Nitrogen isotope effects in the assimilation of inorganic nitrogenous compounds by marine diatoms
作者:
Eitaro Wada,
Akihiko Hattori,
期刊:
Geomicrobiology Journal
(Taylor Available online 1978)
卷期:
Volume 1,
issue 1
页码: 85-101
ISSN:0149-0451
年代: 1978
DOI:10.1080/01490457809377725
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Nitrogen isotope fractionation in the assimilation of inorganic nitrogenous compounds was studied using marine diatoms(Phaeodactylum tricornutum and Chaetocerossp.). The isotopic composition (δ15N) of the diatoms ranged from 7 to ‐18‰ relative to that of the nitrogen source, i.e., ammonium, nitrite, or nitrate. When the growth was light‐limited, the isotope fractionation in nitrate assimilation was inversely correlated with the growth rate. The highest fractionation factor of 1.016 was obtained when the growth rate was as low as 0.025 day‐1. Fractionation was negligible when the growth, rate was higher than 1 day‐1. A steady‐state kinetic model was applied to explain the isotope fractionation in nitrate assimilation. The nitrogen isotope fractionation primarily takes place at the step of N‐O bond breaking in nitrate reduction to nitrite. The extent of the isotope fractionation associated with the nitrate uptake is very small, and barely exceeds the limit of detection.
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