The high resolution record of atmospheric selenium recovered from Greenland snow

Abstract

Selenium concentrations were determined in a continuous series of 70 snow samples collected from a 3.2 m snow pit at northwestern Greenland together with soluble ions such as sodium (Na⁺), calcium (Ca²⁺), methanesulfonic acid (MSA), sulfate (SOsub>4</sub>^2- ) and oxygen isotope ratio (δ¹⁸O). The Se concentrations in the snow samples at the low pg/g level were successfully determined using the inductively coupled plasma sector field mass Spectrometry (ICP-SF-MS) with an APEX high-sensitivity inlet system and ACM membrane desolvation module. The well defined depth profiles of δ¹⁸O, Na+ and Ca²⁺ indicated that the snow pit samples covered the time period from spring 2003 to summer 2009. A strong variability in Se concentrations, ranging from 7.2 to 45.1 pg/g, are observed with generally higher values during winter and spring and lower values during summer and fall. Concentrations of Se showed rather significant correlations with Ca²⁺ (r=0.400) and non-sea salt SO^2- (r=0.447), indicating that significant anthropogenic Se input to the snow is likely controlled by the seasonality of transport efficiency of anthropogenic Se from the source regions of Asia. The high Se/MSA ratios and crustal enrichment factors are generally coincident with relatively high Se concentrations. This supports that a significant part of Se present in the snow layers is primarily attributed to anthropogenic inputs.