Éléments toxiques prioritaires (vanadium, antimoine et arsenic) – Protection des sources d’eau et traitement de l’eau potable

X. Chris Le, professeur et titulaire de la Chaire de recherche du Canada en technologie bioanalytique et en santé environnementale; directeur de la Division de toxicologie analytique et environnementale, Université de l’Alberta, 2008 - 2012
Enjeu

L’arsenic et le vanadium sont deux éléments qui affectent énormément la santé humaine et écologique. Plus de 100 millions de personnes dans le monde sont affectées par l’arsenic présent dans leur eau potable et des données antérieures donnent à penser que plusieurs régions rurales au Canada ont des taux d’arsenic dans l’eau des puits qui dépassent les limites canadiennes actuelles. Bon nombre de ménages installent dans leur maison des systèmes de traitement de l’eau, mais avant la tenue de ce projet, l’efficacité de ces appareils pour éliminer l’arsenic n’avait pas été déterminée. De plus, on ne connaît pas bien les impacts des concentrations élevées d’arsenic et de vanadium sur l’écosystème. Ces deux éléments peuvent être libérés dans l’environnement lors de l’exploitation des mines et des sables bitumineux, mais leur absorption et leur toxicité chez les organismes aquatiques ne sont pas bien comprises.

Ce projet, dirigé par X. Chris Le, avait les objectifs suivants : 1) déterminer les concentrations et les espèces chimiques d’arsenic dans l’eau des puits, ainsi que l’efficacité de l’élimination de l’arsenic par les appareils domestiques de traitement de l’eau; 2) déterminer quels sont les impacts de la mine Quinsam, en Colombie-Britannique, sur le milieu aquatique local; 3) identifier les espèces chimiques (formes) de vanadium présentes dans l’eau affectée par les activités d’exploitation des sables bitumineux et évaluer la toxicité de ces formes de vanadium pour les organismes aquatiques.

Projet

Reducing exposure to arsenic from drinking water is key in areas where well water exceeds the current guidelines. In this study, researchers first determined arsenic concentrations in well water in individual homes, by analyzing untreated and treated water samples in pairs from more than 600 wells with information on home treatment devices.  They compared the concentrations of arsenic species in water before and after the treatment to gain information on the effectiveness of the various treatment methods used in households.  The team then offered advice on removing arsenic from the well water.

The team’s analyses indicated that many treatment methods did not remove arsenic species from well water to meet the Health Canada and World Health Organization guidelines. For example, although iron filters were used by many home owners, the efficiency of removing arsenic from their well water was not consistent. Thirteen out of 51 homes that used iron filters had water arsenic concentrations exceeding the Health Canada and World Health Organization guideline level of 10 µg/L. When maintained properly, reverse osmosis appears to be able to remove arsenic from most well water tested, to meet the Health Canada and World Health Organization guidelines.

The second major component of this research focused on understanding the environmental fate and potential impact of vanadium. The team determined two main forms of vanadium (V+4 and V+5) in the oil sands process water, by-product coke, and sediment. The team then examined aquatic toxicity of these by growing the benthic invertebrate Hyalella azteca in water that was supplemented with vanadium (V+4 and V+5).  The organisms showed dose-dependent uptake of vanadium, and further studies focus on determining toxicity of vanadium to the organisms. An understanding of the bioaccumulation and toxicity of different forms of vanadium will contribute to meaningful environmental impact assessments.

Produits
  • Development of predictive mortality models based on vanadium bioaccumulation and vanadium water concentration.  The predictive mortality models were developed in conjunction with end users in Environment Canada. Environment Canada is using the models in the assessment of contaminated sites.
  • Participation in several key end-user oriented meetings and workshops:

 

  • Canadian Water Network Oil sands annual meetings at the University of Waterloo (2012, 2011)
  • Canadian Water Network annual meetings, 2011 and 2012.
  • 95th Canadian Society for Chemistry Conference and Exhibition, Metals in the Environment Symposium. Calgary May 2012. End users from Environment Canada and Natural Resources Canada participated.
  • Alberta Water Research Institute annual meetings. 2009, 2010, 2011 and 2012.
  • Technical Advisory Committee meeting. Alberta Health and Wellness, Alberta Environment, 2011 and 2012
  • External Advisory Board meeting, Columbia University Superfund Project. New York. Spring 2011.
  • Water, Toxic Substances, and Human Health Workshop. State Key Laboratory of Environmental Chemistry and Eco-toxicology, Chinese Academy of Sciences, Beijing, May 2011.

