The controls on the mobility and fate of arsenic in lakes impacted by historical gold ore roasting in northern Canada have been examined. A detailed characterization of arsenic solid and aqueous phases in lake waters, lake sediments and sediment porewaters as well as surrounding soils was conducted in three small lakes (80 wt%) of arsenic is contained in the form of secondary sulphide precipitates, with iron oxy-hydroxides hosting a minimal amount of arsenic (