CHANGES IN CONTINENTAL AND SEA-SALT ATMOSPHERIC LOADINGS IN CENTRAL GREENLAND DURING THE MOST RECENT DEGLACIATION - MODEL-BASED ESTIMATES

By fitting a very simple atmospheric impurity model to high-resolution data on ice accumulation and contaminant fluxes in the GISP2 ice core , we have estimated changes in the atmospheric concentrations of solub le major ions, insoluble particulates and Be-10 during the transition from glacial to Holocene conditions. For many species, changes in conc entration in the ice typically overestimate atmospheric changes, and c hanges in flux to the ice typically underestimate atmospheric changes, because times of increased atmospheric contaminant loading are also t imes of reduced,snowfall. The model interpolates between the flux and concentration records by explicitly allowing for wet- and dry-depositi on processes. Compared to the warm Preboreal that followed, we estimat e that the atmosphere over Greenland sampled by snow accumulated durin g the Younger Dryas cold event contained on average four-seven times t he insoluble particulates and nearly seven times the soluble calcium d erived from continental sources. and about three times the sea salt bu t only slightly more cosmogenic Be-10.