Proglacial freshwaters are significant and previously unrecognized sinks of atmospheric CO(2)

Carbon dioxide (CO(2)) emissions from freshwater ecosystems are almost universally predicted to increase with climate warming. Glacier-fed rivers and lakes, however, differ critically from those in nonglacierized catchments in that they receive little terrestrial input of organic matter for decompos...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences
Main Authors: St. Pierre, Kyra A., St. Louis, Vincent L., Schiff, Sherry L., Lehnherr, Igor, Dainard, Paul G., Gardner, Alex S., Aukes, Pieter J. K., Sharp, Martin J.
Format: Text
Language:English
Published: National Academy of Sciences 2019
Subjects:
Physical Sciences
Canada
Greenland
Lake Hazen
Nunavut
glacier
glacier*
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6731667/
http://www.ncbi.nlm.nih.gov/pubmed/31427515
https://doi.org/10.1073/pnas.1904241116
Description
Summary:Carbon dioxide (CO(2)) emissions from freshwater ecosystems are almost universally predicted to increase with climate warming. Glacier-fed rivers and lakes, however, differ critically from those in nonglacierized catchments in that they receive little terrestrial input of organic matter for decomposition and CO(2) production, and transport large quantities of easily mobilized comminuted sediments available for carbonate and silicate weathering reactions that can consume atmospheric CO(2). We used a whole-watershed approach, integrating concepts from glaciology and limnology, to conclusively show that certain glacier-fed freshwater ecosystems are important and previously overlooked annual CO(2) sinks due to the overwhelming influence of these weathering reactions. Using the glacierized Lake Hazen watershed (Nunavut, Canada, 82°N) as a model system, we found that weathering reactions in the glacial rivers actively consumed CO(2) up to 42 km downstream of glaciers, and cumulatively transformed the High Arctic’s most voluminous lake into an important CO(2) sink. In conjunction with data collected at other proglacial freshwater sites in Greenland and the Canadian Rockies, we suggest that CO(2) consumption in proglacial freshwaters due to glacial melt-enhanced weathering is likely a globally relevant phenomenon, with potentially important implications for regional annual carbon budgets in glacierized watersheds.

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