TRACE-METALS IN THE LIVERS OF MARINE MAMMALS FROM THE WELSH COAST AND THE IRISH SEA

Samples of liver from forty-two marine mammals of six species found on the coast of Wales and the Irish Sea in 1989-91 have been analysed for a range of trace metals (Cr, Ni, Cu, Zn, Cd, Hg, and Pb). The animals sampled comprised eleven seals, twenty-two porpoises, eight dolphins and one Minke whale. The range of concentrations for each metal were, in mu-g g-1 wet wt: Cr, <0.5-2.1; Ni, <0.5-2.1; Cu, 2.279; Zn, 15-150; Cd, <0.06-2.2; Hg, 0.5-280; Pb, 0.05-7.0. The majority of values for Cr, Ni, and Pb were below the limits of detection for flame AAS, extracts were reanalysed for Pb only using graphite furnace AAS. High concentrations of Hg and Pb. were found in a number of animals from the Liverpool Bay area of the eastern Irish Sea. The highest Cd concentrations were found in an offshore species, the striped dolphin Stenella coeruleoalba, and this is thought to relate to prey preference. Elevated concentrations of Cu were found in a neonatal porpoise and a common dolphin foetus, relative to those found in their mothers, but this finding is also not thought to be pollution-related. Results from post-mortem investigations made on the majority of the animals are also presented.