Nitrous oxide in the Drakes Passage, Bellingshausen Sea and Deception Island during November-December 1992

Concentrations of dissolved and atmospheric nitrous oxide, N2O, were measured in the austral spring of 1992 in the Drake Passage and Bellingshausen Sea as part of the United Kingdom Joint Global Ocean Flux Study expedition to the Southern Ocean. The measured atmospheric mixing ratio was 313 +/- 5 parts per billion by volume, in agreement with the hemispherically corrected global mean. In the Drake Passage, surface N2O saturations were generally very close to atmospheric equilibrium, 99.7 +/- 3%, although several anomalous points were associated with the presence of frontal and eddy-like features within the Antarctic Polar Frontal Zone and at the Continental Water Boundary. Further to the south, a series of oceanographic stations and two surface transects along the 85 degrees W meridian between 65.28 degrees S and 70.32 degrees S revealed a transition from undersaturated conditions in open water to oversaturated conditions in the marginal ice zone, in the upper mixed layer (75-100 m). These observations reflect upwelling of Circumpolar Deep Water at approximately 70 degrees S, resulting in the accumulation of N2O under the winter sea ice and its subsequent release to the atmosphere following the ice retreat. Sea-air N2O fluxes were estimated from the product of the surface N2O anomaly and the modelled gas transfer coefficients of Liss and Merlivat [1986] and Wanninkhof [1992] to find a maximum rate of +3.1 micromole N2O m-2 d -1. North of the upwelling region, Antarctic Surface Water formed from the mixing of surface waters and ice melt was moderately depleted in N2O with respect to the atmosphere, a minimum 90% of saturation. This sink area was estimated to extend between 65.28 degrees S and 69.57 degrees S with a mean sea-air flux of between -0.6 +/- 0.4 and -0.9 +/- 0.7 micromole N2O m-2 d-1. The region studied at 85 degrees W (65.28 degrees S to 70.32 degrees S) revealed source and sink areas which were largely determined by the changing physical hydrography, so that overall there was a small net negative flux of between -0.06 +/- 0.9 and -0.09 +/- 1.4 micromole N2O m-2 d-1.

Funding: The work was supported by NERC funding to the Plymouth Marine Laboratory, the British Antarctic Survey and from the U.K. Biogeochemical Flux Study (BOFS).

Alternate title: Polar Data Centre (PDC) record GB/NERC/BAS/PDC/01838

Date (Publication): 2024-04-22

Citation identifier: http://www.antarctica.ac.uk/dms/metadata.php?id= / GB/NERC/BAS/PDC/01838

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	Rees, A., Owens, N., & Upstill-Goddard, R.	pdc@bas.ac.uk	Originator

Maintenance and update frequency: Unknown

Keywords

NDGO0001

NERC OAI Harvesting

NERC_DDC

GCMD Parameter Valids

EARTH SCIENCE > Oceans > Ocean Chemistry > Nitrous Oxide

BAS Free-text keywords

Antarctic
Bellingshausen Sea
Deception Island
Drakes Passage
Nitrous oxide

Use limitation: This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.

Access constraints: Other restrictions

Other constraints: This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.

Language: English

Topic category

Oceans

Begin date: 1992-11-01

End date: 1992-12-07

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		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: Primary method calibration was through a commercially prepared, certified N2O/CH4 mixture in an UHP N2 matrix (Air Products) with a certified accuracy of +/-1% or better. For routine analytical calibrations a series of four secondary standards (in the linear range of the detector) were used, prepared from the primary mixtures by pressure dilution [Upstill-Goddard et al., 1990]. Consequently, the best estimate for overall accuracy of the N2O secondary standards was +/-2%. The variability of the method during this study was generally better than 2-3% (mean = 0.97%, n=44), based on replicate analyses of standards, atmospheric air, and compressed air. In support of this calibration, the measured atmospheric mixing ratio of 313 +/- 5 parts per billion by volume (ppbv) shows less than 1% deviation from the interhemispheric corrected global mean and at worst provides an overestimate of 1.3% relative to 1992 data for the South Pole [Swanson et al., 1992].