Field observations of the ocean‐atmosphere exchange of ammonia: Fundamental importance of temperature as revealed by a comparison of high and low latitudes

Johnson, Martin; Liss, Peter S.; Bell, Thomas G.; Lesworth, T.; Baker, Alex R.; Hind, Andrew J.; Jickells, Timothy D.; Biswas, Karabi Farhana; Woodward, E Malcolm S; Gibb, Stuart W.

doi:10.1029/2007gb003039

Cited by 95 publications

(83 citation statements)

References 41 publications

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“…Oxidation of NH 3(g) by OH radical is rather slow, and considered insignificant relative to other removal processes (wet and dry deposition, mostly from the particulate phase). [17,22] There is generally a disequilibrium observed between the atmosphere and ocean with respect to ammonia, [22,24,27,29,30] supporting the suggestion that air-sea equilibration is a relatively slow process in the system. Therefore, the major control on the concentration of NH 3(g) in the remote MBL (neglecting advection from other sources) must be the equilibrium between gas and particle phases; i.e.…”

Section: Ammonia (Nh 3 )mentioning

confidence: 59%

“…We have identified in Johnson et al [24] that temperature is a fundamental constraint on the magnitude and direction of ocean-atmosphere ammonia exchange such that, at a global scale, it outweighs the effects of biological activity. We predict that temperature is therefore likely to be a key control on the NH + 4 : nss-SO 2− 4 ratio.…”

Section: Coupling Of Dms Emission and Nh 3 Fluxmentioning

confidence: 99%

“…Its solubility means that for typical surface seawater and MBL concentrations, the ocean and atmosphere are generally close to equilibrium with respect to NH 3 [21,24−27] and thus its ocean-atmosphere exchange can be considered a bidirectional process that is highly sensitive to temperature, pH and concentrations of NH 3 in both surface ocean and MBL. [24] Once in the atmosphere, NH 3(g) will react readily with acidic gases and particles to enter the particulate phase as NH + 4(p) . The direction of NH 3(g) flux between the gas and aerosol phases is determined by the difference in concentration between NH 3(g) and pNH 3(g) (the partial pressure of NH 3 over the aerosol phase).…”

Section: Ammonia (Nh 3 )mentioning

confidence: 99%

“…Ocean-atmosphere exchange of NH 3 is calculated using the thin film model (concentration difference) approach [48] using a scheme identical to that presented by Johnson et al [24] Equilibration time across the air-sea interface according to this scheme is on the order of 100 h under typical conditions. [21] This is much slower than the characteristic time of the other modelled process, the interconversion between NH 3(g) and NH + 4 , which occurs on a timescale of between 0.3 and 7 h. [22] We employ an equilibrium scheme where the rate of flux between gas and particle phases is proportional to the difference between the concentration of NH 3(g) and pNH 3(g) (Eqn A6, Accessory publication).…”

Section: Model Descriptionmentioning

confidence: 99%

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Coupling between dimethylsulfide emissions and the ocean - atmosphere exchange of ammonia

Johnson

Bell

2008

Environ. Chem.

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Environmental context. Dimethylsulfide (DMS) is recognised as a potentially significant climate-forcing gas, owing to its role in particle and cloud formation in the marine atmosphere, where it is the dominant source of acidity. Ammonia, the dominant naturally occurring base in the atmosphere, plays an important role in neutralising particles formed from DMS oxidation products and may even enhance the formation rate of new particles. A biogeochemical coupling has previously been proposed between DMS and ammonia fluxes from the ocean to the atmosphere, in the form of coproduction of the two gases in seawater. We revise this suggestion by introducing the concept of 'co-emission' of the gases, where DMS emission controls the rate of emission of ammonia from the ocean by acidifying the atmosphere. Abstract.A strong correlation between aerosol ammonium and non-sea salt sulfate is commonly observed in the remote marine boundary layer. It has been suggested that this relationship implies a biogeochemical linkage between the nitrogen (N) and sulfur (S) cycles at the cellular biochemical level in phytoplankton in the ocean, or a linkage in the atmosphere (see P. S. Liss and J. N. Galloway, Interactions of C, N, P and S biogeochemical cycles and global change (Springer, 1993), and P. K. Quinn et al. in J. Geophys. Res. -Atmos. 1990, 95). We argue that an oceanic linkage is unlikely and draw on mechanistic and observational evidence to make the argument that the atmospheric connection is based on simple physical chemistry. Drawing on an established analogous concept in terrestrial trace gas biogeochemistry, we propose that any emission of dimethylsulfide (DMS) from the ocean will indirectly influence the flux of NH 3 from the ocean, through the neutralisation of acidic DMS oxidation products and consequent lowering of the partial pressure of NH 3 in the atmosphere. We present a simple numerical model to investigate this hypothesised phenomenon, using a parameterisation of the rate and thermodynamics of gas-to-particle conversion of NH x and explicitly modelled oceanatmosphere NH 3 exchange. The model indicates that emission of acidic sulfur to the atmosphere (e.g. as a product of DMS oxidation) may enhance the marine emission of NH 3 . It also suggests that the ratio of ammonium to non-sea salt sulfate in the aerosol phase is strongly dependent on seawater pH, temperature and wind speed -factors that control the ocean-atmosphere ammonia flux. Therefore, it is not necessary to invoke a stoichiometric link between production rates of DMS and ammonia in the ocean to explain a given ammonium to non-sea salt sulfate ratio in the aerosol. We speculate that this mechanism, which can provide a continuous resupply of ammonia to the atmosphere, may be involved in a series of biogeochemical-climate feedbacks. His research interests are biogeochemical cycles taking place both within and between the ocean and its overlying atmosphere, with a focus on biogenic trace gases. He is currently working with Peter Liss as part of the Surfac...

