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The Fal Estuary passes through the Falmouth area, a Cornish town along the South West coast of England. Globally, it is the third largest natural harbour [3],and is an important area in terms of trade, tourism and its wide biodiversity [4]. The area has been a functioning port as far back as 1170 when the port at Truro became established. The Fal Estuary has 6 main tributaries and 28 tidal creeks, each containing a small central stream (Figure 1). It opens into Carrick Roads which extends for 4 miles [1] , including extensive mudflat areas and streams.

The catchment area of the river Fal suffered greatly from anthropogenic inputs; generally the tributaries to the west received waste from metal mining and tributaries from the east had inputs through tin mining and china clay extraction. These large inputs of heavy metals from mining activity have occurred for many generations, possibly as long ago as the Bronze Age [1] , making the water more acidic as it contains high concentrations of Zn, Fe, Mn, Cu, As and Cd. These metals accumulate in organisms, leading to bioaccumulation particularly of Cu in the estuarine food chain. Paralytic seafood poisoning (PSP) can occur when some nutrients are in high concentrations and bioaccumulate in farmed shellfish, such as in the mussel farms as oyster beds in the Fal estuary.

Overview

Figure 1: Location of the Fal Estuary in relation to the rest of Cornwall.

Photo:https://projects.exeter.ac.uk/geo mincentre/estuary/Main/loc.htm

Figure 2: Tidal prediction chart for Falmouth Harbour 20th June - 2nd July 2016.

Photo:www.tidetimes.org.uk

1.  Bryan, GW; Gibbs, PE. (1983). Heavy metals in the Fal estuary, Cornwall: A study of long term contamination by mining waste and its effects on estuarine organisms. Occasional Publication of the Marine Biological Association 2. Plymouth (UK), Marine Biological Association of the United Kingdom.
2. EU Habitats Directive - www.gov.uk/government/publications/marine-conservation-advice-for-special-area-of-conservation-fal-and-helford-uk0013112/fal-and-helford-sac-site-information-draft)
3. https://www.falmouthtowncouncil.co.uk Falmouth Town Council (2013) About Falmouth. Available at: https://www.falmouthtowncouncil.co.uk/about-falmouth (Accessed: 25 June 2016).
4. Langston, W., Chesman, B., Burt, G., Taylor, M., Covey, R., Cunningham, N., Jonas, P. and Hawkins, S. (2006). Characterisation of the European Marine Sites in South West England: The Fal and Helford Candidate Special Area of Conservation (cSAC). Hydrobiologia, 555(1), pp.321-333.
5. Younger. P. I. (2002) Mine water pollution from Kernow to Kwazulu-Natal: Geochemical remedial options and their selection in practice. Geosci. SW England, 10, 254-265

Mining disaster

Whilst these low background levels can be harmful, the most damage was caused by the Wheal Jane Mine pollution disaster. The Wheal Jane mine was primarily a tin mine, although other materials were also removed from the mine throughout its use from the mid-1700s to the final closure in March 1991 [5]. The pumps were shut off in January 1992, and a few days later the groundwater levels rose to the same height as the river, and the drainage system burst, releasing 50,000 litres of metal-polluted groundwater into Restronguet Creek and into the Fal estuary via Carrick Roads. An orange plume was visible from the sky due to iron hydroxides in the water.

SAC line

In 2005, the Fal estuarine system was designated a Special Area of Conservation (SAC) under the EU Habitats Directive [2]The boundary of the SAC lies between Zone Point and Manacle Point at the mouth of the estuary.