.. as recorded by lake ecosystems;
This clearly demonstrates that the [polycyclic aromatic hydrocarbons] "pollution" associated with oil sands development is insignificant. The PAH concentrations in most of lakes in the study area are unremarkable when compared to remote lakes in the boreal forest in the 18th and 19th century and are more similar to modern remote lakes than they are to urban and agriculturally developed areas.“Canadian oil sands pollute nearby lakes. Report is blow to Keystone pipeline.” (Or Not) | Watts Up With That?
Legacy of a half century of Athabasca oil sands development - Small Dead Animals