Article Highlight | 28-May-2025

Unveiling the secrets of diatom-mediated calcification: Implications for the biological pump

Science China Press

The potential effects of the “missing” extracellular calcification pathway on marine cycling of C, Ca and Si

image: 

“POC”: Particulate Organic Carbon. “PIC”: Particulate Inorganic Carbon. The yellow arrow indicates the transport of carbon, the purple arrow indicates the transport of POC and Si, and the red arrow indicates the transport of PIC and Ca.

view more 

Credit: ©Science China Press

This study was led by professor Yiwen Pan (Institute of Ocean College, Zhejiang University) and Dr. Yifan Li (Institute of Ocean College, Zhejiang University). The team found that under conditions of photosynthesis and significantly below the supersaturation required for the precipitation of inorganic CaCO3 (Ωaragonite=8.8), the diatom Skeletonema costatum (S. costatum), a common diatom species, can induce substantial aragonite precipitation from artificial/natural seawater, and subsequently forming algae-aragonite aggregates.

 

Employing a pH microelectrode and zeta potential analyzer to measure the cell surface, it was discovered that the diatom-mediated promotion of CaCO3 precipitation is realized by creating specific microenvironments with concentrated [CO32-] and [Ca2+] and/or the dehydrating effect of adsorbed Ca2+. Based on this mechanism, it's quite likely that diatom-mediated calcification can take place in the oceans, which is supported by the significant deviation of total alkalinity (TA) from the conservative TA-salinity mixing line during a S. costatum bloom in the East China Sea and other similar situations.

 

The newly discovered calcification pathway builds a connection between particulate inorganic and organic carbon flux, helping to reassess marine carbon export fluxes and CO2 sequestration efficiency. This discovery may have crucial implications for evaluating marine carbon cycling and predicting the potential impacts of future ocean acidification.

 

This study not only changes our understanding of carbon cycling in marine ecosystems but also provides new perspectives for the ocean carbon cycle research.

 

See the article:

Pan Y, Li Y, Chen C T A, Jiang Z P, Cai W J, Shen Y, Ding Z, Chen Q, Di Y, Fan W, Zhu C, Chen Y. 2024. Unveiling the secrets of diatom-mediated calcification: Implications for the biological pump. Science China Earth Sciences, 67(9): 2895-2909, https://doi.org/10.1007/s11430-023-1369-2

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.