View source for Rates of DMS and DMSP oxidation to DMSO

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* [[Page authors|Page authors]]: [[PRIMO]]
* [[Responsible curator|Responsible curator]]:  [[User:Hagi BucknWise|Hagen Buck-Wiese]]
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! DMS and DMSP oxidation rates
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| '''Approach:''' deuterium-labelled DMS/DMSP tracers; D<sub>3</sub>-DMSO and D<sub>6</sub>-DMSO formation by GC-MS
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| '''Context:''' ''in situ'' incubations, lab
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| '''Spatial scale:''' point sample
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| '''Temporal scale:''' 4–12 h
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| '''Units:''' nM d<sup>-1</sup>; rate constants h<sup>-1</sup> or d<sup>-1</sup>
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| '''Community captured:''' all
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| '''Co-measurements:''' (none specified in inventory)
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== Method Overview ==

The oxidation of DMS and DMSP to DMSO is measured using deuterium-labelled tracers. D<sub>3</sub>-DMS is added to measure DMS oxidation (D<sub>3</sub>-DMSO formation), and D<sub>6</sub>-DMSP is added to measure DMSP oxidation to DMSO (D<sub>6</sub>-DMSO formation). These reactions are catalyzed by bacterial mono-oxygenases and represent a significant biological sink for DMS in marine surface waters. The rate of labelled DMSO accumulation, detected by GC-MS and corrected for the fractional enrichment of the substrate pool, gives the gross oxidation rate for each pathway<ref name="McCulloch2023">McCulloch, J. E., & Tortell, P. D. (2023). The determination of dimethyl sulfoxide in natural waters using electrochemical reduction. ''Limnology and Oceanography: Methods'', 21(9), 529–541. https://doi.org/10.1002/lom3.10562</ref>.

=== Scale of measurement ===

Point samples from sealed serum vials for 4–12 h incubations.

=== Data generated ===

Gross DMS oxidation rate and DMSP oxidation rate (nM d<sup>-1</sup>), each measured simultaneously in the same incubation. Together with DMSO reduction rates, the net DMS and DMSO budget can be assembled.

=== Units & currency ===

Units are nM d<sup>-1</sup> or h<sup>-1</sup>/d<sup>-1</sup> (rate constants). The currency is sulfur metabolite (DMSO).

=== Sample size ===

Typical samples are < 200 mL in volume.

=== Repositories & databases ===

== Limitations ==

Deuterium-labelled DMS and DMSP must rapidly equilibrate with the endogenous pools. DMSP may be cleaved to DMS before being oxidized, potentially complicating the DMSP → DMSO pathway measurement. Bottle effects and steady-state assumptions apply as for other DMS/P/O turnover measurements.

== Example Applications & Protocols ==

=== Classic examples ===
* McCulloch & Tortell (2023) ''The determination of dimethyl sulfoxide in natural waters using electrochemical reduction'' <ref name="McCulloch2023" />

=== Recent applications ===
* McNabb & Tortell (2025) ''A potential photo-protective, antioxidant function for DMSO in marine phytoplankton'' <ref name="McNabb2025">McNabb, M. L., & Tortell, P. D. (2025). A potential photo-protective, antioxidant function for DMSO in marine phytoplankton. ''PLOS ONE'', 20(2), e0317951. https://doi.org/10.1371/journal.pone.0317951</ref>

=== Common calculations/conversions ===
* DMS oxidation rate = d[D<sub>3</sub>-DMSO]/dt × ([DMS]<sub>total</sub> / [D<sub>3</sub>-DMS]<sub>added</sub>).
* DMSP oxidation rate = d[D<sub>6</sub>-DMSO]/dt × ([DMSP]<sub>total</sub> / [D<sub>6</sub>-DMSP]<sub>added</sub>).

== References ==

[[Category:Main Pages|Model types]]