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| Titel |
Seasonality of atmospheric nitrogen deposition at a semi-natural peatland site |
| VerfasserIn |
M. Hurkuck, C. Brümmer, W. L. Kutsch |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063776
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| Zusammenfassung |
| Large areas of natural peat bogs in Northwestern Germany have been converted to arable land
and are characterised by decades of draining and peat cutting. Our study site – a semi-natural
raised bog – is one of only very few remaining protected peatland areas. However,
it is surrounded by highly fertilized agricultural land and poultry farms. In this
study, we use a combined approach of independent methods to quantify seasonal
variations of atmospheric nitrogen deposition most likely originated from agricultural
practices.
Concentrations and fluxes of ammonia and its atmospheric reactants are measured by a
KAPS-denuder system integrated over one-week periods. Additionally, total nitrogen input
from the atmosphere into a soil-plant model ecosystem is investigated by a 15N dilution
method called ’Integrated Total Nitrogen Input’ (ITNI). With this approach, we aim to
allocate atmospheric nitrogen after its uptake by the ecosystem in aboveground biomass,
roots and soil.
First results from April to November 2011 show average ammonia concentrations ranging
from 0.9 to 13.0 μg m-3. A first maximum of 8.8 μg m-3 could be observed in
spring followed by relatively stable concentrations (mean: 3.7 μg m-3) in summer.
Autumn ammonia concentrations reached a second peak of 13.0 μg m-3. By now,
winter concentrations tend to be lower than those during the rest of the measuring
period.
Using the KAPS-denuder system within a gradient setup, deposition of ammonia was
found to be between 0.08 to 0.25 kg NH3-N ha-1 week-1. The proportion of concentrations
and fluxes of other N compounds such as HNO3, aerosol NH4 and NO3 was usually around
20 % of total measured nitrogen. During the first months of investigation, we found a total
dry N deposition of about 5.4 kg ha-1. Extrapolation of data to one year amounts
approximately to 9 kg ha-1 yr1.
Our results suggest that the intensive agricultural land management of surrounding areas
most likely leads to increasing N input into the protected peatland area. The critical load for
this nutrient-poor ecosystem might be exceeded and a future change in vegetation and
hydrology is expected.
Key words: nitrogen deposition, raised bog, 15N isotopes, KAPS denuder |
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