Rivers impact on emissions miscalculated

The true impact of the world’s river systems on greenhouse gas release is not being calculated properly, a new report from the Charles Darwin University (CDU) has found.

The research details a ‘critical gap’ in knowledge regarding the connection between groundwater and the release of carbon dioxide into rivers, which is of particular importance to Australia given the high level of carbon dioxide saturation in the nation’s river systems.

Groundwater in the Top End can have as much as 50,000 to 100,000 parts-per-million of CO2. When that water enters streams and rivers the gas is transferred quickly into the air with its much lower levels of CO2. CDU Research Fellow and lead researcher on the paper, Dr Clément Duvert said current methodologies may be missing a large part of this CO2 returning to the atmosphere. “The major problem with measuring the carbon released by rivers is that CO2 is so volatile and tends to dissipate so quickly once in the river,” he said. “In this paper we show that CO2 is released right at the junction between the soil and the river. We suggest that if we want to capture that outgassing CO2, we need to change the way we measure it. “We will need many more measurements along rivers rather than one measurement at the outlet of a catchment, as is currently done,” Dr Duvert said. “With the current approach of measuring carbon at the outlet of a river, large amounts of CO2 transfer has already occurred and won’t be captured in the current methodology.”

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