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| Titel |
Assessing soil erosion at landscape level: A step forward in the up-scaling of 137Cs measurements through the use of in-situ lanthanum bromide scintillator |
| VerfasserIn |
Basil C. Gonsalves, Iain G. Darby, Arsenio Toloza, Lionel Mabit, Ralf B Kaiser, Gerd Dercon |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087938
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| Publikation (Nr.) |
 EGU/EGU2014-1996.pdf |
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| Zusammenfassung |
| Measuring Fallout Radionuclides (FRN), in particular 137Cs, is a well-established method to
estimate soil erosion and deposition in agricultural landscapes. While extremely sensitive,
laboratory based gamma-ray spectrometry requires careful handling and preparation of
measurement samples with a lengthy measuring time (~1 day), In-situ gamma-ray
spectrometry can give near instantaneous results, allowing prompt decisions to be made
and identification of critical spots of soil erosion, while the equipment is in the
field.
The aim of this investigation was to compare the precision of the in-situ FRN
measurements, made by a cost-effective lanthanum bromide (LaBr3 (Ce)) scintillation
detector of 137Cs against those from conventional (high-purity germanium HPGe
detector) but laborious laboratory based gamma-ray spectrometry for assessing soil
erosion.
As preliminary test, five cores of a gleyic Cambisol - per increments of 5 cm until 1 m
depth - were collected at the experimental research station of the Austrian Agency
for Health and Food Safety located in Grabenegg 130 km west of Vienna. Three
soil cores were sampled at the study site and, in the vicinity of this experimental
site, two additional cores were collected at two different undisturbed reference
sites.
Laboratory gamma analyses were carried out during 50 000 seconds using a HPGe
coaxial detector. The gamma measurements performed at the laboratory confirmed the
undisturbed status of the two selected reference sites (i.e. exponential decrease with depth of
the 137Cs content). Using the surface area of the sampling tool, the 137Cs areal activities of
the cores sampled in the study site have been established at 2134±465 Bq m-2, 1835±356
Bq m-2 and 2553±340 Bq m-2, and, for the two reference sites at 3221±444 Bq m-2 and
3946±527 Bq m-2.
At the same location and prior to collect the five soil cores, in-situ measurements using a
lanthanum bromide (LaBr3 (Ce)) scintillator were performed. The detector was
placed at 2 cm above ground and each measurement was conducted for 900 seconds.
A significant positive correlation (i.e. R2=0.82; p < 0.001) has been established
between the 137Cs areal activities obtained with the in-situ and laboratory based
measurements.
The first results relating to in-situ measurement of 137Cs offer an exciting potential
for the application of FRN measurements and their up-scaling in the framework
of soil erosion assessments at the landscape level. This includes cost, time, and
portability, the potential to work in remote areas, pre-screening to develop more
effective sampling strategies and rapid repeat surveys. This work is still in its initial
stage and more research is required to validate this innovative in-situ technique. |
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