| Summary: | The Ross Sea is the most biologically productive sector of the Southern Ocean and a region of substantial bottom water formation. Modulation of these processes has the potential to influence both regional and global climate. Analysis of snow pit and ice core samples from Mt Erebus Saddle (MES) on Ross Island allows reconstruction of Late Holocene climate of this key region of Antarctica. The biogenic sulphur species, methylsulphonate (MS-), is shown to be a quantitative proxy for Ross Sea Polynya conditions. MS- concentrations of the snow pit, dating from 1999-2005 AD, strongly correlate (R2 > 0.9) with interannual changes in open water area and surface ocean primary productivity caused by the sea-ice-damming effect of large icebergs. Trace element analysis of ice core samples allows delineation between: 1) terrestrial and marine sources, 2) anthropogenic Pb pollution, and 3) volcanic trace element deposition. To assess the contribution of mineral dust leaching to trace element concentrations, powdered rock standards were leached in 1 wt.% HNO3 and periodically sampled for analysis. Results demonstrate that trace element leaching in acidified samples is time- and mineral-dependent. Incongruent leaching of trace elements from dust causes errors in crustal enrichment factors and produces trace element ratios, which do not reflect dust provenance. Stable isotope (δD, δ18O, d-excess) and soluble chemistry records of the 120 m MES ice core document the climate of the Ross Sea region since 1446 AD. This includes the Little Ice Age (LIA) - the most recent global climate change event. Lithophile elements (e.g., Al), sourced from mineral dust, are proxies for katabatic wind speed whilst d-excess and marine elements (e.g., Na) are related to the incursion of cyclonic systems into the Ross Sea. δD values of 6.4‰ below the 1950-2006 mean characterise the LIA, suggesting a mean cooling of 1.6 °C. An abrupt 5‰ d-excess increase provides evidence for enhanced cyclonic activity between 1625 and 1875 AD. Mean lithophile ...
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