The ratio of MSA to non-sea-salt sulphate in Antarctic Peninsula ice cores

Abstract

Methane sulphonic acids (MSA) in an ice core from Dolleman Island (70°35′S, 60°56′W) shows significantly high concentrations (typically 1-2 μM, but up to 5 μM) compared to values recorded in ice cores and in snowfall from elsewhere in Antarctica. MSA data from two other higher altitude Antarctic Peninsula ice cores, Dyer Plateau (70°31′S, 65°01′W) and Gomez Nunatak (74°01′S, 70°38′W), show that the high concentrations measured at Dolleman Island are not representative of the Peninsula region as a whole. However the mean molar MSA/nss-SO42- ratios at the three sites are similar (Dolleman Is, 0.46; Gomez, 0.37; Dyer, 0.32). Exceptionally high concentrations observed at Dolleman Island may be related to its proximity to the biologically productive Weddell Sea, an important source of dimethyl sulphide (DMS), the precursor of MSA. -from Authors