaces using 8-quinolinol as an adjunct. As an analytical line, the 1434 keV -photopeak of52V (T1/2=3.75 m) produced in the51V (n,)52V reaction was measured with a conventional -ray spectrometer. The present analytical results show that the vanadium contents in natural water range widely from several tens ppt to about 100 ppb. A relatively larger amount of vanadium was observed in the ground water samples from the locations with basaltic soils or rocks, for example, around Mt. Fuji. This suggests that the geochemical interactions of ground water with such soils or rocks could enhance the vanadium concentrations. As an application, the vanadium contents were measured in the lake water from the five lakes surrounding Mt. Fuji in order to clarity geochemical and geological behaviors of natural water by probing vanadium as an indicator.