FY 1988

Simultaneous observations of ammonia in the atmosphere and ocean

Quinn, P.K., R.J. Charlson, and T.S. Bates

Nature, 335, 336–338, doi: 10.1038/335336a0 (1988)

Ammonia, being the dominant base other than sea salt in the remote marine troposphere, plays an important role in the acid-base chemistry of the atmosphere. An understanding of the cycling of ammonia through the marine environment has, until now, been hampered by the lack of concurrent measurements of key acidic and basic atmospheric and seawater species. Reported here are the results of simultaneous concentration measurements of these species during May 1987 in the coastal north-east Pacific Ocean environment. Gas (g) and particulate (p) phase data suggest that low concentrations of NH₃ (g) in the marine atmosphere lead to partly neutralized H₂SO₄ in aerosol particles and in rainwater. Gas-phase concentrations combined with seawater concentration measurements indicate that for the region and time period studied the ocean was a local source of atmospheric ammonia. These data, combined in a simple box model, suggest a marine boundary layer residence time of 3.6 h and 22 h for NH₃ (g) and NH⁺₄ (p), respectively.