THALLIUM IN FRENCH AGROSYSTEMS .2. CONCENTRATION OF THALLIUM IN FIELD-GROWN RAPE AND SOME OTHER PLANT-SPECIES

The aim of this study was to assess thallium (Tl) uptake into the aeri al parts of selected crop species grown on French soils with high Tl c ontent of pedogeochemical origin (0.3-40 mg Tl kg(-1) on a dry wt (DW) basis). Husked wheat and maize grains contained less than 4 mu g Tl k g(-1) DW, but rape shoots accumulated Tl with a shoot-soil partition c oefficient (PC) > 1, and rape seeds had PC > 3. Tl content of rape see d reached 33 mg Tl kg(-1) DW and higher concentrations in soil corresp onded to increased concentrations in rape seeds. It is argued that par ent material of the soil and pedogenesis have a considerable effect on Tl accumulation in rape seeds. These results show enhanced phytoavail ability of Tl of pedogeochemical origin and prompt questions on the po tential for food chain contamination by Tl in rape cattle cakes. (C) 1 997 Elsevier Science Ltd.