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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Silicon uptake kinetics (V_max, K_s) |- | '''Approach:''' ³²Si incubations at multiple ambient silicic acid concentrations; Michaelis–Menten fitting |- | '''Context:''..."

2026-05-13T00:21:29Z

Created page with "{{BreadcrumbsNutrients}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- __TOC__ <div class="model-box"> {| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Silicon uptake kinetics (Vmax, Ks) |- | '''Approach:''' 32Si incubations at multiple ambient silicic acid concentrations; Michaelis–Menten fitting |- | '''Context:''..."

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* [[Page authors|Page authors]]: [[PRIMO]]
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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;"
! Silicon uptake kinetics (Vmax, Ks)
|-
| '''Approach:''' 32Si incubations at multiple ambient silicic acid concentrations; Michaelis–Menten fitting
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| '''Context:''' incubation, ''in situ'' and lab
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| '''Spatial scale:''' point sample
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| '''Temporal scale:''' hours to days
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| '''Units:''' Vmax (d-1); Ks (µmol Si L-1 or µmol Si cell-1)
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| '''Community captured:''' bulk
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| '''Co-measurements:''' ambient [Si(OH)4], PAR, temperature, BSi
|}
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== Method Overview ==

Silicon uptake kinetics are determined by conducting 32Si tracer incubations across a range of silicic acid concentrations spanning from near-ambient to saturating levels. At each substrate concentration, the uptake rate is measured as for the standard silicon uptake assay, and the resulting uptake rate vs. [Si(OH)4] relationship is fitted to the Michaelis–Menten equation to derive the maximum specific uptake rate (Vmax, d-1) and the half-saturation constant for silicic acid (Ks, µmol Si L-1 or per-cell equivalent)<ref name="Brzezinski1997">Brzezinski, M. A., & Phillips, D. R. (1997). Evaluation of 32Si as a tracer for measuring silica production rates in marine waters. ''Limnology and Oceanography'', 42(5), 856–865. https://doi.org/10.4319/lo.1997.42.5.0856</ref>. These kinetic parameters characterize the community's capacity to access silicic acid at varying concentrations and indicate whether the community is silicon-limited.

=== Scale of measurement ===

Point sample following hours to days of incubation across multiple substrate concentrations.

=== Data generated ===

Vmax (d-1) and Ks (µmol Si L-1); these kinetic parameters characterize the community's affinity for silicic acid and maximum uptake capacity. When ambient [Si(OH)4] < Ks, the community is silicon-limited.

=== Units & currency ===

Units are Vmax (d-1) and Ks (µmol Si L-1 or µmol Si cell-1). The currency is Si.

=== Sample size ===

Typical samples are 100–300 mL per substrate concentration, with multiple replicates.

=== Repositories & databases ===

== Limitations ==

Kinetic parameters derived from short incubations may not represent steady-state values; acclimation to substrate additions can shift Vmax and Ks over longer timescales. Normalization to BSi introduces the same uncertainty as for bulk uptake (inclusion of dead frustules). Vmax and Ks represent the integrated response of all silicifying organisms in the community and cannot be attributed to individual species without additional fractionation.

== Example Applications & Protocols ==

=== Classic examples ===
* Brzezinski & Phillips (1997) ''Evaluation of 32Si as a tracer for measuring silica production rates in marine waters'' <ref name="Brzezinski1997" />

=== Recent applications ===
* Giesbrecht & Varela (2021) ''Summertime biogenic silica production and silicon limitation in the Pacific Arctic Region'' <ref name="Giesbrecht2021">Giesbrecht, K. E., & Varela, D. E. (2021). Summertime biogenic silica production and silicon limitation in the Pacific Arctic Region from 2006 to 2016. ''Global Biogeochemical Cycles'', 35, e2020GB006629. https://doi.org/10.1029/2020GB006629</ref>

=== Common calculations/conversions ===
* VSi = Vmax × [Si(OH)4] / (Ks + [Si(OH)4]); rearranged as a Lineweaver–Burk or Eadie–Hofstee plot to obtain Vmax and Ks.

== References ==

[[Category:Main Pages|Model types]]

Kinetics of silicon uptake - Revision history