% IMPORTANT: The following is UTF-8 encoded. This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.
@PHDTHESIS{Banning:52248,
author = {Banning, Andre},
othercontributors = {Rüde, Thomas R.},
title = {{N}atural arsenic and uranium accumulation and
remobilization in different geological environments},
address = {Aachen},
publisher = {Publikationsserver der RWTH Aachen University},
reportid = {RWTH-CONV-114485},
pages = {175 S. Ill., graph. Darst., Kt.},
year = {2012},
note = {Zsfassung in dt. und engl. Sprache; Aachen, Techn.
Hochsch., Diss., 2012},
abstract = {Despite the fact that both As and U represent geogenic
trace elements potentially toxic to humans, little
information is available on the development of their
enrichments in German sediments and their potential impact
on groundwater quality, let alone a systematic overview of
the country´s natural occurrences. This work aims at
characterizing accumulation processes in aquifers actually
or potentially affected by elevated concentrations of As
and/or U, and their timings in geological history. The five
selected study areas provide different geological and
stratigraphical backgrounds. Identification of As and U
sources, and structural derivation of their environmental
reservoirs as well as remobilization mechanisms potentially
resulting in trace element release to groundwater were
assessed. Drinking water supply in Franconia/Northern
Bavaria is dependent on groundwater extraction from
terrestrial Upper Triassic sandstones where elevated
concentrations of geogenic U and As exceeding German
drinking water limitations were identified. Characterization
of aquifer material in terms of geochemical and
mineralogical composition, trace elements distribution on a
microscale and their mineralogical fractionation and
mobilization behaviour showed that uraniferous
francolite/hematite inclusions within the aquifer sandstones
(“active arkoses”) represent important sources for U and
As in the study area. Francolite exhibits biologically,
structurally and radiation-enhanced solubility; loss of both
U and As during weathering was documented. Jurassic shallow
marine Fe ores from the Upper Rhine Graben exhibit
significant bulk As hosted in mainly goethite ooids slowly
formed in times of condensed sedimentation. The study
indicates that As accumulation was favoured over other
potential contaminants, esp. heavy metals. Conditions for As
accumulation varied during deposition, visible on a macro-
(outcrop) as well as on a microscale (single Fe ooid).
However, the risk of As release to groundwater of the region
is considered rather insignificant. An oxidative terrestrial
paleo redox process during the late Tertiary affected
Santonian shallow marine sands in the western Münsterland
Cretaceous Basin, resulting in a distinct sediment colour
and geochemical boundary in several decametres below ground
surface, and massive element redistribution. Arsenic resides
in pyrite in the reduced section. Its behaviour changes from
homogenous sulfide-control in the unaltered sediments to
very heterogeneous Fe hydroxide-control above the paleo
redox boundary. Early stages of hydroxidic Fe/As
accumulations resulting from mobilization from the reduced
sediments represent precursors of high-As goethite
concretions, widespread in the near-surface oxidized facies.
Widespread Oligocene marine sandy sediments from the Lower
Rhine Embayment exhibit features of a paleo redox event:
primary Fe(II) phases in a reduced facies, hydroxidic Fe
mineralogy and significant major and trace element
redistribution in near-surface sediments. Striking
similarities to the postdepositional redox history of the
Cretaceous sediments became obvious, also in terms of As
control. Preferential As enrichment over heavy metals in Fe
hydroxide concretions was detected. Uranium is rather
homogeneously distributed in low concentrations in both
redox facies and little affected by the redox event. The
reduced deeper sediments are the more probable candidates
for creating elevated As in groundwater. Uranium and As in
deep groundwater of the volcano-sedimentary basin around San
Luis Potosí/north-central Mexico partly exceed drinking
water guidelines and thus endanger the most important
drinking water source in the area. The As/U hydrogeochemical
signatures, their behaviour during rock alteration and
evidence from proxies like REE strongly argue for acid
volcanic glass dissolution as the dominating process of U
and As release to groundwater. The hydrogeochemical
fingerprint is modified by additional mobilization from the
sedimentary basin filling. Common behaviour of both
incompatible elements during magmatic differentiation and
growing drift-apart in sedimentary systems are discussed.
Besides the importance of the obtained results for the
studied regions, geochemical comparison of all study areas
offers additional explanations for the large-scale As and U
distribution in Germany. While Pleistocene geology explains
their absence in sediments and related groundwater in
northern Germany, their distribution in the central and
southern parts is controlled by provenance geochemistry.
Only highly felsic origin (Moldanubian Variscides) enables
creation of elevated U in the systems while Rhenohercynian
provenance allows for As presence only. Subsequent
intrabasinal redistribution contributes to the present-day
situation.},
keywords = {Arsen (SWD) / Uran (SWD) / Urananreicherung (SWD) /
Grundwasser (SWD) / Anreicherung (SWD) / Spurenelement (SWD)
/ Mobilisation <Bodenchemie> (SWD)},
cin = {532220 / 530000},
ddc = {550},
cid = {$I:(DE-82)532220_20140620$ / $I:(DE-82)530000_20140620$},
typ = {PUB:(DE-HGF)11},
urn = {urn:nbn:de:hbz:82-opus-39932},
url = {https://publications.rwth-aachen.de/record/52248},
}
guest ::