| Vol. 12 (1996) | |||
- Geogene Arsenkonzentrationen in Keupergrundwässern
Frankens/Bayern.
[Natural Arsenic Concentrations in Groundwaters of the Frankonian Keuper/Bavaria (Germany)]
Heinrichs, Gerold (1996), 193 p., 70 Fig., 30 Tab.
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Abstract
Geogene Arsenkonzentrationen in Keupergrundwässern Frankens/Bayern.
[Natural Arsenic Concentrations in Groundwaters of the Frankonian Keuper/Bavaria
(Germany)]
Gerold Heinrichs
Abstract: In Franken/Bavaria, groundwater with natural arsenic concentrations
from the Keuper sedimentary formation is used for drinking water. Detailed
sampling of these arsenic groundwaters shows elevated arsenic concentrations
in certain geographic areas apparently related to the geology and stratigraphy
of the aquifers. Using water-chemical data in combination with geochemical
investigations of drill cuttings from five wells, increased sedimentary
arsenic concentrations in certain layers of Keuper were found, being suspect
to increased arsenic concentrations of the groundwater. The arsenic containing
rocks are compact sediments of terrestrial to fluvial-marine depositional
environments in the border facies of the Frankonian Keuper. Source area
is most likely the crystalline continental basement of the Bohemian mass
in the southeast of the research area. In corresponding marine sediments
of the Frankonian Keuper basin facies elevated arsenic concentrations
in sediments and groundwaters are lacking. A correlation of tectonic elements
and increased arsenic concentrations is prevalent in samples taken north
of Nürnberg. Reasons for increased arsenic concentrations are regionally
defined. To the south and southeast of Erlangen sedimentary arsenic dissolves
into the groundwater. Arsenic occurs here within minor sulphide minerals
in the clayey-silty layers (confining layers) between the Keuper and predominantly
at the top (Feuerletten, Rhätholias). Oxygen enriched ground water from
near surface aquifers may intensify the solution of sulfides by oxidation.
Local occurrence of hydroxic arsenic compounds of higher mobility within
the coarse-grained aquifer are the most likely reason for increased arsenic
in groundwaters to the west and south west of the research area. Besides
regional sedimentary arsenic, tectonic influences may also be effective
at certain areas north of Nürnberg. From the river Pegnitz up to Bamberg,
increased arsenic concentrations were locally measured within ground waters.
Here, an intermixture of higher mineralized, arsenic containing deep ground
waters from the Buntsandstein or solutions originating from joint fillings,
previously mineralized, is the most likely source.
Paper language: german; german
abstract
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