Scanning XRF elemental bromine (Br) and chlorine (Cl) data from a temperate fjord in Southeast Alaska for the last 2,000 years

Marine sediment core EW0408-33JC (57.162°N, 135.357°W, 146 m water depth) was recovered from Katlian Bay, a temperate fjord near Sitka, Alaska, in August 2004. EW0408-33JC is the jumbo piston core collected from the same site as EW0408-32MC, which was described in Addison et al. (2013; hereafter referred to as A13). This data release describes the most recent 2,000 years of EW0408-33JC, as established by a combination of radiometric 137Cs and excess 210Pb (see A13), and five accelerator mass spectrometry (AMS) 14C samples (see Table DR1). After calibrating these AMS 14C samples using the INTCAL20 curve (Reimer et al., 2020) in CALIB 8.20 (Stuvier and Reimer, 1993), the full set of geochronology data was input into the R software program (R Core Team, 2021) package CLAM (v. 2.6.1; Blaauw et al., 2010) to generate a composite age-depth model for EW0408-33JC data. The composite depth scale was established using Geotek multi-sensor core logger (MSCL) data and linescan imagery to align EW0408-32MC, EW0408-33JC, and the trigger core for the jumbo piston core system EW0408-33TC. The MSCL data (gamma-ray wet bulk density and whole-round magnetic susceptibility) and linescans showed that EW0408-32JC recovered the sediment-water interface (see A13 for more details), and that a shift of +33 cm was needed to align EW0408-33TC with the datum of -32MC, and a shift of +54 cm was required to align EW0408-33JC; together, these alignments permitted the generation of a continuous composite depth scale from 0 cm (= sediment-water interface) to 553 cm bsf (below sea floor), which is the composite depth horizon associated with 2000 years ago. Scanning X-ray fluorometry (XRF) data were collected from the split surfaces of cores EW0408-32MC, -32TC, and -33JC (see A13 for analytical details). Using the composite depth scale and alignment of the XRF data from the three cores, a continuous XRF data splice was generated. This splice uses the following depth horizons: 0-27 cm bsf in EW0408-32MC; 27.2-65.0 cm bsf in -33TC; and >65.0 cm bsf in -33JC. This data release specifically focuses on the scanning XRF datasets for bromine (Br) and chlorine (Cl), as the Br/Cl ratio has been shown to reflect variations in primary productivity (A13; Table DR2). In addition to the raw counts per second units for Br and Cl, statistical calculations are also included: the geometric mean of all X-ray counts, which is in turn used to calculate the centered natural-log-ratio (clr) transformations of both Br and Cl. The resulting clr Br / clr Cl ratio is calculated, and a two-part linear background is removed from the dataset to correct for sediment compaction (see A13 for more details). The detrended clr Br / clr Cl data are presented in their native format, as well as being normalized to Z-scores; raw and 10-yr multi-pass smoothed data are included in this data release. A multi-decadal (40-yr) variance calculation is also included. References: Addison, J. A., Finney, B. P., Jaeger, J. M., Stoner, J. S., Norris, R. D., & Hangsterfer, A. 2013. Integrating satellite observations and modern climate measurements with the recent sedimentary record: An example from Southeast Alaska. Journal of Geophysical Research: Oceans, 118(7), 3444-3461. doi:10.1002/jgrc.20243. Blaauw, M. 2010. Methods and code for 'classical' age-modelling of radiocarbon sequences. Quaternary Geochronology 5: 512-518 R Core Team (2021). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Reimer P, et al. 2020. The IntCal20 Northern Hemisphere radiocarbon age calibration curve (0-55 cal kBP). Radiocarbon 62. doi: 10.1017/RDC.2020.41. Stuiver, M., and Reimer, P.J. 1993. Radiocarbon, 35, 215-230.

                                            [
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                                            {
  "fn": "Jason A Addison",
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