Agriculture Reference
In-Depth Information
2
Research for Investigating and Managing Soil
Contamination Caused by Winter Maintenance
in Cold Regions
Helen K. French and Sjoerd E.A.T.M. van der Zee
The Norwegian University of Life Sciences,
Department of Plant and Environm. Sciences, Norway
Wageningen University, Environmental Sciences Group, Wageningen,
The Netherlands
1. Introduction
In the north temperate and arctic zones, large amounts of de-icing chemicals are used
during the frozen season for winter maintenance of highways, roads, airports and other
surface areas. The transport sector, and civil aviation in particular, has become a major
industry and is one of the fastest growing sectors of the world economy (Janic, 1999).
Following an increased concern for the environment in general (Lutz, E. & Munasinghe, M.
1994; Willems, 1994; Jackson, 2010; EEA, 2009), pollution from airports and roads (EPA,
1995) has received more attention. It is also considered one of the contamination threats to
soil according to the proposed EU Soil Framework Directive introduced by the European
Commission in 2006 (COM (2006) 232; Tóth et al., 2008). In this chapter we will discuss
various processes that need to be considered from the source to the recipient, which could
be the groundwater or surface waters, and how these are affected by cold climate (winter
frost). The source will be related to road network or runways, but can potentially be both a
line source if no collection or surface drainage is in place, or can constitute a point source. In
cases where road or runway runoff is collected in retention systems with subsequent
infiltration into local soils or release to surface waters such as creeks or rivers it could
potentially be a significant point source. Often there are no legal limitations on total
amounts of salt that can be applied on roads and highways, hence there is no control of their
release to the environment. Climate change may cause increased fluctuations about the
freezing point which is a condition which increases the use of salts (French et al., 2010).
Hence these chemicals may constitute a long term threat to soils in areas with frozen
conditions in winter. The second process is infiltration into frozen, partially frozen or
unfrozen soils, depending on state of soil and snow fall in late autumn/early winter. Frozen
soils may create impermeable surfaces and highly affect hydrological conditions and in
particular boundary conditions for unsaturated flow. Further, the flow and transport in the
unsaturated zone is affected by soil physical and bio-geo-chemical heterogeneities and in
cold climate, high temporal variability in degradation potential due to low temperatures
during winter and snowmelt. If or when chemicals arrive at the groundwater level
heterogeneous conditions continue to influence the fate of de-icing chemicals but the general
