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Researchers uncover the mystery of ocean-level iron



  The Flathead Bio Station Biologist Helps Reveal the Mystery of Ocean Iron Level . Credit: UM
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<p>  The mid-ocean is filled with vast systems of rotating currents known as subtropical fats. These regions occupy 40% of the earth's surface and have long been considered remarkably stable biological deserts, with minor changes in the chemical composition or nutrients needed to sustain life.</p>
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However, there is a strange anomaly in the subtropical ecosystem of the North Pacific that has puzzled scientists for years. In this region, occupying the Pacific between China and the United States, chemistry changes periodically. There is a particularly noticeable fluctuation in the levels of phosphorus and iron, which affects the overall composition of the nutrients and ultimately affects the biological productivity.

In a new study published in Proceedings of the National Academy of Sciences a group of researchers discovered the cause of these changes in the sub-tropical ecosystem of the North Pacific. The group includes Matthew Church, a microbial ecologist with the University of Montana Biological Station at Flathead Lake, as well as Ricardo Letelier of Oregon State University and David Carl of the University of Hawaii.

"Changes in the ocean climate seem to regulate iron supply, altering the types of plankton growing in these waters, which ultimately controls the concentrations of nutrients in the ocean," Church says. "My lab works on role issues. of plankton to control the availability of nutrients in the ocean for many years, and this study puts much of this work in context. As a result of long-term, long-term observations, our work confirms how healthy it is planktonic biology is for the supply of nutrients, in particular iron, from the atmosphere. "

Using three decades of surveillance data from ALOHA Station, a six-mile Pacific Ocean north of Hawaii, dedicated to oceanographic research, the team found that the periodic shift in iron levels was the result of the Asian iron dust being taken into account, taking into account chemical dispersions and providing different amounts of nutrients to sustain life.

The key to dispersion is the Pacific Decadal Oscillation, an ocean-atmosphere relationship. which varies between weak and strong phases of atmospheric pressure in the Northeast Pacific.

In years when low pressure is weakening in the northeast Pacific, the winds from Asia are increasing and moving in a southerly direction. This carries more dust from the Asian continent, "fertilizing" the ocean around the ALOHA station. When the pressure increases, the opposite occurs.

Nutrient supply is a major regulator of ocean productivity, and phosphorus and iron are key components of life. Usually, the upper water column of the ocean is fertilized by nutrient-rich water that mixes with the deep. This is a difficult process in the subtropical gyros of the North Pacific because the waters are very stratified and in fact little mixing takes place.

When strong Asian winds import significant amounts of iron, organisms have the right to grow and use phosphorus in the upper ocean layers. When Asian winds weaken and iron intake is reduced, organisms are forced to return to a deep-water nutrient delivery system. This creates periodic spills and flows at iron and phosphorus levels in the North Pacific.

The church says that the findings of this study highlight the critical need to incorporate atmospheric and oceanic variability when predicting how climate change can affect ocean ecosystems.

"This reaffirms the need to think about how tightly knit plankton biology is to climate change and ultimately also to changes in land use that can directly affect the supply of dust at sea," he says.

As Earth's temperature continues to warm, researchers expect to see long-term changes in wind patterns in the North Pacific. The evolution of land use and pollution caused by human activity in Asia will also affect the sources and magnitude of iron and other nutrients carried by wind across the ocean.

More research is needed to better understand how these changes will ultimately affect ecosystems in this oceanic region, as well as others around the world.


Scientists find unlikely culprit for fertilization of North Pacific: Asian dust


More information:
Ricardo M. Letelier et al., Climate change fluctuations in phosphorus and iron in the subtropical fat restriction of the North Pacific, Proceedings of the National Academy of Sciences (201
9). Doi: 10.1073 / pnas.1900789116

Provided by
University of Montana
Reference :
Researchers unveil the mystery of ocean iron levels (2019, August 30)
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