Marine life in the Pacific Ocean is running out of oxygen as a consequence of high levels of air pollution drifting from East Asia. Researchers at the Georgia Institute of Technology say that warmer water holds less gas, but they have recently found that the temperature change is not the only cause of the lower oxygen levels in the tropical Pacific.
The study led by researchers at GIT was published Monday in the journal Nature Geoscience. It reveals that airborne particles charged with iron released for decades into the air by human activity are having a huge negative impact on the ocean life.
Air pollution is producing excess nutrients which currents carry thousands of miles away to tropical waters, where photosynthesizing phytoplankton consume them and then release more oxygen into the atmosphere. This process increases the amount of microalgae growth, which produces more organic matter that ends up triggering excess bacteria populations.
“If you have more active photosynthesis at the surface, it produces more organic matter, and some of that sinks down,” said study lead author Professor Taka Ito from the Georgia Institute of Technology. “And as it sinks down, there’s bacteria that consume that organic matter”.
Just like humans breathe oxygen and exhale carbon dioxide, these increased amounts of bacteria dissolve oxygen levels deep down in the ocean at a faster rate, releasing in turn carbon dioxide and leaving thousands of marine organisms without the essential gas to exist.
Study lead author noted how essential phytoplankton activity is since it is nothing less than the base of the food chain in the oceans. It also absorbs atmospheric carbon dioxide. However, the excess of such activity triggered by increased iron-rich dust in the air dissolves oxygen from the deeper waters, which cannot be replaced easily.
Study authors created a model that combines ocean circulation, biogeochemical cycles, and atmospheric chemistry to track how ocean currents carry iron-rich dust produced by human activity east toward North America, down the coast and back west along the equator, as reported by Daily Mail.
Iron pollution plus warmer temperatures and ocean current variability significantly reduces oxygen, which is dissolved in seawater and increases the risk of changing habitats for marine organisms, as explained by Professor Ito. Populations of fish, crabs, and several other sea creatures can be displaced or killed by this process.
This study provides more insights about the impact of human industrial activity
Professor Athanasios Nenes, from the School of Earth and Atmospheric Sciences and co-author of the study, said this is the first paper that reveals the extent to which dust can damage the health of the oceans, providing scientists a new perspective to understand the impact of human activity.
Nenes, who is a chemical and biomolecular engineer at Georgia Tech, added that the research also helps to better understand how dust can transport pollution as it circulates across the ocean and hurts ecosystems thousands of miles away.
Source: Phys.org