Using a geochemical method of dissolved and insoluble fractions to characterize surface snow melting and major element elution

Abstract

A geochemical method to characterize post-depositional melting and elution is demonstrated using inductively coupled plasma mass spectrometry to measure concentrations of dissolved and insoluble fractions of major crustal elements in snow samples collected from March 2006 to January 2010 at Urumqi Glacier No. 1, Tien Shan. Dust from these samples has compositional homogeneity, suggesting that dust has a stable dissolved fraction percentage (DFP, calculated as dissolved/(dissolved + insoluble)%). Calcium has the highest DFP (averaging 61.5 ± 19.4%), followed by Na (30.4 ± 19.6%), Mg (13.2 ± 9.8%), and K (7.9 ± 9.8%). Acid input can affect dissolution of Na and Ca. Taking DFP values of unmelted samples as the reference, the higher DFPs refer to strengthened dissolution from acid input, while the lower ones refer to elution. Based on the DFP difference between unmelted and eluted states, an elution sequence Ca > Na > Mg > K is obtained. Some details such as the beginning and the ending stages of elution can be found by DFP and acid input index, while using ion concentration is not capable of this. Our results reveal that acid input is an important mechanism for DFP changes, that the DFP index can provide an effective assessment of snow elution, and that this will aid in understanding low latitude ice cores.

Keywords

• melt-surface
• mountain glaciers
• snow and ice chemistry