Mireille Consalvey PhD Thesis - University of St Andrews

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I'lk and %4"[fio(k
The wet weight was recorded and the sample frozen, lyophilised in the dark
(Edwards Modulyo, Freeze Dryer) and re-weighed prior to analysis.
2.2.4. Core collection
Where expenments could not be conducted in situ cores were collected.
Cores of approximately 8 cm wide and 20 cm long were used. They were
bevelled at one end and inserted into the sediment so that the surface was almost
level with the rim. A petri dish was placed at the base to secure the core. Cores
were transported back to the laboratory and placed in tidal tanks as soon as
possible.
2.3. Water content
(Equation 2.1):
Water content was calculated as a proportion of wet sediment weight
Water Content (%) = Wet Sediment (g) - Dry Sediment (g) x 100 Equation 2.1
Wet Sediment (g)
Traditionally sediments were oven dried to obtain dry weight but
Honeywill (2001) determined that there was no significant difference in the
amount of water removed in the oven and in a freeze-dryer. Therefore, in this
study dry weight was obtained by freeze-drying samples prior to pigment
analysis. The oven drying technique could not be used on samples that were to be
used for pigment extraction because pigments are therniosensitive (Rowan 1989).
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