MOSSO_SnowPhysics&Chemistry_Annual_2009-2020

Snow profiles are described following the AINEVA (Interregional Association for Snow and Avalanches) procedure (Cagnati 2003, Strumenti di misura e metodi di osservazione nivometeorologici: manuale per i rilevatori dei Servizi di previsione valanghe, Associazione Interregionale Neve e Valanghe, Trento). Snow density is measured by sampling and weighing 50-cm sections of the snow column with a snow measuring cylinder. The chemical analyses are performed in the laboratory on filtered samples (0.45 μm, nylon). For trace-element analyses, an aliquot of the filtered samples is acidified to pH<2 with hydrochloric acid, purified by sub-boiling distillation. pH is measured potentiometrically using a WTW-InoLab 7110 pH-meter equipped with Hamilton GelGlass electrode. EC at 20°C is measured using a Crison - Micro CM 2201. N-NH4 is determined spectrophotometrically (Spectrophotometer U-2000, Hitachi, Tokyo, Japan) by a modified Berthelot method involving reaction with salicylate in the presence of alkaline sodium dichloroisocyanurate (Crooke and Simpson 1971, https://doi.org/10.1002/jsfa.2740220104). N-NO3 is determined spectrophotometrically by the Greiss reaction as described by Mulvaney (1996, ISBN-10: ‎ 0891188258; ISBN-13: ‎ 978-0891188254) and modified by Cucu et al. (2014, https://doi.org/10.1007/s00374-013-0893-4). DOC and TDN are determined by a TOC analyzer (Elementar, Vario TOC, Hanau, Germany). DON is determined as the difference between TDN and inorganic nitrogen (N-NH4 + N-NO3). Cations are determined by flame atomic absorption spectroscopy (Perkin Elmer AAnalyst 400, Waltham, Massachusetts, USA). Anions are determined by ion chromatography (Dionex DX-500, Sunnyvale, California, USA). Trace elements are determined by inductively coupled plasma-sector field mass spectrometry (Thermo Finnigan Element 2, Bremen, Germany).