Dr Sanjeev Dasari - Tracking the release of ancient carbon from river surfaces across Arctic tributaries and delta of the Mackenzie River System

Ongoing climate warming of the Arctic is impacting the vast stores of carbon held in peatlands, soils and surface rocks within permafrost zones. One impact of warming-induced thaw on permafrost is the development of new connected hydrological pathways. These pathways can mobilise aged carbon and greenhouse gases (CO2 and CH4) sourced from organic matter decomposition and chemical weathering reactions. As such, the signatures of dissolved greenhouse gases in river waters may allow the detection of hotspots and pulses of CO2 and CH4 release from permafrost zones. Moreover, the magnitude of carbon fluxes from rivers makes them an important component of the Arctic carbon cycle and a conduit for previously stable permafrost stores to the atmosphere. This pathway could become increasingly important in warming Arctic landscapes, such as the Mackenzie River system in northern Canada. However, we currently lack information on the sources, age and fluxes of greenhouse gases in Arctic River systems.

In this talk, I will be sharing our findings from recent field campaigns in the Mackenzie River delta and its tributaries. I will show how radiocarbon (14C)-based fingerprinting of dissolved riverine greenhouse gases provides evidence for the export of ‘old’ C and processes of greenhouse gas release from rivers in this Arctic system. The research findings highlight hydrologically connected waters as viable pathways for mobilization of aged carbon pools from Arctic permafrost soils.