Dredge Spoil (Hansard, 2 February 1990)

§ Mr. Malcolm Bruce
To ask the Minister of Agriculture, Fisheries and Food what is the percentage of mercury contamination in dredge spoil in(a) the Tyne estuary and (b) Liverpool bay.

§ Mr. Gummer
Information on the trace metal composition of dredged materials licensed for disposal at sea is held on a public register maintained by my Department. For the Tyne estuary the concentration of mercury in dredged materials is 0.0001 per cent. In the Mersey estuary concentrations in dredged materials range from 0.0001 to 0.0006 per cent. (1 to 6 mg/kg dry weight).

§ Mr. Malcolm Bruce
To ask the Minister of Agriculture, Fisheries and Food what assessment he has made of the contamination of heavy metals of dredge spoil in(a) the Tyne estuary and (b) Liverpool bay; what monitoring of release of heavy metals in dredge spoil in these areas is being or has been carried out; and if he will make a statement.

§ Mr. Gummer
Licences for the disposal of dredged material at sea are granted for one year and details of trace metal concentrations and other information are placed on a public register held in my Department. For recurrent dredging operations, these data are reviewed annually and locations are resampled at least every three years in accordance with guidelines set down by the Oslo commission. There are currently four licences for the disposal of material in Liverpool bay and three licences for disposal at a site three and a half miles off the mouth of the Tyne estuary.
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The Ministry has conducted a programme of both laboratory and field investigations on the fate of heavy metals in dredged materials. The Ministry has also conducted a survey of trace metal contamination in the Tyne estuary and has identified areas where, in the event of dredging, the sediments are not suitable for disposal at sea. Results of the field monitoring surveys have been published in the fisheries research technical report series and are in the Library of the House.
Further work on the quality of fish and shellfish in these and other coastal areas is published in "Aquatic Environment Monitoring Report No. 16", a copy of which is also in the Library of the House. These investigations have shown that, in the case of mercury in Liverpool bay which has been subject to historical industrial inputs, the concentration of mercury in a range of fish satisfies the EC environmental quality standard of 0.3 mg/kg wet weight. For other heavy metals in both locations, concentrations are well below national standards for food quality.