§ Mr. Alton
asked the Secretary of State for the Environment (1) what inquiries have been made into the deaths of 850 birds in the River Mersey this year; and what comparisons have been made between these deaths and the circumstances of the deaths of 2,400 birds in the same estuary last year;
(2) when he intends to reply, and if he will publish the reply, to the letter sent to him by the hon. Member for Liverpool, Edge Hill on 17 November on bird deaths in the Mersey estuary; if he will now identify the source of the accidental discharge of tetra-ethyl lead in 1979; and what steps have been taken to prevent a repetition;
(3) what additional information he now has as to the circumstances of the accidental discharge which resulted in the deaths of 2,400 and 850 birds, respectively, in the River Mersey estuary; if any evidence has emerged which would connect the causes of bird deaths in each case; and, further to his answer of 11 November 1980, Official Report, column 173, what steps have now been taken to minimise accidental discharges into the water of the estuary.
§ Mr. Fox
Investigation of the recent deaths of 850 birds in the Mersey estuary is a matter for the relevant wildlife organisations and the North-West water authority. I understand that scientific analysis following post mortem examination is being carried out by the Institute of Terrestrial Ecology on behalf of the Nature Conservancy Council. Results so far have not shown any direct connection between this incident and that of autumn 1979.
No additional information is yet available on the circumstances of the deaths of 2,400 birds in the 1979 incident, but an initial report on the progress of a detailed survey of the waters and sediments of the estuary is expected to be published by the North-West water authority in the summer of 1981.
There was no identifiable accidental excess discharge of tetra-ethyl lead to the estuary in 1979. My answer to the hon. Member on 11 November was intended to refer to an unusually large concentration of alkyl lead in the food and body tissues of the affected birds. Alkyl lead is derived from the breakdown of tetra-ethyl lead. I confirm that the source of this large concentration has not been identified.
Accidental discharges of this material are minimised by ensuring that storage areas are properly bunded to avoid loss to drainage systems. In addition the material itself contains a bright red dye so that leakage can be easily detected and dealt with. Authorised industrial waste discharges which might contain this material are subject to conditions limiting its concentration and are regularly monitored by sampling and analysis.
The hon. Member will by now have a reply to his letter of 17 November.