The geomicrobiology of the oxic zone of two base metal mine tailings impoundments: The Kidd Creek Mine and Kam Kotia Mine site

A reconnaisance field study to determine the geomicrobiology of the oxic zone was conducted at two base metal tailings impoundments; the active, 1200 hectare Kidd Creek site ($<$3 years) and the abandoned, 100 hectare Kam Kotia Mine site (30+ years). We combined field microbiology with geochemistry, concentrating on the reactive oxic zone at both impoundments. Comparisons between acidophilic, chemolithotrophic, Fe-oxidizing Thiobacillus spp. and heterotrophic, non-Fe-oxidizing Acidiphilium spp. showed the former to out number the latter within the younger, oxidized sediments of Kidd Creek and the inverse to be true with the heterotrophs outnumbering the chemolithotrophs within the older, metal-sulfide depleted, surficial sediments of Kam Kotia. In addition, a biofilm experiment conducted within the waste-water treatment ponds of the Kidd Creek site suggested that biomineralization may be more effective in immobilizing soluble heavy metals compared to chemical precipitation in both acidic and alkaline environments. Comparison between the 'old' and the 'new' demonstrate the importance of bacteria in the formation and (possible) amelioration of acidic, heavy metal-rich leachates.