Infoscience

Journal article

Diffuse release of environmental hazards by railways

There is increasing concern about environmental pollution by diffuse emissions of various environmental hazards emitted by transportation activities. For the first time substances released by railways to the environment were investigated. We considered the significant sources and the amounts emitted by regular operation within the Swiss Federal Railways (SBB) network (7200 km tracks). The main substances are about 2270 t y−1 metals, 1357 t y−1 hydrocarbons and 3.9 t y−1 herbicides. Most of the released metals are particles emitted by friction processes with iron, followed by copper, zinc, manganese, chromium, nickel, vanadium and lead. Only a small amount of metals is expected to be leached in dissolved phase. The emission of hydrocarbons may be diffusive (e.g. operational losses) or at point-sources (e.g. track-switch). The wooden sleepers seem to be the most important sources of hydrocarbons, followed by lubricants from track-switches and wheel flanges. The emissions reflect a spatial and temporal exposure pattern. The assessment is valuable for regulatory authorities working on soil and water protection as well as for railway companies determining their necessity of water and soil protection measures. Based on the results, selected studies may establish an understanding on relevant processes and environmental risk of railway imissions to soil, drainage water and groundwater.

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