Trace metal composition of the aerosol at Neumayer Station, Antarctica during the year 2008

Aerosol was continuously sampled by sucking ambient air with a flow rate of 120 m**3/h through Whatman 541 filters (diameter 240 mm) using a ventilated electropolished stainless steel inlet stack (total height about 8 m above the snow surface) with a 50% aerodynamic cut-off diameter around 7-10 µm. Trace element analysis was performed by means of inductively coupled plasma - quadrupol mass spectrometry (ICP-QMS, ELAN 6000, Sciex/Perkin Elmer) equipped with a cross-flow nebulizer as sample introduction system. For trace element analyses we chose a total digestion of the samples with a pressurized digestion system (DAS 100, Picotrace) at 200°C in a mixture containing HNO3 (suprapure, 65%, Merck, sub-boiling bi-distilled), HF (suprapure, 40%, Merck, sub-boiling bi-distilled) and H2O2 (suprapure, 30%, Merck). With this device a series of 24 samples could be digested in parallel. Each series included one filter blank and a certified reference sample (NIST 1648 urban particulate matter). For calibration we used commercially available standard solutions (104 ppb multi-element verification standard 1 and 2, Perkin Elmer) which were generally applied in 1 ppb, 10 ppb, and 100 ppb concentrations (1 ppb corresponds to 1 ng of each element in 1 g solute). Each sample was spiked by 10 ppb Rh as internal standard to normalize the signal intensities and compensate instrumental sensitivity variations.