Uranium and arsenic in some aquifers from Mexico and Germany

Two sedimentary basins of Triassic (southern Germany) and Cenozoic (San Luis Potosí, Mexico) age, both affected by elevated As and U concentrations in groundwater (first published for San Luis Potosí in this study), are characterized concerning geogenic sources and distribution of these trace elements. The Mexican basin filling (granular upper aquifer) derives from ongoing weathering of surrounding rhyolites (fractured deeper aquifer). These volcanics are enriched in As and U, yielding a positive correlation with each other, and are therefore identified as primary source rocks. Remobilization from the labile glassy matrix leads to output into groundwater. In the German basin, carbonate flour apatites in “active arkoses”, derived from Triassic weathering of mainly felsic magmatic rocks, are a sink and potential source of both U and As. Besides similar geological situations, both basin fillings were deposited under semiarid, partly playa-like conditions, allowing for an actuogeological comparison to understand trace element dynamics. © 2010 Taylor %26 Francis Group, London.

VIVO