Chemical characterisation of natural and anthropogenic inputs of dust in the seasonal snowpack (2017-2020) at Calderone Glacier (Gran Sasso d'Italia)

Rationale. The Calderone Glacier (Central Apennine, Gran Sasso d'Italia mountain group) is the southernmost glacial apparatus in Europe, split into two glacierets (Upper and Lower Calderone) since the end of the last millennium. Because of its location and altitude, this site is mainly characterised by the long-range transport of air masses which arise from different Mediterranean source regions. Therefore, the seasonal snowpack's chemistry is strongly affected by the dry and wet deposition of contaminants associated with anthropogenic and natural sources. Methodology. In the present study, the seasonal snowpack stratified on the Calderone glacier has been characterised for four consecutive years (2017-2020) in the same monitoring site (2700 m asl), where a snow pit has been dug yearly, to observe the modification of chemical and physical properties depending on local and long-range atmospheric contributions. We determined the concentrations and fluxes of major inorganic ions (MIs) by ion chromatography and of 31 trace elements (TEs) by triple quadrupole ICP-MS. Results. Major and trace element concentration profiles along the snowpack allowed to discriminate the snow layers contaminated by long range advections from the uncontaminated ones. The uncontaminated snow layers' concentrations were used to calculate regional background values. The results have been compared to other remote sites to assess their robustness. Discussion. Different source contributions have been recognised using enrichment factors for the trace elements, particularly crustal, marine and anthropogenic. Deposited atmospheric aerosols, found in the snowpack as distinct layers generated during intense air mass advections, have been correlated to these contributions.