Fate of de-icers in soil and groundwater : A case study at Oslo international Airport Gardermoen

Abstract

Water scarcity is a striking issue all over the world because of increased water utilization resulting from growing population. Prevention and sustainable usage of ground water is the keen concern of every government these days. Possible preventive measures are adopted on all the grounds where there are chances of depletion of water resources. For this reason all major operational projects abide by certain rules to minimise any potential damage they can cause to the environment in general, and water in particular. De-icers are widely used not only to keep roads and airport runways open for winter operation, but also to prevent accidents. To prevent corrosion, organic based de-icers are the preferred choice at airports. Formate and acetate based products are used for runways while propylene glycol is used as anti-freeze on the airplane itself. De-icers are a potential source of contamination at the Oslo International Airport (OSL) which lies above the largest aquifer of Norway. This study is based on the column elution and batch experiments performed on OSL runway soil samples and Glomma river fluvial deposits taken from Elverum municipality. The natural degradation along with sorption due to TOC has been considered to calculate the over all retardation factor for formate. Contaminant velocities have been calculated to measure the attenuation process within the soils. The columns have been eluted on different flow rates to observe changes in degradation accordingly. Chloride is used as a non reactive tracer electrolyte which behaved as the control for the column experiments. Batch experiments played a vital role in understanding the natural tendency of both soil samples to degrade formate. Nitrate was added to both sets of experiments as a nutrient source to enhance the microbial activity. The retardation factor of formate has been calculated as 1.1 and 1.3 in Elverum and OSL soil samples, respectively. EC and COD measurements were considered as parameters to measure degradation/sorption. AAS was used to measure Fe and Mn concentrations and their presence in the column outlets and in the batch experiments indicates the redox processes in both experiments. Detailed analysis of the findings from this study suggests that providing a good air supply and nutrients formate can be completely degraded in the unsaturated zone before it reaches the aquifer.