Increasing Alkalinity Export from Large Russian Arctic Rivers

Riverine carbonate alkalinity (HCO3– and CO32–) sourced from chemical weathering
represents a significant sink for atmospheric CO2. Alkalinity
flux from Arctic rivers is partly determined by precipitation, permafrost
extent, groundwater flow paths, and surface vegetation, all of which
are changing under a warming climate. Here we show that over the past
three and half decades, the export of alkalinity from the Yenisei
and Ob’ Rivers increased from 225 to 642 Geq yr–1 (+185%) and from 201 to 470 Geq yr–1 (+134%);
an average rate of 11.90 and 7.28 Geq yr–1, respectively.
These increases may have resulted from a suite of changes related
to climate change and anthropogenic activity, including higher temperatures,
increased precipitation, permafrost thaw, changes to hydrologic flow
paths, shifts in vegetation, and decreased acid deposition. Regardless
of the direct causes, these trends have broad implications for the
rate of carbon sequestration on land and delivery of buffering capacity
to freshwater ecosystems and the Arctic Ocean.