Department of Chemistry
University of Otago
PO Box 56, Dunedin
New Zealand

Tel: +64-3-4797908
Fax: +64-3-4797906
email: chemistry@otago.ac.nz

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• Research graduates 2000–present
• Abstract
• Life since MSc
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Rebecca Stevenson

Thesis Title:

A study of the chemical composition of the shell of Perna canaliculus (Mollusca: Bivalvia: Mytilidae) and its possible uses as an environmental product.

Supervisor:

Dr. Barrie Peake

Thesis Abstract:

The main constituent of shells of P. canaliculus is Ca, which is in the form of aragonite. Trace element levels within the shell vary with analytical equipment used, and reflect some patterns with respect to location and depth of collection. Not all patterns in element levels in shells between locations were apparent in all analytical techniques, with the exception of Mn, which showed lower levels in shells sampled from Pelorus Sound compared to shells from Portobello and Big Glory Bay. No pattern could be detected between Ca, Sr, or P within a cross-sectional view of shell, but S showed a decrease in concentration on the outer edge of the shell. There was no pattern in element levels from the oldest to newest growth within the shell analysed.

Comparison of leachate from columns of shell waste aged less than one week, 6-months, 2-4 years, and 12-14 years, showed that most elements, with the exception of Ca, leached out in highest concentration in the youngest shell piles (6-months or less). A comparison of elements leaching out after one day and 35 days show that all elements leach out at higher concentration after 35 days, again with the exception of Ca, which had highest concentrations leach out after one day. A number of alternative uses are available for P. canaliculus waste material as element levels leached out of the shell is not at a level that would cause environmental harm. The potential to use mussel waste as a ‘slow-release’ fertiliser (one that releases nutrients slowly to plants over a long period of time) could be feasible, although levels of essential nutrients within the shell are low. Although many options are available to utilise mussel shell waste, the demand needs to be present for the product for it to be commercially feasible, and the cost of producing and marketing the product need to balance with revenue gained.

Life since MSc

 

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