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 studied the contribution of H2S fluxes in the formation of atmospheric aerosol of different size classes (e.g. accumulation, nucleation and coarse mode).
Abstract: Temporal variations in atmospheric hydrogen sulphide concentrations and its biosphere-atmosphere exchanges were studied in the World’s largest mangrove ecosystem, Sundarbans, India. The results were used to understand the possible contribution of H2S fluxes in the formation of atmospheric aerosol of different size classes (e.g. accumulation, nucleation and coarse mode). The mixing ratio of hydrogen sulphide (H2S) over the Sundarban mangrove atmosphere was found maximum during the post-monsoon season (October to January) with a mean value of 0.59 ± 0.02 ppb and the minimum during pre-monsoon (February to May) with a mean value of 0.26 ± 0.01 ppb. This forest acted as a perennial source of H2S and the sediment-air emission flux ranged between 1213 ± 276 μg S m−2 d−1(December) and 457 ± 114 μg S m−2 d−1 (August) with an annual mean of 768 ± 240 μg S m−2d−1. The total annual emissions of H2S from the Indian Sundarban were estimated to be 1.2 ± 0.6 Tg S. The accumulation mode of aerosols was found to be more enriched with non-sea salt sulfate with an average loading of 5.74 μg m−3 followed by the coarse mode (5.18 μg m−3) and nucleation mode (1.18 μg m−3). However, the relative contribution of Non-sea salt sulfate aerosol to total sulfate aerosol was highest in the nucleation mode (83%) followed by the accumulation (73%) and coarse mode (58%). Significant positive relations between H2S flux and different modes of NSS indicated the likely link between H2S, a dominant precursor for the non-sea salt sulfate, and non-sea sulfate aerosol particles. An increase in H2S emissions from the mangrove could result in an increase in enhanced NSS in aerosol and associated cloud albedo, and a decrease in the amount of incoming solar radiation reaching the Sundarban mangrove forest.
5 citations
TL;DR: Bacterioplankton abundances in three major estuaries of the Indian Sundarbans (Saptamukhi, Thakuran and Matla) were determined by flow cytometry and fluorescence microscopy in a post-monsoonal study followed by microbial community composition (16S rRNA clone library) during the period 2012-2016 as mentioned in this paper.
Abstract: Bacterioplankton abundances in three major estuaries of the Indian Sundarbans (Saptamukhi, Thakuran and Matla) were determined by flow cytometry and fluorescence microscopy in a post-monsoonal study followed by microbial community composition (16S rRNA clone library), during the period 2012–2016 All three estuaries were oxygenated and meso - to polyhaline They had similar levels of dissolved inorganic carbon and nutrients and were net heterotrophic, as evidenced by net negative community productivity Mean post-monsoon bacterioplankton abundances (x 109 cells L−1) in these estuaries were: Saptamukhi (130 ± 078 × 109 cells L−1); Matla (138 ± 134 × 109 cells L−1); Thakuran, (092 ± 046 × 109 cells L1) Bacterioplankton abundance was associated with water temperature coupled with dissolved inorganic nutrients and carbonate parameters Highest abundances were at the most upstream sites in the Saptamukhi and Matla estuaries, while a mid-estuarine peak was evident in Thakuran In the Saptamukhi and Thakuran the bacterioplankton was dominated by Proteobacteria (mostly Deltaproteobacteria), with a contribution from Bacteroidetes in the Saptamukhi and from Cyanobacteria and Actinobacteria in the Thakuran Despite the oxygenated nature of these estuaries, clones resembling the sulfate reducer Desulfovibrio sp were detected, and this could be a consequence of anoxic pore water exchange across the sediment-water interface Sulfate reduction may thus be an important pathway for carbon metabolism in these ecosystems
3 citations
TL;DR: The NO2 exchange fluxes were larger in a range of temperatures close to 44°C in the fast-growing stage, whereas there were no evident differences in NO2 exchanged fluxes under widely differing temperatures in the later growth stage.
Abstract: Nitrogen dioxide (NO2) is an important substance in atmospheric photochemical processes and can also be absorbed by plants. NO2 fluxes between the atmosphere and P. nigra seedlings were investigated by a double dynamic chambers method in Beijing from June 15 to September 3, 2017. The range of NO2 exchange fluxes between P. nigra seedlings and the atmosphere was from − 14.6 to 0.8 nmol/(m2·sec) (the positive data represent NO2 emission from trees, while the negative values indicate absorption). Under ambient concentrations, the mean NO2 flux during the fast-growing stage (Jun. 15–Aug. 4) was − 3.0 nmol/(m2·sec), greater than the flux of − 1.5 nmol/(m2·sec) during the later growth stage (Aug. 8–Sept. 3). The daily exchange fluxes of NO2 obviously fluctuated. The fluxes were largest in the morning and decreased gradually over time. Additionally, the NO2 fluxes were larger under high light intensities than under low light intensities during the whole growth period. The effects of temperature on NO2 fluxes were different under two growth periods. The NO2 exchange fluxes were larger in a range of temperatures close to 44°C in the fast-growing stage, whereas there were no evident differences in NO2 exchange fluxes under widely differing temperatures in the later growth stage. Under polluted conditions, the uptake ability of NO2 was weakened. Additionally, the compensation point of NO2 was 5.6 ppb in the fast-growing stage, whereas it was 1.4 ppb in the later growth stage. The deposition velocities of NO2 were between 0.3 and 2.4 mm/sec.
