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

Dutta, Manab Kumar; Chowdhury, Chumki; Jana, T. K.; Mukhopadhyay, Sandip

doi:10.1016/j.atmosenv.2013.05.050

Cited by 53 publications

(34 citation statements)

References 36 publications

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“…Such extreme differences sediment redox potential across different mangrove systems can typically be attributed to the geological setting (sediment porosity, organic matter supply), ecological factors (floral and faunal activities), hydrologic regime (tidal inundation and flushing). Past work has shown that methanogensis typically occurs at a redox of < −150 mV (Wang et al, 1993) similar to values observed in Lothian Island sediments (at depth of 10-25 cm), consistent with our previous work Dutta et al (2013). Surface sediment SO 2− 4 -S concentrations ranged from 15.36 to 25.07 mM, with a mean of 20.54 ± 4.89 mM (Figure 3).…”

Section: Sediment Geochemistry In the Mangroves Of Lothian Islandsupporting

confidence: 76%

“…Collection and analysis of dissolved CH 4 concentration and CH 4 oxidation rates, in the Saptamukhi River estuarine waters, were performed according to the methods described by Dutta et al (2013) and Dutta et al (2015a), respectively; replicates were found to be within 2.30-3.14%. CH 4 fluxes across the air-water interface were calculated based on the wind speed parametization of the gas transfer velocity (k), using the following expression: (Liss and Merlivat, 1986).…”

Section: Analysis Of Estuarine Water Samples and Water-atmosphere Ch mentioning

confidence: 99%

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Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget

2017

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Biogeochemical cycling of CH 4 was investigated at Lothian Island, one of the relatively pristine islands of Indian Sundarbans and its adjacent Saptamukhi estuary, during June 2010 to December 2012. Intertidal mangrove sediments were highly anoxic and rich in organic carbon. Mean rates of methanogenesis were 3,547 and 48.88 µmol m −3 wet sediment d −1 , for intertidal (up to 25 cm depth) and sub-tidal sediments (first 5 cm depth), respectively. CH 4 in pore-water was 53.4 times more supersaturated than in adjacent estuarine waters. This resulted in significant CH 4 efflux from sediments to estuarine waters-via advective and diffusive transport. About 8.2% of the total CH 4 produced in intertidal mangrove sediments was transported to the adjacent estuary through advective flux, which was 20 times higher than diffusive CH 4 flux. Mean CH 4 concentrations in estuarine surface and sub-surface waters were 69.9 and 56.1 nM, respectively, with a dissolved CH 4 oxidation rate in estuarine surface waters of 20.5 nmol L −1 d −1 . An estimated 0.09 Gg year −1 of CH 4 is released from estuaries of Sundarbans to the regional atmosphere. The mean CH 4 mixing ratio over the forest atmosphere was 2 ppmv. On annual basis, only 2.75% of total supplied CH 4 to the forest atmosphere was transported to the upper atmosphere via biosphere-atmosphere exchange. Mean CH 4 photo-oxidation rate over the forest atmosphere was 3.25 × 10 −9 mg cm −3 d −1 . Using new and previously published data we present for the first time, a CH 4 budget for Sundarbans mangrove ecosystem which in part, revealed the existence of anaerobic CH 4 oxidation in the mangrove sediment column.

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Section: Sediment Geochemistry In the Mangroves Of Lothian Islandsupporting

confidence: 76%

Section: Analysis Of Estuarine Water Samples and Water-atmosphere Ch mentioning

confidence: 99%

Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget

2017

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“…They are highly productive terrestrial ecosystems with high rates of carbon sequestration. While there have been a large number of studies investigating these ecosystems (Alongi et al 2005;Allen et al 2007;Chen et al 2010Chen et al , 2012Chen et al , 2014Dutta et al 2013;Leopold et al 2013Leopold et al , 2015, GHG emissions in this environment remain poorly understood. Mangrove-associated carbon sequestration is currently recognized as a means for ameliorating GHG emissions (Alongi 2014).…”

Section: Introductionmentioning

confidence: 99%

Temporal and spatial variations of greenhouse gas fluxes from a tidal mangrove wetland in Southeast China

Wang

Liao

Dsouza

et al. 2015

Environ Sci Pollut Res

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Tidal mangrove wetlands are a source of methane (CH4) and nitrous oxide (N2O); but considering the high productivity of mangroves, they represent a significant sink for carbon dioxide (CO2). An exotic plant Spartina alterniflora has invaded east China over the last few decades, threatening these coastal mangrove ecosystems. However, the atmospheric gas fluxes in mangroves are poorly characterized and the impact of biological invasion on greenhouse gas (GHG) fluxes in the wetland remains unclear. In this study, the temporal and spatial dynamics of key GHG fluxes (CO2, CH4, and N2O) at an unvegetated mudflat, cordgrass (S. alterniflora), and mangrove (Kandelia obovata) sites along an estuary of the Jiulong River in Southeast China were investigated over a 2-year period. The CO2 and CH4 fluxes demonstrated a seasonal and vegetation-dependent variation while N2O fluxes showed no such dependent pattern. Air temperature was the main factor influencing CO2 and CH4 fluxes. Cumulative global warming potential (GWP) ranked in the order of mangrove > cordgrass > mudflat and summer > spring > autumn > winter. Moreover, CH4 accounted for the largest proportion (68%) of GWP, indicating its dominant contribution to the warming potential in mangroves. Notwithstanding the lack of information on plant coverage, cordgrass invasion exhibited a minor influence on GHG emissions. These findings support the notion that mangrove forests are net accumulation sites for GHGs. As vegetation showed considerable effects on fluxes, more information about the significance of vegetation type with a special emphasis on the effects of invasive plants is crucial.

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“…The Sundarbans mangrove ecosystem has been reported as a source for atmospheric CH 4 (Dutta et al, 2013;Mukhopadhyay et al, 2002). The impact of CH 4 emission at a regional level including biosphere-atmosphere exchange and subsequent enrichment of the atmospheric CH 4 mixing ratio have been studied by Mukhopadhyay et al (2002).…”

Section: Introductionmentioning

confidence: 99%

“…Methanogenesis in the mangrove sediment typically occurs below the sulphate reduction zone, depending upon the redox conditions, organic matter content and sediment texture (Dutta et al, 2013). CH 4 produced in the mangrove sediment enters into a complex biogeochemical cycle where it emits into the atmosphere through sediment and aquatic surfaces.…”

Section: Introductionmentioning

confidence: 99%