A land-to-ocean perspective on the magnitude, source and implication of DIC flux from major Arctic rivers to the Arctic Ocean

• Published in: Global biogeochemical cycles 2012-12, Vol.26 (4), p.n/a
• Main Authors: Tank, Suzanne E., Raymond, Peter A., Striegl, Robert G., McClelland, James W., Holmes, Robert M., Fiske, Greg J., Peterson, Bruce J.
• Format: Article
• Language: English
• Subjects: Acidification; Animal and plant ecology; Animal, plant and microbial ecology; Arctic; Biological and medical sciences; Carbon; Carbonate rocks; Climate change; dissolved inorganic carbon; Earth; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fluctuations; Fundamental and applied biological sciences. Psychology; General aspects; Geobiology; Geochemistry; Ions; Ocean acidification; Permafrost; river biogeochemistry; River regulations; Rivers; Seasonal variations; Synecology; Watersheds; weathering
• ISSN: 0886-6236; 1944-9224
• DOI: 10.1029/2011GB004192

A series of seasonally distributed measurements from the six largest Arctic rivers (the Ob', Yenisey, Lena, Kolyma, Yukon and Mackenzie) was used to examine the magnitude and significance of Arctic riverine DIC flux to larger scale C dynamics within the Arctic system. DIC concentration showed considerable, and synchronous, seasonal variation across these six large Arctic rivers, which have an estimated combined annual DIC flux of 30 Tg C yr−1. By examining the relationship between DIC flux and landscape variables known to regulate riverine DIC, we extrapolate to a DIC flux of 57 ± 9.9 Tg C yr−1for the full pan‐arctic basin, and show that DIC export increases with runoff, the extent of carbonate rocks and glacial coverage, but decreases with permafrost extent. This pan‐arctic riverine DIC estimate represents 13–15% of the total global DIC flux. The annual flux of selected ions (HCO3−, Na+, Ca2+, Mg2+, Sr2+, and Cl−) from the six largest Arctic rivers confirms that chemical weathering is dominated by inputs from carbonate rocks in the North American watersheds, but points to a more important role for silicate rocks in Siberian watersheds. In the coastal ocean, river water‐induced decreases in aragonite saturation (i.e., an ocean acidification effect) appears to be much more pronounced in Siberia than in the North American Arctic, and stronger in the winter and spring than in the late summer. Accounting for seasonal variation in the flux of DIC and other major ions gives a much clearer understanding of the importance of riverine DIC within the broader pan‐arctic C cycle. Key Points DIC flux from major Arctic rivers shows large seasonal and regional variation Runoff and catchment carbonates, permafrost, and glaciers control DIC flux Riverwater effects on coastal aragonite saturation appear greatest in spring