Water in Road Structures Movement, Drainage and Effects
Water in and beneath a road pavement has a major impact on the road's performance and its survivability. This book provides a state-of-the-art on the topic of water in pavements and the adjacent ground. It includes coverage of the basic theory; where the
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Sources and Fate of Water Contaminants in Roads Lennart Folkeson∗ , Torleif Bækken∗ , Mihael Brenˇciˇc, Andrew Dawson, Denis Franc¸ois, Petra Kuˇr´ımsk´a, Teresa Leit˜ao, Roman Liˇcbinsk´y and Martin Vojtˇesˇek
Abstract This chapter gives an overview of sources, transport pathways and targets of road and traffic contaminants. Pollution sources include traffic and cargo, pavement and embankment materials, road equipment, maintenance and operation, and external sources. Heavy metals, hydrocarbons, nutrients, particulates and de-icing salt are among the contaminants having received the greatest attention. Runoff, splash/spray and seepage through the road construction and the soil are major transport routes of pollutants from the road to the environment. During their downward transport through road materials and soils, contaminants in the aqueous phase interact with the solid phase. In saturated media, diffusion, advection and dispersion are the major processes of mass transport. In unsaturated soil, mass transport strongly depends on soil-moisture distribution inside the pores. Sorption/desorption, dissolution/precipitation and ion exchange reactions are the most significant chemical processes governing pollutant transport in soils. Redox conditions and acidity largely regulate heavy-metal mobility. Many heavy metals are more mobile under acidic conditions. Plants close to heavily trafficked roads accumulate traffic pollutants such as heavy metals. Heavy metals, organics, de-icing salt and other toxic substances disturb biological processes in plants, animals, micro-organisms and other biota and may contaminate water bodies and the groundwater. European legislation puts strong demands on the protection of water against pollution. Road operators are responsible for ensuring that the construction and use of roads is not detrimental to the quality of natural waters. Keywords Contaminant · pollution · flux · soil process · pathway · chemistry · biota · biology · legislation ∗
Co-ordinating Authors: L. Folkeson Statens v¨ag- och transportforskningsinstitut/Swedish National Road and Transport Research Institute (VTI) e-mail: [email protected] T. Bækken Norsk Institutt for Vannforskning/Norwegian Institute for Water Research (NIVA) e-mail: [email protected]
A.R. Dawson (ed.), Water in Road Structures, DOI 10.1007/978-1-4020-8562-8 6, C Springer Science+Business Media B.V. 2009
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6.1 Context Roads and road traffic influence the natural environment in a complex manner. At the same time as roads serve the transport of people and goods, roads take land and form barriers to the movement of people, animals and water in the landscape. A range of pollutants is emitted from roads and traffic and spread to the environment. The pollutants are transferred away from the road mainly via road-surface runoff and aerial transport but also with percolation through the pavement. Runoff pollution is a much studied issue whereas much less is known about pollutants percolating through the paveme
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