Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean

Fixed nitrogen (N) is a limiting nutrient for algae in the low-latitude ocean, and its oceanic inventory may have been higher during ice ages, thus helping to lower atmospheric CO 2 during those intervals. In organic matter within planktonic foraminifera shells in Caribbean Sea sediments, we found t...

Full description

Bibliographic Details
Published in:Science
Main Authors: Ren, H., Sigman, D. M., Meckler, A. N., Plessen, B., Robinson, R. S., Rosenthal, Y., Haug, G. H.
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (AAAS) 2009
Subjects:
Planktonic foraminifera
Online Access:https://doi.org/10.1126/science.1165787
https://www.science.org/doi/pdf/10.1126/science.1165787
Description
Summary:Fixed nitrogen (N) is a limiting nutrient for algae in the low-latitude ocean, and its oceanic inventory may have been higher during ice ages, thus helping to lower atmospheric CO 2 during those intervals. In organic matter within planktonic foraminifera shells in Caribbean Sea sediments, we found that the 15 N/ 14 N ratio from the last ice age is higher than that from the current interglacial, indicating a higher nitrate 15 N/ 14 N ratio in the Caribbean thermocline. This change and other species-specific differences are best explained by less N fixation in the Atlantic during the last ice age. The fixation decrease was most likely a response to a known ice age reduction in ocean N loss, and it would have worked to balance the ocean N budget and to curb ice age–interglacial change in the N inventory.

Similar Items