The flow of carbon in the oceans: the strange behavior of small particle density interfaces (science daily)

PharmaLive.com (8 December 2010) - researchers at the Max Planck Institute for marine microbiology, Bremen (Germany) and the Massachusetts Institute of Technology have found a remarkable effect while studying how receiving marine particles, which can affect the way in which scientists assess global carbon fluxes. Their question: how fast organic and grouped together debris forming porous particles settle to the bottom of the sea? Microbes colonize these particles degrade organic matter and release carbon dioxide into the water. Particles falling speed determines the amount of carbon exported to deep sea.

The results of this study are presented in the proceedings of the National Academy of Sciences.

Structured as sponges, particle marine are porous aggregates that are mostly empty and made water 95% or more. Because the world's oceans are stratified because of temperature and salinity, density of the water increases with depth. On their way to the deep ocean, marine aggregates can reach a depth where they address buoyancy, stopping in their descent until water low density and heavier ambient water exchange allows to adjust to resume. Kolja Kindler, researcher at the Max Planck Institute for marine microbiology and the Massachusetts Institute of Technology, noted that although the thin layers of marine aggregates were often observed in nature, this effect was previously neglected in particle transport models.

In this study by Kindler and his colleagues, laboratory experiments and mathematical model results demonstrate this effect for the first time. The only means of exchange of water is scattering particles are impermeable to flow. Therefore, already the size of the aggregates, most of time they spend in the stratified layer.

Arzhang Khalili, the Max Planck Institute for marine microbiology said, "great marine aggregates may have a longer period of residence in the column of water than expected." This shows that we should review current approaches to settling particles include the effect of porosity, if we want to improve our estimates of carbon fluxes in the ocean. »

"The deeper we examine microscopic scale phenomena in the ocean, we discover that they are the processes that govern really how the oceans. "Our chances of developing a sustainable approach how interact and use the oceans hinge on how we can understand the processes at small scales" adds Roman Stocker at the Massachusetts Institute of Technology.

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Source of the story:

The story above is reproduced (with drafting adaptations by staff at PharmaLive.com) materials provided by Max-Planck-Gesellschaft.

Reference of the review:

K., kindler, a. Khalili, r. store. Diffusion-limited porous interfaces density particle retention. Proceedings of the National Academy of sciences, 2010; DOI: 10.1073/pnas.1012319108

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