Biolabile ferrous iron bearing nanoparticles in glacial sediments

作者：Jon R. Hawkings, Liane G. Benning, R. Raiswell, Burkhard Kaulich, Tohru Araki, Majid Kazemian Abyaneh, Anthony Stockdale, Monika Koch‐Müller, Jemma Louise Wadham, Martyn Tranter · 发表于：Earth and Planetary Science Letters · 年份：2018 · DOI：10.1016/j.epsl.2018.04.022 · 被引用次数：85 · 研究领域：Polar Research and Ecology、Marine and coastal ecosystems、Microbial Community Ecology and Physiology

Glaciers and ice sheets are a significant source of nanoparticulate Fe, which is potentially important in sustaining the high productivity observed in the near-coastal regions proximal to terrestrial ice cover. However, the bioavailability of particulate iron is poorly understood, despite its importance in the ocean Fe inventory. We combined high-resolution imaging and spectroscopy to investigate the abundance, morphology and valence state of particulate iron in glacial sediments. Our results document the widespread occurrence of amorphous and Fe(II)-rich and Fe(II)-bearing nanoparticles in Arctic glacial meltwaters and iceberg debris, compared to Fe(III)-rich dominated particulates in an aeolian dust sample. Fe(II) is thought to be highly biolabile in marine environments. Our work shows that glacially derived Fe is more labile than previously assumed, and consequently that glaciers and ice sheets are therefore able to export potentially bioavailable Fe(II)-containing nanoparticulate material to downstream ecosystems, including those in a marine setting. Our findings provide further evidence that Greenland Ice Sheet meltwaters may provide biolabile particulate Fe that may fuel the large summer phytoplankton bloom in the Labrador Sea, and that Fe(II)-rich particulates from a region of very high productivity downstream of a polar ice sheet may be glacial in origin.