I observed a similar phenomenon for scallops but after
lipid removal: the d34S was reduced. I bet this has
something to do with the removal of inorganic SO4 and
remaining of organic sulfur, but in fact I don't know.
A comprehensive reference that is freely available in
internet and briefily mentioned the topic is "Stable
Isotopes: Natural and Anthropogenic Sulphur in the
Environment". The link is:

http://www.icsu-scope.org/downloadpubs/scope43/index.html


--- Gilbert Cabana <[log in to unmask]>
escreveu:

> Hi,
> 
> I got 34S values from an outside lab for whole
> invertebrate tissues 
> collected along a salinity gradient over 2 years i
> the St-Laurent estuary, .
> Samples for one mission were acid-washed, all the
> three others weren't.
> The 34S values at all salinities appear to be
> depressed by about 4-5 per 
> mill for the acid-washed run, with respect to the
> data from the other three 
> non washed missions which were all analysed in the
> same run.  Reps are good 
> and so are standards. Acid washing can interfere
> with 15N, but I cannot 
> find a ref on a
> possible effect on 34S.  Does somebody here have
> experience with this or 
> know of a published source?
> 
> Tx and cheers to all!
> 
> Gilbert Cabana
> 
> 


Matheus C. Carvalho
PhD student
Kitasato University - School of Fishery Sciences
Japan


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