The seasonality of oceanic carbon cycling

NOAA National Ocean Service/Wikimedia Commons, public domain">

The global carbon cycle depends on the biological carbon pump in the ocean. Surface phytoplankton captures carbon, stores it in cell walls, and transfers the element to the ocean deep after the algae die. Now, researchers are looking at how the seasons might affect this process. Credit: NOAA National Ocean Service/Wikimedia Commons, public domain

The ebb and flow of carbon within Earth is a complex phenomenon. Carbon is a nomadic element that travels between the atmosphere, ocean, and the soil, rock, and ice of the planet. The ocean is where most of this cycling takes place. The surface of the sea is where atmospheric carbon is fixed. The carbon particles sink from the surface to the deep ocean waters. This carbon can be in the atmosphere for hundreds or thousands of years.

The variability of sinking carbon particles has been observed over the past few decades, but the BCP has been treated as a constant. The changing seasons can affect the amount and rate of carbon and other pollutants that sink into deep ocean waters.

The researchers used a global ocean biogeochemical model to see how the amount of carbon particles reaching the deep ocean would change. They looked at how the pattern and strength of the season would affect the sinking speed of carbon particles.

When they compared their seasonal results to nonseasonal scenarios, they found that there was an increase of up to 196% of carbon particle transfer.

The model they used was a simplified version of a complicated biogeochemical system. The team notes that the study shows the importance of the time of the year when carbon is at its highest. The team says that if other researchers assume BCP is constant, they may be underestimating how much carbon can be sequestered in the ocean.

New observations should be collected to understand how seasonality can affect detrital sinking speeds. The authors note that more nuanced inputs of other factors such as water temperature and phytoplankton sizes and species could reveal more details about BCP related to seasonal fluxes.

More information: Francisco Melo Viríssimo et al, Influence of Seasonal Variability in Flux Attenuation on Global Organic Carbon Fluxes and Nutrient Distributions, Global Biogeochemical Cycles (2022). DOI: 10.1029/2021GB007101 Journal information: Global Biogeochemical Cycles

The story was re-posted by the American Geophysical Union. The original story can be read here.

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