[Determination of Platinum Group Elements in City Roadside Dusts by ICP-MS ]

Platinum group elements (PGEs) can be naturally found only at very low concentration in the earth crust. However, the increasing usage of PGEs in vehicle exhaust catalysts, and some other applications cause their anthropogenic emission and spread in the environment. Currently，the accumulation of PGEs in the environment has increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution. In order to survey PGEs contamination at residential districts in the urban areas of Beijing City, roadside dust samples were collected. The roadside dust samples were digested with aqua regia and separated and purified with cation exchange resin (Dowex AG50W-X8), and then the resulting solutions were analyzed with inductively coupled plasma mass spectrometry (ICP-MS). PGEs pollution degree in dusts was analyzed using Geoaccumulation Index. The results showed that the concentrations of Pd, Pt and Rh in roadside dusts ranged from 14.20～161.80 ng·g-1 (50.76 ng·g-1), 9.39～70.80 ng·g-1(23.82 ng·g-1), 3.18～17.05 ng·g-1(7.54 ng·g-1), respectively. It indicated that concentrations of PGEs in dusts of residential areas were obviously higher than those values in Beijing soil background. The results of Geoaccumulation Index assessment indicated that the roadside dusts in residential areas were obviously polluted by the PGEs in Beijing city. The order of average pollution level of the PGEs is: Pd＞Pt＞Rh.