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Scientists discover unlikely culprit for fertilizing North Pacific Ocean: Asian dust



 Scientists discover unlikely culprit for fertilizing North Pacific Ocean: Asian dust
Credit: Robert Simmon
            

The vast subtropical "gyres-large systems of rotating currents in the middle of the oceans-cover" 40 percent of the Earth's surface has long been considered.
                                               

These regions are, therefore, scientifically proven to be of great importance to the Pacific. Subtropical Gyre ecosystem that has puzzled oceanographers for years: The region's chemistry changes periodically, especially levels of phosphorous and iron, affecting the overall nutrient

In a new study published this week in Proceedings of the National Academy of Sciences researchers document what induces these variations: changes in the amount of iron that are deposited into the Ocean via dust from Asia.

"Ricardo Letelier, Oregon State University biogeochemist and ecologist, who collaborates with David Karl at the University of California, said:" We now know that these areas are thought to be barren and stable University of Hawaii led this study.

The study focussed on the North Pacific Subtropical Gyro, and used three decades of observation data from the station ALOHA by the Hawaii Ocean Time-series program, which is funded by the National Science Foundation.

The surface of the North Pacific gyre is characterized by very clear waters with hardly any nutrients. 1

00 meters (or 328 feet).

Typically, the ocean's upper water column is fertilized by nutrient-rich water from the deep , but these waters are very stratified and little mixing takes place. Sinking in front of the seafloor.




Timelapse of Asian dust movement , Credit: Oregon State University

Letelier said the team.

Letelier said the team What does it mean? "

And the key to that variance is the Pacific Decadal Oscillation, an ocean-to-atmosphere relationship that varies between the Pacific and the Pacific. In years when the low pressure weakens, winds from Asia, move southward, and bring more dust, fertilizing the ocean surrounding station ALOHA.

Strong winds can bring significant amounts of iron into the open layers of the ocean. However, because most of the iron is not soluble, deep waters are enriched in phosphorus relative to iron.

"Sometimes there are periods of 5-6 years of phosphorus enrichment, and then there are periods when it switches over, "Letelier said. "From 2000 to 2007, there was almost no phosphorus." "We may have seen some changes in the function of the ecosystem, but they have not seen significant changes in the biological composition."

As the Artic warms, they expect to see long-term changes in wind patterns across the North Pacific. In addition, the evolution of land use and pollution-driven by anthropogenic activity in Asia seeks to influence the sources of iron and other nutrients carried by wind across the ocean.

the eastern Pacific Ocean continues to open.
                                                                                                                        


Study: Deep-ocean creatures living a 'feast-or-famine' existence because of energy fluxes


More information:
Ricardo M. Letelier et al., "Climate-driven Oscillation of Phosphorus and Iron Limitation in the North Pacific Subtropical Gyre," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1900789116

Provided by
Oregon State University




Citation :
                                                 Scientists discover unlikely culprit for fertilizing North Pacific Ocean: Asian dust (2019, June 10)
                                                 retrieved 10 June 2019
                                                 from https://phys.org/news/2019-06-scientists-culprit-fertilizing-north-pacific.html
                                            

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