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  • 1
    Electronic Resource
    Electronic Resource
    Contemporary and pre-industrial global reactive nitrogen budgets (1999)
    Springer
    Biogeochemistry 46 (1999), S. 7-43 
    Details
    ISSN: 1573-515X
    Keywords: ammonia emissions ; global nitrogen cycle ; nitric oxide ; nitrogen deposition ; nitrogen pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increases and expansion of anthropogenic emissions of both oxidized nitrogen compounds, NOx, and a reduced nitrogen compound, NH3, have driven an increase in nitrogen deposition. We estimate global NOx and NH3 emissions and use a model of the global troposphere, MOGUNTIA, to examine the pre-industrial and contemporary quantities and spatial patterns of wet and dry NOy and NHx deposition. Pre-industrial wet plus dry NOx and NHx deposition was greatest for tropical ecosystems, related to soil emissions, biomass burning and lightning emissions. Contemporary NOy + NHx wet and dry deposition onto Northern Hemisphere (NH) temperate ecosystems averages more than four times that of pre-industrial N deposition and far exceeds contemporary tropical N deposition. All temperate and tropical biomes receive more N via deposition today than pre-industrially. Comparison of contemporary wet deposition model estimates to measurements of wet deposition reveal that modeled and measured wet deposition for both NO− 3 and NH+ 4 were quite similar over the U.S. Over Western Europe, the model tended to underestimate wet deposition of NO− 3 and NH+ 4 but bulk deposition measurements were comparable to modeled total deposition. For the U.S. and Western Europe, we also estimated N emission and deposition budgets. In the U.S., estimated emissions exceed interpolated total deposition by 3--6 Tg N, suggesting that substantial N is transported offshore and/or the remote and rural location of the sites may fail to capture the deposition of urban emissions. In Europe, by contrast, interpolated total N deposition balances estimated emissions within the uncertainty of each.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006148011944
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  • 2
    Electronic Resource
    Electronic Resource
    Contemporary and pre-industrial global reactive nitrogen budgets (1999)
    Springer
    Biogeochemistry 46 (1999), S. 7-43 
    Details
    ISSN: 1573-515X
    Keywords: ammonia emissions ; global nitrogen cycle ; nitric oxide ; nitrogen deposition ; nitrogen pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increases and expansion of anthropogenic emissions of both oxidized nitrogen compounds, NOx, and a reduced nitrogen compound, NH3, have driven an increase in nitrogen deposition. We estimate global NOx and NH3 emissions and use a model of the global troposphere, MOGUNTIA, to examine the pre-industrial and contemporary quantities and spatial patterns of wet and dry NOy and NHx deposition. Pre-industrial wet plus dry NOx and NHx deposition was greatest for tropical ecosystems, related to soil emissions, biomass burning and lightning emissions. Contemporary NOy+NHx wet and dry deposition onto Northern Hemisphere (NH) temperate ecosystems averages more than four times that of preindustrial N deposition and far exceeds contemporary tropical N deposition. All temperate and tropical biomes receive more N via deposition today than pre-industrially. Comparison of contemporary wet deposition model estimates to measurements of wet deposition reveal that modeled and measured wet deposition for both NO 3 − and NH 4 + were quite similar over the U.S. Over Western Europe, the model tended to underestimate wet deposition of NO 3 − and NH 4 + but bulk deposition measurements were comparable to modeled total deposition. For the U.S. and Western Europe, we also estimated N emission and deposition budgets. In the U.S., estimated emissions exceed interpolated total deposition by 3-6 Tg N, suggesting that substantial N is transported offshore and/or the remote and rural location of the sites may fail to capture the deposition of urban emissions. In Europe, by contrast, interpolated total N deposition balances estimated emissions within the uncertainty of each.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007572
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  • 3
    Electronic Resource
    Electronic Resource
    A three-dimensional model of the global ammonia cycle (1994)
    Springer
    Journal of atmospheric chemistry 19 (1994), S. 331-369 
    Details
    ISSN: 1573-0662
    Keywords: Global model ; emission inventory ; ammonia ; ammonium ; nitrous oxide ; acidity ; canopy compensation point
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Using a three-dimensional (3-D) transport model of the troposphere, we calculated the global distributions of ammonia (NH3) and ammonium (NH 4 + ), taking into account removal of NH3 on acidic aerosols, in liquid water clouds and by reaction with OH. Our estimated global 10°×10° NH3 emission inventory of 45 Tg N-NH3 yr− provides a reasonable agreement between calculated wet NH 4 + deposition and measurements and of measured and modeled NH 4 + in aerosols, although in Africa and Asia especially discrepancies exist. NH3 emissions from natural continental ecosystems were calculated applying a canopy compensation point and oceanic NH3 emissions were related to those of DMS (dimethylsulfide). In many regions of the earth, the pH found in rain and cloud water can be attributed to acidity derived from NO, SO2 and DMS emissions and alkalinity from NH3. In the remote lower troposphere, sulfate aerosols are calculated to be almost neutralized to ammonium sulfate (NH4)2SO4, whereas in the middle and upper troposphere, according to our calculations, the aerosol should be more acidic, as a result of the oxidation of DMS and SO2 throughout the troposphere and removal of NH3 on acidic aerosols at lower heights. Although the removal of NH3 by reaction with the OH radical is relatively slow, the intermediate NH2 radical can provide a substantial annual N2O source of 0.9 −0.4 +0.9 Tg, thus contributing byca. 5% to estimated global N2O production. The oxidation by OH of NH3 from anthropogenic sources accounts for 10% of the estimated total anthropogenic sources of N2O. This source was not accounted for in previous studies, and is mainly located in the tropics, which have high NH3 and OH concentrations. Biomass burning plumes, containing high NO x and NH3 concentrations provide favourable conditions for gas phase N2O production. This source is probably underestimated in this model study, due to the coarse resolution of the 3-D model, and the rather low biomass burning NH3 and NO x emissions adopted. The estimate depends heavily on poorly known concentrations of NH3 (and NO x ) in the tropics, and uncertainties in the rate constants of the reactions NH2 + NO2 → N2O + H2O (R4), and NH2 + O3 → NH2O + O2 (R7).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694492
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