Fate and Transport of PFCs in a Peat Bog Environment

Per- and poly fluorinated compounds (PFCs) is a large group of chemicals with a strong variation in chemical composition. They have previously been used in extensive amounts which has caused wide spreading in the environment. Studies have shown that these compounds tend to accumulate in biota and can contribute to several health issues. The present study has been performed to increase the understanding of the sorption and leaching behaviour of PFCs accumulated in a peat bog as a result of fire fighting activities. A fire training field at Evenes Airport has been investigated to study PFC presence at the training field and transport to its run-off area. Water, soil and undisturbed soil column samples were collected at the field site. After homogenization the soil and water samples were analyzed to find the distribution of different PFCs within the peat bog following the direction of water drainage. Batch experiments were carried out to estimate distribution coefficients and establish the compounds sorption and mobility. Both field and experimental distribution coefficients were compared. The leaching behaviour of selected PFCs were studied through column experiments. The study focussed on the influence of the length of the compounds carbon chain on their leaching behaviour. The size of the peat bog basin receiving contaminants from the fire training area was estimated, in addition to the amount of PFOS present to evaluated its potential as reservoir for future contaminant transport. Rainwater was assumed to be the main contributor to run-off from this area. Using PFOS concentrations in water sampled at the assumed outlet of the peat bog and the annual leaching intensity allowed to estimate the number of years before all PFOS will have been washed out. The main finding of this study is that PFOS is the most hazardous compound in the area of interest at Evenes Airport due to its high concentration in the peat bog and showing strongest sorption. It is the compound with highest relative concentration in all the batch experiments, even though the relative concentrations of shorter PFCs increase as the distance between sampled soil and contamination source increase. This indicates that shorter PFCs are more mobile and will elute faster. This study does not give clear indications of higher sorption with increasing of the carbon chain length. The peat soils are very organic rich and show much higher Kd values than the mineral soils (e.g. sand, silt, clay, lake sedi