Mineral dust and Earth’s oxygen levels

Mineral dust played a key role in raising oxygen levels in the Earth's atmosphere billions of years ago, with major implications for the way intelligent life later evolved, say researchers. Up to now, scientists have argued that oxygen levels rose as the result of photosynthesis by algae and plants in the sea, where oxygen was produced as a by-product and released into the atmosphere. But a research team at the University of Leeds say the photosynthesis theory does not fully explain the increase in oxygen levels. In a paper published in the journal Nature Geoscience , the researchers argue that when the algae and plants died, they would have been consumed by microbes, a process that takes oxygen from the atmosphere. As a result, the amount of atmospheric oxygen was a balance between what was produced through photosynthesis and what was lost as a result of decomposition of the dead plants and algae. To enable the atmospheric oxygen levels to get higher, the scientists say the process of decay must have been slowed or halted. They believe this happened through what is known as mineral-organic carbon preservation, where minerals in the oceans, particularly iron particles, bind onto the dead algae and inhibit decay and decomposition.