Project

Back to overview

AeroTope: A novel method for mass spectrometric measurements of nitrogen isotopes in NH4+, an aerosol derived proxy to quantify nutrient cycling efficiency in the Southern Ocean

English title AeroTope: A novel method for mass spectrometric measurements of nitrogen isotopes in NH4+, an aerosol derived proxy to quantify nutrient cycling efficiency in the Southern Ocean
Applicant Fischer Hubertus
Number 157671
Funding scheme R'EQUIP
Research institution Klima- und Umweltphysik Physikalisches Institut Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.01.2015 - 31.12.2015
Approved amount 79'075.00
Show all

All Disciplines (2)

Discipline
Other disciplines of Physics
Other disciplines of Environmental Sciences

Keywords (5)

isotopes; ice cores; nutrient cycling; climate; biogeochemical cycles

Lay Summary (German)

Lead
Da sich die isotopische Zusammensetzung von chemischen Verbindungen im Verlauf von biogeochemischen Prozessen verändert, stellen Isotopenuntersuchungen in der Biogeochemie ein einzigartiges Instrument dar, um mehr über die Quellen dieser Verbindungen und deren Austauschprozesse zwischen Biosphäre, Ozean und Atmosphäre zu lernen. So benutzen wir in unserer Arbeitsgruppe an der Universität Bern diese Technik ausgiebig in Treibhausgasstudien an polaren Eisbohrkernen. Auch das Spurengas Ammoniak (NH3) wird im Nährstoffkreislauf des Ozeans und in Böden produziert und emittiert, wird aber dann in saurem Aerosol als Ammonium (NH4+) gebunden, welches auch im Eis nachgewiesen werden kann. In AeroTope entwickeln wir eine neue massenspektrometrische Methode, die es ermöglichen soll, auch die isotopische Zusammensetzung von NH4+ in polaren Eisbohrkernen zu quantifizieren.
Lay summary

NH3 ist eine wichtige intermediäre Verbindung des Stickstoffkreislauf im Südozean. Nachdem NH3 aus dem Oberflächenwasser entwichen ist, wird es in saurem Aerosol in der Atmosphäre gebunden und als NH4+ auch teilweise zum Antarktischen Eisschild transportiert, wo es im Schnee deponiert wird. In mittleren und hohen Breiten der Nordhalbkugel stammt NH4+ sowohl vom marinen als auch vom Stickstoffkreislauf in Böden und ein Teil des NH4+ haltigen Aerosols wird zum Grönländischen Eisschild transportiert.

Mithilfe einer speziellen kontaminationsfreien, kontinuierlichen Schmelzanalytik (CFA), die in unserer Arbeitsgruppe entwickelt wurde, können wir auch die Konzentration von NH4+ im Eis sehr präzise bestimmen. Quantitative Information zur Effizienz des Stickstoffkreislaufs im Südozean und zu den relativen Quellbeiträgen terrestrischer und mariner NH3 Quellen in hohen nördlichen Breiten könnte jedoch gewonnen werden, wenn es möglich wäre, auch die isotopische Zusammensetzung von NH4+ zu messen.

Eine solche hochpräzise isotopische Messmethode für NH4+, welches im Eis nur in sehr geringen (parts-per-billion) Konzentrationen vorhanden ist und welches sehr leicht durch Laborkontamination verfälscht werden kann, ist das Ziel von AeroTope. Dazu verbinden wir unsere umfangreiche Expertise auf dem Gebiet der Gaschromatographie-Massenspektrometrie für isotopische Spurengasuntersuchungen mit unserem einzigartigen CFA System für online Messungen von chemischen Aerosolkomponenten. Das R’Equip Projekt AeroTope liefert dazu einen Teil der  finanziellen Mittel, um ein neues Massenspektrometer für diese Anwendung anzuschaffen und dieses an unser CFA System zu koppeln.

