Hydrogeological aspects of petroleum hydrocarbon spills management in peatlands

Abstract:

Increasing hydrocarbon resource developments in and around peatlands impose risks of petroleum hydrocarbon spills on these landmarks. Despite the severity of consequences, there is a big gap of knowledge on parameter values controlling liquid hydrocarbons’ redistributions in peat soil after a spill accident. Complete excavation of contaminated peat soil which is a common practice in contaminated sites adds to this lack of knowledge regarding the problem. To partially fill this knowledge gap and to examine potential remediation strategies that are less destructive than contaminated peat excavations, we have examined the fate, transport, and degradation of petroleum hydrocarbons in peat soils via a series of intact peat column tests. Three-phase flow experiments with numerical simulations provided values of multiphase flow parameters that control liquid hydrocarbons’ redistributions in a number of peat soils. The results could help environmental scientist in forecasting the behavior of spilled non-aqueous phase liquids (NAPLs) in peatland. Furthermore, in a series of NAPL degradation experiments we observed that the water table dynamics reduces residual NAPL saturation from 8.1-11.3% to 7.7-9.5%; increases an average 163.7% and 13.4% headspace concentrations of n-C₈ and n-C₁₂ due to volatilization. Results also illustrated that water table dynamics promote growth (from 10⁴ CFU/gram to 10⁶ CFU/gram peat) of specialized microbial communities in NAPL polluted peat column. These suggest that water table fluctuation can be a suitable tool for physical and microbial NAPL removal in peat soils, and for the first time provide the evidence for it. We also observed a high ratio of Proteobacteria to Acidobacteria in the NAPL contaminated zone, which can be linked to the restoration success for a NAPL polluted peatland.