Figure 7
(a) Normalized EXAFS and corresponding radial structure functions (uncorrected for phase shift of backscattering atoms) for cadmium in unleached and leached sediment samples from core SC4 at approximately the same depth (34 cm). Dashed red line is the non-linear least-squares best fit; green line is the fit component corresponding to CdS; blue line is the fit for a cadmium-oxygen component that probably represents cadmium adsorption on iron (oxy)hydroxides that form from pyrite oxidation. (b) Normalized EXAFS and corresponding radial structure functions (uncorrected for phase shift of backscattering atoms) for zinc in unleached and leached sediment samples from core SC4. Dashed red line is the non-linear least-squares best fit; green line is the fit component corresponding to sphalerite; blue line is the fit for a zinc-oxygen component that probably represents zinc adsorption on iron (oxy)hydroxides that form from pyrite oxidation and zinc substitution in phyllosilicate or oxide minerals noted previously. (c) Normalized EXAFS and corresponding radial structure functions (uncorrected for phase shift of backscattering atoms) for chromium in unleached and leached sediment samples from core SC4. Dashed red line is the non-linear least-squares best fit. (d) Normalized XANES spectra for lead in samples in unleached and leached sediment from core SC4 compared to reference crystalline lead carbonate (PbCO3). (e) Normalized XANES spectra for manganese in samples in unleached and leached sediment from core SC4 compared to a reference manganese phosphate (Fe, Mn(PO4)). (f) Normalized EXAFS and corresponding radial structure functions (uncorrected for phase shift of backscattering atoms) for iron in unleached and leached sediment samples from core SC4. Dashed red line is the non-linear least-squares best fit; green line is the fit component corresponding to pyrite; blue line is the fit for an iron-oxygen component that probably represents formation of an iron (oxy)hydroxide in addition to iron substitution in phyllosilicate or oxide minerals discussed previously.