Seafloor Is Dissolving Due To More Acidic Water

Posted: Nov 7 2018, 2:41pm CST | by , in Latest Science News


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Seafloor is Dissolving Due to More Acidic Water
Credit: Southern Cross University

New study says that chalky white seafloor is becoming more of a murky brown as rising levels of CO2 are absorbed by the world's oceans.

The seafloor is dissolving rapidly as oceans around the world are becoming more acidic. Acidification occurs when increasing levels of carbon dioxide from the atmosphere is absorbed by the oceans, resulting in more acidic water with a lower pH.

The bottom of the sea is typically chalky white and consists of calcite-based sediments. But as a result of human activities, the level of carbon dioxide in the oceans is so high that it has started to dissolve the calcite in the seafloor.

“Because it takes decades or even centuries for CO2 to drop down to the bottom of the ocean, almost all the CO2 created through human activity is still at the surface. But in the future, it will invade the deep-ocean, spread above the ocean floor and cause even more calcite particles at the seafloor to dissolve,” said lead author Olivier McGill University. “The rate at which CO2 is currently being emitted into the atmosphere is exceptionally high in Earth’s history, faster than at any period since at the extinction of the dinosaurs. And at a much faster rate than the natural mechanisms in the oceans can deal with, so it raises worries about the levels of ocean acidification in future.”

It is well known that increasing CO2 level is severely threatening marine life with the shells of many animals like oysters are already dissolving in the more acidic water. Now, it is also affecting the seafloor’s ability to control the degree of ocean acidification.

Seafloor plays a crucial role in dealing with increase in ocean acidity. When a burst of acidic water from a natural source such as a volcanic eruption reaches the ocean floor, it causes dissolution of calcite and neutralizes the acidity of the CO2. The process usually prevents seawater from becoming too acidic. But these days, at least in certain hotspots such as the Northern Atlantic and the southern Ocean, more and more carbon dioxide and other pollutants are reaching the seafloor and making ocean’s chalky bed murky brown.

To understand what controls the dissolution of calcite in marine sediments, researchers created a set of seafloor-like microenvironments in the laboratory and reproduced bottom currents, seawater temperature, chemistry as well as sediment compositions. These experiments allowed researchers to quantify the calcite dissolution rate and the factors that are driving the process.

“This study shows that human activities are dissolving the geological record at the bottom of the ocean,” said University of Michigan physical oceanographer Brian Arbic. “This is important because the geological record provides evidence for natural and anthropogenic changes.”

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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