Omrani Mehrazin, Goriaux Mathieu, Jean-Soro Liliane, Ruban Véronique
Gustave Eiffel University, F-44344, Bouguenais, France.
IRSTV, FR CNRS 2488, 44321, Nantes Cedex 3, France.
Environ Sci Pollut Res Int. 2021 Feb 26. doi: 10.1007/s11356-021-12916-8.
Platinum group elements (PGEs, i.e. platinum, Pt; palladium, Pd; and rhodium, Rh) catalyse over 90% of carbon monoxide, nitrogen oxides and hydrocarbons from combustion residues into water vapour, carbon dioxide and nitrogen in the vehicle's catalytic converter. But there is a major concern over these metals in the scientific world, since they are emitted by catalytic converters and accumulating in the environment. The distribution of PGEs in PM fraction was studied in an open urban site (Nantes, France) and in a tunnel (Paris, France) using low- and high-volume air samplers. PGEs were also investigated in dry deposition particles and deposited dust sampled in the tunnel. Pd occurred at the highest levels in both PM and dry deposition samples, followed by Rh and Pt. Maximum concentrations in PM fraction were 114 pg m for Pd, 14.3 pg m for Rh and 3.3 pg m for Pt in the urban site (Nantes) and 91 pg m for Pd and 16 pg m for Rh in the tunnel (Paris). The concentrations for dry depositions in the tunnel were 261 μg kg for Pt, 431 μg kg for Pd and 85 μg kg for Rh. The results on PGEs levels in atmospheric particles and dry depositions are the first data of their kind in France and will provide new insights into the contribution of catalytic converters to the environment. We also observed Pd and Rh being 2 times higher PM particles compared to dry depositions, leading us to suggest that particles rich in Pd and Rh are smaller than 10 μm. An overall concentration trend of Pd > Rh > Pt was observed in all samples, showing the replacement of Pt by Pd and Rh in newer catalytic converters.
铂族元素（PGEs，即铂，Pt；钯，Pd；铑，Rh）在车辆的催化转化器中可将90%以上燃烧残余物中的一氧化碳、氮氧化物和碳氢化合物催化转化为水蒸气、二氧化碳和氮气。但科学界对这些金属极为关注，因为它们会从催化转化器中排放出来并在环境中不断累积。利用低流量和高流量空气采样器，在法国南特的一个城市露天场所和法国巴黎的一条隧道中，研究了铂族元素在颗粒物中的分布情况。还对隧道中采集的干沉降颗粒物和沉积灰尘中的铂族元素进行了研究。在颗粒物和干沉降样品中，钯的含量最高，其次是铑和铂。在城市露天场所（南特），颗粒物中钯的最大浓度为114 pg/m³，铑为14.3 pg/m³，铂为3.3 pg/m³；在隧道（巴黎）中，钯的最大浓度为91 pg/m³，铑为16 pg/m³。隧道中干沉降物的浓度分别为：铂261 μg/kg，钯431 μg/kg，铑85 μg/kg。大气颗粒物和干沉降物中铂族元素含量的研究结果是法国首次此类数据，将为催化转化器对环境的影响提供新的见解。我们还观察到，与干沉降物相比，颗粒物中钯和铑的含量高出2倍，这使我们推测富含钯和铑的颗粒物小于10微米。在所有样品中均观察到钯>铑>铂的总体浓度趋势，表明在新型催化转化器中铂正被钯和铑所取代。
