Gschwend%20thesis.pdf

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were the dimethyl polysulfides, CH3SSCH3 (DMDS), CH3SSSCH3 (DMTS), CH3SSSSCH3
(DM4S). DMDS appeared in the spring and summer. DMTS and DM4S were found
in the restrips of winter samples and in both the strips and restrips of
the spring samples of 1978.
These compounds are frequently recovered in greater amounts in the
second 2 hours of stripping than in the original strips (figure 3-22).
As discussed in Schwarzenbach et al. (1978), a capacity for the formation
of these polysulfides must be contained within the samples.
DMDS may be formed by the oxidation of methyl mercaptan (Reid, 1958),
a common product from marine algae (Haas, 1935; Challenger, 1959) and
microorganisms (Kadota and Ishida, 1972). DMDS, DMTS, and DM4S may all
be produced by the reaction of methyl mercaptan and elemental sulfur at
room temperature (Mc~1illan and King, 1948; Vineyard, 1966). Possibly, the
analytical conditions increase the release of methyl mercaptan by micro-
organisms into seawater; allowing the concentration of this thiol to
build up. As a result, the rate of production of polysulfides would also
increase in time, and restrips would contain higher yields than the
original 2 hours of stripping.
Elemental sulfur may also add to DMDS to yield DMTS and DM4S.
The ratio of sulfur to starting disulfide (Murdock and Angier, 1970) or
mercaptan (Vineyard, 1966) has been shown to control the distribution of
polysulfide products. Excess elemental sulfur levels favor the production
of compounds with longer sulfide chains. Thus the different distributions
of polysulfides seen in the year-round study may reflect the concentration
of elemental sulfur in the seawater throughout the year.
Also these compounds may be derived from other metabolites. Cyclic
polysulfides (Wratten and Faulkner, 1971) and acyclic forms (Moore, 1971)
have been reported and their degradation may be the source of these