SITE CHARACTERIZATION OF POLLUTED SOILS AND COMPARISON OF SCREENING TECHNIQUES FOR HEAVY-METALS BY MOBILE ICP-MS, GFAAS ICP-AES (FIXED LABORATORY) AND EDXRF (FIXED LABORATORY)/

A disused industrial/mining site in the former DDR was chosen to evalu ate the performance of a mobile laboratory equipped with inductively c oupled plasma-mass spectrometry (ICP-MS) by comparing the results with fixed-lab based ICP-AES/GFAAS and XRF. New rapid digestion methods we re used to rapidly recover the metals from complex soil matrices for I CP-MS analysis in less than 6 h which permitted fast-screening of samp les. Hot aqua-regia (180 degrees C), with addition of perchloric acid appears to be a better medium for rapidly extracting heavy metals than a hot (180 degrees C) nitric acid leach. 'Hot spot' identification of heavy metal anomalies were located quickly and the environmental asse ssment report accomplished within weeks of the field-based analyses. T he precision on standard soil reference materials run by ICP-MS for Be , V, Cr, Mn, Co, Cu, Zn, As, Cd, Pb and Ni in the European Community's Advanced Mobile Analytical Laboratory (AMAL) is better than results f or ICP-AES/GFAAS (except for Be, Mn, and Zn), and as good as XRF for l ow-medium contamination. Generally, the results obtained for the parti al digestion using aqua-regia compare favourably with the range for aq ua-regia soluble values published for the reference materials (BCR-144 , CRM-320 and BCR-142) for Cr, Ni, Pb, Cu, occasionally Zn; however, n ot all metals are favourable (Cd, Co, Mn +/- Zn). The measured element concentrations for nitric acid partial digestion have a small negativ e to large negative bias compared to the BCR leach values partly becau se the fraction of the sample carrying the metals is not fully leached and the metal yields vary according to the concentration and solubili ty of the metal in the soil. The source of the contamination appears t o be from lignite mining dumps and tar products of the coking industry which were operating in this part of the former DDR from the late 19t h Century until 1931. A sampling grid was set up over the contaminated area and soil samples taken adjacent to a tailings dump are character ized by high V (> 140 mg/kg), Mn (> 600 mg/kg), Cr (> 60 mg/kg), Co (> 35 mg/kg), Cu (> 30 mg/kg), Zn (> 300 mg/kg), As (> 60 mg/kg), Sb (> 3 mg/kg), Ba (> 400 mg/kg), and Pb (> 40 mg/kg) leading to high levels of toxicity on the mine dumps, and responsible for the lack of vegeta tion presently experienced by the mine site.