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| Titel |
Greenhouse gas fluxes influenced by a penguin colony on Bird Island/Antarctica |
| VerfasserIn |
Julia Drewer, Sim Tang, Margaret Anderson, Christine Braban, Ulrike Dragosits, Ute Skiba |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075373
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| Zusammenfassung |
| The influence of reactive nitrogen (Nr) emissions from a penguin colony on local
greenhouse gas (GHG) fluxes was investigated on the remote sub-Antarctic Bird Island
(54Ë 00’S, 38Ë 03’W) in November and December 2010 (8 weeks). Bird Island
has a hilly topography and a maximum elevation of 350 m. Winds predominate
from the west, however, due to the local topography there were expected to be a
significant influences from the local marine environment and local fauna such as
seabirds (40,000 pairs of Macaroni penguins at the colony, and other more disperse
species) and seals who ranged over the area. Measurements of N2O and CH4 were
made using static chambers along a transect with sampling points at a distance of
23, 36, 70, 143 and 338 m downwind from the penguin colony. Gas samples were
taken in 3 ml pre-evacuated exetainers and sent back to the UK for analysis on
GC-ECD/FID. In addition, parameters including soil moisture, soil respiration, soil and air
temperature, total C/N in vegetation and soil, and NO3/NH4 in soil were measured.
Mean air temperature was 3.1 Ë C with minimum and maximum of -1.9 and 9 Ë
C.
Laboratory incubations were carried out on soil cores taken from the chambers at the end
of the measurement campaign. Soils were very shallow and cores collected close to the
colony were a mixture of decomposing litter and soil, whereas further inland they
consisted of organic soils. Cores were defrosted very slowly to simulate spring
warming to 2 oC for 5 days, then to 5 Ë C for 3 days and subsequently to 10 Ë C for 2
days. Soil moisture was kept constant during this time to investigate the influence
of temperature on NO and GHG emissions. After 10 days soils were left to dry
out.
Mean CH4 fluxes from 8 different days in the field were in the range of -5.5 to 245 μg
m-2 h-1,with minimum and maximum fluxes of -83 and 4065 μg m-2 h-1. Mean N2O
fluxes ranged from 7 to 23 μg N2O-N m-2 h-1, with minimum and maximum fluxes of -0.6
and 226 μg N2O-N m-2 h-1. NO fluxes ranged from 5 to 60 ng NO-N g-1 dry soil h-1 and
were highly spatially variable. Direct Nr emissions from the penguin colony were
predominantly ammonia (NH3), and the highest concentrations were close to the penguin
colony and decreased exponentially with distance away. Both in situ chamber GHG fluxes
and incubated soil cores results show a high spatial variability. The highest N2O fluxes were
measured 143 m away from the penguin colony, while the highest CH4and NO fluxes were
measured 143-338 m away from the colony and therefore did not directly correlate
to the NH3 concentration. Thus large variability of vegetation cover, topography,
soil depth and moisture content along the transect appeared to influence GHG and
NO production and flux rates more than raised atmospheric NH3 concentrations. |
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