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TitleDistribution of As, Ni and Co in tailings and surface waters in the Cobalt area, Ontario
AuthorPercival, J BORCID logo; Kwong, Y T J; Dumaresq, C G; Michel, F A
SourceProceedings of the Mining and Environment IV International Conference - Sudbury 2007; 2007, 10 pages; 1 CD-ROM
Alt SeriesEarth Sciences Sector, Contribution Series 20060693
MeetingSudbury 2007, Mining and the Environment IV International Conference; Sudbury, Ontario; CA; October 19-27, 2007
Documentcomputer file
MediaCD-ROM; digital
AreaCobalt; Farr Creek drainage basin; Lake Timiskaming
Lat/Long WENS-80.0000 -79.5000 47.5000 47.2500
Subjectsgeochemistry; environmental geology; arsenic geochemistry; nickel geochemistry; cobalt geochemistry; surface waters; tailings; wetlands; erythrite; scorodite; thenardite; environmental impacts; pore water samples; attenuation; arsenic; nickel; cobalt; Precambrian; Proterozoic
Illustrationssketch maps; photographs; graphs; tables
ProgramEnvironment and Health
Released2007 01 01
AbstractFrom 1904 until the mid 1930's and intermittently until 1989, over 450 million troy ounces of silver was mined from the Cobalt area, Ontario. Currently there is no active mining of silver, but the area has seen recent exploration activities for other commodities such as diamonds. Cobalt, however, has not only a renowned mining history, but also an environmental legacy. The area is characterized by remnant historic mine workings and numerous waste rock piles and tailings ponds. Several elements of concern including arsenic, nickel and cobalt continually enter the local watershed from the tailings and waste rock piles. These elements are transported through surface waters to the wetlands in the Farr Creek drainage basin and ultimately enter Lake Timiskaming.

Tailings samples are composed of abundant plagioclase with subordinate quartz, chlorite, calcite and dolomite. Less common are K-feldspar, amphibole and mica as well as trace minerals such as erythrite, scorodite and pharmocolite. When efflorescent mineral crusts form on tailings surfaces they are dominated by either gypsum or thenardite. The tailings may contain up to 3.5 wt % Co and 2.2 wt% Ni. Lake sediment and tailings cores show concentrations up to 1.8 wt% As, 0.62 wt% Co and 0.27 wt% Ni in the solids, and 160 mg/L As, 74 mg/L Co and 42 mg/L Ni in the pore waters. One core collected from the infilled Hebert Pond situated within the Nipissing Low Grade Mill tailings impoundment show pore water concentrations in excess of 1,500 mg/L As associated with an organic-rich layer. The concentrations of these elements sustain significant aqueous transport through the drainage basin as tailings are continually weathered, eroded or leached. Surface waters contain up to 20 mg/L dissolved As which decreases downstream through the wetlands with a mean annual discharge of over 10,000 kg to Lake Timiskaming.

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