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| Titel |
Seasonal variability of soil sink for atmospheric hydrogen: a case study from southern Poland |
| VerfasserIn |
J. Bartyzel, M. Pycia, J. M. Necki, K. Rozanski |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250019632
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| Zusammenfassung |
| Although hydrogen is rarely mentioned as a greenhouse gas, it is expected that elevated
concentrations of this gas in the atmosphere in the coming decades, associated with massive
anthropogenic emissions may lead to longer residence time of atmospheric CH4 and
associated enhancement of the greenhouse effect. The global average mixing ratio of
atmospheric H2 amounts at present to approximately 500 ppb. The sources and
sinks of hydrogen are not well quantified. In particular, little is known about the
strength and spatial and temporal variability of hydrogen uptake by soils. The EU 6th
Framework Project EUROHYDROS is aimed at initialising European monitoring
capability for atmospheric hydrogen, including the ability to derive isotope ratios and
to use these observations, together with studies on sinks and sources of H2 and
modelling work, to improve the understanding of hydrogen budget on the global
scale.
As a part of EUROHYDROS project, a dedicated study aimed at quantifying
seasonal variability of soil sink for atmospheric hydrogen is being conducted in
southern Poland. The experimental site is located on the outskirts of Krakow, a
large city with numerous anthropogenic sources of H2. To quantify the soil sink
for H2, a dedicated equipment has been constructed, based on the inverted cap
principle.
To quantify the uptake of H2 by soils, a 20-liter chamber made of stainless steel and
plexiglas is placed on the soil surface and concentration of hydrogen inside the chamber is
measured in regular time intervals in order to quantify the dynamics H2 removal via
enzymatic reactions taking place in the upper soil layers. The concentration of hydrogen was
measured in samples of air collected under the chamber in specified time intervals. A
commercially available instrument (Peak Performer 1, Peak Laboratories, USA) equipped
with RGA detector was used for this purpose. The measurements were performed regularly
every two weeks. Apart of hydrogen concentrations, also several other field parameters
(soil and air temperatures, soil water content) were measured during each sampling
campaign.
The results of the field experiment available do date indicate that H2 flux into the soil
generally increases with rising soil temperature, although this trend is apparent only
for the lower range of the observed soil temperatures, between ca. 3.5 and 12oC.
In the upper range, between ca.13 and 20oC, the influence of soil temperature on
H2 flux seems to be negligible, if any. The H2 uptake generally decreases with
increasing water content in the soil, although the available data suggest that when the
soil moisture drops below a certain threshold, the H2 uptake is reduced. Seasonal
fluctuations of soil temperature and water content lead to a distinct seasonality of
the H2 uptake observed at the experimental site; the H2 flux into the soil changes
from ca. 30 μmolh-1m-2 during summer months to values close to zero during
winter.
Acknowledgements:
This work was supported by EU project EUROHYDROS and by the statutory
funds of the AGH University of Science and Technology (project No.11.11.220.01). |
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