Effects of composition of labile organic matter on biogenic production of methane in the coastal sediments of the Arabian Sea

• Published in: Environmental monitoring and assessment Vol. 182; no. 1-4; pp. 385 - 395
• Main Authors: Gonsalves, Maria-Judith, Fernandes, Christabelle E. G., Fernandes, Sheryl Oliveira, Kirchman, David L., Bharathi, P. A. Loka
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2011; Springer; Springer Nature B.V
• Subjects: Air Pollutants - analysis; Air Pollution - statistics & numerical data; Atmospheric Protection/Air Quality Control/Air Pollution; Bacteria - growth & development; Bacteria - metabolism; Bathing Beaches - statistics & numerical data; Carbohydrates; Coastal ecosystems; Coastal plains; Coastal zone; Earth and Environmental Science; Earth sciences; Earth, ocean, space; Ecology; Ecotoxicology; Engineering and environment geology. Geothermics; Environment; Environmental Management; Environmental Monitoring; Environmental testing; Estuaries; Exact sciences and technology; Gases; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Global warming; Laboratories; Lipids; Marine and continental quaternary; Marine sediments; Methane; Methane - analysis; Methane - metabolism; Methanogenesis; Monitoring/Environmental Analysis; Niches; Oceanography; Oceans and Seas; Oil and gas production; Organic matter; Pollution, environment geology; Proteins; Seawater - chemistry; Seawater - microbiology; Sediments; Studies; Surficial geology; Water Pollutants, Chemical - analysis; Arabian Sea; Indian Ocean; Goa India; Asia; India; Methane; Labile; Proteins; Carbohydrates; Organic matter; Lipids; Sediments; carbohydrates; lipids; Organic matter; coastal environment; biogenic origin; mangrove swamps; proteins; organic materials; methane; biogenic effects; marine sediments
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-011-1883-3

Coastal regions are potential zones for production of methane which could be governed by ecological/environmental differences or even sediment properties of a niche. In order to test the hypothesis that methanogenesis in most marine sediments could be driven more by proteins than by carbohydrates and lipid content of labile organic matter (LOM), incubation experiments were carried out with sediments from different environmental niches to measure methane production. The methane production rates were examined in relationship to the sediment biochemistry, i.e., carbohydrates, proteins, and lipids. The gas production measured by head space method ranged from 216 ng g  − 1  day  − 1 in the mangrove sediments to 3.1 μg g  − 1  day  − 1 in the shallow Arabian Sea. LOM ranged from 1.56 to 2.85 mg g  − 1 in the shallow Arabian Sea, from 3.35 to 5.43 mg g  − 1 in the mangrove estuary, and from 0.66 to 0.70 mg g  − 1 in the sandy sediments with proteins contributing maximum to the LOM pool. Proteins influenced methane production in the clayey sediments of shallow depths of the Arabian Sea ( r  = 0.933, p  < 0.001) and mangrove estuary ( r  = 0.981, p  < 0.001) but in the sandy beach sediments, carbohydrates ( r  = 0.924, p  < 0.001) governed the net methane production. The gas production was more pronounced in shallow and surface sediments and it decreased with depth apparently governed by the decrease in lability index. Thus, the lability index and protein content are important factors that determine methane production rates in these coastal ecosystems.