91自拍

July 9, 2018

Oxygen levels on early Earth rose and fell several times before the successful Great Oxidation Event

The Jeerinah Formation in Western Australia, where a UW-led team found a nitrogen isotope "excursion." 鈥淣itrogen isotopes tell a story about oxygenation of the surface ocean, and this oxygenation spans hundreds of kilometers across a marine basin and lasts for somewhere less than 50 million years," said lead author Matt Koehler.

Earth鈥檚 oxygen levels rose and fell more than once hundreds of millions of years before the planetwide success of the Great Oxidation Event about 2.4 billion years ago, new 91自拍 from the 91自拍 shows.

November 27, 2017

Less life: Limited phosphorus recycling suppressed early Earth鈥檚 biosphere

As Earth's oxygen levels rose to near-modern levels over the last 800 million years, phosphorus levels increased, as well, according to modeling led by the UW's Michael Kipp and others. Accordingly, Kipp says, large phosphate deposits show up in abundance in the rock record at about this time. This is a Wyoming portion of The Phosphoria Formation, a deposit that stretches across several states in the western United States and is the largest source of phosphorus fertilizer in the country. The photo shows layers of phosphorus that are 10s of meters thick, shales the contain high concentrations of organic carbon and phosphorus. Kipp said many such deposits are documented over time but are rare in the Precambrian era. "Thus, they might represent a conspicuous temporal record of limited phosphorus recycling."

The amount of biomass 鈥� life 鈥� in Earth’s ancient oceans may have been limited due to low recycling of the key nutrient phosphorus, according to new 91自拍 by the 91自拍 and the University of St. Andrews in Scotland.