RII Track-4: Peering into Nature's Glass Boxes - using nano-Raman Spectroscopy to answer Novel Questions in Diatom-focused Environmental Research

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Nontechnical DescriptionDiatoms are abundant microscopic oceanic 'plants' which have a protective shell made of glass. Despite their small size, diatoms' collective importance in marine ecosystems is immense. They produce as much oxygen globally as all the rain forests combined. Their glass shell (i.e. diatomaceous earth) also has many industrial applications. Unlike land plants which grow relatively slow, diatom biomass accumulates fast and is rapidly recycled in seawater. The recycling of diatom biomass releases 5-10 billion metric tons of carbon back into the ocean annually -a quantity of carbon which exceeds global fossil-fuel emissions. This project will use state-of-the-art technology to examine the properties of the glass shell and determine how they affect diatom-biomass recycling. This technology uses single-cell analysis, instead of traditional methods which require thousands of cells, thereby enabling new understanding and insight of single-cell material composition and structure. This project will help entrench this technology into diatom-based research and provide training for a Ph.D. student. The project collaboration with Stony Brook University based scientist will help researchers at the Alabama-based Dauphin Island Sea Lab personnel to emerge as leaders in their subfields. Also considering the vast industrial application for diatomaceous earth, these approaches may be useful for industry. This expertise will enable future work to serve the unique environmental research needs in the northern Gulf of Mexico (Alabama, Mississippi, Louisiana).Technical DescriptionDiatoms are aquatic phytoplankton, characterized by their silica shell, which account for 20-40% of marine primary production. Post-mortem silica dissolution liberates diatom organic matter within days or weeks after production, this equates to 5-10 Pg of carbon being recycled back into the ocean annually -a quantity of carbon which exceeds global fossil-fuel emissions. Because the long-term fate of diatom organic matter is governed in part by whether their shell dissolves, this project aims to understand how organic matter within diatom silica affects its dissolution. This project will move away from reliance on current methods (which require thousands of cells) and examine processes at the single-cell level. Raman spectroscopy can provide detailed single-cell information on material composition and structure. Sample analyses will be done at the NARMIL facility at Stony Brook University. This facility houses the state-of-the-art instrumentation necessary to test hypotheses related to understanding how silica-encased organic matter is affected by diatom growth conditions and whether sediment-preserved diatoms share common organic-matter traits. This project will have broader impact beyond its duration. The PI's group will build a methodological tool set that has yet to be fully utilized in his subfield and considering the vast industrial application of diatom silica (diatomaceous earth) these approaches may be useful for industry. A Ph.D. student will be trained in these methods and analyses. This collaboration will also foster data set development and publications which will enable the Alabama-based PI to be competitive for future proposals by applying these approaches to address novel questions in the northern Gulf of Mexico and beyond.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.