A team of researchers, including Rensselaer professor Morgan Schaller, has used mathematical modeling to show that continental erosion over the last 40 million years has contributed to the success of diatoms, a group of tiny marine algae that plays a key role in the global carbon cycle. The research was published today in the Proceedings of the National Academy of Sciences.
Diatoms consume 70 million tons of carbon from the world's oceans daily, producing organic matter, a portion of which sinks and is buried in deep ocean sediments. Diatoms account for over half of organic carbon burial in marine sediments. In a mechanism known as a the "oceanic biological pump," the diatoms absorb and bury carbon, then atmospheric carbon dioxide diffuses into the upper ocean to compensate for that loss of carbon, reducing the concentration of carbon dioxide in the atmosphere.
"What we really have here is a double whammy: The chemical breakdown of rocks on land efficiently consumes carbon dioxide from the atmosphere, and those minerals are delivered to the ocean basins by rivers where, in this case, they fueled the massive expansion of diatoms," said Schaller, an assistant professor of earth and environmental sciences.
"Diatoms are photosynthetic, so they also consume atmospheric carbon dioxide. The combination of both of these effects may help explain the drastic decrease in atmospheric carbon dioxide over the last 35 million years that has plunged us into the current condition where we have glacial ice cover at both of the poles."
Diatoms appeared in the Mesozoic about 200 million years ago as descendants of the red algal lineage. However, it was not until the last 40 million years that this group of marine microalgae rose to dominate marine primary productivity.
Unlike other microalgae, diatoms require silicic acid to form tiny cases of amorphous silica (glass) called frustules, which are a means of defense against predators. Therefore, understanding the sources of silicic acid in the ocean is essential to understanding the evolutionary success of diatoms, and this is where the Earth sciences come into play.
Silicate rocks such as granites and basalts comprise the majority of Earth's crust, and their chemical decomposition represents a major source of silicic acid to the world oceans. Continental erosion depends on a complex interaction of physical, chemical, and biological forces that ultimately combine to enhance the dissolution of minerals that make up the rocks. The elevation of mountain ranges such as the Himalayas over the last 40 million years favored the fracture and dissolution of continental silicate rocks facilitating the expansion of diatoms in marine ecosystems.
Previous work has associated the evolutionary expansion of diatoms with a superior competitive ability for silicic acid relative to other plankton that use silica, such as radiolarians, which evolved by reducing the weight of their silica skeleton.
But in their work, the researchers used a mathematical model in which diatoms and radiolarians compete for silicic acid to show that the observed reduction in the weight of radiolarian tests is insufficient to explain the rise of diatoms. Using the lithium isotope record of seawater as a proxy of silicate rock weathering and erosion, they calculated changes in the input flux of silicic acid to the oceans. Their results indicate that the long-term massive erosion of continental silicates was critical to the subsequent success of diatoms in marine ecosystems over the last 40 million years and suggest an increase in the strength and efficiency of the oceanic biological pump over this period.
The research team was led by Pedro Cermeño, and included Sergio M. Vallina, both of the Instituto de Ciencias del Mar in Spain, as well as Schaller, Paul G. Falkowski of Rutgers University, and Òscar E. Romero, of the University of Bremen in Germany.
Mary Martialay | EurekAlert!
Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America
Hurricane Harvey: Dutch-Texan research shows most fatalities occurred outside flood zones
19.04.2018 | European Geosciences Union
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy