Biosphere-atmosphere exchange of NOx in the tropical mangrove forest
TL;DR: In this paper, the Sundarban mangrove forest along the northeast coast of the Bay of Bengal, India, showed uptake rate of −0.84 to −1.63 ng N m−2 s−1 during the day and both uptake and emission rates of − 0.36 to 5.19 ng Nm−2 S−1 in the night from September to February.
Abstract: [1] Biosphere-atmosphere exchange of NOx at the Sundarban mangrove forest along the northeast coast of the Bay of Bengal, India, showed uptake rates of −0.84 to −1.63 ng N m−2 s−1 during the day and both uptake and emission rates of −0.36 to 5.19 ng N m−2 s−1 during the night from September to February. However, during the period from March to August, NOx emission ranged between 0.34 and 2.13 ng N m−2 s−1 and 0.88 and 3.26 ng N m−2 s−1 in daytime and nighttime, respectively. During the postmonsoon period, NOx uptake could be attributed to mangrove stomatal activity during the day. Mangroves absorbed nitrogen from both the soil and the atmosphere. Seasonal and diurnal variability of NOx and O3 is partly due to plant growth in the postmonsoon period. In addition to the NOx-O3 photochemical cycle, stomatal uptake of NOx could also be an important process for keeping a low-ozone state at the land-ocean boundary of the northeast coast of the Bay of Bengal.
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TL;DR: In this paper, the authors used a box model approach to assess the nitrogen budget in the Sundarban mangrove ecosystem, which acts as a sink for atmospheric nitrogen in terms of NOx, NH3, N2, and water column dissolved inorganic nitrogen.
56 citations
TL;DR: In this article, the distribution and exchange fluxes of methane (CH4) were measured in a mangrove vegetated island and its bordering estuarine system of the Sundarbans biosphere from June 2010 to December 2011 on monthly basis.
47 citations
TL;DR: In this paper, a ship-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed within the SHIVA campaign on board RV Sonne in the South China and Sulu Sea.
35 citations
TL;DR: In this paper, the capacity of world's largest mangrove, the Sundarbans (Indian part) to sequester anthropogenic CO 2 emitted from the proximate coal-based thermal power plant in Kolaghat (∼100 km away from mangroves site).
34 citations
TL;DR: In this article, the relative changes in present level of reservoirs organic carbon contents in response to the future increase of atmospheric carbon dioxide were examined in the Avicennia-dominated mangrove forest at the land-ocean boundary of the northeast coast of the Bay of Bengal.
Abstract: Because of the difficulties in setting up arrangements in the intertidal zone for free-air carbon dioxide enrichment experimentation, the responses to increasing atmospheric carbon dioxide in mangrove forests are poorly studied. This study applied box model to overcome this limitation, and the relative changes in present level of reservoirs organic carbon contents in response to the future increase of atmospheric carbon dioxide were examined in the Avicennia- dominated mangrove forest at the land–ocean boundary of the northeast coast of the Bay of Bengal. The above- and below-ground biomass (AGB+BGB) and sediment held different carbon stock (53.20±2.87Mg C ha −1 (mega gram carbon per hectare) versus 18.52±2.77Mg C ha −1 ). Carbon uptake (0.348mg C m −2 s −1 ) is more than offset by losses from plant emission (0.257mg C m −2 s −1 ), and litter fall (13.52µg C m −2 s −1 ) was more than soil CO 2 and CH 4 emission (8.36 and 1.39µg C m −2 s −1 , respectively). Across inventory plots, Sundarban mangrove forest carbon storage in above- and below-ground live trees and soil increased by 18.89 and 5.94Mg C ha −1 between June 2009 and December 2011. Box model well predicted the dynamics of above- and below-ground biomass and soil organic carbon, and increasing atmospheric carbon dioxide concentrations could be the cause of 1.1- and 1.57-fold increases in carbon storage in live biomass and soil, respectively, across Sundarban mangrove forest rather than recovery from past disturbances. Keywords: carbon stock, CO 2 sensitivity, box model, mangrove forest, India (Published: 23 April 2013) Citation: Tellus B 2013, 65 , 18981, http://dx.doi.org/10.3402/tellusb.v65i0.18981
33 citations
References
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TL;DR: In this article, air quality measurements in the rural Upper Green River Basin, Wyoming, show rapid, diurnal photochemical production of ozone during air temperatures as low as −17 ∘C.
Abstract: Photochemical ozone production near the Earth’s surface is considered to be a summertime, urban phenomenon. However, air-quality measurements in the rural Upper Green River Basin, Wyoming, show rapid, diurnal photochemical production of ozone during air temperatures as low as −17 ∘C.
177 citations
TL;DR: Patterns of nitrogen trace gas emissions, soil nitrogen flux, and nutrient availability were evaluated at five sites that form a chronosequence in Hawaiian montane rain forest, finding high N{sub 2}O emissions were associated with high soil N transformation rates.
