Drivers of methane oxidation in dry streambeds

Abstract

Despite the advances in understanding methane dynamics in dry inland waters, the potential of dry riverbeds as sinks of methane and its drivers like soils remain unclear. Here we tested three main drivers of methane oxidation from soils in sediments from a dry riverbed: gravimetric water content (GWC), temperature and light quality and intensity. We measured potential methane oxidation (PMO) along a gradient of GWC, of temperature and at green and growth light. Our results reveal that dry streambed sediments have the potential to oxidize methane. The major driver was GWC, following a monotonic function with the highest PMO around 5%. While light and temperature played a minor role. PMO was lower at 10ºC and the highest above 20ºC. Interestingly, light reduced PMO by 3-5x compared to dark conditions, and growth light reduced PMO about 0.3x compared to green light. Our results indicate that there will be day-night and seasonal variations in the methane oxidation from dry riverbeds as a function of temperature and light, between reaches depending on canopy cover. Overall, our results highlight the potential of dry riverbeds to act as sinks of methane from the atmosphere.