paf_778_779 PatriciaFoxLawrence Berkeley National Laboratorypmfox@lbl.gov https://orcid.org/0000-0002-5264-1876 SergioCarreroUniversity of California Berkeleysergio.carrero@berkeley.edu https://orcid.org/0000-0003-3029-425X CamAndersonUniversity of Massachusetts Amherstcganderson@umass.edu https://orcid.org/0000-0003-4211-5765 ChristianDeweyStanford Universitycwdewey@stanford.edu https://orcid.org/0000-0003-1954-8298 MarcoKeiluweitUniversity of Massachusetts Amherstkeiluweit@umass.edu HannaNaughtonLawrence Berkeley National Laboratoryhnaughton@lbl.gov BenjaminGilbertLawrence Berkeley National Laboratorybgilbert@lbl.gov https://orcid.org/0000-0003-0853-0826 ScottFendorfStanford Universityfendorf@stanford.edu https://orcid.org/0000-0002-9177-1809 PeterNicoLawrence Berkeley National Laboratorypsnico@lbl.gov https://orcid.org/0000-0002-4180-9397 U.S. DOE > Office of Science > Biological and Environmental Research (BER) http://dx.doi.org/10.13039/100006206 fundingOrganization 2022 This dataset includes sulfur x-ray absorption near edge spectroscopy (XANES) data collected on solid samples as a part of the Watershed Function Scientific Focus Area (SFA) located in the Upper Colorado River Basin. The data were collected in order to investigate the speciation of sulfur and degree of shale weathering in solid samples across the watershed and their impact on riverine export of sulfate. Solid samples, including shale, hillslope soil, and floodplain sediment samples collected in 2016-2018, were analyzed by bulk XANES. Density fractions of hillslope soil, including a light fraction representing particulate organic matter and a heavy fraction representing minerals are also analyzed by bulk XANES. Micro-focused XANES on a weathered shale sample (PLM6, 2.7 m) was also performed. Sample locations are included in the 'sample meta data.csv' file, and XANES data for each sample type are included in csv files.XANES speciation weathering pyriteCATEGORICAL:NONESpectroscopyVARIABLE:NONE

Fox, P.M., Carrero, S., Anderson, C., Dewey, C., Keiluweit, M., Conrad, M., Naughton, H.R., Fendorf, S., Carroll, R., Dafflon, B., Malenda-Lawrence, H., Dwivedi, D., Fakra, S., Gilbert, B., Christensen, J.N., Boye, K., Beutler, C., Brown, W., Newman, A., Versteeg, R., Williams, K.H., and Nico, P.S. Sulfur biogeochemical cycling and redox dynamics in a shale-dominated mountainous watershed. J. Geophys. Res: Biogeosciences. In ReviewAdditional metadata on specific locations within the watershed are provided in the following related data package:Varadharajan C ; Kakalia Z ; Banfield J ; Berkelhammer M ; Brodie E ; Christianson D ; Dafflon B ; Carbone M S ; Carroll R ; Chadwick K D ; Christensen J ; Enquist B J ; Fox P ; Henderson M ; Gochis D ; Kueppers L ; Powell T ; Matheus Carnevali P ; Singha K ; Sorensen P ; Tokunaga T ; Versteeg R ; Wilkins M ; Williams K ; Worsham M ; Wu Y ; Agarwal D (2020): Location Identifiers, Metadata, and Map for Field Measurements at the East River Watershed, Colorado, USA. Watershed Function SFA. doi:10.15485/1660962

This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. 2016-06-012018-07-10 The East River (ER) is a snow‐dominated, headwater basin of the Upper Colorado River Basin (UCRB) located in the western United States. The ER is the designated testbed of Lawrence Berkeley National Laboratory's Watershed Function Scientific Focus Area (WFSFA). Through WFSFA, observational networks have been established to measure stream discharge and precipitation chemistry. The ER is considered representative of many snow‐dominated headwaters of the Rocky Mountains. The study domain encompasses nearly 85 square km, a 1.4‐km vertical drop in elevation (4,120 to 2,760 m) and pristine alpine, subalpine, montane, and riparian ecosystems. The ER contains high‐energy mountain streams to low‐energy meandering floodplains and is eroding primarily into the Cretaceous, carbon‐rich, marine shale of the Mancos Formation. Additional metadata on specific locations within the watershed are provided in the following related data package: Varadharajan C. et al. (2020) doi:10.15485/1660962 -107.05-106.8839.03438.88 PatriciaFoxLawrence Berkeley National Laboratorypmfox@lbl.gov https://orcid.org/0000-0002-5264-1876 Watershed Function SFA Sample Collection:Solid-phase samples for this study include floodplain sediment, hillslope soils, and shale samples. Sediment samples were collected from two floodplain locations in a meandering reach of the East River (Lower Montane Floodplain site and Brush Creek Site) at elevations of 2760 and 2727 m, respectively. Sediments were collected from two active meanders (Meander C: MCB3 and Meander Z: MZA2) and the former river channel of a meander cutoff (Meander Y; MYC3). Cores were collected from Meander C in June 2017 and July 2018 and from Meander Z and Y in June 2018. Soil samples were collected from the hillslope on the southwestern side of the river, adjacent to deep groundwater wells PLM1 and PLM3 in June 2017; soil samples are denoted upper hillslope