HEAVY-METAL ACCUMULATION AND TOLERANCE IN BRITISH POPULATIONS OF THE METALLOPHYTE THLASPI-CAERULESCENS J-AND-C-PRESL (BRASSICACEAE)

Heavy metal uptake, accumulation and tolerance were investigated in fi ve British populations of the metallophyte Thlaspi caerulescens from m etalliferous sites from the north and south Pennines orefields. Analys is of field samples showed mean shoot Zn, Ph and Cd concentrations of up to 21000, 660 and 164 mu g g(-1) respectively. A solution culture e xperiment designed to investigate both tolerance and metal accumulatio n 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 e levated concentrations in the parent soils. This was paralleled by exc eptionally high uptakes of all metals studied. Zn, Cd, Co, Mn and Ni w ere readily transported to the shoot whereas Al, Cr Cu, Fe and Pb were predominantly immobilized in the roots. The data suggest common mecha nisms of absorption and transport of several metals in this species.