TY  - JOUR
A1  - Wilke, Franziska Daniela Helena
A1  - Schettler, Georg
A1  - Vieth-Hillebrand, Andrea
A1  - Kühn, Michael
A1  - Rothe, Heike
T1  - Activity concentrations of U-238 and Ra-226 in two European black shales and their experimentally-derived leachates
JF  - Journal of Environmental Radioactivity
N2  - We performed leaching tests at elevated temperatures and pressures with an Alum black shale from Bomholm, Denmark and a Posidonia black shale from Lower Saxony, Germany. The Alum shale is a carbonate free black shale with pyrite and barite, containing 74.4 mu g/g U. The Posidonia shales is a calcareous shale with pyrite but without detectable amounts of barite containing 3.6 mu g/g U. Pyrite oxidized during the tests forming sulfuric acid which lowered the pH on values between 2 and 3 of the extraction fluid from the Alum shale favoring a release of U from the Alum shale to the fluid during the short-term and in the beginning of the long-term experiments. The activity concentration of U-238 is as high as 23.9 mBq/ml in the fluid for those experiments. The release of U and Th into the fluid is almost independent of pressure. The amount of uranium in the European shales is similar to that of the Marcellus Shale in the United States but the daughter product of U-238, the Ra-226 activity concentrations in the experimentally derived leachates from the European shales are quite low in comparison to that found in industrially derived flowback fluids from the Marcellus shale. This difference could mainly be due to missing Cl in the reaction fluid used in our experiments and a lower fluid to solid ratio in the industrial plays than in the experiments due to subsequent fracking and minute cracks from which Ra can easily be released.
KW  - Unconventional gas production
KW  - Black shales
KW  - Flowback
KW  - Radioactivity
KW  - NOR
KW  - Batch experiments
Y1  - 2018
U6  - https://doi.org/10.1016/j.jenvrad.2018.05.005
SN  - 0265-931X
SN  - 1879-1700
VL  - 190
SP  - 122
EP  - 129
PB  - Elsevier
CY  - Oxford
ER  -