期刊
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
卷 113, 期 G3, 页码 -出版社
AMER GEOPHYSICAL UNION
DOI: 10.1029/2007JG000651
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[1] In this study we examine the effects of varying Fe, Mo, and P concentrations on delta(15) N fractionation during N-2 fixation in the cyanobacterium Anabaena variabilis. We show that when grown in Fe-enriched media ([Fe]>= 50 nM), this organism produces biomass up to 3% lower in delta(15) N than when grown in Fe-limited media ([Fe]< 50 nM). A compilation of our data with previous measurements of delta(15) N in N-2-fixing cyanobacteria reveals a general trend toward the production of more N-15-depleted biomass at higher Fe concentrations. We discuss our results in the context of negative delta(15) N values preserved in Archean and some Phanerozoic sediments, generally attributed to the production of marine organic matter with low delta(15) N by N-2 fixation (and potentially NH4+ regeneration) during periods of fluctuating nutrient dynamics. We suggest that enhanced Fe availability during periods of widespread ocean anoxia can further stimulate the production of delta N-15-depleted biomass by N-2-fixing organisms, contributing to the isotopic record.
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