Limited migration of soluble ionic species in a Siple Dome, Antarctica, ice core

Abstract

High-resolution (>10 samples a-1) glaciochemical analyses covering the last 110 years from a Siple Dome, Antarctica, ice core reveal limited migration of certain soluble ionic species (methane sulfonic acid, NO3- and Mg2+). The observed chemical migration may be due in part to seasonal alternation between less acidic winter (from high sea-salt concentrations) and more acidic summer (from high marine biogenic acid concentrations) layers, common at coastal sites such as Siple Dome. Exact mechanisms to explain the migration are unclear, although simple diffusion and gravitational movement are unlikely since new peaks are formed where none previously existed in each case. Initial migration of each species is both shallower and earlier at Siple Dome than at other sites in Antarctica where similar phenomena have been observed, which may be related to the relatively low accumulation rate at Siple Dome (~ 13.3 cm ice a-1). Migration appears to be limited to either the preceding or following seasonal layer for each species, suggesting that paleoclimatic interpretations based on data with lower than annual resolution are not likely to be affected.