Lyubomirova Valentina, Djingova Rumyana, van Elteren Johannes T
Faculty of Chemistry, University of Sofia, 1, J. Bouchier Blvd., 1164 Sofia, Bulgaria.
J Environ Monit. 2011 Jun;13(6):1823-30. doi: 10.1039/c1em10187k. Epub 2011 Apr 14.
The introduction of catalytic converters has led to a new environmental problem since catalysts emit platinum group elements (PGEs) which are among the least distributed elements in nature. Along with PGEs the vehicle exhaust catalysts contain also a number of stabilizers, commonly oxides of rare earth elements and alkaline earth elements such as Ce, La and Zr. Since vehicular emission of these elements has received little attention so far this work attempts to offer insight into their distribution and fate in the environment by measuring their speciation in road dust samples collected along several highways in Germany and a city centre (Saarbrücken). Speciation of the elements (fractionation into associated mineralogical phases) was carried out via a conventional sequential extraction protocol and the complexing abilities of humic substances in the organic matter were investigated by selective extraction methods in combination with size segregation. For evaluation purposes soil samples spiked with catalytic converter material were analyzed, showing a much lower fraction of Ce, La and Zr mobilized in comparison to the road dust samples. It was found that the elements were effectively bound to humic substances in road dust with a preference for complexation with low molecular weight compounds (<1600 Da).
催化转化器的引入引发了一个新的环境问题，因为催化剂会释放铂族元素（PGEs），而这些元素是自然界中分布最少的元素之一。除了铂族元素，汽车尾气催化剂还包含一些稳定剂，通常是稀土元素和碱土元素的氧化物，如铈（Ce）、镧（La）和锆（Zr）。由于迄今为止这些元素的车辆排放很少受到关注，这项工作试图通过测量在德国几条高速公路和一个市中心（萨尔布吕肯）采集的道路灰尘样本中的元素形态，来深入了解它们在环境中的分布和归宿。通过传统的连续萃取方案对元素进行形态分析（分离成相关的矿物相），并结合粒度分离，通过选择性萃取方法研究了有机物中腐殖质的络合能力。为了进行评估，对添加了催化转化器材料的土壤样本进行了分析，结果表明，与道路灰尘样本相比，铈、镧和锆的可移动部分要低得多。研究发现，这些元素在道路灰尘中有效地与腐殖质结合，并且更倾向于与低分子量化合物（<1600 Da）络合。