 

  • Several scholarly articles and end-user reports:
    • McGuigan, C.F. et al. A review on arsenic concentrations in Canadian drinking water. Environmental Review, 18, 291-307 (2010).
    • McKnight-Whitford, A. et al. New method and detection of high concentrations of monomethylarsonous acid detected in contaminated groundwater. Environmental Science and Technology, 44, 5875-5880 (2010).
    • Liu, F. et al. Antimony speciation and contamination of waters in the Xikuangshan antimony mining and smelting area, China. Environmental and Geochemical Health, 32, 401-413 (2010).
    • Naranmandura, H. et al. Comparative toxicity of arsenic metabolites in human bladder cancer EJ-1 cells. Chemical Research in Toxicology, 24, 1586-1596 (2011).
    • Chen, B. et al. Mouse arsenic (+3 oxidation state) methyltransferase genotype affects metabolism and tissue dosimetry of arsenicals after arsenite administration in drinking water. Toxicological Science, 124, 320-326 (2011).
    • Shen, S. et al. Arsenic binding to proteins. Chemical Reviews, 113, 7769-7792 (2013).  
    • Jensen-Fontaine, M. et al. Uptake and speciation of vanadium in the benthic invertebrate Hyalella Azteca. Environmental Science and Technology, 2013. DOI: 10/1021/es403252k.
    • Normandin, L. et al. Biomarkers of arsenic exposure and effects in a Canadian rural population exposed through groundwater consumption. Journal of Exposure Science and Environmental Epidemiology, 2013. DOI: 10.1038/jes.2013.80.
Résultats
  • Several public meetings were held in Campbell River, B.C.  The Campbell River Environmental Committee, the City of Campbell River, and the Strathcona Regional District representative have all voiced concerns about the proposed mine expansion. Campbell River Environment Committee and Citizens group have written thanks for supporting the project, and the work has been mentioned in newspapers over 10 times.  For example the work has been covered by Reporter Paul Rudan of The Mirror Newspaper, Campbell River. 
  • The mine has responded to the 2010 report by modifying its expansion plans.
  • The work on effectiveness of arsenic treatment methods has been of interest to partners; Alberta Health and Wellness has requested a copy, and the work has also been shared with Alberta Environment and Alberta Health Services.
  • The team’s work on the Quinsam watershed has helped understanding the potential impact of Quinsam mine on the aquatic system.  This has led to the mine to re-evaluate their expansion plans in light of the results.
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Équipe de Recherche et Partenaires:

Équipe de Recherche

X. Chris Le, Professor and Canada Research Chair in Bioanalytical Technology and Environmental Health, Director of the Analytical and Environmental Toxicology Division; University of Alberta
William Cullen, Professor Emeritus; University of British Columbia
George Dixon, Vice-President, University Research; University of Waterloo
Graham Gagnon, Professor and NSERC / Halifax Regional Water Commission Industrial Research Chair, Canada Research Chair in Water Quality & Treatment; Dalhousie University
Gary Kachanoski, Professor, University of Alberta
Patrick Levallois, Professeur titulaire, National Public Health Institute of Quebec
Kenneth Reimer, Professor, Royal Military College

Partenaires

Alberta Environment
Alberta Health and Wellness
Chinese Academy of Sciences
Environment Canada
Goldbar Water Treatment Plant
EPCOR Water Services
Health Canada
National Cancer Institute
Nature Works Remediation Corp.
Nova Scotia Environment and Labour
Reseau de recherche en santé environnementale
Stantec Consulting Ltd.
Syncrude Canada Ltd.
Trojan Technologies
US Environment Protection Agency
US Geological Survey
Zhejiang University