Skip to Main content Skip to Navigation
Journal articles

Glacial influence on the geochemistry of riverine iron fluxes to the Gulf of Alaska and effects of deglaciation

Abstract : Riverine iron (Fe) derived from glacial weathering is a critical micronutrient source to ecosystems of the Gulf of Alaska (GoA). Here we demonstrate that the source and chemical nature of riverine Fe input to the GoA could change dramatically due to the widespread watershed deglaciation that is underway. We examine Fe size partitioning, speciation, and isotopic composition in tributaries of the Copper River which exemplify a long-term GoA watershed evolution from one strongly influenced by glacial weathering to a boreal-forested watershed. Iron fluxes from glacierized tributaries bear high suspended sediment and colloidal Fe loads of mixed valence silicate species, with low concentrations of dissolved Fe and dissolved organic carbon (DOC). Iron isotopic composition is indicative of mechanical weathering as the Fe source. Conversely, Fe fluxes from boreal-forested systems have higher dissolved Fe concentrations corresponding to higher DOC concentrations. Iron colloids and suspended sediment consist of Fe (hydr)oxides and organic complexes. These watersheds have an iron isotopic composition indicative of an internal chemical processing source. We predict that as the GoA watershed evolves due to deglaciation, so will the source, flux, and chemical nature of riverine Fe loads, which could have significant ramifications for Alaskan marine and freshwater ecosystems.
Complete list of metadatas

Cited literature [35 references]  Display  Hide  Download

https://hal-insu.archives-ouvertes.fr/insu-00645879
Contributor : Adminhal Univbrestbu <>
Submitted on : Tuesday, February 28, 2012 - 7:00:07 AM
Last modification on : Monday, June 22, 2020 - 7:50:04 AM
Long-term archiving on: : Tuesday, May 29, 2012 - 2:20:07 AM

File

GRL-Rouxel_al-2011.pdf
Publisher files allowed on an open archive

Identifiers

Collections

Citation

Andrew Schroth, J. Crusius, Fanny Chever, Benjamin Bostick, Olivier Rouxel. Glacial influence on the geochemistry of riverine iron fluxes to the Gulf of Alaska and effects of deglaciation. Geophysical Research Letters, American Geophysical Union, 2011, 38, pp.L16605. ⟨10.1029/2011GL048367⟩. ⟨insu-00645879⟩

Share

Metrics

Record views

521

Files downloads

1145