The concentration of the main soluble ions in the ice wedges of IW-5 and IW-7 of the Batagay yedoma

This work delineates the macroelements compositions in the Late Pleistocene syngenetic ice wedges (IW-5 and IW-7) situated in the bottom section of the Batagay Yedoma complex. Ice samples were extracted from ice wedges at 10 cm intervals using Makita and Bosch GSR drills equipped with steel ice crowns of 51 mm in diameter. The composition of macroelements in the ice wedges was analyzed using the ion chromatograph "Steyer." The concentrations of potassium, sodium, calcium, magnesium, chlorine, nitrates, and sulfates were measured. The mineralization of Late Pleistocene ice wedges ranges from 67 to 425 mg/L. In the analyzed ice wedges, calcium predominates among the cations (IW-5 ranging from 17.8 to 82.5 mg/L, IW-7 from 12.0 to 52.1 mg/L). Magnesium ranks second (IW-5 ranging from 3.1 to 13.6 mg/L, IW-7 ranging from 2.6 to 8.3 mg/L). Sodium and potassium cations are present in minimal concentrations: Na – IW-5 ranges from 0.8 to 6.8 mg/L, IW-7 from 0.45 to 4.0 mg/L, and K – IW-5 from 17.8 to 82.5 mg/L, IW-7 from 1.1 to 5.6 mg/L. Nitrates dominate among the anions. The nitrate concentration varies from 6.9 to 27.9 mg/L for IW-5 and from 5.0 to 54.8 mg/L for IW-7. Mean nitrate concentration IW-5: 14.5 mg/L; IW-7: 12.2 mg/L. In IW-5, the concentration of sulfate anions ranges from 2 to 17 mg/L, with an average of 6.4 mg/L, whereas the chloride concentration ranges from 1.08 to 7 mg/L, averaging 2.6 mg/L. The sulfate concentration in IW-7 ranges from 1.4 to 40.5 mg/L, with an average of 5.79 mg/L; the chloride concentration ranges from 1.13 to 4.5 mg/L, with an average of 1.96 mg/L. In IW-5, the chloride-to-sulfate ratio ranges from 0.16 to 1.45, with an average of 0.44; in IW-7, the ratio ranges from 0.04 to 1.12, with an average of 0.47. Upon comparing these data with the chloride to sulfate ratios in ground ice and surface water in North-West Siberia, we observe that the ratios most closely resemble those found in the snowfields of the Seyakha (Mutnaya) River valley on the northern Yamal Peninsula, where the chloride to sulfate ratio is 0.54, in rainwater on the Yamal Peninsula with a ratio of 1.44, and in segregated ice on the first terrace of Bely Island, where the ratio is 1.08. The chloride to sulfate ratio in IW-5 and IW-7 significantly differs from that of cryopegs (ratio 49.45) and the majority of the massive ice in the Yamal Peninsula (68.91; 26.39; 9.77, etc.). The ionic composition of the ice wedges indicative that they was formed from thawed snow generated under the influence of continental air masses.

permafrost, yedoma, ice wedge, radiocarbon age, cryogeochemistry, ionic composition, major elements, Batagay, Siberia, Yakutia