Has sheep wool got potential as a bio-monitoring device for heavy metal concentrations in the UK uplands? J.C. Sneddon & M Powell Liverpool John Moores University [email protected] Plate 1a,1b. Washed & unwashed wool. Introduction & Methods
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Has sheep wool got potential as a bio-monitoring device for heavy metal concentrations in the UK uplands?
J.C. Sneddon & M Powell Liverpool John Moores University [email protected]
Plate 1a,1b. Washed & unwashed wool
Introduction & Methods
Upland sheep in the UK often graze on land containing naturally high concentrations of heavy metals. This pilot trial set out to assess the potential of wool matrix as a bio-indicator of farm heavy metal concentration in North Wales & Cumbria. A questionnaire administered via the Rare Breeds Survival Trust produced wool samples from 12 farm-bred and mainly rare breeds of sheep from 15 farms (Table 1; Plates 2a, b). Wool was washed according to an established protocol (Plates 1a, b). Copper and lead concentrations in the wool matrix (ng.g-1) were obtained by ICP-MS (n=3; repeated measures/sample =3; total measured samples 720). The British Geological Survey G-BASE data base was employed to correlate wool element concentrations with stream sediment concentrations for elements in the farm localities (Plates 2 a, b). OS 4 digit grid references were used to locate farms based on their holding numbers, and the stream sediments had been mapped on a 2x2 km grid square.
Plate 2 a,b. G-BASE maps for stream sediment concentrations for Pb & Cu with superimposed farm locations coded for wool element concentrations
Table 1. Data on experimental subjects in the study
Results & Discussion
Significant associations between wool and stream sediment concentrations were found for copper (χ2 = 6.32 p<0.04 df=2) and lead (χ2 = 193.18 p<0.001 df=2) n =720. Between-individual variation in wool element concentration was 2.5 times higher for copper than for lead indicating differences in metabolic bioavailability & or environmental sources of variation.
There were significant effects of breed for both wool copper (χ2 = 132.85 p<0.001 df=11) and wool lead (χ2 = 264.95 p<0.001 df=11).
Llanwenog had higher median copper concentration in a low Cu area and Shetland lower median lead concentration in an intermediate Pb area than other breeds (p<0.05) . North Ronaldsay had high median copper concentrations in an intermediate Cu area. This technique could be used to indicate where N. Ronaldsay sheep could be at risk from copper toxicity in view of their unique copper metabolism .
In spite of an unavoidable bias in sex ratio in the data (621 females to 99 males), & in agreement with literature on deer antler, there were significantly higher values for wool element concentration in male animals for both copper (χ2 = 42.98 p<0.001 df=1.) and lead (χ2 = 3.86 p<0.05 df =1).Anabolic influence of androgens has been implicated in enhanced metal uptake in deer.
Further studies are planned to include & consider a balanced and expanded survey design in collaboration with the Wool Board, the effect of age, wool sample site on matrix & adsorbed elementconcentration, the potential use of wool as a bio-indicator in bio-remediation studies in brownfield locations.
Acknowledgements:The Rare Breeds Survival Trust & British Geological Survey, Nottingham.