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TitleDevelopment of an in situ ion-exchange technique for the determination of free Cd, Co, Ni, and Zn concentrations in freshwaters
AuthorCrémazy, A; Leclair, S; Mueller, K K; Vigneault, B; Campbell, P G C; Fortin, C
SourceAquatic Geochemistry vol. 21, 2015 p. 259-279,
Alt SeriesNatural Resources Canada, Contribution Series 20200349
Mediapaper; on-line; digital
File formatpdf; html
ProvinceAlberta; Quebec; Ontario
NTS32D/02; 32D/03; 32D/06; 32D/07; 41I/05; 41I/06; 41I/07; 41I/10; 41I/11; 41I/12; 41I/13; 41I/14; 41I/15; 74D/11; 74D/12; 74D/13; 74D/14; 74E/03; 74E/04; 74E/05; 74E/06
AreaAthabasca River; Fort McMurray; Rouyn-Noranda; Lac Dasserat; Lac Dufault; Lac Vaudray; Sudbury; Geneva Lake; Raft Lake; Whitson Lake
Lat/Long WENS-112.0000 -111.0000 57.5000 56.5000
Lat/Long WENS -79.4833 -78.6667 48.3667 48.0500
Lat/Long WENS -81.5667 -80.9167 46.7833 46.3833
Subjectsenvironmental geology; geochemistry; Nature and Environment; Science and Technology; Economics and Industry; surface waters; lakes; rivers; petroleum industry; hydrocarbons; oil sands; mining; smelting; acid mine drainage; refining processes; tailings; pollutants; metals; cadmium geochemistry; cobalt geochemistry; nickel geochemistry; zinc geochemistry; lake water geochemistry; stream water geochemistry; models; Canadian Shield; Methodology; Fresh water; cumulative effects; Mining industry; Aquatic animals
Illustrationsplots; bar graphs; tables
ProgramEnvironmental Geoscience Environmental impact of diluted bitumen
Released2015 03 12
AbstractIt is now well established that the bioavailability of metals toward aquatic organisms varies as a function of the free metal concentration. The ion-exchange technique (IET), which consists of equilibrating a calibrated cation-exchange resin with the water sample, is one of the few existing speciation methods that provide sufficient sensitivity and specificity to measure free metals in natural waters. In the present study, we developed an in situ IET (field-IET) in which the resin was directly equilibrated on site using dialysis cassettes. The field-IET was tested in six Canadian Shield lakes and in the Athabasca River (AB, Canada) for Cd2+, Co2+ (only in the Athabasca River), Ni2+, and Zn2+. Measurements were compared with those obtained on samples collected from the same sites with in situ diffusion samplers and analyzed in the laboratory (lab-IET). IET results were also compared with predictions from the Windermere Humic Aqueous Model [WHAM VII; the Co and Ni carbonato complex formation constants were updated according to the US National Institute of Science and Technology (NIST compilation)]. Good agreement was obtained between the field-IET and the lab-IET for Co2+ and Ni2+ concentrations, but field-IET Cd2+ and Zn2+ concentrations were systematically higher than the lab-IET results (factors of ~1.5x and ~2.4x, respectively). Uncertainties in the field-IET resin calibration and a significant Zn contamination could explain these results. WHAM VII predicted the free metal concentrations reasonably well, except for Ni2+ concentrations in the lakes, probably due to inappropriate formation constants for complexation of Ni with dissolved organic matter. This study showed that the field-IET, with its relative simplicity and its low detection limits, could be a useful method for the determination of free metal concentrations in acidic to neutral freshwaters.
Summary(Plain Language Summary, not published)
One of the best predictor for trace metals aquatic fate and impacts is the free metal concentration, i.e. the fraction of metal in water that is not in particles or chemically bound to other compound in solution. This fraction is very difficult to measure however due to the low concentrations and several potential artifacts when samples are transported to laboratory for analysis. The publication summarizes the effort to develop a method that would measure directly in surface waters the free metal concentration. The methodology development was conducted using water analysis in the Rouyn-Noranda, Sudbury and Fort McMurray area. The results show that the proposed methodology is simple and can detect low concentrations in acidic to neutral freshwaters.

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