Isotopic evidence for sources of dissolved carbon and the role of organic matter respiration in the Fraser River basin, Canada

Voss, B. M., Eglinton, T. I., Peucker-Ehrenbrink, B., Galy, V., Lang, S. Q., Mcintyre, C. , Spencer, R. G. M., Bulygina, E., Wang, Z. A. and Guay, K. A. (2023) Isotopic evidence for sources of dissolved carbon and the role of organic matter respiration in the Fraser River basin, Canada. Biogeochemistry, 164, pp. 207-228. (doi: 10.1007/s10533-022-00945-5)

Abstract

Sources of dissolved and particulate carbon to the Fraser River system vary significantly in space and time. Tributaries in the northern interior of the basin consistently deliver higher concentrations of dissolved organic carbon (DOC) to the main stem than other tributaries. Based on samples collected near the Fraser River mouth throughout 2013, the radiocarbon age of DOC exported from the Fraser River does not change significantly across seasons despite a spike in DOC concentration during the freshet, suggesting modulation of heterogeneous upstream chemical and isotopic signals during transit through the river basin. Dissolved inorganic carbon (DIC) concentrations are highest in the Rocky Mountain headwater region where carbonate weathering is evident, but also in tributaries with high DOC concentrations, suggesting that DOC respiration may be responsible for a significant portion of DIC in this basin. Using an isotope and major ion mass balance approach to constrain the contributions of carbonate and silicate weathering and DOC respiration, we estimate that up to 33 ± 11% of DIC is derived from DOC respiration in some parts of the Fraser River basin. Overall, these results indicate close coupling between the cycling of DOC and DIC, and that carbon is actively processed and transformed during transport through the river network.

• Item Type: Articles
• Additional Information: Open Access funding provided by the MIT Libraries. This work was supported by the WHOI Academic Programs Office, the MIT EAPS Department Student Assistance Fund, and the PAOC Houghton Fund to BMV; NSF-ETBC grants OCE-0851015 to BPE, VG, and TIE and OCE-0851101 to RGMS; NSF grant EAR-1226818 to BPE; NSF grant OCE-0928582 to TIE and VG; and a WHOI Arctic Research Initiative grant to ZAW.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mcintyre, Dr Cameron
• Authors: Voss, B. M., Eglinton, T. I., Peucker-Ehrenbrink, B., Galy, V., Lang, S. Q., Mcintyre, C., Spencer, R. G. M., Bulygina, E., Wang, Z. A., and Guay, K. A.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Biogeochemistry
• Publisher: Springer
• ISSN: 0168-2563
• ISSN (Online): 1573-515X
• Published Online: 10 July 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Biogeochemistry 164:207-228
• Publisher Policy: Reproduced under a Creative Commons License