Risk Analysis zinc - The road border scenarios
Alex Coursier - Umicore Zinc Alloys & Chemicals, Balen (B)
Almost half of the zinc emissions from the wearing of tyres take place in urban arears, where they are capture with the rainwater, end up in STP's and are not released to the environment. Along regional roads the zinc load at the target zone is of the same order of magnitude as background deposition. The impact will be minimanl. Along highways the zinc load at the target zone is of the same order of magnitude as in fertilised agricultural land. In The Netherands only 1.1 to, or 0.5 % of the 184 ton of zinc released per year from tyre wear and guard rail corrosion will enter this target zone along highways. This amount will further decrease by the use of porous asphalt. Special cases such as bridges, crossings and squares are to be considered where the release of zinc may be a source of local pollution. A proper management of the solids in drains or on the top soil of the road border is required and should be determined on a case by case basis.