Rico, Kathryn; Ostrander, Chadlin; Heard, Andrew; Swanner, Elizabeth (2024): Major and trace elements in sediments from Deming Lake, MN, USA (2022-2023) [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.971078,

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In: Rico, K et al. (2024): Major and trace element data from Deming Lake, MN, USA (2022-et seq.) [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.970399

Sediment samples from the lake bottom were collected from the boat in May 2022. Ten samples capturing a few centimeters depth of the upper sediment layer were collected from depths between 1 m and 16.5 m depth along a transect from the northern shore and slope of the lake using a Wildco Ekman dredge. Additionally, one gravity core was collected at 4 m depth that yielded seven discrete samples from depths between 0 and 7 cm into the sediment column. All sediment samples were transferred into acid-cleaned 50 mL centrifuge tubes aboard the boat and frozen on return from the field for transportation. These samples were subsequently freeze-dried on return to WHOI using a benchtop freeze dryer with a Polytetrafluoroethylene coated stainless steel collector (Labcono FreeZone). Once dry, each sample was ground to a fine powder using a FRITSCH Mini-Mill Pulverisette 23 with zirconium oxide bowl and grinding balls. Approximately 50 mg of bulk sediment powders were weighed into Savillex Teflon reactors and digested in 2 mL concentrated HF + 1 mL concentrated HNO3. These samples were then sequentially dried down and digested in aqua regia followed by 1:1 concentrated HNO3:H2O2 to destroy organics. Samples were dried down, fluxed in concentrated HNO3, redried, and constituted in 5 mL of 2 % HNO3. Aliquots (<1 %) of the sediment bulk digests in 2 % HNO3 were then taken, diluted, and analyzed for major, minor, and trace elements on the Thermo iCAP-Q ICP-MS at the WHOI Plasma Facility. Indium (In) was added to samples at a concentration of 1 ng/g prior to analyses to monitor and correct for instrument drift by normalizing to In intensities. Concentrations were calculated using a five-point calibration curve obtained by fitting of ion beam intensities measured for serial dilutions of a gravimetrically prepared multi-element standard. The relative standard deviation (RSD) for five measurements of each sample was ~10% on the iCAP-Q. The accuracy and precision of similar concentration measurements on iCAP-Q at WHOI have previously been determined to be ± 5-10 % (1SD) based on comparison with USGS reference materials AGV-1, AGV-2, BHVO-1, BHVO-2, BIR-1, and BCR-2 prepared and analyzed as unknowns during earlier runs (Jochum et al., 2016; Shu et al., 2017).