Biogeochemical records of past global iron connections

• Main Authors: An, Z. S., Cao, J. J., Anderson, K. K., Kawahata, H., Arimoto, R.
• Other Authors: Institute of Earth Environment Xi’an, Chinese Academy of Sciences Xi’an, Niels Bohr Institute Copenhagen (NBI), Faculty of Science Copenhagen, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Geological Survey of Japan, Carlsbad Environmental Monitoring and Research Center, New Mexico State University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Southern Ocean; Pacific; Subarctic
• Online Access: https://hal.archives-ouvertes.fr/hal-00298129; https://hal.archives-ouvertes.fr/hal-00298129/document; https://hal.archives-ouvertes.fr/hal-00298129/file/cpd-2-233-2006.pdf

International audience Paleorecords of dust deposition can be used to evaluate global iron connections under conditions different from those today. Dust production and deposition has co-varied with ocean paleoproductivity, p CO 2 , and climate over glacial-interglacial cycles, and in this paper we review the current understanding and highlight research needs with respect to paleorecords of global iron connections. These records, which include data from terrestrial (loess) deposits, marine sediments, and ice cores, suggest that average eolian deposition rates were approximately 2?20 times higher during glacial periods than during interglacials. Enhanced dust fluxes to the oceans during glacial times, particularly to the main high-nutrient/low-chlorophyll (HNLC) areas of the open ocean (i.e., the Pacific subarctic, the equatorial Pacific, and the Southern Ocean), may have "fertilized" marine biota, thereby enhancing ocean productivity (1?2 fold) and driving atmospheric CO 2 lower. Current models yield variable results, however, with glacial-interglacial changes in dust fluxes changing atmospheric p CO 2 by the equivalent of 5 to >50% of the total glacial-interglacial change of 80?100 ppm. Positive correlations among Asian dust, ocean productivity and atmospheric CO 2 in last 130 kyr, 1200 yr and 50 yr indicate that eolian iron has played an important role in global biogeochemical cycles of the past. A simple calculation suggests that one-tenth to one-third of the global change in CO 2 due to dust-supplied Fe could be ascribed to variations in the dust supply flux from Asia and its associated effects on productivity in the Pacific Ocean.