3 citations
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Book•
31 Mar 1980
TL;DR: In this article, the authors focus on one major aspect of cloud microphysics, which involves the processes that lead to the formation of individual cloud and precipitation particles, and provide an account of the major characteristics of atmospheric aerosol particles.
Abstract: Cloud physics has achieved such a voluminous literature over the past few decades that a significant quantitative study of the entire field would prove unwieldy. This book concentrates on one major aspect: cloud microphysics, which involves the processes that lead to the formation of individual cloud and precipitation particles. Common practice has shown that one may distinguish among the following additional major aspects: cloud dynamics, which is concerned with the physics responsible for the macroscopic features of clouds; cloud electricity, which deals with the electrical structure of clouds and the electrification processes of cloud and precipitation particles; and cloud optics and radar meteorology, which describe the effects of electromagnetic waves interacting with clouds and precipitation. Another field intimately related to cloud physics is atmospheric chemistry, which involves the chemical composition of the atmosphere and the life cycle and characteristics of its gaseous and particulate constituents. In view of the natural interdependence of the various aspects of cloud physics, the subject of microphysics cannot be discussed very meaningfully out of context. Therefore, we have found it necessary to touch briefly upon a few simple and basic concepts of cloud dynamics and thermodynamics, and to provide an account of the major characteristics of atmospheric aerosol particles. We have also included a separate chapter on some of the effects of electric fields and charges on the precipitation-forming processes.
5,427 citations
1,809 citations
TL;DR: In this article, two important aerosol species, sulfate and organic particles, have large natural biogenic sources that depend in a highly complex fashion on environmental and ecological parameters and therefore are prone to influence by global change.
Abstract: Atmospheric aerosols play important roles in climate and atmospheric chemistry: They scatter sunlight, provide condensation nuclei for cloud droplets, and participate in heterogeneous chemical reactions. Two important aerosol species, sulfate and organic particles, have large natural biogenic sources that depend in a highly complex fashion on environmental and ecological parameters and therefore are prone to influence by global change. Reactions in and on sea-salt aerosol particles may have a strong influence on oxidation processes in the marine boundary layer through the production of halogen radicals, and reactions on mineral aerosols may significantly affect the cycles of nitrogen, sulfur, and atmospheric oxidants.
1,589 citations
Book•
03 Feb 1984
TL;DR: In this article, an up-to-date summary of the current knowledge of the statistical characteristics of atmospheric turbulence and an introduction to the methods required to apply these statistics to practical engineering problems is presented.
Abstract: Presents, in a single volume, an up-to-date summary of the current knowledge of the statistical characteristics of atmospheric turbulence and an introduction to the methods required to apply these statistics to practical engineering problems. Covers basic physics and statistics, statistical properties emphasizing their behavior close to the ground, and applications for engineers.
1,138 citations
TL;DR: A significant suppression of the global land-carbon sink is found as increases in ozone concentrations affect plant productivity, and the resulting indirect radiative forcing by ozone effects on plants could contribute more to global warming than the direct radiativeforcing due to tropospheric ozone increases.
Abstract: The evolution of the Earth's climate over the twenty-first century depends on the rate at which anthropogenic carbon dioxide emissions are removed from the atmosphere by the ocean and land carbon cycles. Coupled climate-carbon cycle models suggest that global warming will act to limit the land-carbon sink, but these first generation models neglected the impacts of changing atmospheric chemistry. Emissions associated with fossil fuel and biomass burning have acted to approximately double the global mean tropospheric ozone concentration, and further increases are expected over the twenty-first century. Tropospheric ozone is known to damage plants, reducing plant primary productivity and crop yields, yet increasing atmospheric carbon dioxide concentrations are thought to stimulate plant primary productivity. Increased carbon dioxide and ozone levels can both lead to stomatal closure, which reduces the uptake of either gas, and in turn limits the damaging effect of ozone and the carbon dioxide fertilization of photosynthesis. Here we estimate the impact of projected changes in ozone levels on the land-carbon sink, using a global land carbon cycle model modified to include the effect of ozone deposition on photosynthesis and to account for interactions between ozone and carbon dioxide through stomatal closure. For a range of sensitivity parameters based on manipulative field experiments, we find a significant suppression of the global land-carbon sink as increases in ozone concentrations affect plant productivity. In consequence, more carbon dioxide accumulates in the atmosphere. We suggest that the resulting indirect radiative forcing by ozone effects on plants could contribute more to global warming than the direct radiative forcing due to tropospheric ozone increases.
913 citations