Using normal ranges for interpreting results of monitoring and tiering to guide future work: A case study of increasing polycyclic aromatic compounds in lake sediments from the Cold Lake oil sands (Alberta, Canada) described in Korosi et al. (2016)

Since the publishing of the Kelly et al. papers (2009, 2010) describing elevated contaminants in snow near the Alberta oil sands, there has been a significant expansion of monitoring efforts, enhanced by $50M a year contributed by industry to a regional Joint Oil Sands Monitoring (JOSM) program. In parallel to the intensification of research and monitoring efforts, including expansion of measured indicators, techniques for chemical analysis have also become more sensitive. Both factors contribute to the increased sensitivity and power, and improve our capacity to detect any change. The increase in capability requires a counterbalance to account for trivial change. This can be done using an interpretative approach that requires contextualization of differences to meaningfully inform environmental monitoring programs and provide focus for action. Experience obtained through 25 years of involvement with Canada's Environmental Effects Monitoring (EEM) program has shown that a tiered program informed by triggers can provide the context to make decisions about monitoring priorities. Here we provide a potential interpretation framework using a case study around the Korosi et al. (2016) study which found recent increases in alkylated polycyclic aromatic compounds (aPACs) in the Cold Lake in situ oil sands area. Public contaminant profiles from the JOSM studies in the oil sands region are used to evaluate the changes using an interpretation framework based on estimated normal ranges using existing data for site-specific, local and regional (distant) levels that was modelled after the tiered Canadian EEM design.