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DOI: http://dx.doi.org/10.1065/jss2000.11.001 - - - This work represents a summary of our test results over emissions of platinum-group elements (PGE) in soils, which were won in the context of an interdisciplinary research project on ecological future research sponsored by the Hessian government. Directly
related to this investigation was the time-dependent entry of concentrations of PGE in soils along roadsides, their further rise in control and the investigation of the geochemical behaviour of these metals regarding their solubility and mobility in the soil. Soil samples were taken along the motorways of Frankfurt-Wiesbaden (A66), Frankfurt-Mannheim (A5/A67/A6), and the
A3 and A45 in the area of Hanau, and the PGE were examined here. The test results do not leave a doubt that the increased PGE
contents in the soils in the direct environment of the motorway
are to be attributed to motor vehicles with catalysts. In sections
of the soil samples of Hanau, Ir and Ru are also seen to occur
beside Pt, Pd and Rh. Since these items are not constituents of the
catalyst, their origin is possibly due to emissions from the precious
metal-processing industry in Hanau.
The highest concentrations of PGE in the soil occur directly at the
edge of the motorway and decrease with increasing distance from
the motorway. The PGE emissions depend on traffic volume and
driving characteristics. Based on Pt concentrations found in soils
near roadsides and observed traffic volumes, automotive catalytic
converters are estimated to emit an average of 270 ng/km.
Currently, the Pt and Rh deposited behave immobile in soils. At
present, Pt and Rh from catalytic converters present no danger to
the groundwater.
Although platinum does not represent an acute danger, due to
its low concentrations in the environment at the present, this
rise in concentration may necessitate the use of routine checks
in the future.