Additionally, we expect that T7 Tag the higher salinity of the studied streams may be additional factor leading to greater variability of the measured δ66Zn compared to some of the adsorption effects measured in laboratory studies ( Pokrovsky et al., 2005, Juillot et al., 2008 and Balistrieri et al., 2008). Solutions with elevated salinity have been shown to affect dissolved δ66Zn ( Juillot et al., 2008 and Bryan et al., 2015). For example, we do find relatively weak correlations between decreasing δ66Zn and increasing SO4, Cl, HCO3 concentrations for some samples (Fig. 7). This could suggest an isotopic impact due to the speciation of Zn in aqueous solution, as inferred by Bryan et al. (2015). However, our data imply that aqueous Zn speciation has rather minor effect on δ66Zn (Fig. 7) compared to more evident pH effect in the studied area (Fig. 4).
Fig. 7. Changes of dissolved δ66Zn versus concentration of sulfate (A), chloride (B), and alkalinity (C). Because of high concentration of sulfate (400 to 1400 mg/L), on plot A we did not present the samples collected in Silverton area (Locations 1–10) for better clarity. Symbols are the same as in Fig. 2. The error bars show 1σ uncertainties calculated from replicate analyses.Figure optionsDownload full-size imageDownload high-quality image (250 K)Download as PowerPoint slide
Fig. 7. Changes of dissolved δ66Zn versus concentration of sulfate (A), chloride (B), and alkalinity (C). Because of high concentration of sulfate (400 to 1400 mg/L), on plot A we did not present the samples collected in Silverton area (Locations 1–10) for better clarity. Symbols are the same as in Fig. 2. The error bars show 1σ uncertainties calculated from replicate analyses.Figure optionsDownload full-size imageDownload high-quality image (250 K)Download as PowerPoint slide