Fatty acid composition of particulate organic matter (POM) collected from surface waters and bottom sea-ice of the Central Arctic Ocean during the MOSAiC expedition in 2019/2020
During the MOSAiC expedition in the Central Arctic Ocean (CAO, 2019-2020), POM was sampled weekly to fortnightly from surface waters and the Chlorophyll a maximum layer (Chl a max) via CTD casts and from bottom sea ice of the floe via ice coring (first- and second-year ice, two layers nearest to the water-ice interface). The POM was filtered onboard (GF/F filters) and deep frozen for the subsequent analysis of a suite of lipid biomarkers, including fatty acids (FA), FA-compound-specific stable isotopes (FA-CSIA), sterols, and highly-branched isoprenoids (HBI). These biomarkers can provide valuable information about the nutritional value, the taxonomic composition (e.g. diatoms vs flagellates), and the origin of the POM that represents the basis of the Central Arctic food web. This dataset comprises the results from the FA analysis only, those from other biomarkers will be submitted in due cause. The separation of the various lipid biomarkers was carried out at the University of Plymouth. After addition of internal standards for each of the 3 components, the filters were saponified with KOH. Thereafter, non-saponifiable lipids (HBI and sterols) were extracted with hexane and purified by open column chromatography (SiO2). Fatty acids were obtained by adding concentrated HCl to the saponified solution and re-extracted with hexane. Further steps of the FA analysis were carried out at the Alfred-Wegener-Institute (AWI) in Bremerhaven. Here samples were converted into fatty acid methyl esters (FAME) and analysed using an Agilent 6890N gas chromatograph. The Clarity chromatography software system (DataApex, Czech Republic) was used for chromatogram data evaluation. FAME were quantified via the internal standard, Tricosanoic acid methyl ester (23:0) (Supelco, Germany) to provide the total amount of FA (TFA) per filter. These TFA quantities per filter can be normalised to the volume of filtered seawater or melted ice core water. Additionally, we provide the mass percentage composition of the TFA, considering 48 individual FA. The FA are presented in shorthand notation, i.e., A:B(n-x), where: A indicates the number of carbon atoms in the straight fatty acid chain, B represents the number of double bonds present, n represents the terminal methyl group and x denotes the position of the first double bond from the terminal end. The biochemical nomenclature of the fatty acids is provided. The dataset is linked to a manuscript that compares pattern seen in sea ice- and water column POM in the CAO with previously published data from Arctic shelf regions. This manuscript focusses mainly on two key long-chain omega-3 FA (eicosapentaenoic acid and docosahexaenoic acid) that are considered essential for the nutrition of higher trophic levels, including humans, and their production to decline with global temperature rise.
Contributions by KS were funded by the UK''s Natural Environment Research Council MOSAiC Thematic project SYM-PEL: "Quantifying the contribution of sympagic versus pelagic diatoms to Arctic food webs and biogeochemical fluxes: application of source-specific highly branched isoprenoid biomarkers" (NE/S002502/1).
Simple
- Alternate title
- Polar Data Centre (PDC) record GB/NERC/BAS/PDC/01751
- Date (Publication)
- 2023-09-06
- Identifier
- http://www.antarctica.ac.uk/dms/metadata.php?id= / GB/NERC/BAS/PDC/01751
- Maintenance and update frequency
- unknown Unknown
- Keywords
-
- NDGO0001
- NERC OAI Harvesting
-
- NERC_DDC
- GCMD Parameter Valids
-
- EARTH SCIENCE > Oceans > Marine Environment Monitoring
- EARTH SCIENCE > Oceans > Ocean Chemistry > Chlorophyll
- BAS Free-text keywords
-
- Central Arctic Ocean (CAO)
- DHA
- EPA
- MOSAiC
- bottom sea ice
- chlorophyll a maximum
- fatty acids
- lipid biomarker
- particulate organic matter
- surface waters
- Use limitation
- This data is supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.
- Access constraints
- otherRestrictions Other restrictions
- Other constraints
- This data is supplied under Open Government Licence v3.0 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.
- Metadata language
- EnglishEnglish
- Topic category
-
- Biota
- Begin date
- 2019-11-04
- End date
- 2020-09-25
- Reference system identifier
- OGP / urn:ogc:def:crs:EPSG::4326
- Distribution format
-
- OnLine resource
- https://multimedia.awi.de/mosaicvideo
- Hierarchy level
- dataset Dataset
Domain consistency
- Measure identification
- INSPIRE / Conformity_001
Conformance result
- Date
- Explanation
- See the referenced specification
- Pass
- No
- Statement
- Due to the low concentrations of the POM, the water volume that needed to be filtered was often >10000 mL and filtration of replicate samples was not feasible. A total of 9, out of 153 samples, were lost for FA analysis due to the low amount of material filtered. The fatty acid profiles were compared to several commercial- and self-produced standards (e.g. Arctic algae standard, Bacteria standard, Calanus spp. standard), and fatty acid peaks were identified accordingly. In a few cases, samples were also analysed with the mass spectrometer and peaks were identified via (1) the mass of the compound, (2) the retention time of the compound and (3) the equivalent chain length method.
- File identifier
- GB_NERC_BAS_PDC_01751 XML
- Metadata language
- EnglishEnglish
- Hierarchy level
- dataset Dataset
- Date stamp
- 2023-09-06
- Metadata standard name
- NERC profile of ISO19115:2003
- Metadata standard version
- 1.0