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| Titel |
Methanotrophic activity in the water column above shallow gas flares west of Prins Karls Forland, Arctic Ocean |
| VerfasserIn |
Friederike Gründger, Mette M. Svenning, Helge Niemann, Anna Silyakova, Pavel Serov, Alexey K. Pavlov, Mats A. Granskog, Benedicte Ferre, JoLynn Carroll |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134396
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| Publikation (Nr.) |
 EGU/EGU2016-15118.pdf |
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| Zusammenfassung |
| Numerous gas flares, interpreted to be streams of methane bubbles, were discovered in
shallow waters (average water depth about 90 m) on the continental shelf west of Prins Karls
Forland (Western Svalbard) in the Arctic Ocean. Gas is released from the seabed to the water
column and potentially transferred into the atmosphere where it acts as a potent greenhouse
gas.
In order to resolve the fate of dissolved methane in the water column, we carried out
grid-pattern biogeochemical measurements in the study area of 30 x 15 km. Specifically, we
measured concentrations of dissolved methane and microbial methane oxidation
(MOx) rates at 8 water depths at 31 sampling stations and performed 16S rRNA
sequencing analysis on selected samples to characterize the microbial community
composition.
Availability of dissolved methane is essential for the process of microbial methane
oxidation. However, our measurements reveal that high concentrations of dissolved methane
in the water column do not necessarily lead to high MOx rates. Our results indicated that the
presence of marine methanotrophic biomass as well as dissolved organic matter is of larger
importance for the process of microbial methane oxidation. For example, we found
MOx hot spots with values up to 13 nmol l−1 d−1 at bottom water depth with
dissolved methane concentrations less than 160 nmol l−1. In contrast, at stations
where bottom methane concentration values reached 640 nmol l−1, MOx rates
were less than 0.7 nmol l−1 d−1. To interpret observed interconnection between
methane concentrations and MOx rates, we use vertical distributions of seawater
temperature, salinity and properties of colored dissolved organic matter (CDOM). This
information helps us characterize the oceanographic setting and circulation patterns in
the area, which we believe has a major impact on the origin and distribution of
methanotrophic microbial biomass and methane oxidation in methanerich bottom
water.
This study is part of the Centre for Arctic Gas Hydrate, Environment and Climate and was
supported by the Research Council of Norway through its Centres of Excellence funding
scheme grant No. 223259. |
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