期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 111, 期 43, 页码 15468-15473出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1408134111
关键词
phosphorus; redox chemistry; phosphonates; element cycling; biogeochemistry
资金
- National Science Foundation (NSF)
- NASA Astrobiology Program, under NSF Center for Chemical Evolution Grant [CHE-1004570]
- NASA Exobiology and Evolutionary Biology Program [NNX14AN96G]
- NASA [676199, NNX14AN96G] Funding Source: Federal RePORTER
The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine-PH3-a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis.
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