Ammonia, the dominant base in the remote marine troposphere: a review

Abstract

Ammonia appears to be the dominant base in the remote marine troposphere, yet its rôle in atmospheric acid‐base chemistry is not well understood. The physical and chemical interactions of ammonia with acidic species is complicated by its presence in the gas and particle phases and in cloud‐, rain‐ and seawater. This review summarizes the reported ammonia concentration data in these 5 phases as well as existing sampling and analysis methods. An attempt is made to compare these data using equilibrium and scavenging calculations. The lowest measured ammonia gas phase concentrations appear to be consistent with reported sulfate and ammonium concentrations in the particulate phase. The high gas phase concentrations of ammonia found in older data appear to be a result of sampling artifacts. Reported ammonium particle and rainwater data also appear to be consistent with each other. Calculations suggest that ammonia may be in equilibrium between the gas phase and the ocean surface. To confirm or refute these conclusions, the simultaneous measurement of ammonia and relevant acidic species in all 5 phases is needed.

A global budget for atmospheric NH3

“…Low concentrations of NH, in the remote marine atmosphere led Quinn et al (1987) to postulate gaseous losses of NH, from the sea surface following Henry's law for the distribution of soluble gases between the solution and gaseous phase. Subsequent measurements in a wide area of the Pacific Ocean suggested a flux of 7 pmol/m2/day (Quinn et al 1990) and 10 pmol/m2/day (Q uinn et al 1988) from pelagic and nearshore environments, respectively.…”

Size-resolved sulfate and ammonium measurements in marine boundary layer over the North and South Pacific

“…Since the concentration of the atmospheric total ammonia (aerosol NH 4 + + gaseous NH 3 ) was much lower in the oceanic air over the Pacific than in the air over the land, the land is the major contributor to the total ammonia in the oceanic air (Tsunogai and Ikeuchi, 1968;Tsunogai, 1971). Later works (Quinn et al, 1987;Quinn et al, 1990;Zhuang and Huebert, 1996;Lee et al, 1998;Gibb et al, 1999;Sorensen et al, 2003) estimated the air-sea flux of ammonia by comparing their concentrations in the air and ocean. These studies concluded that ocean surfaces are potential sources of ammonia in marine air.…”

The past, present and future of nitrogenous compounds in the atmosphere, and their interactions with plants

“…Earlier work by Asman & Janssen (1986) used values of 6-13 nmol m −$ for gaseous NH $ as well as for aerosol NH % + as the 1980 background concentration for Europe, while acknowledging that this may still have an anthropogenic component via long-distance atmospheric transport despite the small residence time, of the order of days, for atmospheric NH y (Dentener & Crutzen, 1994). These values may be compared with values as low as 1n0-3n3 nmol NH $ m −$ for marine air (Ayres & Gras, 1980, 1983Quinn et al, 1987 ;Quinn et al, 1988), 20 nmol m −$ for ' pure ' continental air (Ayers & Gras, 1980, 1983 and NH $ compensation concentrations 18 nmol m −$ for ' semi-natural ' terrestrial vegetation, 9-76 nmol m −$ for crop canopies, and " 165 nmol m −$ for crop plants in chambers (Sutton et al, 1995 ;Sutton et al, 1997). Pitcairn, Fowler & Grace (1995) estimate a deposition of total combined N from the atmosphere between 1890 and 1960 to have shown relatively little change over Northern Scotland (0n05-2 kg N ha −" yr −" ) and Rothamsted (5 kg N ha −" yr −" ), on the basis inter alia of regressions of the measured combined N deposition per year today on the N content of organic matter from bryophytes and from Calluna in relatively ' clean air ' regions.…”

“…Gottleib (1982) has suggested that lignin synthesis only became possible when the NH $ concentration in the atmosphere fell to values low enough to permit phenylalanine ammonia-lyase, the enzyme which equilibrates phenylalanine with cinnamic acid and ammonia, to bring about the net conversion of phenylalanine to cinnamic acid and ammonia. However, we have seen the global atmospheric NH $ concentration was never high enough to significantly slow down the conversion of phenylalanine to cinnamic acid, and that if anything the NH $ concentration in the atmosphere in equilibrium with lignifying (and photorespiring) terrestrial land plants is higher than that in equilibrium with mainly non-lignifying (and usually non-photorespiring) aquatic plants see Ayers & Gras, 1980, 1983Dentener & Crutzen, 1994 ;Quinn, Charlson & Zoller, 1987 ;Quinn, Charlson & Bates, 1988). As with photorespiration, so with lignin synthesis : there seems to be no impact of these NH $ \NH % + -recycling processes on the NH $ compensation of the shoots of terrestrial plants .…”

“…Although subject to less genetic investigation, the current anthropogenic elevations of levels of oxides of nitrogen, ammonia\ammonium and tropospheric ozone would appear in general terms to be more analogous to heavy metals than to triazines, since at least somewhere on earth there have been plants Ayers & Gras , 1983) Quinn et al (1987) Sutton et al (1995) Levine (1989 N # O 275 nmol mol −" (from the core measurements)…”