and lower hillslope for the PLM1 and PLM3 locations, respectively. Sediment and soil samples were collected in approximately 15-cm increments using a 5 cm diameter soil core sampler with slide hammer until coarse alluvium was reached. After reaching coarse alluvium, sediment was sampled using an 8.3 cm diameter bucket auger. Floodplain sediment samples collected from Meander C, Meander Y, and Meander Z in 2018 were placed in polyethylene bags, sealed into aluminized BoPET (Biaxially-oriented polyethylene terephthalate, or MylarTM) bags containing O2 absorbers (IMPAKTM corporation), shipped to the laboratory, and stored at 4°C until processing in order to preserve anaerobic conditions observed in some cores. Sediment samples were then sieved through a 2-mm sieve under field-moist conditions in a Coy anaerobic chamber filled with a gas mixture of 97% N2 and 3% H2. Samples were freeze-dried and ground by hand with an agate mortar and pestle. Hillslope soil samples and sediment samples from 2017 were freeze-dried, sieved through a 2-mm sieve, and ground by hand. Shale samples were collected from the hillslope location (PLM6, approximately 4.5 m from PLM3 at the same elevation) and from a shale outcrop on Gothic Road (GRO). At the hillslope, a continuous vertical core to a depth of approximately 10 m below ground surface (bgs) was collected using a track-mounted drill rig and a 0.14-m diameter ODEX drilling bit. A shale weathering profile was observed from 1-3 m bgs. The sample denoted “Pristine” was subsampled from a piece of solid core at a depth of 9 m. Between 2 – 3 m bgs, numerous fractures were observed along with iron oxide discoloration. The sample denoted “Weathered” was subsampled at a depth of 2.7 m from within the weathering region of one such fracture surface. At the GRO site, a horizontal core 1-m above the ground surface and approximately 1-m long was collected from the outcrop using a hand drill with a 24.5-mm diameter diamond drilling bit using water as a drilling fluid. The sample denoted “Top” was taken from the exposed section of the core, which exhibited signs of weathering such as iron oxide discoloration. The samples denoted “Middle” and “Bottom” were subsampled at depths of approximately 40 cm and 80 cm in the core.Density Fractionations:To isolate S in particulate organic matter, mineral-organic associations, and shale, we employed a density fractionation procedure that relies on a density gradient established in sodium polytungstate solution. Two density cutoffs were chosen to separate soils into (1) a light fraction consisting primarily of particulate organic matter (< 1.8 g cm-3), (2) an intermediate fraction composed of mineral-organic associations (1.8 < x < 2.4 g cm-3, and (3) a heavy fraction, comprised predominantly of minerals (> 2.4 g cm-3). The fractionation was conducted on 3 g of bulk soil by floatation in 12 mL of a low-C and -N sodium polytungstate (SPT-0, Geoliquids Inc., Prospect Hills, IL). Only the light and heavy fractions were analyzed by X-ray absorption spectroscopy.X-Ray Absorption Spectroscopy:All samples were analyzed at the sulfur K-edge by x-ray absorption near edge spectroscopy (XANES) at the Canadian Light Source (CLS), Stanford Synchrotron Radiation Laboratory (SSRL), or the Advanced Light Source (ALS). Samples analyzed at the SXRMB beamline at the CLS included shale, hillslope soil, and Meander C 2017 sediments. SXRMB spectra were recorded in fluorescence yield mode with 2 scans for each sample. The absolute energy position of the sulfur K-edge white line of calcium sulfate was calibrated to 2481.8 eV. The energy resolution was 0.24 eV. Samples analyzed at beamline 14-3 at SSRL (Meander C 2018 sediments, Meander Y and Meander Z sediments) were analyzed in fluorescence mode using a 4 element Vortex detector. Multiple scans (14-19) were collected and averaged in order to reduce noise in the data. Microscale XANES analysis of hillslope shale (PLM6, 2.7 m) was performed using beamline 10.3.2 at Advanced Light Source. The ALS beamline was equipped with a 1-element silicon drift fluorescence detector (Amptek FAST XR-100SDD). Three spots were analyzed for microscale XANES, including one spot in the "S pristine zone", located approximately 1 cm from a fracture surface (spot 1), one spot in the "carbonate pristine zone", located approximately 2 mm from the fracture surface (spot 2), and one spot in the "S precipitation zone", located less than 1 mm from the fracture surface (spot 3). All XANES spectra were processed in Athena. The energy was calibrated with sulfate using a white line energy of 2481.8 eV. Multiple scans were averaged, and the pre-edge and post-edge were normalized using linear functions and an edge-step of 1.0. Watershed Function SFA [PI: Eoin Brodie]metadataProviderDOE:DEAC0205CH11231 (Lawrence Berkeley National Laboratory) S_XANES_bulk soil and sediment.csv text/csv sample meta data.csv text/csv S_XANES_density fractions.csv text/csv S_XANES_shale.csv text/csv S_microXANES_PLM6.csv text/csv