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In this study, pore-water and solid-phase samples were collected at four stations in the inner to mid Kongsfjorden, Svalbard, and analyzed in a multi-proxy geochemical approach, which included pore-water analyses, solid-phase operational reactive silica extractions, and lithium isotope analyses of pore-water. The goal of this study was to investigate possible forward and reverse weathering alteration in glacially influenced high-latitude systems by focusing on the early diagenetic processes occurring at several stations in Kongsfjorden, Svalbard, extending from the immediate vicinity of a marine-terminating glacier to a mid-fjord, bioturbated station. Our study focused on deciphering the pathways of the weathering reactions, and their relative roles in controlling reactive silica burial rates and benthic cation fluxes. This study is presented in a manuscript entitled "Rapid forward and reverse weathering reactions drive cryptic silica and cation cycling in Arctic fjord sediments" currently undergoing review."]}
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This content will become publicly available on December 1, 2026
Rapid Forward and Reverse Weathering Reactions Drive Cryptic Silica and Cation Cycling in Arctic Fjord Sediments
Early diagenetic forward and reverse weathering reactions play a significant role in controlling alkalinity fluxes and silica, alkali metal and alkaline earth metal cycling in coastal systems. In Kongsfjorden, Svalbard, the inputs of autochthonous biogenic debris (diatomaceous silica) and allochthonous lithogenic material of varying reactivity (dominated by clays, especially illite and chlorite, and primary aluminosilicates, mostly plagioclase) drive complex balances of diagenetic silicate reactions in sediments. The rapid dissolution of reactive silica results in the release of dissolved silica (Sid) into pore‐waters and sustains elevated benthic Sidfluxes (−0.2 to −0.8 mmol m−2 d−1), which are on the upper end of values previously determined for Arctic environments. Increases with depth in pore‐water lithium (Li+), potassium, magnesium, and barium concentrations within the top centimeters provided evidence for forward weathering of clays quickly upon burial. Due to the prevalent occurrence of forward weathering, the benthic net Li+flux was associated with a light isotope signal. Decreases in pore‐water rubidium concentrations with depth at the near‐glacier station, elevated ratios of the authigenically altered silica to the biogenic silica pool at all sites, and small increases of pore‐water δ7Li values with depth showed that reverse weathering also takes place. Anoxic incubation of diatom frustule probes provided further evidence for the neoformation of cation‐rich clays. The superposition of reverse and forward weathering results in cryptic silica and cation cycling that muted net benthic fluxes. In deeper sediments, changes in pore‐water solute patterns indicated an interconnected occurrence of reverse and forward weathering, potentially driven by reactive silica‐limitation.
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- Award ID(s):
- 2338157
- PAR ID:
- 10651019
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Global Biogeochemical Cycles
- Volume:
- 39
- Issue:
- 12
- ISSN:
- 0886-6236
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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