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| Titel |
How important is the unsaturated zone in the terrestrial nitrogen budget? |
| VerfasserIn |
Matthew Ascott, Lei Wang, Robert Ward, Marianne Stuart |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102246
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| Publikation (Nr.) |
 EGU/EGU2015-1554.pdf |
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| Zusammenfassung |
| Inputs of nitrogen to agricultural land have had significant effects on aquatic and marine
ecosystems through eutrophication, algal blooms and habitat loss. In order to manage this
problem, terrestrial nitrogen budgets at the national scale have been developed. However,
explicit representation of nitrate transport in the subsurface is seldom considered. Using
derived estimates of unsaturated zone travel time and nitrate loading at the base of the
soil zone, we quantify the total mass of nitrate held in in the unsaturated zone of
aquifers in the United Kingdom. In the unsaturated zone of moderate and highly
productive aquifers of the UK this is estimated to have peaked in 2008 at 1400 kt N;
substantially greater than previous approximations. Currently 70% of the nitrate
mass in the unsaturated zone is in the Chalk, with the remainder split between the
Permo-Triassic Sandstones, Oolitic Limestones and other less important aquifers. The UK
unsaturated zone is now a source of nitrate and in 2014 we estimate the net nitrate flux
from the unsaturated zone to groundwater and surface water to be approximately
70 kt N a-1. The mass of nitrate in the unsaturated zone should be considered in
future terrestrial nitrogen budgets to improve national scale ecosystem management. |
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