Organic matter compositions of rivers draining into Hudson Bay: Present-day trends and potential as recorders of future climate change
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Date
2017-07-26
Authors
Godin, Pamela
Macdonald, Robie W.
Kuzyk, Zou Zou A.
Gonr, Miguel A.
Stern, Gary A.
Journal Title
Journal ISSN
Volume Title
Publisher
American Geophysical Union
Abstract
Concentrations and compositions of particulate and dissolved organic carbon (POC and DOC,
respectively) and aromatic compounds including lignin were analyzed in water samples from 17 rivers
flowing into Hudson Bay, northern Canada. These rivers incorporate basins to the south with no permafrost to
basins in the north with continuous permafrost, and dominant vegetation systems that include Boreal Forest,
the Hudson Plains, Taiga Shield, and Tundra. Major latitudinal trends in organic carbon and lignin
concentrations and compositions were evident, with both DOC and dissolved lignin concentrations
dominating over their particulate counterparts and exhibiting significant correlations with total dissolved
and suspended solids, respectively. The composition of lignin reaction products in terms of the syringyl,
cinnamyl, and vanillyl compositions indicate mixed sources of vascular land plant-derived organic carbon,
with woody gymnosperms contributions dominating in the southern river basins whereas nonwoody
angiosperm sources were more important in the most northerly rivers. The composition of nonlignin
aromatic compounds, which provides a tracer for nonvascular plant contributions, suggests stronger
contributions from Sphagnum mosses to dissolved organic matter in rivers below the tree line, including
those with large peat bogs in their basins. Acid/aldehyde ratios of the lignin products together with Δ14C data
for DOC in selected rivers indicate that DOC has generally undergone greater alteration than POC.
Interestingly, several northern rivers exhibited relatively old DOC according to the Δ14C data suggesting that
either old DOC is being released from permafrost or old DOC survives river transport in these rivers.
Description
Keywords
Organic Matter, River drainage, Hudson Bay, Climate Change, Organic Carbon
Citation
Godin, P., R. W. Macdonald, Z. Z. A. Kuzyk, M. A. Goñi, and G. A. Stern (2017), Organic matter compositions of rivers draining into Hudson Bay: Present-day trends and potential as recorders of future climate change, J. Geophys. Res. Biogeosci., 122, 1848–1869, doi:10.1002/2016JG003569.