When water rushed over the dry riverbed of the Colorado River Delta for the first time in two decades, thousands of bubbles popped up in the sand. Alongside the bank, a group of scientists stood in awe, theorizing that oxygen and nitrogen trapped in the sediment were the cause. But nearly two years later, in early 2016, the team discovered those bubbles were actually composed of greenhouse gases – methane and carbon dioxide – that dissolved into the water, traveled downstream, and eventually made their way into the air.
“It’s still a big unknown on the true magnitude of these fluxes, but these large river(beds) are turning out to have really high concentrations of carbon dioxide and methane,” says David Butman, an environmental science and engineering professor at the University of Washington who worked on the study. “Looking at the exchanges of carbon gasses between landscapes, the atmosphere, and water as we look to restore these disturbed ecosystems may be important.”