EFFECTS OF ABANDONED GOLD MINE TAILINGS ON THE ARSENIC CONCENTRATIONSIN WATER AND SEDIMENTS OF JACK OF CLUBS LAKE, BC

From 1933 to 1964 gold was extracted by underground mining at the nort heast shore of Jack of Clubs Lake. At present, tailings and waste rock 4.5 m thick covers approximately 25 hectares of land adjacent to the lake. Arsenic concentrations (>2,000 mug.g-1) were found in the tailin g materials. Two simultaneous processes are controlling the elevated A s concentrations in the lake sediments (up to 1,104 mug.g-1), depositi on of suspended particles enriched with As and subsequent diagenetic c ycling of sedimentary As. Arsenic concentrations (as high as 556 mu.L- 1) in water samples adjacent to the tailings indicate mobilization of As. However, dissolved As is readily scavenged or coprecipitated with iron hydroxides. The greatest proportion of As in the sediment cores i s associated with iron oxides and sulphides. Under oxic conditions the high concentrations of Fe in the tailings is actually beneficial and very effective at limiting the migration of undesirable elements.