Agriculture Reference
In-Depth Information
good methods for measuring the total water content in a frozen soil are for instance still
lacking. What scale of heterogeneity is relevant during snow melting conditions compared
to the thawed situation? Cold climate conditions add extra complications to the contaminant
site management, for one; the need for use of de-icing chemicals. Since the use is generally
not regulated, there is a great potential for reduced environmental impacts by implementing
such limitations. At Oslo airport, Gardermoen, only a certain amount of de-icing chemicals
is allowed per winter season. De-icing chemicals that are highly concentrated such as at the
de-icing platforms are collected, hence reducing the amount released to the green areas.
Since soil temperature has a large effect on surface infiltration patterns, this should be
monitored as part of the regular monitoring programme along roads and at airports.
Strategies to deal with both frozen and non-frozen conditions during snowmelt must exist,
e.g. pump and store contaminated melt water in local depressions for later infiltration when
conditions are more optimal, e.g. in summer.
7. Conclusion
This chapter gives an overview of properties of de-icing chemicals and the processes that
affect their fate in the unsaturated zone. Inorganic salt concentrations can only be reduced
by dilution and is only discussed briefly here, while degrading organic de-icing chemicals
are the main focus. Conventional methods of soil and soil water samples are still required
for interpretation of emerging technologies such as different geophysical techniques. The
importance of heterogeneity of the infiltration process and unsaturated flow is emphasised.
The method of spatial moments is an efficient way of describing average movement of
contaminants in the unsaturated zone. An ergodic situation, i.e. when the size of the
contaminant source is much larger than the scale of soil heterogeneity, makes average
assumptions more certain while small plumes in a system of large variability causes great
uncertainty. Geophysical methods can be used in time lapse mode to obtain a more
continuous impression of the flow and transport processes and is recommended in
combination with point measurement for quantification of absolute levels of contaminants.
Flow and transport modelling within a stochastic framework is another important
complementary technique for optimised management strategies at contaminated sites.
8. Acknowledgement
The study was supported by the European Commission's 7th Framework Project SoilCAM
(212663) on monitoring contaminated soil, we also thank the Stichting Retourschip,
Wassenaar, Netherlands, for partial support. Appreciation of collaboration and discussions
with the Oslo airport management team is also acknowledged.
9. References
Aagaard, P. et al. (2004), Saturated and Unsaturated Zone, Integration of Process Knowledge
into Effective Models, La Goliarda Pavese, COST Action 629, Fate Impact and
Indicators of Water Pollution in Natural Porous Media, 397 pp
Amundsen, C.E., French, H.K., Haaland, S., Pedersen, P.A., Riise, G., Roseth, R., (2008),
Miljøkonsekvenser ved salting av veger-en litteraturgjennomgang, (Consequences
of road salt on the environment - a literature review), Salt SMART, Statens
