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Sandip Mukhopadhyay

Bio: Sandip Mukhopadhyay is an academic researcher from University of Calcutta. The author has contributed to research in topic(s): Mangrove & Callus. The author has an hindex of 17, co-authored 57 publication(s) receiving 1258 citation(s).
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Journal ArticleDOI
Abstract: The Ganges drains much of the southern slopes of the Himalayas and yields high-suspended sediment load during the monsoon. The Hooghly estuary, the first deltaic offshoot of the Ganges and flows through the western part of the Sundarbans mangrove forest is a source for inorganic nutrients due to the high input of litter and sediment associated nutrients that are released during estuarine transport. Dissolved inorganic carbon (DIC), dissolved inorganic nitrogen (DIN), dissolved reactive phosphate (DRP) and silicate budgets and fluxes of the coastal zone of the Hooghly River system have been done by biogeochemical modeling and their annual fluxes were calculated to be 230 × 10 9 mol (2.76 × 10 6 t), 4705 × 10 6 mol (65.8 × 10 3 t), 415 × 10 6 mol (12.8 × 10 3 t), 15.28 × 10 9 mol (42.8 × 10 3 t), respectively. Out of the total transport, monsoonal runoff could account 64% for DIC, 71% for DIN and 76% for both DRP and silicate. Annual load of sediment out of the estuary to the NE coast of Bay of Bengal was estimated to be 65.19 × 10 6 t. During the estuarine transport 7.5% of DIC and 7.0% of silicate were removed while addition for DIN and DRP were found to be 59% and 44%, respectively. Occurrence of light limited conditions and auto-heterotrophic coupling within the estuary results regeneration of nutrients from organic matter originated from external source. Comparison was made with the estimates of nutrient fluxes through the some mangrove dominated Southeast Asian estuaries.

198 citations


Journal ArticleDOI
Raghab Ray1, Dipnarayan Ganguly1, Chumki Chowdhury1, M. Dey1  +7 moreInstitutions (1)
Abstract: Here we show carbon stock is lower in the tropical mangrove forest than in the terrestrial tropical forest and their annual increase exhibits faster turn over than the tropical forest. Variable for above ground biomass are in decreasing order of importance, breast height diameter ( d ), height ( H ) and wood density ( ρ ). The above ground biomass (AGB) and live below ground biomass (LBGB) held different biomass (39.93 ± 14.05 t C ha −1 versus 9.61 ± 3.37 t C ha −1 ). Carbon accrual to live biomass (4.71–6.54 Mg C ha −1 a −1 ) is more than offset by losses from litter fall (4.85 Mg C ha −1 a −1 ), and carbon sequestration differs significantly between live biomass (1.69 Mg C ha −1 a −1 ) and sediment (0.012 Mg C ha −1 a −1 ). Growth specific analyses of taxon density suggest that changes in resource availability and environmental constrains could be the cause of the annual increase in carbon stocks in the Sundarbans mangrove forest in contrast to the disturbance – recovery hypotheses.

142 citations


Journal ArticleDOI
Haimanti Biswas1, Sandip Mukhopadhyay1, Tarun Kumar De1, Sayan Sen1  +1 moreInstitutions (1)
Abstract: The Sundarban mangrove forest (4,264 km 2 ) constitutes about 3% of the total area of the world mangrove. We measured diurnal and seasonal variations of air‐water CO2 exchange in relation to the occurrence of phytoplankton during January‐December 2001. Diurnal variations of airflows showed that the minimum and maximum CO2 flux of 216.2 mmol m 22 h 21 and 49.9 mmol m 22 h 21 , respectively, occurred during the higher sea breeze. The average ratio of dissolved inorganic nitrogen (DIN 5 13.85 6 7.19 mmol L 21 ) to dissolved inorganic phosphorus (DIP 5 1.23 6 0.57 mmol L 21 ) was 11 6 4 and the surface water was undersaturated with respect to dissolved oxygen. The mean value of 0.1 6 0.08 for the ratio of phytoplankton production (P) to community respiration (R) indicated that the ecosystem was heterotrophic. The saturation of dissolved carbon dioxide with respect to the atmosphere varied seasonally between 59% and 156%, with minimum levels in postmonsoon and maximum levels in premonsoon/early monsoon (June/July). Out of the 36 genera of diatoms, 1 blue green alga, and 3 dinoflagellates that occurred throughout the year, only 6 reached bloom proportions in postmonsoon, when mangrove water was a sink of atmospheric CO2. Although 59.3% of the emitted CO2 was removed from the atmosphere by biological processes, on an annual basis, the Sundarban mangrove forest supplies 13.8 kg C ha 21 yr 21 of CO2 from water surface to the atmosphere. Even though it is important to compare all in and out fluxes, there is no direct link between CO 2 emission and the later CO2 removal by biological processes.

