Heavy metal accumulation and tolerance in British populations of the metallophyte Thlaspi caerulescens J. & C. Presl (Brassicaceae)



Heavy metai uptake, accumulation and tolerance were investigated in five British populations of the metallophyte Thlaspi caerulescens from metalliferous sites from the north and south Pennines orefields. Analysis of field samples showed mean shoot Zn, Pb and Cd concentrations of up to 21000, 660 and 164/zMug g-1 respectively. A solution culture experiment designed to investigate both tolerance and metal accumulation is reported. Indices of tolerance of five populations to 12 metals (Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Zn) showed few population differences but unexpectedly high tolerance to metals not present at elevated concentrations in the parent soils. This was paralleled by exceptionally high uptakes of all metals studied. Zn, Cd, Co, Mn and Ni were readily transported to the shoot whereas Al, Cr Cu, Fe and Pb were predominantly immobilized in the roots. The data suggest common mechanisms of absorption and transport of several metals in this species.