Paleolimnological tools for assessing the impact of road salt contamination on eastern Canadian lakes

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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. This is a major issue in eastern Canada where road salt has been in wide spread use since the 1940s. Rock salt (NaCl) is the most commonly applied de-icer because of its cost effectiveness, and suitability for the regional climate (effective to -18°C). Road salt runoff damage is cumulative, and as levels of salinity increase in lakes aquatic species diversity and abundances decline, which can lead to ecological collapse and altered water quality. Despite the environmental impact of the application of NaCl it's use is tolerated, as a result of deicing leading to a significant (88%) reduction in road accidents and fatalities. Regular monitoring of the impacts of road salt on aquatic communities and salt-damaged drinking water supplies is critical to gain a full understanding of the pathways and lifespan of these contaminants in the environment and to develop strategies to restore the environment to pre-disturbance (natural) conditions. Such monitoring is costly and salinity measurements may be subject to sizable daily fluctuations, which can influence results. ******The research aim 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: 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.**