Nav: Home

Ocean changes almost starved life of oxygen

March 02, 2020

Chemical changes in the oceans more than 800 million years ago almost destroyed the oxygen-rich atmosphere that paved the way for complex life on Earth, new research suggests.

Then, as now, the planet had an "oxidizing" atmosphere, driven by phytoplankton - the "plants" of the ocean - releasing oxygen during photosynthesis.

However, new research from an international team including the University of Exeter and spanning Toulouse, Leeds, London and Nanjing, suggests ocean changes in the early Neoproterozoic era (from one billion to 800 million years ago) may have locked away phosphorus - a vital nutrient for life - limiting phytoplankton growth and oxygen release.

The study suggests the amount of phosphorus available remained "just sufficient" to support the oxidising atmosphere - preventing a return to the "reducing" (oxygen-poor) atmosphere that existed over a billion years earlier.

"Ocean chemistry in this period changed to become 'ferruginous' (rich in iron)," said Dr Romain Guilbaud, of CNRS (Toulouse).

"We know ocean chemistry affects the cycle of phosphorus, but the impact on phosphorus availability at this time hadn't been investigated until now.

"By analysing ocean sediments, we found that iron minerals were very effective at removing phosphorus from the water."

Phytoplankton growth also boosts atmospheric oxygen because, having split carbon and oxygen and released the oxygen, plants die and their carbon is buried - so it cannot recombine with oxygen to form carbon dioxide.

Despite reductions in photosynthesis and this organic burial of carbon, both due to limited phosphorus, the study suggests oxygen in the atmosphere dropped no lower than 1% of current levels - "just enough" to maintain an oxidizing atmosphere.

"Our observations suggest significant potential variability in atmospheric oxygen concentrations across Earth's 'middle age'," said Professor Tim Lenton, Director of the Global Systems Institute at the University of Exeter.

He added: "One question about the emergence of complex life is why it didn't happen sooner.

"Lack of oxygen and lack of nutrients are two possible reasons, and our study suggests both of these may have been the case in the early Neoproterozoic era.

"In fact, if phosphorus levels in the water had dropped any lower, it could have tipped the world back into a 'reducing' atmosphere suitable for bacteria but not for complex life."

A return to a "reducing" atmosphere would have reversed the Great Oxidation Event, which occurred about 2.5 billion years ago, during which photosynthesis by cyanobacteria in the oceans introduced free oxygen to the atmosphere.
-end-
The study, which used samples from the Huainan Basin in north China, was funded by the Natural Environment Research Council (NERC) and the National Science Foundation of China.

The paper, published in the journal Nature Geoscience, is entitled: "Phosphorus-limited conditions in the early Neoproterozoic ocean maintained low levels of atmospheric oxygen."

The Global Systems Institute aims to work with others to secure a flourishing future for humanity as an integral part of a life-sustaining Earth system.

University of Exeter

Related Phosphorus Articles:

Phosphorus deficit may disrupt regional food supply chains
Phosphorus-based fertilizer is essential in modern agriculture. In regions with high population growth, more phosphorus will be needed to produce more food.
SwRI scientist searches for stellar phosphorus to find potentially habitable exoplanets
SAN ANTONIO -- Sept. 16, 2020 -- A Southwest Research Institute scientist has identified stellar phosphorus as a probable marker in narrowing the search for life in the cosmos.
Worldwide loss of phosphorus due to soil erosion quantified for the first time
Phosphorus is essential for agriculture, yet this important plant nutrient is increasingly being lost from soils around the world.
Stars rich in phosphorus: Seeds of life in the universe
The journal Nature Communications today is publishing the discovery of a new type of stars, very rich in phosphorus, which could help to explain the origin of this chemical element in our Galaxy.
Black phosphorus future in 3D analysis, molecular fingerprinting
Many compact systems using mid-infrared technology continue to face compatibility issues when integrating with conventional electronics.
Fostering a sustainable use of phosphorus
Phosphorus is critical to food security, ecosystem functioning and human activities.
Newly discovered plant gene could boost phosphorus intake
Researchers from the University of Copenhagen have discovered an important gene in plants that could help agricultural crops collaborate better with underground fungi -- providing them with wider root networks and helping them to absorb phosphorus.
Anaerobically disinfect soil to increase phosphorus using diluted ethanol
Anaerobic disinfection of soil is an effective method to kill unwanted bacteria, parasites and weeds without using chemical pesticides.
Graphene heterostructures with black phosphorus, arsenic enable new infrared detectors
MIPT scientists and their colleagues from Japan and the U.S.
Recovering phosphorus from corn ethanol production can help reduce groundwater pollution
Dried distiller's grains with solubles (DDGS), a co-product from corn ethanol processing, is commonly used as feed for cattle, swine and poultry.
More Phosphorus News and Phosphorus Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.