A monumental amount of work has gone into getting this project off the dock. The seeds of this were planted during a different research cruise Dr. Jeffrey Krause led aboard the Research Vessel Pelican, many years ago. It is not uncommon for scientists to observe phenomena that warrant further study, which leads from one project to another.
Dr. Krause studies silicon in the ocean. Silicon is the second most abundant element in the earth’s crust, and it combines with other elements to form silicate minerals, which comprise 90 percent of the crust. Broadly speaking, earth’s materials cycle through phases, forms, and places. Mountains are broken into rocks, which may be weathered into sand, which may dissolve into water, and these processes don’t have one pathway. For example, the sand in this example may next be cemented together to form new rocks instead of dissolving into water. All the while, the materials may be moving, transported in rivers, streams, ocean currents, sinking from surface to bottom, etc. If we expand the timescale for these processes, over a very long time, the mountain mentioned will break down, the material will move to the ocean, settle to the seafloor, move on a tectonic “conveyor belt”, and at the same time, over very long time periods, new mountains arise.
Scientists work to understand the pathways in these cycles – how materials move and change form. They also work to understand the “budgets” for these materials – total quantities for particular earth materials, where they are, how they move, and the rates at which they move and change. These are complex processes, and there are many questions to address to refine our understanding of these cycles.
During the aforementioned research project, Dr. Krause was examining the role of diatoms in the silica cycle. Diatoms are single-celled algae that have shells made of silica (like glass), and they produce a significant portion of the planet’s oxygen. Diatoms use silica that’s dissolved in seawater to build their shells. When they die, they sink, moving silica from surface waters to the seafloor. At the seafloor, the silica from diatom shells mixes with other materials, forming clays. Theoretically, there are a few potential pathways the silica may follow from here. It may stay at the seafloor in a “storage” phase that lasts a very long time. The clay may get stirred up from the bottom by certain processes, including storms. Dissolved silica from the dead diatoms may move up through the water column, potentially becoming available for live diatoms to use. There’s a lot left to learn about biogeochemical processes at the seafloor.
Microorganisms play a role in breaking down dead diatom shells. Dr. Krause began to wonder how to characterize the microbial contribution to the silica cycle.
In 2015, he connected with another scientist, Panagiotis Michalopoulos, at a professional meeting of diatom scientists in France. Dr. Michalopoulos, from the Hellenic Centre for Marine Research, in Greece, was examining the ways that certain metals interact with diatom silica in the formation of clays at the seafloor. This chemical reaction releases carbon dioxide in a process dubbed ‘reverse weathering’. Weathering processes tend to remove carbon dioxide from the atmosphere, while reverse weathering releases carbon dioxide to the atmosphere.
Dr. Michalopoulos’ research suggests that the rate of this reverse weathering is much faster than previously thought, and this process might have a larger effect on the carbon budget than formerly understood. Dr. Brandi Kiel Reese, a geomicrobiologist, arrived at the Dauphin Island Sea Lab and the University of South Alabama, just when Dr. Krause was looking for a collaborator to investigate these processes, and together, they crafted a proposal to address this research question.
Small-scale initial studies were conducted during earlier research cruises with a different research objective. The results of the pilot study suggested that these processes warranted further investigation, which led to the current project.
In 2023, their proposal was selected for funding by the National Science Foundation (NSF Award # OCE-2319429), and they started putting their plan into action. This is the first of two scheduled research cruises for the QUALIFIED Project. Research project titles are often long and may be given shortened names for efficient communication. QUALIFIED is an acronym for ‘quantifying the effect of sediment microbial activity in facilitating silica sequestration during early diagenesis’.
