Document Type

Article

Publication Date

2021

DOI

10.5194/bg-18-6349-2021

Publication Title

Biogeosciences

Volume

18

Issue

23

Pages

6349-6375

Abstract

Glacial meltwater from the western Antarctic Ice Sheet is hypothesized to be an important source of cryospheric iron, fertilizing the Southern Ocean, yet its trace-metal composition and factors that control its dispersal remain poorly constrained. Here we characterize meltwater iron sources in a heavily glaciated western Antarctic Peninsula (WAP) fjord. Using dissolved and particulate ratios of manganese to iron in meltwaters, porewaters, and seawater, we show that surface glacial melt and subglacial plumes contribute to the seasonal cycle of iron and manganese within a fjord still relatively unaffected by climate-change-induced glacial retreat. Organic ligands derived from the phytoplankton bloom and the glaciers bind dissolved iron and facilitate the solubilization of particulate iron downstream. Using a numerical model, we show that buoyant plumes generated by outflow from the subglacial hydrologic system, enriched in labile particulate trace metals derived from a chemically modified crustal source, can supply iron to the fjord euphotic zone through vertical mixing. We also show that prolonged katabatic wind events enhance export of meltwater out of the fjord. Thus, we identify an important atmosphere–ice–ocean coupling intimately tied to coastal iron biogeochemistry and primary productivity along the WAP.

Comments

© The Authors 2021.

This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0).

Original Publication Citation

Forsch, K. O., Hahn-Woernle, L., Sherrell, R. M., Roccanova, V. J., Bu, K., Burdige, D., Vernet, M., & Barbeau, K. A. (2021). Seasonal dispersal of fjord meltwaters as an important source of iron and manganese to coastal Antarctic phytoplankton. Biogeosciences, 18(23), 6349-6375. https://doi.org/10.5194/bg-18-6349-2021

ORCID

0000-0002-8859-7096 (Burdige)

Share

Article Location

 
COinS