ENVIRONMENTAL CONTAMINATION THROUGH RESIDUAL TRACE-METAL DISPERSAL FROM A DERELICT LEAD-ZINC MINE

Studies of historical and current environmental problems in the vicinity of a derelict Pb-Zn mine at Parc, near Elanwrst in North Wales, have shown that heavy metal dispersal occurs through contaminated mine drainage waters and episodal erosion of an unstable tailings dam. Since the discontinuation of mining operations an estimated 13,000 metric tons of metalliferous spoil, equivalent to 43 metric tons Pb, 104 metric tons Zn, and 1 metric ton Cd, have been eroded from the main tailings dam. Dispersal by a tributary of the River Conwy and redeposition during flooding events has caused extensive contamination of lowland agricultural pastures. Streamwater pollution by tailings and dissolved metal salts in mine effluent continues to have a pronounced adverse effect on the flora and fauna of the tributary.