Water‐dispersible nanocolloids and higher temperatures promote the release of carbon from riparian soil

Abstract

Additional experiments were conducted using the same sediments, but with an illite amendment added to test the influence of additional surface area and nanominerals that many sediments along the Nisqually River contain. These higher‐ and lower‐surface‐area sediments (i.e., sediments with and without the illite amendment) were incubated for 90 d at 4 or 20 °C, followed by batch and column OC leaching tests. Results show that OC leaching rates for 20 °C were two to three times greater than for 4 °C. Further, our results suggest that nanocolloids are responsible for moving this increased OC load from these sediments. When hydrologically connected, OC is released from bank sediments to rivers faster than presently anticipated in fluvial environments experiencing climate change‐induced glacial retreat. Further, a one‐dimensional, finite‐element computational model developed for this study estimates that a 1 °C increase in temperature over a 90‐d summer runoff period increases the OC release rate from sediments by 79%.