Mapping airborne lead contamination near a metals smelter in Derbyshire, UK: spatial variation of Pb concentration and 'enrichment factor' for tree bark.
Samples of tree bark, collected over an area of 4 km2 near a small non-ferrous metals smelter in Derbyshire, UK, were analysed for Pb and Al by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Analyte concentrations varied from 100 to over 25,000 mg kg-1 and 5 to 1000 mg kg-1, respectively. While an inverse relationship between the Pb content of bark and distance from the smelter was observed, concentrations fluctuated, indicating a variability in sample collection efficiency and problems in standardization. To overcome these effects, the Pb/Al ratio was calculated and subsequently normalized to the average Pb/Al ratio in continental crust (0.00015). On the assumption that the time-averaged concentration of airborne Al in this area is relatively constant and derived principally from wind-blown soil, the measurement represents an anthropogenic 'enrichment factor' (PbEF). PbEF varied from 10,000 to over 1,000,000, and showed a consistent reduction with distance from the smelter. Isolines of equal PbEF were subsequently defined on a map of the sampled area. Pb contamination was greatest in the vicinity of the smelter, and preferential transport along the NW-SE axis of the valley (in which the smelter is situated) was observed. The use of enrichment factors thus proved valuable in defining the relative level of airborne-derived Pb pollution.
Bellis
D
D
Centre for Analytical Sciences, Department of Chemistry, University of Sheffield, Dainton Building, Brook Hill, Sheffield, UK S3 7HF.
Cox
A J
AJ
Staton
I
I
McLeod
C W
CW
Satake
K
K
D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005843:Geography; D007221:Industry; D007854:Lead / Q000032:analysis*; D024301:Plant Bark / Q000737:chemistry*; D013057:Spectrum Analysis; D014018:Tissue Distribution; D014197:Trees
D000393:Air Pollutants; D007854:Lead