title: Dissolved methane in Indian freshwater reservoirs.
abstract: Emission of methane (CH4), a potent greenhouse gas, from tropical reservoirs is of interest because such reservoirs experience conducive conditions for CH4 production through anaerobic microbial activities. It has been suggested that Indian reservoirs have the potential to emit as much as 33.5 MT of CH4 per annum to the atmosphere. However, this estimate is based on assumptions rather than actual measurements. We present here the first data on dissolved CH4 concentrations from eight freshwater reservoirs in India, most of which experience seasonal anaerobic conditions and CH4 buildup in the hypolimnia. However, strong stratification prevents the CH4-rich subsurface layers to ventilate CH4 directly to the atmosphere, and surface water CH4 concentrations in these reservoirs are generally quite low (0.0028-0.305 μM). Moreover, only in two small reservoirs substantial CH4 accumulation occurred at depths shallower than the level where water is used for power generation and irrigation, and in the only case where measurements were made in the outflowing water, CH4 concentrations were quite low. In conjunction with short periods of CH4 accumulation and generally lower concentrations than previously assumed, our study implies that CH4 emission from Indian reservoirs has been greatly overestimated.
authors: National Institute of Oceanography (Council of Scientific & Industrial Research), Dona Paula, Goa, 403004, India. sgayatree@gmail.com
authors: G
authors: G
authors: Narvenkar
authors: S W A
authors: SW
authors: Naqvi
authors: S
authors: S
authors: Kurian
authors: D M
authors: DM
authors: Shenoy
authors: A K
authors: AK
authors: Pratihary
authors: H
authors: H
authors: Naik
authors: S
authors: S
authors: Patil
authors: A
authors: A
authors: Sarkar
authors: M
authors: M
authors: Gauns
mesh_terms: D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry*; D007194:India; D008697:Methane / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*; D014881:Water Supply / Q000706:statistics & numerical data*
chemical_list: D014874:Water Pollutants, Chemical; D008697:Methane
references: J Biosci Bioeng. 2012 Jun;113(6):759-64
references: 22293676
references: Science. 2011 Jan 7;331(6013):50
references: 21212349
references: Chemosphere. 2002 Jun;47(8):883-9
references: 12079082
references: Appl Environ Microbiol. 1979 Feb;37(2):303-9
references: 434809
references: Chemosphere. 2005 Jun;59(11):1697-702
references: 15894055
references: Appl Environ Microbiol. 2005 Dec;71(12):8925-8
references: 16332891
references: Nature. 2006 Nov 30;444(7119):524-5
references: 17136056
references: Mar Pollut Bull. 2008 Dec;56(12):2043-51
references: 18814890
references: Environ Manage. 2001 Apr;27(4):547-57
references: 11289453
references: Proc Natl Acad Sci U S A. 2011 Dec 6;108(49):19657-61
references: 22089233