Raghab Ray

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

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−2s−1) is more than offset by losses from plant emission (0.257mg C m−2s−1), and litter fall (13.52µg C m−2s−1) was more than soil CO2 and CH4 emission (8.36 and 1.39µg C m−2s−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.

Implication of organic matter on arsenic and antimony sequestration in sediment: evidence from Sundarban mangrove forest, India.

This study reports the measurement of stability constants for the interaction of As (V and III) and Sb (V and III) with humic substances extracted from aquatic sediments of the Sundarban mangrove forest ecosystem. It was observed that As and Sb formed a slightly more stable association with fulvic acid (FA) than with its humic acid (HA) counterpart. Quenching of fluorescence at increasing As (III and V) or Sb (III and V): FA or HA ratios was obtained that ideally correspond to a 1:1 complexation model. Quite strong complexation of As and Sb by FA and HA occurs at neutral pH, indicating that HA and FA probably markedly affect the mobility of As and Sb in the mangrove environment.

Microbial Ecosystem in Sunderban Mangrove Forest Sediment, North-East Coast of Bay of Bengal, India

This is the first documentation of seasonal and spatial fluctuation of the culturable microbial population collected from different zones in the sediment of the Sunderban mangrove forest. The population of cellulose degrading bacteria, [mean value of CFU 6.189 ± 1.025 × 106 (g dry weight of sediment)−1] was found to be maximum during post monsoon in the deep forest region, whereas, the fungal population [mean value of CFU 3.424 ± 0.886 × 106 (g dry weight of sediment)−1] was found to be maximum during pre-monsoon in the rooted region. The abundances of microbes, in decreasing order, studied from different zones are nitrifying bacteria [mean value of CFU 1.125 ± 0.359 × 106 (g dry weight of sediment)−1], phosphorous solubilizing bacteria (PSB) [mean value of CFU 0.805 ± 0.322 × 106 (g dry weight of sediment)−1], free living nitrogen fixing bacteria [mean value of CFU 0.417 ± 0.120 × 106 (g dry weight of sediment)−1] and sulfur reducing bacteria (SRB) [mean value of CFU 0.356 ± 0.125 × 106 (g dry weight of sediment)−1]. The content of organic carbon in the soil decreased from the deep forest region to the rooted and unrooted region but a reverse profile was found for soil salinity and soil silicate concentration. The results from the present study indicate that the monsoon cycle has a pronounced effect on the microbially dominated biogeochemistry in the sediment and consequently on the ecology of the Sundarban mangrove forest.

Wood chemistry and density: An analog for response to the change of carbon sequestration in mangroves

This study aimed to resolve the variations of physical and chemical properties of wood records measured in different mangroves with their annual carbon sequestration. The methods of investigation used were to examine growth rate by monitoring breast height diameter, wood chemistry and density, FTIR spectroscopy and thermogravimetry. Carbon sequestration rate showing an increase with density varied between 0.088 and 0.171 μg C kg(-1) AGB s(-1), and Avicennia marina showed the maximum value and Bruguiera gymnorrhiza, the minimum. The changes in FTIR bands at 4000-2500 cm(-1) and 1700-800 cm(-1) were correlated to the variations in cellulose in mangrove woods and lignin to cellulose ratio ranged between 0.21 and 1.75. Thermal analyses of mangrove wood suggested that the fuel value index (985-3922) exhibited an increase with the decrease in maximum decomposition temperature and density. The seasonal variation of temperature and CO2 were likely to affect chemical properties through changes in wood density.

Quantitative Study of As (V) and As (III) Interaction with Mangrove DNA by Molecular Fluorescence Spectroscopy

This study describes the in vitro study of (1:1) one step nucleophilic displacement (

Level of Heavy Metals in Some Edible Marine Fishes of Mangrove Dominated Tropical Estuarine Areas of Hooghly River, North East Coast of Bay of Bengal, India

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Phytoplankton abundance in relation to cultural eutrophication at the land-ocean boundary of Sunderbans, NE Coast of Bay of Bengal, India

SN1) of phosphate by heavier anion arsenate and arsenite in the DNA of arsenic ridden Sundarban mangroves. Mangrove DNA was found to give rise to a broad fluorescence and its integrated fluorescence intensity was enhanced on addition of As (V) and As (III), respectively. Analyses of the fluorescence parameter showed adequacy of 1:1 model to describe substitution of phosphate of mangrove DNA chain exiplex by arsenate and arsenite with equilibrium constant (log Kc) ranging between 4.19 and 4.32 for As (V), and between 3.77 and 3.89 for As (III) at pH 7 and 25°C. In the cases, the melting temperature (Tm) and reassociation rate constant of mangrove DNA was increased on treatment with As (V) and As (III). It is suggested that heavier ion arsenate and arsenite may substitute phosphate in natural DNA.