MINERAL, PHYSICAL AND CHEMICAL-ANALYSIS OF THE SOLID MATTER CARRIED BY MOTORWAY RUNOFF WATER

This study forms part of the physical and chemical study of the runoff water From a motorway catchment area in the Herault region. The distr ibution of particle sizes and the physical, chemical and mineral chara cteristics of the sediment contained in the runoff water were analysed for rainfall between February 1993 and March 1994. On average, 90% of the solid matter by weight was in the form of particles smaller than 100 mu m. The main organic and metallic constituents of motorway traff ic pollution were contained in this sediment. The analysis of the sedi ment carried by the runoff showed that it contained mineral and organi c matter. The contents of this matter were further analysed using X-ra y diffraction, thermogravimetry and specific mass measurement. Particl es smaller than 50 mu m were composed of clays (56%), quartz (15%), ch alk (12%), organic matter (9%), feldspars (5%) and dolomite (2%). The specific mass of the particles decreased with the size of the particle s and, simultaneously, the percentage of organic matter increased. Exc essive lead and zinc contamination was found in both the organic matte r and the clay, which formed the largest fraction of particles smaller than 50 mu m. (C) 1998 Elsevier Science Ltd. All rights reserved.