GEOMORPHOLOGY AND POLLUTION - THE ENVIRONMENTAL IMPACTS OF LEAD MINING, LEADHILLS, SCOTLAND

The Glengonnar Water has experienced severe environmental degradation resulting from historic lead mining operations. Though now abandoned, the legacy of the mining era remains in the form of river and floodpla in sediments grossly polluted with metals, particularly lead which exh ibits surface concentrations in excess of 75 000 mg kg-1 total-Pb. Geo morphological investigations link the most recent mining period to a m ajor phase of floodplain aggradation, which acted as an efficient sink for particulate-bound metals. The pattern of metal contamination with in the floodplain has been complicated by subsequent fluvial entrenchm ent. However, preliminary evidence indicates that lateral and vertical variations of metals (both total and available) can be accounted for in terms of age of deposit, distance downstream and local hydraulic co nditions. The effectiveness of floodplains to interrupt the delivery o f sediment-bound contaminants was highlighted by a metals budget devel oped for the main channel length. This confirmed that channel-bank ero sion of contaminated floodplains soils is now the major source of meta ls to the fluvial system.