Biosphere-atmosphere exchange of NOx in the tropical mangrove forest

Biogeochemical cycle of nitrogen in a tropical mangrove ecosystem, east coast of India

Abstract: Like many coastal systems, nitrogen is the critical limiting factor for mangrove net production. This study 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. The coupling of biosphere and atmosphere in terms of atmospheric NOx and NH3 uptake showed that uptake of ammonia (130 × 106 mol yr− 1) was about six fold as large as that of NOx, (22 × 106 mol yr− 1). The nitrogen stored by the processes such as plant uptake of NOx, NH3 from the atmosphere, nitrogen fixation (5 × 109 mol yr− 1), and sediment water exchange (8 × 106 mol yr− 1) was about two times as large as that of recycled nitrogen from litter (3 × 109 mol yr− 1), and could account 74% of the nitrogen required for mangrove net production. Most of the nitrogen was conserved in the living biomass (living biomass: 118 × 103 mol ha− 1 versus soil: 3 × 103 mol ha− 1). The loss of nitrogen was 23% of the total amount that was conserved from the external sources in the Sundarban mangrove system. Thus, the coastal ecosystem like Sundarban mangroves could retain only 0.2% (8 × 106 mol) of the annual river flux of nitrogen to the coastal waters and nitrogen is generally conserved within the system.

Dynamics and exchange fluxes of methane in the estuarine mangrove environment of the Sundarbans, NE coast of India

Abstract: The distribution and exchange fluxes of methane (CH4) were measured in a mangrove vegetated island and its bordering estuarine system of the Sundarbans mangrove biosphere from June 2010 to December 2011 on monthly basis. The onset of methane production is evident in the forest sediment at about 25 cm deep sediment layer under strong redox condition having an average Eh value of −175.7 mV and showing a 2.8 folds increase in the pore water dissolved methane concentration at that depth in comparison to the surface layer. The average diffusive flux of methane from this methane producing layer to surface was calculated to be 591 ± 106 nmol m−2 d−1. The depth profiles of NO2−–N, SO4−2–S, acid volatile sulphide, organic carbon and dissolved methane in the sediment cores from inter-tidal zones showed distinct trends representing signatures of denitrification, sulfate reduction and methanogenesis in the sediment layers. The methane emission from the sediment–atmosphere interface was observed to be maximum during monsoon and higher emission rates was recorded from upper littoral zone. The annual average atmospheric methane mixing ratio was 2.038 ± 0.07 ppmv. This mangrove biosphere was found to act as source for methane during monsoon while as sink during pre and postmonsoon seasons. Estuarine surface water showed a very high degree of super saturation about 2748 ± 730% for dissolved methane at an annual basis and act as a significant source of methane having an annual average exchange flux of 408 ± 110 nmol m−2 h−1. A box model approach has been adopted at annual basis to understand the distribution and dynamics of methane in this mangrove environment.

Ship-based MAX-DOAS measurements of tropospheric NO2 and SO2 in the South China and Sulu Sea

Abstract: In November 2011, 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. Spectral measurements for a total of eleven days could be used to retrieve tropospheric slant column densities (SCDs) of nitrogen dioxide (NO2) and sulfur dioxide (SO2) in the marine environment. The NO2 fit was performed following recommendations developed during the CINDI campaign and adapted for the ship-based measurements. We found that the inclusion of a cross section for liquid water and an empirical correction spectrum accounting for the effects of liquid water and vibrational Raman scattering (VRS) slightly improved the NO2 fit quality, especially at lower elevation angles and for lower NO2 levels. The conversion of SCDs into tropospheric NO2 vertical columns (TVC NO2) has been achieved using both a simple geometric approach and the Bremian advanced MAX-DOAS Retrieval Algorithm (BREAM), which is based on the optimal estimation method and accounts for atmospheric radiative transfer. We found good agreement between the geometric approach using the 15

Carbon sequestration by mangrove forest: One approach for managing carbon dioxide emission from coal-based power plant

Abstract: Mangroves are known as natural carbon sinks, taking CO 2 out of the atmosphere and store it in their biomass for many years. This study aimed to investigate 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 mangrove site). Study also includes Kolkata, one of the largest metropolises of India (∼150 km away from mangrove site) for comparing micrometeorological parameters, biosphere-atmosphere CO 2 exchange fluxes and atmospheric pollutants between three distinct environments: mangrove-power plant-metropolis. Hourly sampling of atmospheric CO 2 in all three sites (late December 2011 and early January 2012) revealed that CO 2 concentrations and emission fluxes were maximum around the power plant (360–621 ppmv, 5.6–56.7 mg m −2 s −1 respectively) followed by the metropolis (383–459 ppmv, 3.8–20.4 mg m −2 s −1 respectively) and mangroves (277–408 ppmv, −8.9–11.4 mg m −2 s −1 , respectively). Monthly coal consumption rates (41–57, in 10 4 ton month −1 ) were converted to CO 2 suggesting that 2.83 Tg C was added to the atmosphere in 2011 for the generation of 7469732 MW energy from the power plant. Indian Sundarbans (4264 km 2 ) sequestered total of 2.79 Tg C which was 0.64% of the annual fossil fuel emission from India in the same time period. Based on these data from 2010 to 2011, it is calculated that about 4328 km 2 mangrove forest coverage is needed to sequester all CO 2 emitted from the Kolaghat power plant.

Improved model calculation of atmospheric CO 2 increment in affecting carbon stock of tropical mangrove forest

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

Microphysics of Clouds and Precipitation

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.

Atmospheric aerosols: Biogeochemical sources and role in atmospheric chemistry

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.

Atmospheric Turbulence: Models and Methods for Engineering Applications

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.

Indirect radiative forcing of climate change through ozone effects on the land-carbon sink

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.