Multiphase flow behavior of diesel in bog, fen, and swamp peats.

Hydrocarbon fate and transport in various categories of peatlands is complicated by the botanical origin, and thus variations in the hydraulic structures and surface chemistry of its peat soils. There has been no systematic evaluation of the role of different peat types on hydrocarbon migration. Thus, two-phase, and three-phase flow experiments were performed for living and partially decomposed peat cores from bog, fen, and swamp peatlands.

Projecting the hydrochemical trajectory of a constructed fen watershed: Implications for long-term wetland function.

Surface mining operations for bitumen have fundamentally altered large areas of boreal forest and fen peatland in the Athabasca Oil Sands Region (AOSR) of Alberta, Canada. Pilot projects intended to assess the feasibility of fen construction as a reclamation option have been designed, built, and are currently undergoing monitoring. Initial assessments of ecohydrologic function have been conducted for these systems but offer limited insight into their evolution and likely successional pathway.

Characterizing the hydraulic and transport properties of a constructed coarse tailings sand aquifer.

Millions of tonnes of coarse tailings sand are produced every year as a byproduct of the bitumen extraction process in the Athabasca Oil Sands Region. These tailings materials contain residual quantities of mobile solutes, which can be transported through groundwater to downgradient terrestrial and aquatic ecosystems. The anticipated ubiquity of coarse tailings sand on the post-mined landscape necessitates the characterization of its hydraulic and transport properties.

Temperature, moisture and freeze-thaw controls on CO production in soil incubations from northern peatlands.

Peat accumulation in high latitude wetlands represents a natural long-term carbon sink, resulting from the cumulative excess of growing season net ecosystem production over non-growing season (NGS) net mineralization in soils. With high latitudes experiencing warming at a faster pace than the global average, especially during the NGS, a major concern is that enhanced mineralization of soil organic carbon will steadily increase CO emissions from northern peatlands. In this study, we conducted laboratory incubations with soils from boreal and temperate peatlands across Canada.

Assessing benzene and toluene adsorption with peat depth: Implications on their fate and transport.

After a hydrocarbon spill in a peatland, dissolution of water-soluble compounds including benzene and toluene introduces a dissolved-phase plume to the peatland groundwater system, while the adsorption of these solutes onto the peat matrix restrains their distribution velocity. The adsorption of benzene and toluene and its dependency on peat depth, thus degree of decomposition, are investigated. The batch adsorption experiments revealed that benzene and toluene adsorption isotherms in peat are linear, with adsorption coefficients ranging from 16.

Dynamics of microbial populations and diversity in NAPL contaminated peat soil under varying water table conditions.

Despite the risks that hydrocarbon contamination from pipeline leaks or train derailments impose on the health of peatlands in hydrocarbon production areas and transportation corridors, assessing the effect of such contaminations on the health and sustainability of peatlands has received little attention. This study investigates the impacts of hydrocarbons on peat microbial communities. Column experiments were conducted on non-aqueous phase liquid (NAPL) contaminated undisturbed peat core (0-35 cm) under static and fluctuating water table conditions.

Modelling the hydrologic effects of vegetation growth on the long-term trajectory of a reclamation watershed.

Reclamation watersheds that integrate fen peatlands into the design require the inclusion of uplands that are capable of supporting forest development while concurrently supplying sufficient groundwater recharge to downgradient wetland ecosystems. This necessitates selecting materials with suitable soil hydraulic properties and identifying the appropriate thickness and layering to fulfill the dual function of uplands as water storage, and water conveyance features. Currently, these systems incorporate tailings sand - a mine waste material - overlain by a cover soil of fine forest-floor material.

Soil moisture dynamics modelling of a reclaimed upland in the early post-construction period.

Mine reclamation landscapes typically comprise layers of mine waste materials such as tailings sands, capped with a cover soil. In addition to the arrangement and placement of these materials, their hydraulic properties govern the performance of the built system. Soil evolution due to freeze-thaw cycling can result in dramatically altered soil hydraulic properties compared to the as-built material.

Characterizing the immiscible transport properties of diesel and water in peat soil.

Extensive pipeline and railway corridors crossing Canadian peatlands make them vulnerable to hydrocarbon spills, potentially impairing ecosystem health, so it is important to be able to forecast hydrocarbon fate and transport within and beyond the peatland. The redistribution of hydrocarbon liquids in groundwater systems are controlled by the multiphase flow characteristics of the aquifer material including capillary pressure-saturation-relative permeability (P-S-k) relations. However, these relations have never been characterized for the hydrocarbon-water phases in peat.

Competitive transport processes of chloride, sodium, potassium, and ammonium in fen peat.

There is sparse information on reactive solute transport in peat; yet, with increasing development of peatland dominated landscapes, purposeful and accidental contaminant releases will occur, so it is important to assess their mobility. Previous experiments with peat have only evaluated single-component solutions, such that no information exists on solute transport of potentially competitively adsorbing ions to the peat matrix. Additionally, recent studies suggest chloride (Cl) might not be conservative in peat, as assumed by many past peat solute transport studies.

The distribution and migration of sodium from a reclaimed upland to a constructed fen peatland in a post-mined oil sands landscape.

Post-mine landscape reclamation of the Athabasca Oil Sands Region requires the use of tailings sand, an abundant mine-waste material that often contains large amounts of sodium (Na). Due to the mobility of Na in groundwater and its effects on vegetation, water quality is a concern when incorporating mine waste materials, especially when attempting to construct groundwater-fed peatlands. This research is the first published account of Na redistribution in groundwater from a constructed tailings sand upland to an adjacent constructed fen peat deposit (Nikanotee Fen).

The hydrological functioning of a constructed fen wetland watershed.

Mine reclamation requires the reconstruction of entire landforms and drainage systems. The hydrological regime of reclaimed landscapes will be a manifestation of the processes operating within the individual landforms that comprise it. Hydrology is the most important process regulating wetland function and development, via strong controls on chemical and biotic processes.

Solute pools in Nikanotee Fen watershed in the Athabasca oil sands region.

Overburden and tailings materials from oil sands production were used as construction materials as part of a novel attempt to create a self-sustaining, peat accumulating fen-upland ecosystem. To evaluate the potential for elemental release from the construction materials, total elemental concentrations in the tailings sand, petroleum coke and peat used to construct a fen ecosystem were determined using microwave-assisted acid digestions and compared to a leaching experiment conducted under environmentally-relevant conditions. A comparison of solid phase to aqueous Na, Ca, S and Mg concentrations showed they were highly leachable in the materials.

Landscape analysis of nutrient-enriched margins (lagg) in ombrotrophic peatlands.

Scientific knowledge of the wet zone - the lagg - that tends to form at the edge of ombrotrophic peatlands is surprisingly limited. In this study, we aim to improve the understanding of the ecohydrological functions of this transition by describing the form and abiotic controls of the laggs and margins of bog peatlands. Data collected in wells and piezometers along 10 transects (within 6 bogs), of the New Brunswick Eastern Lowlands are used to analyse the hydraulic and hydrochemical gradients, while airborne LiDAR data provides new insight on the geomorphology and the vegetation patterns of the bog-lagg-mineral transition zone.