800-year ice-core record of nitrogen deposition in Svalbard linked to ocean productivity and biogenic emissions

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Wendl, I. A., Eichler, A., Isaksson, E., Martma, T., Schwikowski, M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2015
• Subjects: article; Verlagsveröffentlichung; Arctic; Lomonosovfonna; Svalbard; glacier; ice core; Phytoplankton
• Online Access: https://doi.org/10.5194/acp-15-7287-2015; https://noa.gwlb.de/receive/cop_mods_00044313; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00043933/acp-15-7287-2015.pdf; https://acp.copernicus.org/articles/15/7287/2015/acp-15-7287-2015.pdf

We present the records of the two nitrogen species nitrate (NO3-) and ammonium (NH4+) analysed in a new ice core from Lomonosovfonna, Svalbard, in the Eurasian Arctic covering the period 1222–2009. Changes in melt at the Lomonosovfonna glacier are assumed to have a negligible effect on the decadal variations of the investigated compounds. Accordingly, we use decadal records to investigate the major emission sources of NO3- and NH4+ precursors and find that during the twentieth century both records are influenced by anthropogenic pollution from Eurasia. In pre-industrial times NO3- is highly correlated with methane sulfonate (MSA), which we explain by a fertilising effect. We propose that enhanced atmospheric NO3- concentrations and the corresponding nitrogen input to the ocean trigger the growth of dimethyl-sulfide-(DMS)-producing phytoplankton. Increased DMS production results in elevated fluxes to the atmosphere where it is oxidised to MSA. Eurasia was presumably the main source area also of pre-industrial NO3-, but a more exact source apportionment could not be performed based on our data. This is different for NH4+, where biogenic ammonia (NH3) emissions from Siberian boreal forests were identified as the dominant source of pre-industrial NH4+.