Comparisons of Nutrients Exported From Greenlandic Glacial and Deglaciated Watersheds

Authors

Jonathan B. Martin, University of FloridaFollow
Andrea J. Pain, University of Florida
Ellen E. Martin, University of Florida
Shaily Rahman, University of FloridaFollow
Philip Ackerman, University of FloridaFollow

Document Type

Article

Publication Date

12-1-2020

Department

Marine Science

School

Ocean Science and Engineering

Abstract

Recent work demonstrates extensive nutrient exports from outlet glaciers of the Greenland Ice Sheet. In comparison, nutrient exports are poorly defined for deglaciated watersheds that were exposed during ice retreat and retain reactive comminuted glacial sediments. Nutrient exports from deglaciated watersheds may differ from glacial watersheds due to their longer exposure times, more mature chemical weathering, and ecosystem succession. To evaluate nutrient exports from glacial and deglaciated watersheds, we compare discharge and dissolved (<0.45 μm filtered) nutrient concentrations in two glacial and six non-glacial streams in southwestern and southern Greenland. Glacial streams have orders of magnitude greater instantaneous discharge than non-glacial streams but their specific discharges are more similar, differing by up to a factor of 10. Compared with non-glacial streams, filtered water of glacial streams have on average (1) higher inorganic nitrogen (DIN) and PO₄ concentrations, lower Si concentrations, and Fe concentrations that are not statistically different; (2) higher DIN and PO₄ but lower Si specific yields; and (3) lower DIN/PO₄, Si/DIN, and Fe/PO₄ ratios, but indistinguishable Fe/DIN. Maximum specific yields occur in early melt season prior to maximum solar radiation for non-glacial streams, and in mid-melt season as solar radiation wanes for proglacial streams. Impacts to coastal ecosystems from nutrient exports depend on suspended sediment loads and processing in the estuaries, but landscape exposure during glacial terminations should decrease DIN and dissolved PO₄ and increase dissolved Si exports, while increased meltwater runoff associated with future warming should increase DIN and dissolved PO₄ and decrease dissolved Si exports.

Publication Title

Global Biogeochemical Cycles

Volume

34

Issue

12

Recommended Citation

Martin, J., Pain, A., Martin, E., Rahman, S., Ackerman, P. (2020). Comparisons of Nutrients Exported From Greenlandic Glacial and Deglaciated Watersheds. Global Biogeochemical Cycles, 34(12).
Available at: https://aquila.usm.edu/fac_pubs/19062