Projets de l'axe 1 (traduction en cours)
Project leader: Yves Prairie
Summary: Even if lakes and rivers occupy less than 1% of the globe, they collectively emit CO2 and CH4 in amounts that are of the same order of magnitude as that taken up by the other 99% (the sum of terrestrial and oceanic net uptakes). Canadian lakes and rivers represent a disproportionately large share of all inland waters of the world. Yet, because of the large diversity of the Canadian landscape, there is currently no estimate of the Canadian contribution to global lake emission. While we know that they are nearly all supersaturated with both carbon dioxide (CO2) and methane (CH4), their degree of oversaturation varies widely among lakes, even within a small geographical region. This is particularly true with the more complex biogeochemistry of CH4 relative to CO2. These knowledge gaps impede the development of up-scaling rules to estimate regional or countrywide emission rates beyond the application of simple averages. A central issue pertaining to this high variability is the origin and in situ transformation of the gases. In this project, we propose to use isotopic (13C) signatures of CO2 and CH4 in a large number of lakes from different regions to trace the probable origin (organic decomposition vs mineral weathering) and extent of transformation (e.g. CH4 oxidation to CO2) and these may be driven by regional and local features of the landscape.
Project leader: Yves Prairie
Summary: Inland waters are sites of intense carbon processing where inflowing carbon meets one of 3 ultimate fates: exchange at the air-water interface, sequestration in sediments or hydrological transport further downstream. The transformation processes that occur within the system are key to determining the relative dominance of these 3 processes in individual lakes. This project will tap into the data emanating from the core sampling program of Lake Pulse to provide the diversity of environmental conditions (both regional and limnological) needed to identify which configuration of various carbon process-based models (known as data-fusion models) currently in development (separate Solomon, del Giorgio and Prairie FQRNT project) is best able to account for the observed variability in carbon processing. These models will then be used to explore scenarios of how the cycling of carbon in lakes is likely to be altered in future climate change scenarios.
Project leader: Hubert Cabana
Summary: We are interested in studying the presence and fate of emerging contaminants (EOCs) such as pharmaceuticals, personal care products, etc., in the aquatic environment. More specifically, we want to understand how EOCs behave in surface waters once they are released into the environment, how they interact with and are distributed among other abiotic and biotic components of aquatic ecosystems (such as particles, sediments and biota) and how and in what new compounds they transform or degrade. First, the project consists of the development of new analytical approaches for the detection and quantification of polar and non-polar EOCs based on using liquid chromatography coupled to both low resolution and high resolution mass spectrometry. The student in charge of the project will participate in sampling campaigns and will validate analysis methods. Then, for the most detected EOCs, we will determine the behaviour of these chemicals in the water column (including the solid phases). To date, most studies dealing with the fate and behaviour of these chemicals has focused on the aqueous phase, and concentrations of EOCs in the solid fraction have rarely been determined, partly because of the analysis challenge in these matrices and the assumption that EOCs are highly water soluble. For this part of the project, we will determine the interactions of the EOCs between the aqueous and solid phases. In addition, we will determine the transformation products generated in these systems.
Project leader: John Smol
Summary: The paleolimnological project will collect sediment cores from the Network lakes and use biological remains preserved in the sediments to obtain information on how lakes across Canada have responded to human influences over the past ~200 years. We will identify changes through time by examining two groups of organisms with remains that preserve well in sediments: diatoms, a group of siliceous algae and chironomids, an insect family containing many taxa with aquatic larvae that are highly responsive to deepwater oxygen conditions. By comparing diatom and chironomid assemblages preserved in recent sediments with those deposited prior to widespread industrialization we will provide a broad assessment of how key water quality variables (e.g., pH, TP and bottom-water oxygen) have changed across the country. Furthermore, a subset of the lakes will be analyzed in greater detail (i.e. the full sediment core) to determine the timing of any changes, rather than simply how the lakes differ from pre-impact conditions. VIRS inferred chlorophyll-a will also be analysed to provide an estimate of changes in lake primary productivity with time. Analyses of DNA, as well as cyanobacteria and cladocerans will also be performed, but these aspects of the project are described in projects 4 and 6.
Project leader: David Walsh
Summary: In this project, we will develop and refine a paleogenetic approach for tracking lake health through time. Targeting the eukaryotic community, we aim to evaluate whether the similarity between subfossil and genetic analyses varies predictably as a function of environmental parameters (e.g., lake mixis, DOC or nutrient concentration). We will address the following questions: (1) How coherent are the results between classical taxonomic subfossil analyses and genetic techniques?; (2) Can we detect the presence of organisms through genetic analyses that do not leave a distinct morphological element?; (3) Is there significant genetic diversity within groups that leave a morphological fossil that would be otherwise undetected in the absence of a genetic analysis. The deliverables of this project are expected to include a greatly improved knowledge on the interpretation of genetic data in a paleolimnological context and the proposal of new DNA-based biological indicators for change in lakes.