For decades, scientists have been thinking about the so-called “phosphate problem” as they try to understand the origins of life on Earth. The question revolves around the fact that phosphorus is one of the six major chemical formations in life, but its scarcity raises the question of how the early Earth provided this basic element. Now a new study offers a possible explanation.
The study, carried out by researchers at the University of Washington, analyzed carbonate-rich lakes that form in a dry environment when water is discharged into depressions from the surrounding landscape. Because of the high evaporation rate of these shallow lakes, these waters become highly salty and alkaline solutions, so they are called “alkali lakes” or “soda lakes”.
The researchers examined the levels of phosphorus in existing carbonate-rich lakes found on all seven continents. Although phosphorus concentrations are affected by the time and place of sampling, the team found that phosphorus levels found in such lakes may be 50,000 times higher than those found in seawater, rivers and other types of lakes. This led researchers to believe that there was a common natural mechanism responsible for the accumulation of phosphorus in these lakes.
The team looked at the explanation of the carbonate content in the lake. In most lakes, calcium, which is much richer than phosphorus, binds to form a solid calcium phosphate substance that is inaccessible to life. However, in carbonate-rich lakes, carbonates are preferred in combination with calcium, leaving no “dancing partners” for phosphates. The researchers conducted laboratory tests that combined different concentrations of ingredients and found that calcium did bind to carbonates, while phosphates in the water were freely available.
The researchers say phosphate levels can rise sharply in pools separate from the main body of the lake, or during the dry season when the lake evaporates, up to a million times that of seawater. Study co-author David Catling, a professor of Earth and space science at the University of Washington, said: “The extremely high phosphate levels in these lakes and ponds drive the reaction, allowing phosphorus to enter the molecular structure units of RNA, proteins and fats, all of which are essential to life. “
The added added fact in theory is that when the basic components of earthlife developed, the early Earth had an atmosphere rich in carbon dioxide. This will provide excellent conditions for the creation of a lake rich in phosphorus and carbonate. In addition, carbon dioxide from the atmosphere dissolves in water to create acidic conditions that cause phosphorus to be released from the rock.
“Early Earth was a volcanically active place, so you’ll have a lot of fresh volcanic rock that reacts with carbon dioxide and supplies the lake with carbonateand and phosphorus,” said Jonathan Toner, associate professor of Earth and space science at the University of Washington. Early Earth may have had many carbonate-rich lakes that had high phosphorus concentrations to begin life. “
The study was published in the journal PNAS.