Delineation of carbonate dust, aluminous dust, and sea salt deposition in a Greenland glaciochemical array using positive matrix factorization

Abstract

High‐resolution trace element records from polar ice cores are fundamental to identifying spatial and temporal variability in dust and sea salt aerosols. Here, we developed high temporal resolution glaciochemical records over recent centuries from an array of seven recently collected Greenland ice cores. Positive matrix factorization (PMF) was used to assess apportionment of trace elements between three unique sources, which were identified as proxies of carbonate dust, aluminous dust, and sea salt. The three PMF factors agree well with literature values and represent the first time carbonate and aluminous dust sources have been quantifiably differentiated using high‐resolution glaciochemistry. The concentrations of all three sources varied with ice core site. However, the large array of ice cores provided a regional‐scale understanding of the sources and magnitude of dust and sea salt impurities deposited on the Greenland ice sheet. At the regional level, all three sources varied on seasonal, annual, and multiyear timescales. The seasonal deposition of sea salt impurities reached a maximum in the winter, followed by spring peaks of carbonate and aluminous dust. Over the 331 year composite record, only aluminous dust exhibited a long‐term increasing trend that peaked in the 1930s and was followed by a 20% decline in recent decades.