Iron Mineralogy and Speciation in Clay-Sized Fractions of Chinese Desert Sediments

Wanyi Lu, Wancang Zhao, William Balsam, Huayu Lu, Pan Liu, Zunli Lu, Junfeng Ji

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Iron released from Asian desert dust may be an important source of bioavailable iron for the North Pacific Ocean and thereby may stimulate primary productivity. However, the Fe species of the fine dusts from this source region are poorly characterized. Here we investigate iron species and mineralogy in the clay-sized fractions (<2 μm), the size fraction most prone to long-distance transport as dust. Samples were analyzed by sequential chemical extraction, X-ray diffraction, and diffuse reflectance spectrometry. Our results show that Fe dissolved from easily reducible iron phases (ferrihydrite and lepidocrocite) and reducible iron oxides (dominated by goethite) are 0.81 wt % and 2.39 wt %, respectively, and Fe dissolved from phyllosilicates extracted by boiling HCl (dominated by chlorite) is 3.15 wt %. Dusts originating from deserts in northwestern China, particularly the Taklimakan desert, are relatively enriched in easily reducible Fe phases, probably due to abundant Fe contained in fresh weathering products resulting from the rapid erosion associated with active uplift of mountains to the west. Data about Fe speciation and mineralogy in Asian dust sources will be useful for improving the quantification of soluble Fe supplied to the oceans, especially in dust models.

Original languageEnglish (US)
Pages (from-to)13,458-13,471
JournalJournal of Geophysical Research: Biogeosciences
Volume122
Issue number24
DOIs
StatePublished - Dec 27 2017

Keywords

  • Chinese deserts
  • chlorite
  • clay-sized fractions
  • iron oxides
  • iron species
  • soluble Fe

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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