Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget
Biogeochemical cycling of CH4 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 methanogene...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2017-06-01
|
| Series: | Frontiers in Marine Science |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/article/10.3389/fmars.2017.00187/full |
| _version_ | 1818194639213035520 |
|---|---|
| author | Manab K. Dutta Manab K. Dutta Thomas S. Bianchi Sandip K. Mukhopadhyay |
| author_facet | Manab K. Dutta Manab K. Dutta Thomas S. Bianchi Sandip K. Mukhopadhyay |
| author_sort | Manab K. Dutta |
| collection | DOAJ |
| description | Biogeochemical cycling of CH4 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. CH4 in pore-water was 53.4 times more supersaturated than in adjacent estuarine waters. This resulted in significant CH4 efflux from sediments to estuarine waters-via advective and diffusive transport. About 8.2% of the total CH4 produced in intertidal mangrove sediments was transported to the adjacent estuary through advective flux, which was 20 times higher than diffusive CH4 flux. Mean CH4 concentrations in estuarine surface and sub-surface waters were 69.9 and 56.1 nM, respectively, with a dissolved CH4 oxidation rate in estuarine surface waters of 20.5 nmol L−1 d−1. An estimated 0.09 Gg year−1 of CH4 is released from estuaries of Sundarbans to the regional atmosphere. The mean CH4 mixing ratio over the forest atmosphere was 2 ppmv. On annual basis, only 2.75% of total supplied CH4 to the forest atmosphere was transported to the upper atmosphere via biosphere-atmosphere exchange. Mean CH4 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 CH4 budget for Sundarbans mangrove ecosystem which in part, revealed the existence of anaerobic CH4 oxidation in the mangrove sediment column. |
| first_indexed | 2024-12-12T01:05:29Z |
| format | Article |
| id | doaj.art-742a65917373414da59adec07a7afffe |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-12-12T01:05:29Z |
| publishDate | 2017-06-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-742a65917373414da59adec07a7afffe2022-12-22T00:43:36ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452017-06-01410.3389/fmars.2017.00187260612Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed BudgetManab K. Dutta0Manab K. Dutta1Thomas S. Bianchi2Sandip K. Mukhopadhyay3Department of Marine Science, University of CalcuttaKolkata, IndiaGeosciences Division, Physical Research LaboratoryAhmedabad, IndiaDepartment of Geological Sciences, University of FloridaGainesville, FL, United StatesDepartment of Marine Science, University of CalcuttaKolkata, IndiaBiogeochemical cycling of CH4 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. CH4 in pore-water was 53.4 times more supersaturated than in adjacent estuarine waters. This resulted in significant CH4 efflux from sediments to estuarine waters-via advective and diffusive transport. About 8.2% of the total CH4 produced in intertidal mangrove sediments was transported to the adjacent estuary through advective flux, which was 20 times higher than diffusive CH4 flux. Mean CH4 concentrations in estuarine surface and sub-surface waters were 69.9 and 56.1 nM, respectively, with a dissolved CH4 oxidation rate in estuarine surface waters of 20.5 nmol L−1 d−1. An estimated 0.09 Gg year−1 of CH4 is released from estuaries of Sundarbans to the regional atmosphere. The mean CH4 mixing ratio over the forest atmosphere was 2 ppmv. On annual basis, only 2.75% of total supplied CH4 to the forest atmosphere was transported to the upper atmosphere via biosphere-atmosphere exchange. Mean CH4 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 CH4 budget for Sundarbans mangrove ecosystem which in part, revealed the existence of anaerobic CH4 oxidation in the mangrove sediment column.http://journal.frontiersin.org/article/10.3389/fmars.2017.00187/fullmethanemethanogenesismethanotrophybudgetmangroveSundarbans |
| spellingShingle | Manab K. Dutta Manab K. Dutta Thomas S. Bianchi Sandip K. Mukhopadhyay Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget Frontiers in Marine Science methane methanogenesis methanotrophy budget mangrove Sundarbans |
| title | Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget |
| title_full | Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget |
| title_fullStr | Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget |
| title_full_unstemmed | Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget |
| title_short | Mangrove Methane Biogeochemistry in the Indian Sundarbans: A Proposed Budget |
| title_sort | mangrove methane biogeochemistry in the indian sundarbans a proposed budget |
| topic | methane methanogenesis methanotrophy budget mangrove Sundarbans |
| url | http://journal.frontiersin.org/article/10.3389/fmars.2017.00187/full |
| work_keys_str_mv | AT manabkdutta mangrovemethanebiogeochemistryintheindiansundarbansaproposedbudget AT manabkdutta mangrovemethanebiogeochemistryintheindiansundarbansaproposedbudget AT thomassbianchi mangrovemethanebiogeochemistryintheindiansundarbansaproposedbudget AT sandipkmukhopadhyay mangrovemethanebiogeochemistryintheindiansundarbansaproposedbudget |