Major 20th century changes of carbonaceous aerosol components (EC, WinOC, DOC, HULIS, carboxylic acids, and cellulose) derived from Alpine ice cores

Abstract : An extended array of carbonaceous species including elemental carbon (EC), water insoluble organic carbon (WinOC) as well as dissolved organic carbon (DOC), humic-like substances (HULIS), and single organic compounds like carboxylic acids, levoglucosan, and cellulose was investigated for the first time in Alpine snow deposits. These investigations were done on selected discrete ice cores sections extracted from Mount Rosa and Mount Blanc glaciers covering the 20th century and extending back to previous centuries. Here we focus on major changes in summer ice layers. Among carbonaceous components, EC reveals an outstanding increase with a sharp summer increase after World War II. This result is discussed against available past EC emission inventories in Europe which are thought to be mainly driven by emissions from road transport and residential sector. The long-term trend of organic carbon (OC) aerosol preserved in ice, WinOC as well as water soluble organic carbon (WSOC), was successfully reconstructed using the suitable array of organic compounds we investigated in this study. It is shown that the level of OC preserved in ice has increased by a factor of 2 after 1950 likely as a result of the enhancement of the oxidative capacity of the atmosphere over the last decades producing more secondary organic atmospheric aerosol from biogenic gaseous precursors.