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Section: Ammonia (Nh 3 )mentioning

confidence: 59%

Section: Coupling Of Dms Emission and Nh 3 Fluxmentioning

confidence: 99%

Section: Ammonia (Nh 3 )mentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

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Coupling between dimethylsulfide emissions and the ocean - atmosphere exchange of ammonia

Johnson

Bell

2008

Environ. Chem.

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“…Schafer et al (1993) have reported the concentration of NH 3 gas over BoB of the order of 14.29-29.29 nmol m −3 (0.243-0.500 µg m −3 ). Johnson et al (2008a, b) This study is the first time ambient NH 3 has been monitored precisely over BoB based on chemiluminescence method along with the other trace gases NO, NO 2 and SO 2 onboard Sagar Kanya (a research vessel). The meteorological parameters (temperature, sea surface temperature (SST), relative humidity (RH), wind direction and wind speed) were also recorded over BoB during the campaign to correlate with trace gases.…”

Section: Introductionmentioning

confidence: 99%

Measurement of ambient NH<sub>3</sub> over Bay of Bengal during W_ICARB Campaign

et al. 2012

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Abstract. Concentrations of ambient NH 3 , NO, NO 2 and SO 2 were measured over Bay of Bengal (BoB) during 28 December 2008 to 25 January 2009 to study their diurnal variation and relationship of NH 3 with other trace gases over BoB. The measurements were done under the winter phase of Integrated Campaign on Aerosols and Radiation Budget (W ICARB). For the first time, ambient NH 3 was monitored precisely over BoB based on chemiluminescence method, having estimation efficiency more precise than the chemical trap method. The average concentration of ambient NH 3 , NO, NO 2 and SO 2 were recorded as 4.78 ± 1.68, 1.89 ± 1.26, 0.31 ± 0.14 and 0.80 ± 0.30 µg m −3 , respectively, over BoB. The prominent latitudinal and longitudinal variations of the trace gases were observed over BoB, whereas NH 3 and NO showed the non-significant diurnal variation. Results reveal that the concentration of ambient NH 3 negatively correlated with ambient NO 2 (r 2 = −0.56), SO 2 (r 2 = −0.58) and ambient temperature (r 2 = −0.27) during the study.

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Isotopic evidence for a marine ammonium source in rainwater at Bermuda

Altieri

Hastings

Peters

et al. 2014

Global Biogeochemical Cycles

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Emissions of anthropogenic nitrogen (N) to the atmosphere have increased tenfold since preindustrial times, resulting in increased N deposition to terrestrial and coastal ecosystems. The sources of N deposition to the ocean, however, are poorly understood. Two years of event-based rainwater samples were collected on the island of Bermuda in the western North Atlantic, which experiences both continent-and ocean-influenced air masses. The rainwater ammonium concentration ranged from 0.36 to 24.6 μM, and the ammonium δ 15 N from À12.5 to 0.7‰; and neither has a strong relationship with air mass history (6.0 ± 4.2 μM, À4.1 ± 2.6‰ in marine air masses and 5.9 ± 3.2 μM, À5.8 ± 2.5‰ in continental air masses; numerical average ± standard deviation). A simple box model suggests that the ocean can account for the concentration and isotopic composition of ammonium in marine rainwater, consistent with the lack of correlation between ammonium δ 15 N and air mass history. If so, ammonium deposition reflects the cycling of N between the ocean and the atmosphere, rather than representing a net input to the ocean. The δ 15 N data appear to require that most of the ammonium/a flux to the ocean is by dissolution in surface waters rather than atmospheric deposition. This suggests that the atmosphere and surface ocean are near equilibrium with respect to air/sea gas exchange, implying that anthropogenic ammonia will equilibrate near the coast and not reach the open marine atmosphere. Whereas~90% of the ammonium deposition to the global ocean has previously been attributed to anthropogenic sources, the evidence at Bermuda suggests that the anthropogenic contribution could be much smaller.

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Field observations of the ocean‐atmosphere exchange of ammonia: Fundamental importance of temperature as revealed by a comparison of high and low latitudes

Cited by 95 publications

References 41 publications

Coupling between dimethylsulfide emissions and the ocean - atmosphere exchange of ammonia

Coupling between dimethylsulfide emissions and the ocean - atmosphere exchange of ammonia

Measurement of ambient NH<sub>3</sub> over Bay of Bengal during W_ICARB Campaign

Isotopic evidence for a marine ammonium source in rainwater at Bermuda

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Field observations of the ocean‐atmosphere exchange of ammonia: Fundamental importance of temperature as revealed by a comparison of high and low latitudes

Cited by 95 publications

References 41 publications

Coupling between dimethylsulfide emissions and the ocean - atmosphere exchange of ammonia

Coupling between dimethylsulfide emissions and the ocean - atmosphere exchange of ammonia

Measurement of ambient NH&lt;sub&gt;3&lt;/sub&gt; over Bay of Bengal during W_ICARB Campaign

Isotopic evidence for a marine ammonium source in rainwater at Bermuda

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Measurement of ambient NH<sub>3</sub> over Bay of Bengal during W_ICARB Campaign