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Rates of DMS and DMSP oxidation to DMSO

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DMS and DMSP oxidation rates
Approach: deuterium-labelled DMS/DMSP tracers; D3-DMSO and D6-DMSO formation by GC-MS
Context: in situ incubations, lab
Spatial scale: point sample
Temporal scale: 4–12 h
Units: nM d-1; rate constants h-1 or d-1
Community captured: all
Co-measurements: (none specified in inventory)

Method Overview

The oxidation of DMS and DMSP to DMSO is measured using deuterium-labelled tracers. D3-DMS is added to measure DMS oxidation (D3-DMSO formation), and D6-DMSP is added to measure DMSP oxidation to DMSO (D6-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[1].

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-1), 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-1 or h-1/d-1 (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 [1]

Recent applications

  • McNabb & Tortell (2025) A potential photo-protective, antioxidant function for DMSO in marine phytoplankton [2]

Common calculations/conversions

  • DMS oxidation rate = d[D3-DMSO]/dt × ([DMS]total / [D3-DMS]added).
  • DMSP oxidation rate = d[D6-DMSO]/dt × ([DMSP]total / [D6-DMSP]added).

References

  1. ↑ 1.0 1.1 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
  2. ↑ 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
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