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@PHDTHESIS{Niedre:845759,
author = {Niedrée, Bastian},
title = {{E}ffects of $^{137}${C}s and $^{90}${S}r on structure and
functional aspects of the microflora in agricultural used
soils},
volume = {162},
school = {Universität Bonn},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2018-02968},
isbn = {978-3-89336-843-3},
series = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
Umwelt / Energy $\&$ Environment},
pages = {92 S.},
year = {2013},
note = {Dissertation, Universität Bonn, 2012},
abstract = {At long sight $^{137}$Cs and $^{90}$Sr are the main
radionuclides responsible for the contamination
ofagricultural soils due to core melts in nuclear power
plants such as Chernobyl or Fukushima.Once deposited on the
soil surface, the two radionuclides remain in the upper soil
layer forseveral decades. In the upper soil layer the
highest microbial activity can be found, due tohigh organic
matter contents, warm temperatures and gas exchange with the
atmosphere.Hence, in contaminated soils microorganisms in
upper soil layers (e.g. the plow layer onagricultural
fields) are exceedingly exposed to radioactivity. However,
no data are availablehow radioactive contaminations with
$^{137}$Cs or $^{90}$Sr in a realistic order of magnitude
affect themicrobial community and its functions in soils.
This dissertation discusses the effects of radioactive
contaminations on the microbial community structure and some
of its functions in soils. Therefore, typical agricultural
soils, an Orthic Luvisol from field site Merzenhausen and a
$\textit{Gleyic Cambisol}$ from field site
Kaldenkirchen-Hülst were artificially contaminated with
various concentrations of $^{137}$Cs and $^{90}$Sr and
partly applied with radiolabeled substrates and incubated in
soil microcosms under controlled laboratory conditions. The
lower radionuclide concentrations corresponded to the
contaminations in the Chernobyl exclusion zone, the higher
concentrations were up to 50-fold that of the maximum
occurring hotspots ($^{137}$Cs) in this zone. In three
experiments the effects of the ionizing radiation on the
bacterial and the fungal community structure (16S and 18S
rDNA DGGE), the degradation of $^{14}$C-labeled wheat straw
or uniformly ring-labeled 2,4- dichlorophenoxyacetic acid,
the development of the fungal biomass (ergosterol
quantification) and the chemical composition of the soil
organic matter ($^{13}$C CP/MAS NMR) were investigated. In
half of the microcosms the soils were autoclaved and
reinoculated with native soil, with intention to enhance the
microbial growth. Radiation induced shifts in the microbial
community structure could be observed in all experiments.
Some species were directly inhibited which could be seen by
a loss of bands in the DGGE gels. Other species benefited
from the radiation. The loss of competitors and thus a
better nutrient supply are supposed to cause these effects.
However, a radiation induced impact on microbial functions
could only be seen in the 2,4-D mineralization experiment.
The mineralization of the uniformly $^{14}$C-ring-labeled
herbicide 2,4-D was delayed for 4 days. Compared to the
mineralization of wheat straw, only a limited amount of
different species [...]},
keywords = {Ackerboden (gnd) / Mikroflora (gnd) / Cäsium-137 (gnd) /
Strontium-90 (gnd)},
cin = {IBG-3},
ddc = {500},
cid = {I:(DE-Juel1)IBG-3-20101118},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/845759},
}