Study on chemical composition of snowpack in southeast and southwest of Tibetan Plateau in winter北大核心CSCD

According to 73 snow samples collected in the southeast and southwest of Tibetan Plateau in January，2021，the characteristics of hydrogen and oxygen stable isotopes（δD and δ18O）fractionation in dry season and the influence of water vapor migration on the chemical composition change of snow profile were revealed by measuring the stable isotopes of hydrogen and oxygen and soluble inorganic ions in snow，and the relationship between stable isotopes of hydrogen and oxygen and climate and the composition and source of soluble inorganic ions were discussed. The results show that the local meteoric waterline of snowpack in the whole study area is δD=7. 86δ18O+11. 8（R2=0. 95），which is close to the Lhasa winter meteoric waterline，and the slope and inter⁃ cept of the meteoric waterline in the southeast are slightly lower than those in the southwest. δD and δ18O fluctu⁃ ates from -178. 11% to -68. 07% and -23. 80% to -9. 61%，respectively，and the d-excess values fluctuate from 11. 03% to 23. 49%，showing low values of δD and δ18O in winter，and high d-excess values. The surface layer is relatively enriched in heavy isotopes，and the isotope values are higher than those of the lower snow sam⁃ ples，and the water vapor migration inside the snow makes the slope of the relationship between δD and δ18O dif⁃ ferent. The concentration sequence of the main soluble inorganic ions is Ca2+>SO42->Na+>NO3->Cl->K+>Mg2+> NH4+，of which Ca2+（42. 47%），SO42-（23. 53%）accounted for the largest proportion of cation and anion，re⁃ spectively，and the average concentration of ions in the southeast was higher than that in the southwest. The re⁃ sults of principal component analysis show that terrigenous sources are the main source of ions in snow，and NH4+ and some NO3- are related to human activities. The backward air mass trajectory shows that the source of water vapor is related to the water vapor transport controlled by the upper-altitude westerly circulation，and most of the ions are terrestrial mineral dust carried by westerly winds in winter. © 2023 The Author(s).