Hi Dr. Towe, thank you for your insight.

Specifically, I'm looking at sites located along the Athabasca River within a 30 km radius of Fort McKay (I suppose more likely to interact with clearwater formation) and one distal site that is about 120 km north up the Athabasca (about 50 km North of McLelland Lake and 50 km South of Richardson Lake), which seems to show signatures of the McMurray Fm. Perhaps some background might help. Essentially, I have Hg and Al loadings in snowpacks at those sites and I would like to compare the Hg to Al ratio to that of the underlying bedrock. I do realize this will be very approximated. Interestingly, the Hg:Al range in my samples is quite vast, which to me, indicates that Hg is not solely of lithogenic source, so I was looking for an approximate ratio or ratio range to check the validity of this idea.

Thanks again.

I'm attempting to normalize trace elements for Al to normalize for inputs of lithogenic material as in the following studies:

• Shotyk, W.; Weiss, D.; Heisterkamp, M.; Cheburkin, A.; Appleby, P.; Adams, F. New Peat Bog Record of Atmospheric Lead Pollution in Switzerland: Pb Concentrations, Enrichment Factors, Isotopic Composition, and Organolead Species. Environ. Sci. Technol. 2002, 36, 3893-3900.
• Wiklund, J. A.; Hall, R. I.; Wolfe, B. B.; Edwards, T. W. D.; Farwell, A. J.; Dixon, D. G. Use of pre-industrial floodplain lake sediments to establish baseline river metal concentrations downstream of Alberta oil sands: a new approach for detecting pollution of rivers. Environ. Res. Lett. 2014, 9, 1-9.
• Uglietti, C.; Gabrielli, P.; Cooke, C.; Vallelonga, P.; Thompson, L. Widespread pollution of the South American atmosphere predates the industrial revolution by 240 y, PNAS, 2015, 112, 2349-2354.

Thank you Dr. Vafadar.