Mössbauer, X-ray photoelectron spectroscopy, and iron speciation data for sediments from Saanich Inlet, British Columbia, Canada

This dataset supports the study "Pathways to pyrite through polysulfides and metastable iron sulfides in marine sediments" (Figueroa et al., submitted to Communications Earth & Environment). It contains solid-phase iron and sulfur speciation data for four sediment samples from Saanich Inlet, British Columbia, Canada. The samples come from two 2-cm intervals at each of two sites: a basin site with seasonally euxinic bottom waters (S3, 205 m water depth) and a slope site with seasonally fluctuating redox conditions (S4, 105 m water depth). The sediments were collected in July 2019. The dataset includes three files: Supplementary_Data_1_Mossbauer.xlsx: ⁵⁷Fe Mössbauer spectra collected at 10 K and 25 K, with the modelled fits, individual fitted components, residuals and phase abundances. Supplementary_Data_2_XPS.xlsx: X-ray photoelectron Fe 2p and S 2p spectra, fitted components and peak parameters, and surface elemental composition from duplicate spot analyses. Supplementary_Data_3_Fe_speciation.xlsx: Total Fe, Al and S concentrations, porewater dissolved sulfide, and Fe pools from sequential chemical extractions (ascorbate, acetate, dithionite, oxalate, acid-volatile sulfide and chromium-reducible sulfide). It also includes the derived Fe fractions and paleoredox proxy ratios. Each file includes a README sheet describing the samples, methods, units and column definitions. Sample identifiers used by the analytical facility (1744-A to 1744-D) are mapped to the sediment intervals in each file's Sample_Key sheet. Mössbauer and XPS analyses were performed at the Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory.