1. Benthic Dissolved Silicon and Iron Cycling at Glaciated Patagonian Fjord Heads
- Author
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Ng, Hong Chin, Hawkings, Jon R, Bertrand, Sebastien, Summers, Brent A, Sieber, Matthias, Conway, Tim M, Freitas, Felipe S, Ward, James PJ, Pryer, Helena V, Wadham, Jemma L, Arndt, Sandra, Hendry, Katharine R, Ng, Hong Chin [0000-0002-2707-8372], Hawkings, Jon R [0000-0003-4813-8474], Bertrand, Sebastien [0000-0003-0374-4040], Sieber, Matthias [0000-0001-5510-6126], Hendry, Katharine R [0000-0002-0790-5895], and Apollo - University of Cambridge Repository
- Subjects
silicon and iron ,fjord biogeochemistry ,Atmospheric Science ,Global and Planetary Change ,Earth and Environmental Sciences ,reaction transport modeling ,early diagenesis ,stable isotopes ,Environmental Chemistry ,sediment nutrient cycling ,General Environmental Science - Abstract
Funder: University of South Florida; Id: http://dx.doi.org/10.13039/100008900, Funder: Royal Society Wolfson Merit Award, Glacier meltwater supplies silicon (Si) and iron (Fe) sourced from weathered bedrock to downstream ecosystems. However, the extent to which these nutrients reach the ocean is regulated by the nature of the benthic cycling of dissolved Si and Fe within fjord systems, given the rapid deposition of reactive particulate fractions at fjord heads. Here, we examine the benthic cycling of the two nutrients at four Patagonian fjord heads through geochemical analyses of sediment pore waters, including Si and Fe isotopes (δ30Si and δ56Fe), and reaction-transport modeling for Si. A high diffusive flux of dissolved Fe from the fjord sediments (up to 0.02 mmol m-2 day-1) compared to open ocean sediments (typically 0.1 mmol m-2 day-1). High pore water δ30Si (up to +3.3‰) observed near the Fe(II)-Fe(III) redox boundary is likely associated with the removal of dissolved Si by Fe(III) mineral phases, which, together with high sedimentation rates, contribute to the low diffusive flux of Si at the sampled sites. Our results suggest that early diagenesis promotes the release of dissolved Fe, yet suppresses the release of dissolved Si at glaciated fjord heads, which has significant implications for understanding the downstream transport of these nutrients along fjord systems.
- Published
- 2022