DETERMINATION OF THALLIUM IN SEDIMENTS OF THE RIVER ELBE USING ISOTOPE-DILUTION MASS-SPECTROMETRY WITH THERMAL IONIZATION

By using isotope dilution mass spectrometry with thermal ionization, Tl concentrations were determined in sediments from six sampling positions of the River Elbe in the area of the former GDR (Bad Schandau, Dresden, Barby, Magdeburg, Werben/Havel and Cumlosen). For comparison, two samples from the River Rhine near Emmerich taken in 1978 and 1990 and the Community Bureau of Reference (BCR) certified reference material (CRM) 320 River Sediment were also analysed. Thallium concentrations after complete decomposition by high-pressure digestion (HNO3 + HF) and aqua regia [HCl-HNO3 (3 + 1)] ranged from 537-mu-g kg-1 in the BCR CRM 320 to 5192-mu-g kg-1 in the River Rhine sediment (1978) near Emmerich. The reproducibility of the method ranged from 0.06 to 4.7%. Only 49-94% of the total amount of Tl was found after extraction with 1 mol dm-3 HNO3 and 43-86% after extraction with aqua regia. Sediments from Dresden, Barby, Werben/Havel and Cumlosen were found to have virtually identical Tl concentrations as the River Rhine sediment sampled in 1990. In comparison with the extremely high Hg and As concentrations found in the River Elbe in an earlier study, the Tl concentrations were not as high as expected.