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Climate of the Past An interactive open-access journal of the European Geosciences Union
© Author(s) 2006. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
08 Jun 2006
Review status
This discussion paper is a preprint. It has been under review for the journal Climate of the Past (CP). The revised manuscript was not accepted.
Biogeochemical records of past global iron connections
Z. S. An1, J. J. Cao1, K. K. Anderson2, H. Kawahata3, and R. Arimoto4 1State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, P.O. Box 17, Xi’an 710075, China
2Niels Bohr Institute for Astronomy, Physics and Geophysics, University of Copenhagen, Denmark DK-2100 Copenhagen Denmark
3Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba-higashi 1-1-1, Ibaraki 305–8567, Japan
4Carlsbad Environmental Monitoring and Research Center, New Mexico State University, 1400 University Drive, Carlsbad, NM 88220, USA
Abstract. 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, pCO2, 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 CO2 lower. Current models yield variable results, however, with glacial-interglacial changes in dust fluxes changing atmospheric pCO2 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 CO2 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 CO2 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.
Citation: An, Z. S., Cao, J. J., Anderson, K. K., Kawahata, H., and Arimoto, R.: Biogeochemical records of past global iron connections, Clim. Past Discuss., 2, 233-265,, 2006.
Z. S. An et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
RC S185: 'Review of An et al.', Anonymous Referee #2, 12 Jul 2006 Printer-friendly Version 
RC S191: 'An insufficiency of data support', Anonymous Referee #1, 13 Jul 2006 Printer-friendly Version 
RC S277: 'Specific comments', Anonymous Referee #2, 14 Aug 2006 Printer-friendly Version 
AC S559: 'Response to Reviewer Comments', Junji Cao, 07 Nov 2006 Printer-friendly Version 
Z. S. An et al.
Z. S. An et al.


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