Storage and Bioavailability of Molybdenum in Soils Increased by Organic Matter Complexation
The micronutrient molybdenum is a necessary component of the nitrogen-fixing enzyme nitrogenase1, 2. Molybdenum is very rare in soils, and is usually present in a highly soluble form, making it susceptible to leaching3, 4. However, it is generally thought that molybdenum attaches to mineral surfaces in acidic soils; this would prevent its escape into the groundwater, but would also impede uptake by microbes3. Here we use X-ray spectroscopy to examine the chemical speciation of molybdenum in soil samples from forests in Arizona and New Jersey. We show that in the leaf litter layer, most of the molybdenum forms strong complexes with plant-derived tannins and tannin-like compounds; molybdenum binds to these organic ligands across a wide pH range. In deeper soils, molybdenum binds to both iron oxides and natural organic matter. We suggest that the molybdenum bound to organic matter can be captured by small complexing agents that are released by nitrogen-fixing bacteria; the molybdenum can then be incorporated into nitrogenase. We conclude that the binding of molybdenum to natural organic matter helps prevent leaching of molybdenum, and is thus a critical step in securing new nitrogen in terrestrial ecosystems.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 980475
- Report Number(s):
- BNL-93393-2010-JA; TRN: US201015%%1860
- Journal Information:
- Nature Geoscience, Vol. 2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
BACTERIA
CHELATING AGENTS
COMPLEXES
ENZYMES
FORESTS
IRON OXIDES
LEACHING
LIGANDS
MINERALS
MOLYBDENUM
NEW JERSEY
NITROGEN
NITROGENASE
ORGANIC MATTER
SOILS
STORAGE
TERRESTRIAL ECOSYSTEMS
UPTAKE
USES
X-RAY SPECTROSCOPY
national synchrotron light source