Main Pollen taxa and Grain-Size Data Summarize in Surface Sediments from Hurleg and Toson Lakes, Northeastern Qaidam Basin

Surface sediment samples were collected from Hurleg Lake (H1–H25) and Toson Lake (T1–T69) in 2015 and 2023 using an Ekman grab sampler. Pollen extraction followed a standard acid-base procedure. Freeze-dried sediments (2 cm3) were processed, with a Lycopodium tablet (10,315 grains/tablet) added for pollen concentration calculations. Samples were sieved through a 200 μm mesh and treated with 10% HCl and 10% KOH to remove calcareous minerals and humic substances. A 40% HF solution was used to digest fine silica, and residues were sieved through a 7 μm mesh to eliminate clay-sized particles. The processed samples were mounted in glycerin jelly for microscopic identification at 400× and 1,000× magnifications, using reference descriptions and illustrations. Approximately 300 pollen grains were counted per sample. Grain size analysis was performed using a Malvern Mastersizer 3000 particle analyzer (0.01–3,500 μm range). Samples were pretreated with H2O2 and HCl to remove organic matter and carbonates, then dispersed in a 10% (NaPO3)6 solution with ultrasonic treatment before measurement. Each sample was measured three times to ensure consistency, with the average value used for analysis. All experiments were conducted at the Qinghai Institute of Salt Lakes, Chinese Academy of Sciences. This dataset provides a summary of surface sediment pollen and grain size end-member information; the remaining raw data will be uploaded in due course.