Salinity and Isotopic Pore Water Variations as Climate Indicators in Glacier-Affected Billefjord, Spitsbergen (2024)

In this article, the data from the bottom sediment column study were presented. In the solid phase of the column layers, 210Pb, 226Ra, and 137Cs were determined. Stable isotopes δ18O, δ2H and salinity were determined in the liquid phase of the pore waters. On April 7, 2024, a 16 centimeter (cm) sediment core was collected from Billefjord, Svalbard Archipelago (depth: 94 meters (m)). The main objective of this study is to examine how glacier melting—driven by rising air temperatures due to climate change—affects marine sedimentation parameters, with a focus on pore water salinity and stable isotope composition. Sediment core was collected using a GOIN-1.5 gravity corer tube (40 millimeter (mm) inner diameter). The core was frozen at (–20 degrees Celsius (°C)), then sliced into 1 cm layers while frozen and thawed in sealed containers. The pore water extraction was performed via centrifugation (9,000 revolutions per minute (rpm), 50 milliliter (mL) tubes) and samples were transported for analysis. The solid phase was freeze-dried, and moisture content was determined by pre- and post-drying weight. Measurements of the specific activities of radionuclides ²¹⁰Pb, ²²⁶Ra, and ¹³⁷Cs in bottom sediments were conducted at the laboratory of the Murmansk Marine Biological Institute (MMBI RAS) utilizing a multichannel gamma spectrometer designed for X-ray and gamma radiation detection (Canberra Semiconductors NV, Olen, Belgium). The ages of sediment layers, along with the sediment accumulation rates, were determined through the analysis of excess ²¹⁰Pb (²¹⁰Pbₑₓ). The excess ²¹⁰Pb (²¹⁰Pbₑₓ) was calculated by subtracting ²²⁶Ra activity from total ²¹⁰Pb activity, representing both atmospheric deposition and in-situ ²²⁶Ra decay. In the liquid phase of the bottom sediment (pore water), salinity, as well as δ¹⁸O and δ²H values, were measured. The isotopic composition of pore water was analyzed for δ¹⁸O and δ²H utilizing a Picarro L2130-i laser analyzer at the Research Center for X-ray Diffraction Methods within the SPbGU Science Park. The reference standards employed for calibration included USGS50 (δ¹⁸O = 4.95 permil (‰), δ²H = 32.8‰), USGS45 (δ¹⁸O = -2.238‰, δ²H = -10.3‰), and USGS46 (δ¹⁸O = -29.8‰, δ²H = -235.8‰). The analytical measurement uncertainties were established at ±0.07‰ for δ¹⁸O and ±0.2‰ for δ²H. The salinity of the pore water samples was measured in the laboratory using a salinometer. Samples were diluted with distilled water, and the dilution coefficients were monitored by precisely weighing the samples to three decimal places (g) both before and after the dilution process. Salinity corrections were applied accordingly. The overall analytical error associated with the salinity determinations was ±0.3 practical salinity units (psu). This study utilized monthly mean air temperature data from the Barentsburg meteorological station.