Preprints
https://doi.org/10.5194/os-2021-78
https://doi.org/10.5194/os-2021-78

  07 Sep 2021

07 Sep 2021

Review status: this preprint is currently under review for the journal OS.

Occurrence of structural aluminum (Al) in marine diatom biological silica: Visible evidence from microscopic analysis

Qian Tian1,2,3, Dong Liu1,2,4,a, Peng Yuan1,2, Mengyuan Li1,2,3, Weifeng Yang4, Jieyu Zhou1,2,3, Huihuang Wei1,2,3, Junming Zhou1,2,3, and Haozhe Guo1,2,3 Qian Tian et al.
  • 1CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Institutions of Earth Science, Chinese Academy of Sciences, Guangzhou 510640, China
  • 2CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
  • 3University of Chinese Academy of Sciences, Beijing 100049, China
  • 4State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
  • acurrent addresses: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences Wushan, Guangzhou 510640, China

Abstract. The global marine biogeochemical cycle of aluminum (Al) is believed to be driven by marine diatoms, due to the uptake of dissolved Al (DAl) by living diatoms from surface seawater. The occurrence of Al in diatom biogenic silica (BSi) can inhibit the dissolution of BSi, thus benefiting the effects of the ballast role of diatoms in the biological pump and forming a coupled Si-Al biogeochemical cycle. However, the occurrence mechanism of Al in marine diatoms is still unclear. In particular, whether or not Al is incorporated into the structure of BSi of living diatoms is unrevealed, resulting in difficulties in understanding the biogeochemical behaviors of Al. In this study, Thalassiosira weissflogii, a widely distributed marine diatom in marginal seas, was selected as the model to evaluate the occurrence of structural Al in BSi based on culturing experiments with the addition of DAl. The structural Al in BSi was detected by combining focused ion beam (FIB) scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) mapping analysis. Direct evidence of structural Al in living BSi was obtained for the first time. The distribution and content of this Al were revealed by the EDS-mapping analysis. The structural Al in the BSi exhibited a homogeneous distribution, and the average Al / Si atomic ratio obtained through the FIB-EDS mapping analysis was 0.011. The effects of structural Al on BSi dissolution-inhibition are discussed based on the content of this Al. The fundamental results indicate the significant contribution of marine diatoms to the biogeochemical migration of marine Al.

Qian Tian et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on os-2021-78', Christopher Exley, 08 Sep 2021
    • CC2: 'Reply on CC1', Christopher Exley, 08 Sep 2021
  • RC1: 'Comment on os-2021-78', Anonymous Referee #1, 01 Nov 2021
    • CC3: 'Reply on RC1', Christopher Exley, 08 Nov 2021
  • RC2: 'Comment on os-2021-78', Anonymous Referee #2, 12 Nov 2021

Qian Tian et al.

Qian Tian et al.

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Short summary
In this study, we present visible direct evidence for Al occurrence in biogenic silica (BSi). Homogeneous distribution of Al was shown in BSi and the average Al / Si atomic ratio was 0.011. Considering structural Al has dissolution-inhibition for BSi, the fundamental results not only indicate the significant contribution of marine diatoms to the biogeochemical migration of marine Al, but also imply the contribution mechanism of Al on the carbon sequestration of marine diatoms.