Lead isotopic compositions of atmospheric suspended particulate matter in Nagoya City as measured by HR-ICP-MS

Lead isotope ratios in atmospheric suspended particulate matter (SPM) collected in Nagoya City were measured by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) after microwave-assisted acid digestion. Before analyzing SPM samples, the present method was evaluated by analyzing standard reference material (SRM 981) for common lead isotopic standard from NIST. The analytical results for Pb-207/Pb-206 and Pb-208/Pb-206 for SRM 981 were 0.9160 +/- 0.0006 and 2.136 +/- 0.003, respectively, which were almost coincident with the certified values of 0.91464 +/- 0.00033 and 2.1681 +/- 0.0008, respectively. The lead isotope ratios in SPM samples collected daily in Nagoya University were analyzed in order to elucidate their origins, and the results were compared with various kinds of ores. It was found that most SPM samples showed some mixed compositions of lead isotope ratios of lead ores from USA and Australia, which suggested utilization of large amount of lead ores imported from these two countries. On the other hand, some samples showed mixed compositions of lead ores from Asian continent, which might be resulted from the long-range transportation of atmospheric SPM from Asian continent to Japan.