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@PHDTHESIS{Boester:843757,
author = {Boester, Uwe},
othercontributors = {Rüde, Thomas R. and Schwarzbauer, Jan},
title = {{G}adolinium als {U}mwelttracer anthropogenen {E}influsses
auf {G}rundwasser :
{O}berflächengewässer-{G}rundwasser-{I}nteraktion},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2022-03378},
pages = {1 Online-Ressource : Illustrationen},
year = {2022},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2022},
abstract = {Gadolinium (Gd) is an element of the rare earth element
(REE) group. It has been used as an environmental tracer in
surface waters since 1996. The method is based on the
determination of the enrichment of Gd in the environment
compared to geological background values. Gd represents a
group of contrast agents in magnetic resonance imaging
(MRI), which have been emitted into surface waters since the
1980s. Consequently, an anthropogenic enrichment relates to
the patients excreting these contrast agents shortly after
ambulant medication in hospitals or at home. Sewage
treatment is currently unable to hold back Gd from this
anthropogenic source. Therefore, the Gd concentration in the
receiving channel increases significantly, and it does not
only influence surface water but propagates into adjacent
groundwater bodies due to its conservative behavior in the
environment.As this research focuses on surface water and
porous aquifers, however, the anthropogenic Gd-anomaly is a
very stable environmental tracer. The investigation of three
study sites, which represent a high groundwater velocity and
high Gd-concentration case in karst “Mittelstreu” (125
to ca. 3000 m/d), a mid-case “Eisch” and a case with
lower groundwater velocities and lower Gd-concentrations in
a sandstone aquifer “Brombachsee” (50 m/a). These
investigations aim to prove that Gd is a suitable
environmental tracer for different usages in solid rock
aquifers as well. The karst aquifer study site displays a
connection between a river/ponor (input) and three springs
(output), which show a Gd anomaly. The sampling of springs
and brooks in the vicinity of the karst proved the Gd’s
anthropogenic origin. Another study site is situated at the
river Eisch in Luxembourg. In this location, the
anthropogenic Gd-anomaly in the river is used to determine
groundwater dilution of the anthropogenic Gd-Signal in the
river over some distance and a groundwater influx diluting
the river’s Gd-Signal. The third investigation site shows
a different situation. In this case, the anthropogenic
Gd-anomaly in the sandstone aquifer originates in a
freshwater reservoir filled with river water, leading to the
infiltration of the river water’s Gd-signature into the
aquifer. The karst and the sandstone aquifer investigation
sites display surface water-groundwater interaction and
highlight the environmental tracer capabilities of Gd.To
quantify the anthropogenic part of the Gd-Signal, natural Gd
backgrounds were calculated statistically for each
investigation site and at the karst site for surface water
and groundwater as well as different aquifer lithologies.
The differences between the lithologies and the water types
regarding natural Gd-concentrations is the result of a water
sampling campaign in the catchment of the springs.
Furthermore, two time series were taken at the ponor and the
springs, one in summer and one in winter. As a result, the
weekly anthropogenic Gd-Signal in surface water and spring
water produced Gd-peaks that are correlated between the
ponor and the springs. The flux and mass evaluations enable
to calculate a distance velocity (2,500 m/d) between the
ponor and the springs as well as the surface water share in
the spring water (winter: $5\%;$ summer: 20 $\%).$ Moreover,
the anthropogenic emissions stay the same during the year as
the mass-sum is the same in both sampling periods (summer
and winter). At the “Brombachsee”, the anthropogenic Gd
input reaches the lake in pulses, as the lake system
receives only water if the river “Altmühl” experiences
flooding. However, the Gd-Signal reaches the northern lake
shore and infiltrates the sandstone aquifer (“Mittlerer
Burgsandstein” (kmBm)). This signal is traceable over one
kilometer into the aquifer at its widest distance to the
lake shore. Furthermore, the surface area and hot spots of
the infiltration are mapped. In addition to Gd, both sites
experienced concentration measurements of five other
anthropogenic, organic environmental tracers. Of these, just
acesulfame could be correlated to Gd at the
“Mittelstreu” without quantification. In the
“Brombachsee” area, acesulfame just proves the input
path but does not have the environmental stability to reach
out into the sandstone aquifer.Finally, Gd represents a
conservative, anthropogenic, environmental tracer, that is
not interacting with its surroundings and, therefore, stays
stable over long periods (20 years, “Brombachsee”). It
is measured directly out of the sample and the Gd-anomaly is
much higher in the surface waters (2-25 times) so that it
can be measured even with high dilution in groundwater. All
of this taken into account, Gd is a powerful environmental
tracer for surface water - groundwater interaction in solid
rock aquifers, even over decades.},
cin = {532220 / 530000},
ddc = {550},
cid = {$I:(DE-82)532220_20140620$ / $I:(DE-82)530000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2022-03378},
url = {https://publications.rwth-aachen.de/record/843757},
}
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