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Notes for the CEN on the Arsenic Technical Workshop
Catherine Coumans, Ph.D. MiningWatch Canada
The arsenic technical workshop was organized by the Mining Association
of Canada and CANMET, in association with the Arsenic Workshop
Organization Committee.
It was held in Winnipeg on November 7 & 8, 2002. CEN representatives
were Glenda Ferris and Catherine Coumans. There were about 74
participants.
Brief introductory presentations were made by: Heather Jamieson
(Queen’s University); Ken Reimer (Royal Military College);
Barbara Sherriff (University of Manitoba); JimVance (NRCan); Bill
Mitchell (DIAND); Denis Kemp (Falconbridge); Ron Connell (Miramar);
Wayne Fraser (Hudson Bay Mining & Smelting); Catherine Coumans
(Mining Watch Canada); Glenda Ferris (Northern Ecology Action
Committee); Bill Price (Mines Branch, BC Ministry of Energy &
Mines); Claude Gignac (Ministere de l’environnement du Quebec);
Leslie Cooper (Ministry of Northern Development and Mines, Ontario);
Barbara Hard (Jacques Whitford Environment Limited); Alan Martin
(Lorax); Diana Sollner (SRK)
Minutes from the meeting are forthcoming, and a commitment
was made to make most presentations available (also forthcoming).
The following notes are not exhaustive but constitute
some points of interest.
* The introductory presentations made it clear that there is still
a lot that is not yet well understood about arsenic, for example:
- how arsenic is retained and released i.e. the binding processes,
and how this affects long term stability.
- arsenic microbial transformation, chemical mobility and chemical
speciation.
- microbiological aspects of bioremediation
- arsenic stabilization including arsenic precipitation in
the presence of dissolved iron, the precipitation of arsenic-sulphate-hydroxide
species at high temperatures and adsorption of arsenic on ferrihydrite
like materials at lower temperatures.
- need to develop data on bioavailable forms of arsenic, and
environmental health and risk factors associated with arsenic,
specifically; stability, speciation and bioavailability.
- the long term stability of the arsenic in the submerged tailings
and other reducing conditions
- long term stability and potential bioavailability in various
ecosystems of scordite type II
- treatment methods for arsenic trioxide
- need to study aerobic and anaerobic conditions for long term
arsenic generation.
- more research is needed in arsenic ecological and human risk
assessment
- need to know more about the fate and behavior of arsenic
during mill processing and waste treatment
* The presentations also identified a need for better guidelines
around arsenic
*Specific mine site presentations dealt with arsenic problems
at: Goldcorp’s Red Lake Mine, the Giant Mine in Yellowknife,
Teck/Cominco’s Trail site (for more information on specific’s
at these sites contact Catherine Coumans).
* Points of interest:
- Arsenic in reducing environments (under water in natural
or artificial impoundments – such as lakes or tailings
ponds) will be more readily mobilized to the water column through
reduction of arsenic scavenging mechanisms. Reducing conditions
are created where there is a food source for micro-organisms.
In mining areas high concentrations of nutrients, such as natrium
and potassium resulting from the mining process, encourage biological
production, creating reducing conditions and increasing the
likelihood of arsenic mobilization to the water column. In the
case of Balmer Lake, a naturally oligotrophic lake became eutrophic
through nutrient loadings as a result of mining and so the lake
become more susceptible to arsenic mobilization.
- Bill Cullen of the University of British Columbia presented
on the use of bitumen as a material to mix with arsenic trioxide
to stabilize arsenic trioxide. Apparently it is a relatively
cheap solution, works well, especially under water and “doesn’t
leach much.”
* The workshop concluded with agreement that some form of arsenic
working group should be established.
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