Research Projects

Salt contamination of fresh water lakes as the result of runoff from the application of winter de-icing salts to roads and other infrastructure presents a significant environmental challenge.  The research aim for this new research initiative is to develop a novel, widely applicable and cost effective technique of monitoring salt contamination in lakes, using microscopic Arcellinida (shelled amoeba), that are widely present in lake sediments, which have been shown to have a quantifiable sensitivity to road salt contamination. The research will initially focus road salt contamination on lakes in the Greater Toronto Area (GTA), where winter road salt application is particularly high (220t/km on 400 series highways and 30t/km on regional roads). The overarching objectives of the research program will be to: statistically quantify the relationships between specific Arcellinida taxa and key road-salt related water property and sediment-based geochemical variables in a large set of lakes from the GTA and elsewhere in eastern Canada; use the distributional dataset to develop an arcellinidan ‘Salt Contamination Index’ (SCI) that can be readily applied to lake surficial sediments throughout the region to categorize salt damage; and use the distributional SCI training set to determine the cumulative impact of road salt contamination on lake ecosystems through analysis of cores spanning from baseline non-road salt impacted conditions of the early 20th century to present. The innovative approach proposed for development of the SCI will result in a cost-effective way to assess the cumulative impacts of salt contamination on lake aquatic ecosystems across the landscape and through time. This information will support efforts by policy makers and stakeholders to strategically manage the impact of road salt contamination, and will contribute to a valuable integrative training program for HQP.

This project consists of three primary objectives: 1) design equipment and adapt methodologies to enable analysis of freeze cores using Itrax X-Ray fluorescence core scanning (XRF-CS); 2) test different XRF-CS calibration techniques to determine the optimal method; and, 3) apply these techniques to perform multi-proxy climate analysis of freeze core material subarctic and arctic lakes. During previous years, we finalized the adapted methodology for analysis of freeze core material using (objective 1); results have been submitted for publication to peer reviewed journals. This year, we completed testing of different calibration methods on surface samples to convert semi-quantitative Itrax-XRF-CS data to absolute elemental concentrations. The results of these tests are currently in preparation for publication in a peer reviewed output. Full application of these methods to sediment cores is currently underway. Itrax-XRF-CS analysis of sediment cores from lakes from the Yellowknife and Tundra Mine area (Milner and Contorl lakes) are now completed. Particle size analysis of the Milner Lake core at 1-mm resolution is currently ongoing, with a projected completion date of the end of June. Micropalentological analysis of both sediment cores, to be used as a method of ground-truthing arsenic concentrations in sediment, will be completed by the end of August. Cross wavelet analysis will be used to compare paleoclimate results derived through particle size analysis to geochemical results from Itrax-XRF-CS to help understand the impact of decadal-scale climate cycles on the mobility of As.

This project aims to develop Arcellinida, a group of shelled benthic protists, as a robust geoscience tool for tracking arsenic  contamination in lakes around historical and prospective gold mining sites by: 1) assessing the spatio-temporal relationship between Arcellinida and arsenic; 2) define arsenic-tolerance limits for different arcellinidan taxa; and, 3) develop a Arcellinida sample-processing protocol to reduce time associated with micropaleontological analysis. The assessment of the spatial variability of Arcellinida and arsenic in 93 lacustrine surface sediment samples from the Yellowknife area (regional-scale) as well as analysis of arsenic-tolerace limits of 25 arcellinidan taxa was completed in December of 2017. Results of this work will be detiled in a publication that will be submitted to a peer reviewed journal (June, 2018). A new Arcellinida sample-preparation protocol for reducing the organic content was designed in 2017 and is currently going through a three-stages testing procedureto assess the effectiveness of the protocol in enhancing the quality and accuracy of micropaleontological analysis. The testing procedure will be completed in June 2018 and a manuscript detailing the results of this work will be submitted to a peer reviewed journal. Assessment of the the spatial (at a local scale) and temporal relationship between Arcellinida and arsenic is currently under way. Sub-sampling the a freeze core collected from the Yellowknife study area at 1-mm resolution for arcellinidan analysis and PSA will be completed in June, 2018. Micropaleotological analysis (surface sediment and freeze core samples) will be carried out between June and November, 2018. Multivariate statistical analysis will be performed on the generated spatial and temporal data sets in December, 2018 to quantify the relationship between Arcellinida and arsenic.

The primary focus of this study is 1) to establish the impact of a tephra layer observed in the core on the algal community in Pocket Lake and 2) to reconstruct long term climatic variability using changes in diatom communities preserved in a sediment core collected from Pocket Lake. Diatom counts were completed at 1-mm intervals 1 cm above and below an observed tephra layer to determine the impact of the deposition of this material on the aquatic ecosystem of Pocket Lake. This study was developed into a manuscript submitted to a peer reviewed journal and is currently under review. The second objective of this activity is ongoing. Diatoms counts for 131 subsamples obtained from Pocket Lake will be completed and compared to other paleolimnological data to reconstruct the paleoenvironment during the last ~3500 years to understand how paleoenvironmental change impacted contaminant concentrations in the lake and the region. Particle size analysis, Rock Eval pyrolysis and measurement of sediment geochemistry using ICP-MS are completed. Diatom analysis is currently underway.