Fate of US and Canadian combustion nitrogen emissions

摘要: While approximately 7.5 × 1012 grams (7.5 Tg) of combustion nitrogen are emitted yearly in the United States and Canada1–3, only 1.5–2.3 Tg deposited as acid rain over that same region4–6. Past budget estimates4,10 well recent observations11 suggest dry deposition export play major roles. Here we report how accumulated transport is simulated for first time by a global model with realistic meteorology. The predicts Canada accounts at least 2.1 most probably 3.5 emissions. remainder exported, principally North Atlantic. But 0.2 Tg, less than 3% estimated European emissions4, predicted to reach Europe from America. Furthermore, that, while 40% northeastern eastern comes emissions region, almost all dry-deposited half total there.