800-year ice-core record of nitrogen deposition in Svalbard linked to ocean productivity and biogenic emissions
We present the records of the two nitrogen species nitrate (NO 3 - ) and ammonium (NH 4 + ) 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 dec...
| Published in: | Atmospheric Chemistry and Physics |
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| Main Authors: | , , , , |
| Format: | Text |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/acp-15-7287-2015 https://www.atmos-chem-phys.net/15/7287/2015/ |
| Summary: | We present the records of the two nitrogen species nitrate (NO 3 - ) and ammonium (NH 4 + ) 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 NO 3 - and NH 4 + precursors and find that during the twentieth century both records are influenced by anthropogenic pollution from Eurasia. In pre-industrial times NO 3 - is highly correlated with methane sulfonate (MSA), which we explain by a fertilising effect. We propose that enhanced atmospheric NO 3 - 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 NO 3 - , but a more exact source apportionment could not be performed based on our data. This is different for NH 4 + , where biogenic ammonia (NH 3 ) emissions from Siberian boreal forests were identified as the dominant source of pre-industrial NH 4 + . |
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