115 citations


Journal ArticleDOI
Abstract: Seasonal and spatial variation of dissolved and atmospheric methane (CH 4 ) was measured in the estuaries of the Sundarban mangrove ecosystem from January to December 2003. This unique mangrove forest ecosystem (9630 km 2 ), a part of the Hooghly–Matla estuarine system (NE coast of Bay of Bengal) comprises about 3% of the total area of the world's mangroves. Dissolved methane concentrations in the mangrove dominated estuarine water (Muriganga, Saptamukhi and Thakuran) were observed between 11.0 and 129.0 nmol L − 1 with emission rates between 1.97 and 134.6 μmol m − 2 d − 1 . Methane emission showed maximum rate during post-monsoon when phytoplankton reached blooming proportion. During post-monsoon materials transported from the mangrove forest could stimulate phytoplankton bloom when transparency of water column was increased and river input of nutrient was low. However, dissolved methane concentrations in the Hooghly estuary, the main river water flushing channel showed lower values between 10.3 and 59.25 nmol L − 1 with emission rates between 0.88 and 148.6 μmol m − 2 d − 1 . Methane concentrations in the salinity gradient zone of the Hooghly estuary did not show any decreasing trend with increased salinity due to its lateral transport from the mangrove forest situated at the lower stretch of the estuary. Dissolved methane concentration in the pore water collected from the virgin mangrove forest showed a maximum concentration of 5769 nmol L − 1 which was considerably lower compared to that of coastal salt marsh, tidal fresh water wetland. This indicated intense oxidation or out competition of methanogenic bacteria by sulfate and nitrate reducing bacteria. Methane emission from the adjacent forest ecosystem (18.36 mmol m − 2 d − 1 ) was higher compared to that in the mangrove water. Considering methane emission rates from the aquatic and forest ecosystems, an area average rate of 47.28 × 10 5 mol km − 2 yr − 1 for Sundarban mangrove environment was obtained. Extrapolating over the global area covered by mangrove forest with area average soil methane emission rate without considering its emission from water could yield inaccurate estimation.

98 citations


Journal ArticleDOI
Sandip Mukhopadhyay1, Haimanti Biswas1, Tarun Kumar De1, Sayan Sen1  +1 moreInstitutions (1)
TL;DR: Monthly variation of CO2 fugacity in surface water and related atmospheric exchanges were measured in the Hooghly estuary to compare with those predicted from seasonal changes in temperature, salinity and the ratio of gross primary production to community respiration using empirical equations.
Abstract: Monthly variation of CO2 fugacity (fCO2) in surface water and related atmospheric exchanges were measured in the Hooghly estuary which is one of the most important estuaries, since it is fed by one of the world's largest rivers, the Ganges with a flow of 15646 m3 s−1 (1.6% of the world's combined river flow). Carbon dioxide fluxes averaged over the entire estuary are in the range of −2.78 to 84.4 mmol m−2 d−1. This estuary acts as a sink for CO2 during monsoon months and seasonal variation of its flux is controlled by dilution of seawater by river water. Since the solubility of CO2 and the disassociation of carbonic acid in estuarine water are controlled by temperature and salinity, the observed variations of CO2 fluxes are compared with those predicted from seasonal changes in temperature, salinity and the ratio of gross primary production to community respiration using empirical equations with an explained variability of 55%.

87 citations


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Journal Article
Abstract: results in a conservative estimate of 218 ± 72 Tg C a 1 . When using the best available estimates of various carbon sinks (organic carbon export, sediment burial, and mineralization), it appears that >50% of the carbon fixed by mangrove vegetation is unaccounted for. This unaccounted carbon sink is conservatively estimated at 112 ± 85 Tg C a 1 , equivalent in magnitude to 30–40% of the global riverine organic carbon input to the coastal zone. Our analysis suggests that mineralization is severely underestimated, and that the majority of carbon export from mangroves to adjacent waters occurs as dissolved inorganic carbon (DIC). CO2 efflux from sediments and creek waters and tidal export of DIC appear to be the major sinks. These processes are quantitatively comparable in magnitude to the unaccounted carbon sink in current budgets, but are not yet adequately constrained with the limited published data available so far.

