9:45 AM - 10:00 AM
[ACC29-04] Nitrogen isotope of nitrate in Arctic ice core and its relation to past anthropogenic energy shift
Keywords:isotope, nitrate, anthropogenic activity, nitrogen cycle, Nitrogen oxides
Nitrogen and oxygen isotopic compositions of NO3− provide information on changes in the nitrogen source and its formation pathways, but ice core records for NO3− concentrations and its isotopic compositions are problematic because of post depositional loss of NO3− via photolysis. In this study, we analyzed isotopic compositions of NO3− preserved in the high-accumulation dome ice core, South East Greenland, which has a dome with high accumulation rate (about 1 m yr -1 ) in water equivalent. In this study, delta15N value of NO3− was measured by the bacterial method coupled with N2O decomposition via microwave-induced plasma (MIP).
The nitrogen isotopic compositions for NO3− were generally lower than those reported in Summit, Greenland, suggesting that some extent of NO3− deposited in Summit is removed via photolysis. Based on the trend of reconstructed delta15N values and NOx emission inventory, switches from coal to oil combustion mainly in North
America was likely a factor changing the nitrogen cycle in the Arctic environments.