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6233464 
Book/Book Chapter 
Chemosynthesis☆ 
Bastviken, D; Crill, P; Enrich-Prast, A; Sanseverino, AM; Santoro, AL; Signori, CN 
2014 
Elsevier 
Reference Module in Earth Systems and Environmental Sciences 
Chemosynthesis is defined as the biological production of organic compounds from one-carbon (C-1) compounds and nutrients, using the energy generated by the oxidation of inorganic or C-1 organic molecules. In oceanic and inland waters, chemosynthesis is commonly measured as dark carbon fixation (i.e., the formation of organic carbon from carbon dioxide in the dark). In general, chemosynthesis has received less attention than the associated energy-yielding redox processes, which drive many biogeochemical cycles and have profound impacts on the production and cycling of greenhouse gases such as carbon dioxide, methane, and nitrous oxide. Therefore, although knowledge about these associated processes may be significant, there is a lack of knowledge regarding the spatial distribution of chemosynthesis among various types of ecosystems and the magnitude of its contribution to overall primary production. Chemosynthetic organisms are widespread and highly diverse in terms of phylogeny, substrates used, morphology, habitats, and metabolism. These organisms have the potential to account for more than 50% of ecosystem carbon fixation under certain conditions. This chapter focuses on (1) some underlying chemosynthetic processes such as carbon fixation pathways and associated redox processes, (2) major groups of chemosynthetic microorganisms, (3) in situ chemosynthesis rates in aquatic environments, (4) the importance of chemosynthesis in food webs, and (5) major needs for new knowledge. 
Acetogenesis; Ammonium oxidation; Biogeochemical cycles; Carbon cycling; Carbon fixation; Chemosynthesis; Energy metabolism; Hydrogen oxidation; Methane oxidation; Methanogenesis; Methylotrophy; Nitrification; Oxic–anoxic interface; Primary production; Redox reactions; Sulfur oxidation; Sulfur reduction