797 citations


Journal ArticleDOI
Abstract: results in a conservative estimate of 218 ± 72 Tg C a 1 . When using the best available estimates of various carbon sinks (organic carbon export, sediment burial, and mineralization), it appears that >50% of the carbon fixed by mangrove vegetation is unaccounted for. This unaccounted carbon sink is conservatively estimated at 112 ± 85 Tg C a 1 , equivalent in magnitude to 30–40% of the global riverine organic carbon input to the coastal zone. Our analysis suggests that mineralization is severely underestimated, and that the majority of carbon export from mangroves to adjacent waters occurs as dissolved inorganic carbon (DIC). CO2 efflux from sediments and creek waters and tidal export of DIC appear to be the major sinks. These processes are quantitatively comparable in magnitude to the unaccounted carbon sink in current budgets, but are not yet adequately constrained with the limited published data available so far.

783 citations


Journal ArticleDOI
Daniel M. Alongi1Institutions (1)
TL;DR: Of immediate concern are potential carbon losses to deforestation that are greater than these ecosystems' rates of carbon storage, and large reservoirs of dissolved inorganic carbon in deep soils are a large loss of carbon.
Abstract: Mangroves are ecologically and economically important forests of the tropics. They are highly productive ecosystems with rates of primary production equal to those of tropical humid evergreen forests and coral reefs. Although mangroves occupy only 0.5% of the global coastal area, they contribute 10–15% (24 Tg C y−1) to coastal sediment carbon storage and export 10–11% of the particulate terrestrial carbon to the ocean. Their disproportionate contribution to carbon sequestration is now perceived as a means for conservation and restoration and a way to help ameliorate greenhouse gas emissions. Of immediate concern are potential carbon losses to deforestation (90–970 Tg C y−1) that are greater than these ecosystems' rates of carbon storage. Large reservoirs of dissolved inorganic carbon in deep soils, pumped via subsurface pathways to adjacent waterways, are a large loss of carbon, at a potential rate up to 40% of annual primary production. Patterns of carbon allocation and rates of carbon flux in mangrove f...

633 citations


Journal ArticleDOI
01 Aug 2008-Aquatic Botany
Abstract: We review 72 published articles to elucidate characteristics of biomass allocation and productivity of mangrove forests and also introduce recent progress on the study of mangrove allometry to solve the site- and species-specific problems. This includes the testing of a common allometric equation, which may be applicable to mangroves worldwide. The biomass of mangrove forests varies with age, dominant species, and locality. In primary mangrove forests, the above-ground biomass tends to be relatively low near the sea and increases inland. On a global scale, mangrove forests in the tropics have much higher above-ground biomass than those in temperate areas. Mangroves often accumulate large amounts of biomass in their roots, and the above-ground biomass to below-ground biomass ratio of mangrove forests is significantly low compared to that of upland forests (ANCOVA, P

599 citations


Journal ArticleDOI
Abstract: [1] Air-water CO2 fluxes were up-scaled to take into account the latitudinal and ecosystem diversity of the coastal ocean, based on an exhaustive literature survey. Marginal seas at high and temperate latitudes act as sinks of CO2 from the atmosphere, in contrast to subtropical and tropical marginal seas that act as sources of CO2 to the atmosphere. Overall, marginal seas act as a strong sink of CO2 of about −0.45 Pg C yr−1. This sink could be almost fully compensated by the emission of CO2 from the ensemble of near-shore coastal ecosystems of about 0.40 Pg C yr−1. Although this value is subject to large uncertainty, it stresses the importance of the diversity of ecosystems, in particular near-shore systems, when integrating CO2 fluxes at global scale in the coastal ocean.

507 citations


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Performance
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Author's H-index: 17

No. of papers from the Author in previous years
YearPapers
20213
20204
20193
20182
20171
20163

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Author's top 5 most impactful journals

Cytologia

8 papers, 49 citations

Nucleus

4 papers, 15 citations

Atmospheric Environment

3 papers, 237 citations

Tropical Ecology

2 papers, 16 citations