Abstract
Anthropogenic NO(x) emissions have altered the biogeochemical nitrogen cycle since the Industrial Revolution, yet Arctic ice core nitrate (NO(3)(-)) records are inconsistent with post-1970s NO(x) emission reductions. Here we show a NO(3)(-) deposition history covering 1800-2020 using an ice core from the southeastern Greenland dome with high snow accumulation. The ice core NO(3)(-) concentrations are particularly disconnected from NO(x) source regions during the peak pollution period and post-1990s. A global chemical transport model reproduced these discordances between total NO(3)(-) and NO(x) emissions by altering gaseous HNO(3) and particulate NO(3)(-) (p-NO(3)(-)) ratios and subsequently NO(3)(-) lifetime. This result and correlations with acidity parameters recorded in the ice core, suggest that acidity-driven gas-particle partitioning of NO(3)(-) regulates its transport to Arctic regions alongside changes in NO(x) emissions. In the future, despite NO(x) reductions, the increase in proportion of p-NO(3)(-) with longer atmospheric lifetime becomes crucial to control the Arctic NO(3)(-) burden.