Water and mass exchanges in mosses: Towards an understanding of the movement of solutes and hydrocarbons

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Peatlands comprises ~14% of Canada's land area where climate and landscape result in persistently wet soil conditions. Because of poor oxygen diffusion into wet soil, the vegetation growing there decays slowly when it dies, resulting in the accumulation of organic carbon, or "peat". Peat formation is the largest terrestrial carbon sink, so is of global significance. Peat is dominantly formed by mosses because they are resistant to decay. Many peatlands in Canada are damaged by horticultural peat harvesting and by industrial activities that cause contamination. Understanding the moisture dynamics of mosses and how it affects carbon uptake is one goal of this study. Harvested peatlands can be managed to provide optimal conditions for mosses if we recognize their water needs. Peatlands that have been contaminated by industrial activities, burst pipelines or train derailments require strategies for remediation or protection of adjacent areas. However, knowledge of the transport of chemicals dissolved in water, or of petroleum-based fluids (hydrocarbons) in peatlands, is very poor. With the improved understanding of how water movement occurs in mosses, we can focus on how dissolved substances are transported, and whether they can migrate up the unsaturated moss profile and threaten to kill the mosses. This study examines these transport processes. Finally, with knowledge of transport of dissolved chemicals, this study will examine how hydrocarbons (which do not readily dissolve) move in the moss layer, what processes inhibit movement or encourage its breakdown. The research proposes to focus on a site near Lévis, QC, where in 2004 a freight train derailment spilled ~200,000 litres of gasoline and heating oil onto a bog peatland. The site is still contaminated, but without this study any decisions on how (or if) to remediate it will not be made with a good understanding of the processes.