Ref ID : 5997
M.A. Wright and A. Stringer; Lead, zinc and cadmium content of earthworms from pasture in the vicinity of an industrial smelting complex. Environ.Pollut.A 23:313-321, 1980
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Comparison was made of the heavy metal concentrations of lead, zinc and cadmium in earthworms and soil from pasture near a large lead and zinc smelting plant and a control area 9 km away. The concentration of lead in the earthworms was less than that in the soil, whereas zinc and cadmium concentrations were several times the value in the soil. The zinc and cadmium concentration factors for all worm species were significantly lower at the contaminated site than at the control site and both were significantly greater than for lead. There was 7-9 times as much zinc and cadmium in the soil from the smelting site as in that from the control area and 1.6 times as much lead. Corresponding values in the worms were 1-3.5 times as much zinc and cadmium and 1.4-4.0 times as much lead. The zinc:cadmium ratio decreased from 81 in soil to 26 for earthworms (average of aggregation of species) at the control site and from 63 to 18 at the contaminated site. The best overall relationship between metal concentration in earthworms and concentration in soil was y=k.x(b) where y=concentration of metal per gramme of worm, dry weight, and x=concentration of metal per gramme of soil, dry weight. Comparison of regression slopes of the log transformed data showed that uptake was greater for lead than for the other two metals. For each metal the worms are in two species groups. For the Lumbricus terrestris, Allolobophora chlorotica, A. rosea group the rates of uptake for zinc and cadmium were not significantly different. There was no evidence that the earthworm populations near the smelting plant had been reduced by the heavy metal contamination.