globalchange  > 影响、适应和脆弱性
DOI: 10.1111/gbi.12113
Scopus记录号: 2-s2.0-84907958296
论文题名:
Spatial variability in photosynthetic and heterotrophic activity drives localized δ13Corg fluctuations and carbonate precipitation in hypersaline microbial mats
作者: Houghton J.; Fike D.; Druschel G.; Orphan V.; Hoehler T.M.; Des Marais D.J.
刊名: Geobiology
ISSN: 1472-4677
EISSN: 1472-4669
出版年: 2014
卷: 12, 期:6
起始页码: 557
结束页码: 574
语种: 英语
Scopus学科分类: Earth and Planetary Sciences: General Earth and Planetary Sciences ; Environmental Science: General Environmental Science ; Agricultural and Biological Sciences: Ecology, Evolution, Behavior and Systematic
英文摘要: Modern laminated photosynthetic microbial mats are ideal environments to study how microbial activity creates and modifies carbon and sulfur isotopic signatures prior to lithification. Laminated microbial mats from a hypersaline lagoon (Guerrero Negro, Baja California, Mexico) maintained in a flume in a greenhouse at NASA Ames Research Center were sampled for δ13C of organic material and carbonate to assess the impact of carbon fixation (e.g., photosynthesis) and decomposition (e.g., bacterial respiration) on δ13C signatures. In the photic zone, the δ13Corg signature records a complex relationship between the activities of cyanobacteria under variable conditions of CO2 limitation with a significant contribution from green sulfur bacteria using the reductive TCA cycle for carbon fixation. Carbonate is present in some layers of the mat, associated with high concentrations of bacteriochlorophyll e (characteristic of green sulfur bacteria) and exhibits δ13C signatures similar to DIC in the overlying water column (-2.0‰), with small but variable decreases consistent with localized heterotrophic activity from sulfate-reducing bacteria (SRB). Model results indicate respiration rates in the upper 12 mm of the mat alter in situ pH and HCO3- concentrations to create both phototrophic CO2 limitation and carbonate supersaturation, leading to local precipitation of carbonate minerals. The measured activity of SRB with depth suggests they variably contribute to decomposition in the mat dependent on organic substrate concentrations. Millimeter-scale variability in the δ13Corg signature beneath the photic zone in the mat is a result of shifting dominance between cyanobacteria and green sulfur bacteria with the aggregate signature overprinted by heterotrophic reworking by SRB and methanogens. These observations highlight the impact of sedimentary microbial processes on δ13Corg signatures; these processes need to be considered when attempting to relate observed isotopic signatures in ancient sedimentary strata to conditions in the overlying water column at the time of deposition and associated inferences about carbon cycling. © 2014 John Wiley & Sons Ltd.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/85191
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作者单位: Department of Earth and Planetary Sciences, Washington University, St. Louis, MO, United States; Department of Earth Sciences, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States; Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, United States

Recommended Citation:
Houghton J.,Fike D.,Druschel G.,et al. Spatial variability in photosynthetic and heterotrophic activity drives localized δ13Corg fluctuations and carbonate precipitation in hypersaline microbial mats[J]. Geobiology,2014-01-01,12(6)
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