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).

Alternate title: Polar Data Centre (PDC) record GB/NERC/BAS/PDC/01751

Date (Publication): 2023-09-06

Citation identifier: http://www.antarctica.ac.uk/dms/metadata.php?id= / GB/NERC/BAS/PDC/01751

Point of contact

Organisation name	Individual name	Electronic mail address	Role
British Antarctic Survey		pdc@bas.ac.uk	Custodian
NERC EDS UK Polar Data Centre	Schmidt, K., Graeve, M., Welteke, N., Hoppe, C., Fong, A., Hildebrandt, N., Castellani, G., Vortkamp, M., Belt, S., & Atkinson, A.	pdc@bas.ac.uk	Originator

Maintenance and update frequency: 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: 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/.

Language: English

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

Distributor contact

Organisation name	Individual name	Electronic mail address	Role
Polar Data Centre - British Antarctic Survey		pdc@bas.ac.uk	Distributor

OnLine resource

Protocol	Linkage	Name
http	https://ramadda.data.bas.ac.uk/repository/entry/show?entryid=d7708d08-4bd4-439a-99e2-307a175977ea	GET DATA

Hierarchy level: Dataset

Domain consistency

Measure identification: INSPIRE / Conformity_001

Conformance result

Title: INSPIRE Data Specification on unknown theme Guidelines

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.