dc.contributor.author |
Mdutyana, M. |
|
dc.contributor.author |
Burger, J. |
|
dc.contributor.author |
Thomalla, S.J. |
|
dc.contributor.author |
Ward, B.B. |
|
dc.contributor.author |
Fawcett, S.E. |
|
dc.coverage.spatial |
Atlantic Southern Ocean |
|
dc.coverage.spatial |
Southern Ocean |
|
dc.date.accessioned |
2021-03-05T15:52:46Z |
|
dc.date.available |
2021-03-05T15:52:46Z |
|
dc.date.created |
18-Aug |
|
dc.date.issued |
18-Aug |
|
dc.identifier.uri |
http://hdl.handle.net/123456789/28403 |
|
dc.description.abstract |
The Southern Ocean (SO. is an important sink for anthropogenic carbon dioxide, which depends in part on phytoplankton and bacterial cycling of nutrients in the surface mixed layer (ML.. Nitrogen (N. limits primary production in much of the ocean, yet SO surface waters are perennially high in nitrate (NO3-. due to combined iron and light limitation of phytoplankton. Nonetheless, the seasonal drawdown of NO3-, supplied to ML waters largely through winter mixing, can be quantitatively related to carbon export provided that nitrification, the oxidation of ammonium (NH4+. to nitrite (NO2-. and NO3-, occurs in the ML at a rate that is insignificant relative to autotrophic NO3- uptake. Our work in the Atlantic SO has shown strong seasonality in ML nitrification, with wintertime rates that are 30-70 times higher than those measured in summer when nitrification accounts for <5% of the NO3- consumed by phytoplankton. This suggests that summertime NO3- drawdown from surface waters is a reasonable proxy for SO carbon export. However, high winter ML nitrification rates affect the NO3- pool available for consumption in the following spring/summer season because the winter ML evolves into both the spring/summer ML and the subsurface “winter water” layer that underlies and exchanges with the spring/summer ML. The implications of this for SO carbon export are not yet clear. To address this uncertainty, we conducted a series of high depth-resolution nitrification experiments across the Indian sector of the SO in winter 2017. In addition, we investigated the physiological capabilities of NH4+ and NO2- oxidizing bacteria through kinetic (i.e., Michaelis-Menten. experiments that deduce the theoretical maximum oxidation rate (Vmax. and half saturation constant (Ks; an indicator of substrate affinity. parameters. These results will yield insights into the controls on nitrification under varying conditions. For example, our work-to-date suggests that NH4+ oxidation is the rate-limiting step for nitrification, but the controls on this remain unknown. - Abstract as displayed in the - Abstract booklet. There was no presentation. |
en_ZA |
dc.description.sponsorship |
Sponsored by the the Department of Science and Innovation(DSI) through National Research Foundation (NRF) - South Africa |
en_ZA |
dc.description.statementofresponsibility |
Antarctic Legacy of South Africa |
en_ZA |
dc.format |
PDF |
en_ZA |
dc.language |
English |
en_ZA |
dc.language.iso |
en_ZA |
en_ZA |
dc.publisher |
South African National Antarctic Programme (SANAP. |
en_ZA |
dc.relation |
SANAP Symposium 2018 |
en_ZA |
dc.rights |
Copyright |
en_ZA |
dc.rights |
Copyright |
en_ZA |
dc.subject |
Research |
en_ZA |
dc.subject |
Science |
en_ZA |
dc.subject |
Meetings |
en_ZA |
dc.subject |
Symposium |
en_ZA |
dc.subject |
SANAP Symposium 2018 |
en_ZA |
dc.subject |
Earth Systems |
en_ZA |
dc.subject |
Oceanography |
en_ZA |
dc.subject |
Ocean Science |
en_ZA |
dc.subject |
Southern Ocean |
en_ZA |
dc.subject |
Phytoplankton |
en_ZA |
dc.subject |
Nutrients |
en_ZA |
dc.subject |
Nitrogen |
en_ZA |
dc.subject |
Primary Production |
en_ZA |
dc.subject |
Atlantic Southern Ocean |
en_ZA |
dc.subject |
Bacteria |
en_ZA |
dc.title |
The kinetics and implications of nitrification in the Southern Ocean mixed layer |
en_ZA |
dc.type |
Abstracts |
en_ZA |
dc.rights.holder |
Antarctic Legacy of South Africa |
en_ZA |
dc.rights.holder |
Mdutyana, M. |
en_ZA |
dc.rights.holder |
Burger, J. |
en_ZA |
dc.rights.holder |
Thomalla, S.J. |
en_ZA |
dc.rights.holder |
Ward, B.B. |
en_ZA |
dc.rights.holder |
Fawcett, S.E. |
en_ZA |
iso19115.mdconstraints.uselimitation |
This item and the content of this website are subject to copyright protection. Reproduction of the content, or any part of it, other than for research, academic or non-commercial use is prohibited without prior consent from the copyright holder. |
en_ZA |
iso19115.mddistributor.distributorcontact |
South African National Antarctic Programme -SANAP. |
en_ZA |
iso19115.mdformat.name |
PDF |
en_ZA |
iso19115.mdidentification.deliverypoint |
Antarctic Legacy of South Africa, Faculty of Science, Private Bag X1, Matieland. Stellenbosch. South Africa. |
en_ZA |
iso19115.mdidentification.electronicmailaddress |
antarcticlegacy@sun.ac.za |
en_ZA |
iso19115.mdidentification.organizationname |
University of Cape Town |
en_ZA |
iso19115.mdidentification.organizationname |
Council for Scientific and Industrial Research |
en_ZA |
iso19115.mdidentification.organizationname |
Princeton University |
en_ZA |