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THE STUDY SITE
The Firth of Forth is situated on the east coast of Scotland (Figure 1.1), separating
Edinburgh and the Lothians to the south from the Kingdom of Fife to the north. The
Firth of Forth stretches from the Forth Bridges in the west to Dunbar/Fifeness in the
east and contains several harbours and boatyards for commercial and pleasure craft.
The Firth is a channel for the passage of large vessels to and from Grangemouth,
Rosyth and Leith. The oil industry has an oil-exporting terminal at Houndpoint and
several construction/repair yards on the north coast of the Firth of Forth. Treated
sewage and industrial effluent are disposed of at numerous outfalls along the coasts of
the Firth of Forth. There are also numerous recreational uses and the Firth is an
important area for nature conservation.
The Firth of Forth is monitored and regulated by the Scottish Environment Protection
Agency (SEPA), duties formerly carried out by the Forth River Purification Board
(FRPB). Annual nutrient and phytoplankton levels in the Firth of Forth are typical of
those found in British estuarine and coastal waters (FRPB, 1993). Salinity shows
annual variability between 29-33ppt due to seasonal weather conditions (Webb and
Metcalfe, 1987; FRPB, 1993). The water temperature also varies between 5-15°C
following the annual cycle of irradiance levels and ambient air temperature (Webb and
Metcalfe, 1987; FRPB, 1993).
All the sampling for the present study was carried out on Drum Sands which is a
large, intertidal sandflat (Figure 1.2). The majority of the sandflat is relatively flat and
a large proportion lies below mid-tide level (Figure 1.3). Personal observations have
shown that the sediments vary on a large scale over the beach: although most of the
sandflat can be described as clean beach sand it varies from mud at the top to coarse
sand/gravel in patches towards the lower end of the sandflat. Monitoring programmes
have shown the biological and chemical water qualities at nearby Cramond to be
generally good with no detectable effects from the oil exporting terminal and treated
ballast water outfall at Houndpoint (Griffiths, 1987; FRPB, 1988; 1992). Traces of
sewage solids along the strandline of Drum Sands have been found during several
studies which were presumed to result from both the septic tank discharge from
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