Atmospheric Nitrogen

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Mats Jansson - One of the best experts on this subject based on the ideXlab platform.

Daven K Henze - One of the best experts on this subject based on the ideXlab platform.

  • Atmospheric Nitrogen deposition to the northwestern pacific seasonal variation and source attribution
    Atmospheric Chemistry and Physics, 2015
    Co-Authors: Yuanhong Zhao, Lin Zhang, Yuesi Wang, F Paulot, Daven K Henze
    Abstract:

    Abstract. Rapid Asian industrialization has led to increased downwind Atmospheric Nitrogen deposition threatening the marine environment. We present an analysis of the sources and processes controlling Atmospheric Nitrogen deposition to the northwestern Pacific, using the GEOS-Chem global chemistry model and its adjoint model at 1/2° × 2/3° horizontal resolution over East Asia and its adjacent oceans. We focus our analyses on the marginal seas: the Yellow Sea and the South China Sea. Asian Nitrogen emissions in the model are 28.6 Tg N a−1 as NH3 and 15.7 Tg N a−1 as NOx. China has the largest sources with 12.8 Tg N a−1 as NH3 and 7.9 Tg N a−1 as NOx; the high-NH3 emissions reflect its intensive agricultural activities. We find Asian NH3 emissions are a factor of 3 higher in summer than winter. The model simulation for 2008–2010 is evaluated with NH3 and NO2 column observations from satellite instruments, and wet deposition flux measurements from surface monitoring sites. Simulated Atmospheric Nitrogen deposition to the northwestern Pacific ranges 0.8–20 kg N ha−1 a−1, decreasing rapidly downwind of the Asian continent. Deposition fluxes average 11.9 kg N ha−1 a−1 (5.0 as reduced Nitrogen NHx and 6.9 as oxidized Nitrogen NOy) to the Yellow Sea, and 5.6 kg N ha−1 a−1 (2.5 as NHx and 3.1 as NOy) to the South China Sea. Nitrogen sources over the ocean (ship NOx and oceanic NH3) have little contribution to deposition over the Yellow Sea, about 7 % over the South China Sea, and become important (greater than 30 %) further downwind. We find that the seasonality of Nitrogen deposition to the northwestern Pacific is determined by variations in meteorology largely controlled by the East Asian monsoon and in Nitrogen emissions. The model adjoint further estimates that Nitrogen deposition to the Yellow Sea originates from sources over China (92 % contribution) and the Korean peninsula (7 %), and by sectors from fertilizer use (24 %), power plants (22 %), and transportation (18 %). Deposition to the South China Sea shows source contribution from mainland China (66 %), Taiwan (20 %), and the rest (14 %) from the southeast Asian countries and oceanic NH3 emissions. The adjoint analyses also indicate that reducing Asian NH3 emissions would increase NOy dry deposition to the Yellow Sea (28 % offset annually), limiting the effectiveness of NH3 emission controls on reducing Nitrogen deposition to the Yellow Sea.

  • Atmospheric Nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution
    Atmospheric Chemistry and Physics Discussions, 2015
    Co-Authors: Y. H. Zhao, Lin Zhang, F Paulot, Y. S. Wang, Daven K Henze
    Abstract:

    Abstract. Rapid Asian industrialization has led to increased Atmospheric Nitrogen deposition downwind threatening the marine environment. We present an analysis of the sources and processes controlling Atmospheric Nitrogen deposition to the northwestern Pacific, using the GEOS-Chem global chemistry model and its adjoint model at 1/2° × 2/3° horizontal resolution over the East Asia and its adjacent oceans. We focus our analyses on the marginal seas: the Yellow Sea and the South China Sea. Asian Nitrogen emissions in the model are 28.6 Tg N a−1 as NH3 and 15.7 Tg N a−1 as NOx. China has the largest sources with 12.8 Tg N a−1 as NH3 and 7.9 Tg N a−1 as NOx; the high NH3 emissions reflect its intensive agricultural activities. We find Asian NH3 emissions are a factor of 3 higher in summer than winter. The model simulation for 2008–2010 is evaluated with NH3 and NO2 column observations from satellite instruments, and wet deposition flux measurements from surface monitoring sites. Simulated Atmospheric Nitrogen deposition to the northwestern Pacific ranges 0.8–20 kg N ha−1 a−1, decreasing rapidly downwind the Asian continent. Deposition fluxes average 11.9 kg N ha−1 a−1 (5.0 as reduced Nitrogen NHx and 6.9 as oxidized Nitrogen NOy) to the Yellow Sea, and 5.6 kg N ha−1 a−1 (2.5 as NHx and 3.1 as NOy) to the South China Sea. Nitrogen sources over the ocean (ship NOx and oceanic NH3) have little contribution to deposition over the Yellow Sea, about 7% over the South China Sea, and become important (greater than 30%) further downwind. We find that the seasonality of Nitrogen deposition to the northwestern Pacific is determined by variations in meteorology largely controlled by the East Asian Monsoon and in Nitrogen emissions. The model adjoint further estimates that Nitrogen deposition to the Yellow Sea originates from sources over China (92% contribution) and the Korean peninsula (7%), and by sectors from fertilizer use (24%), power plants (22%), and transportation (18%). Deposition to the South China Sea shows source contribution from Mainland China (66%), Taiwan (20%), and the rest 14% from the Southeast Asian countries and oceanic NH3 emissions. The adjoint analyses also indicate that reducing Asian NH3 emissions would increase NOy dry deposition to the Yellow Sea (28% offset annually), limiting the effectiveness of NH3 emission controls.