Direct link to Lay Summary Last update: 17.11.2014

Lay Summary (English)

Lead
As the isotopic composition of chemical compounds changes during natural biogeochemical processes, isotopes represent a unique tool in biogeochemical research to learn more about the sources of such compounds and their exchange processes between the biosphere, ocean and atmosphere. This technique is for example extensively used in ice core research in our working group at the University of Bern to study greenhouse gas cycles. The trace gas ammonia (NH3) is also produced and emitted during nutrient cycling in the ocean and in soils, but is then incorporated into acidic aerosol in the atmosphere as ammonium (NH4+), which can also be found in the ice. Within AeroTope we will develop a novel mass spectrometric method that will also allow us to measure the nitrogen isotopic composition of NH4+ in polar ice cores.
Lay summary

NH3 is a key intermediate species of the nutrient turnover in the Southern Ocean. After emission from the surface ocean it is incorporated into acidic atmospheric aerosol and partly transported to the Antarctic Ice Sheet, where it is deposited onto the snow surface. In the middle and high latitude northern hemisphere, NH4+ stems from both marine biological as well as soil nitrogen turnover and part of the NH4 bearing aerosol is transported to the Greenland ice sheet.

Using a unique contamination-free Continuous Flow Analysis (CFA) developed in our working group at the University of Bern, we are able to precisely quantify the concentration of NH4+ in the ice. However, quantitative information about the efficiency of nutrient turnover in the Southern Ocean and a quantitative attribution of terrestrial and marine sources in high northern latitudes could be accomplished, if the nitrogen isotopic composition of NH4+ could be measured as well.

To develop such a high precision isotopic measurement technique for NH4+, which is present in the ice only at the parts-per-billion level and which is prone to lab contamination, is the ultimate goal of AeroTope. To this end we combine our extensive experience in coupled gas chromatography-mass spectrometry techniques for isotopic trace gas studies with our unique CFA system for online measurements of chemical aerosol species. The R’Equip project AeroTope will provide part of the funds to purchase a new mass spectrometer for this application and to couple it to our CFA system.

Direct link to Lay Summary Last update: 17.11.2014

Responsible applicant and co-applicants

Collaboration

Group / person Country
Types of collaboration
Dr. R. Mulvaney, British Antarctic Survey, Cambridge Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. A. Svensson, Dr. P. Vallelonga, Center for Ice and Climate, University of Copenhagen Denmark (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Todd Sowers, Penn State University, University Park United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. J. Chappellaz, Dr. M. Legrand, LGGE-CNRS Grenoble France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Associated projects

Number Title Start Funding scheme
147174 Climate and Environmental Physics 01.04.2013 Project funding (Div. I-III)
172506 iCEP - Climate and Environmental Physics: Innovation in ice core science 01.04.2017 Project funding (Div. I-III)

Abstract

One of the major scientific foci of the Division for Climate and Environmental Physics (CEP) at the Physics Institute, University of Bern, is the investigation of biogeochemical cycles and in particular of the global carbon cycle using the atmospheric archive in polar ice cores jointly with climate and biogeochemical model studies. In this field CEP has gained wide experience in the analysis and interpretation of the three greenhouse gases CO2, CH4, and N2O and especially their isotopic composition using novel mass spectrometric methods. To be able to do this, CEP has developed new mass spectrometric methods for isotopic ice core studies on all these gases over the last 6 years. Moreover, CEP previously developed a Continuous Flow Analysis (CFA) system to derive high-resolution aerosol chemistry records from polar ice cores and is routinely using this unique technique in international ice core projects.With this proposal we plan to extend our analytical capacity by establishing a completely new mass spectrometric application, which will provide important additional quantitative insight into the marine carbon cycle. To this end we will join the two analytical strains “mass spectrometry” and “CFA” of chemical aerosol tracers by measuring for the first time the nitrogen isotopic composition of aerosol derived NH4+ in Antarctic ice cores. This application is targeted at quantifying the nutrient cycling efficiency in the Southern Ocean (SO) over the last up to 800,000, as NH4+ is a key intermediate species of the nutrient turnover in the SO. Accordingly, its isotopic composition is expected to be strongly dependent on the efficiency of nutrient uptake in the surface ocean, which strongly affects atmospheric CO2. To achieve this new aerosol isotopic application we will develop a novel coupled CFA/mass spec-trometry method within AeroTope. Part of the funding for this new analytical infrastructure (one mass spectrometer plus the required periphery for sample preparation) are requested in this R’Equip proposal.
-