Abstract: Patterns of nitrogen trace gas emissions, soil nitrogen flux, and nutrient availability were evaluated at five sites that form a chronosequence in Hawaiian montane rain forest. The estimated age of basaltic parent material from which soils developed at the Kilauea site was 200 yr, 6000 yr at the Puu Makaala site, 185000 yr at the Kohala site, 1.65 x 10{sup 6} yr at the Molokai site, and 4.5 x 10{sup 6} yr at the Kauai site. Peak net N mineralization and nitrification values were found in soils from the 185000-yr-old Kohala site. Nitrogen content of foliage and leaf litter was highest in the intermediate age sites (Puu Makaala and Kohala) and N and P retranslocation was lowest at the Puu Makaala site. Soil cores fertilized with nitrogen had significantly higher rates of root ingrowth than control cores at the two youngest sites (200 and 6000 yr old) but not in older sites (185000 and 4.5 x 10{sup 6}-yr-old sites) and total fine root growth into control cores was greatest at the Kohala site. The highest N{sub 2}O emissions were found at the 185000-yr-old Kohala site, while the highest combined flux of N{sub 2}O + NO was observed at the 4.5more » x 10{sup 6}-yr-old Kauai site. While overall N{sub 2}O emission rates were correlated with rates of N transformations, soil water content appeared to influence the magnitude of emissions of N{sub 2}O and the ratios of emissions of NO vs. N{sub 2}O. N{sub 2}O emissions occurred when water-filled pore space (WFPS) values were >40%, with highest emissions in at least two sites observed at WFPS values of 75%. Among sites, high N{sub 2}O emissions were associated with high soil N transformation rates. Large NO fluxes were observed only at the Kauai site when WFPS values were <60%. 50 refs., 8 figs., 4 tabs.« less
156 citations
TL;DR: In this paper, the photostationary state (PSS) involving NO, NO2, and O3 has been studied at a site located in the Colorado mountains, and the results indicate that an additional oxidant OX other than O3 is converting NO to NO2.
Abstract: The photostationary state (PSS) involving NO, NO2, and O3 has been studied at a site located in the Colorado mountains. During the daytime in summer the concentration of NO2 relative to the concentration of NO is greater than expected from the PSS. These results indicate that an additional oxidant OX other than O3 is converting NO to NO2. The level of OX depends on season, NOx (NO + NO2) concentration, and solar UV intensity. The maximum OX levels occur for an NOx mixing ratio of about 0.4 parts per billion by volume (ppbv). For NOx mixing ratios below 0.1 ppbv, no substantial imbalance in the PSS is observed. For NOx concentrations between 0.25 and 1.0 ppbv, the OX level depends linearly on solar UV intensity. In the winter the level of OX is much lower than in the summer for all NOx concentrations and solar UV intensities. The nature of OX, as indicated from the NOx-catalyzed formation of O3, is examined.
121 citations
TL;DR: In this paper, the authors found that the NO2 flux to the leaves of spruce needles increased linearly with increasing NO2 concentrations, and that the internal resistances for NO2 influx can largely be explained by light dependent changes in shoot conductance.
Abstract: summary
When spruce (Picea abies L., Karst.) branches were exposed to 5.2–18.7 nl NO2 l−1the flux to the shoots increased linearly with increasing NO2 concentrations. At NO2 concentrations below 2.6 nl l−1uptake of NO2 by the shoots was not observed. The measured flux of NO2 to the shoots was found to be lower than the NO2 flux predicted from the shoot conductance to diffusion of H2O. These results are consistent with the existence of internal resistances for NO2 influx, e.g. production and emission of NO2 by the leaves. However, emission of NO2 was not observed. When the NO2 flux to the shoots was plotted versus transpiration rate, a linear increase was found with an y-axis intercept. The intercept may be interpreted as the NO2 flux to the cuticle and the bark; its value increased with increasing atmospheric NO2 concentrations.
The flux of NO2 to the shoots showed diurnal variation with high levels in the light and low levels during darkness. NO2 flux to the branches was dependent on light intensity. This dependency can largely be explained by light dependent changes in shoot conductance. Daytime light intensity determined also the night-time shoot conductance and, hence, the NO2 flux to the branches during the night. The ratio of NO2 flux to transpiration rate was higher in the dark than in the light. Whether this observation can be explained by a light dependency of internal resistances remains to be elucidated.
The absorption of NO2 by the shoots enhanced the in vitro NR activity of the needles, while NiR and GS activities were not increased significantly. One day after exposure to NO2 concentrations of 60 nl l−1, nitrate reductase (NR) activity was three times higher than that of untreated controls. However, after three days of NO2 exposure the NR activity declined to the level of untreated controls. Apparently, the increased in vitro NR activity upon NO2 fumigation is a transient phenomenon in spruce needles. The regulatory events that may modulate NR activity of the needles, when exposed to atmospheric NO2, are discussed.
116 citations
TL;DR: In this article, the contribution of atmospheric NH3 and NO2 deposition to the N budget of the whole plant has been calculated for various atmospheric pollutant concentrations and relative growth rates (RGRs), and it is concluded that at current ambient atmospheric N concentrations the direct impact of gaseous N uptake by foliage on plant growth is generally small.
Abstract: Dry deposition of NH3 and NOx (NO and NO2) can affect plant metabolism at the cellular and whole-plant level. Gaseous pollutants enter the plant mainly through the stomata, and once in the apoplast NH3 dissolves to form NH4+, whereas NO2 dissolves to form NO3- and NO2-. The latter compound can also be formed after exposure to NO. There is evidence that NH3-N and NOx-N can be reversibly stored in the apoplast. Temporary storage might affect processes such as absorption rate, assimilation and re-emission. Once formed, NO3- and NO2- can be reduced, and NH4+ can be assimilated via the normal enzymatic pathways, nitrate reductase (NR), nitrite reductase and the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle. Fumigation with ion; concentrations of atmospheric NH3 increases in vitro glutamine synthetase activity, but whether this involves both or only one of the GS isoforms is still an open question. There seems to be no correlation between fumigation with low concentrations of NH3 and in vitro GDH activity. The contribution of atmospheric NH3 and NO2 deposition to the N budget of the whole plant has been calculated for various atmospheric pollutant concentrations and relative growth rates (RGRs). It is concluded that at current ambient atmospheric N concentrations the direct impact of gaseous N uptake by foliage on plant growth is generally small.
110 citations