Michal Hajek - One of the best experts on this subject based on the ideXlab platform.

  • Atmospheric Nitrogen deposition promotes carbon loss from peat bogs
    Proceedings of the National Academy of Sciences of the United States of America, 2006
    Co-Authors: Luca Bragazza, Hakan Rydin, Juul Limpens, Michal Hajek, Chris Freeman, Timothy G Jones, Nathalie Fenner, T Ellis, Renato Gerdol
    Abstract:

    Peat bogs have historically represented exceptional carbon (C) sinks because of their extremely low decomposition rates and consequent accumulation of plant remnants as peat. Among the factors favoring that peat accumulation, a major role is played by the chemical quality of plant litter itself, which is poor in nutrients and characterized by polyphenols with a strong inhibitory effect on microbial breakdown. Because bogs receive their nutrient supply solely from Atmospheric deposition, the global increase of Atmospheric Nitrogen (N) inputs as a consequence of human activities could potentially alter the litter chemistry with important, but still unknown, effects on their C balance. Here we present data showing the decomposition rates of recently formed litter peat samples collected in nine European countries under a natural gradient of Atmospheric N deposition from ≈0.2 to 2 g·m−2·yr−1. We found that enhanced decomposition rates for material accumulated under higher Atmospheric N supplies resulted in higher carbon dioxide (CO2) emissions and dissolved organic carbon release. The increased N availability favored microbial decomposition (i) by removing N constraints on microbial metabolism and (ii) through a chemical amelioration of litter peat quality with a positive feedback on microbial enzymatic activity. Although some uncertainty remains about whether decay-resistant Sphagnum will continue to dominate litter peat, our data indicate that, even without such changes, increased N deposition poses a serious risk to our valuable peatland C sinks.

  • nutritional constraints in ombrotrophic sphagnum plants under increasing Atmospheric Nitrogen deposition in europe
    New Phytologist, 2004
    Co-Authors: Luca Bragazza, Teemu Tahvanainen, Lado Kutnar, Hakan Rydin, Juul Limpens, Michal Hajek, P Grosvernier, Tomas Hajek, Petra Hajkova, Ina Hansen
    Abstract:

    Nutritional constraints in ombrotrophic Sphagnum plants under increasing Atmospheric Nitrogen deposition in Europe

Eun Ha Choi - One of the best experts on this subject based on the ideXlab platform.

  • Effects of tooth whitening by a cold Atmospheric Nitrogen plasma
    2012 Abstracts IEEE International Conference on Plasma Science, 2012
    Co-Authors: Hye-suk Choi, Jae-sung Kwon, Eun Ha Choi
    Abstract:

    Summary form only given. This study is to verify effects of tooth whitening by a direct-current cold Atmospheric Nitrogen plasma as a light source for tooth whitening. Cold plasma was examined in 35% HP, 5% HP and distilled water, respectively for 20 minutes whereas control group is conducted to examine tooth whitening effect of 35% HP without cold plasma. The result of research showed that color change CIE(L*,a*,b*) are increased as time takes longer in 5 min, 10 min, 15 min and 20 min respectively and statistically it showed significant differences (p<0.01). After 20 min, A group which experiments plasma applied with 35% HP and B group that experiments plasma applied with 5% showed high changes of colors. For the result of comparing surface roughness, significant differences was indicated statistically in each group (p<O.01). A group showed highest surface roughness, followed by D group which was conducted with 35 HP solely. When compared tooth whitening effect before and after experiments by using scanning electron microscope (SEM), the group A showed highest surface roughness, followed by the group D which was conducted tooth whitening with 35 HP solely.

  • Effects of tooth whitening by a cold Atmospheric Nitrogen plasma
    2012 Abstracts IEEE International Conference on Plasma Science, 2012
    Co-Authors: Hye-suk Choi, Jae-sung Kwon, Eun Ha Choi
    Abstract:

    This study is to verify effects of tooth whitening by a direct-current cold Atmospheric Nitrogen plasma as a light source for tooth whitening. Cold plasma was examined in 35% HP, 5% HP and distilled water, respectively for 20 minutes whereas control group is conducted to examine tooth whitening effect of 35% HP without cold plasma. The result of research showed that color change CIE(L*,a*,b*) are increased as time takes longer in 5 min, 10 min, 15 min and 20 min respectively and statistically it showed significant differences (p0.01). After 20 min, A group which experiments plasma applied with 35% HP and B group that experiments plasma applied with 5% showed high changes of colors. For the result of comparing surface roughness, significant differences was indicated statistically in each group (pO.01). A group showed highest surface roughness, followed by D group which was conducted with 35 HP solely. When compared tooth whitening effect before and after experiments by using scanning electron microscope (SEM), the group A showed highest surface roughness, followed by the group D which was conducted tooth whitening with 35 HP solely.

Annkristin Bergstrom - One of the best experts on this subject based on the ideXlab platform.

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