CLIMATIC IMPLICATIONS OF BACKGROUND ACIDITY AND OTHER CHEMISTRY DERIVED FROM ELECTRICAL STUDIES OF THE GREENLAND ICE CORE PROJECT ICE CORE

High-resolution continuous profiles were obtained on the Greenland Ice Core Project (GRIP) ice core using two different electrical methods. After correction for temperature and density, the electrical conductiv ity method (ECM) technique responds only to acidity, while dielectric profiling (DEP) responds to acid, ammonium, and chloride. Detailed che mistry on a section of glacial-age ice allows us to confirm the calibr ation factor for chloride in DEP. Acidity dominates the DEP variabilit y in the Holocene, Allerod/Bolling, and larger interstadials; ammonium dominates in the Younger Dryas, while chloride is the major contribut or in cold periods including smaller interstadials. From the electrica l signals plotted on a linear timescale we can deduce the background ( nonvolcanic) acidity of the ice, varying from always acidic in the Hol ocene to always alkaline in the cold periods. In the interstadials, th e ice is close to neutral, with most of it acidic in larger interstadi als, most of it alkaline in smaller ones, and rapid alternations withi n interstadials. It is not clear whether neutralization of individual acidic particles occurred in the atmosphere or whether acid and alkali ne particles coexisted until deposition in the snowpack. The changes i n acidity observed at GRIP apply at least to all of Greenland and prob ably to much of North America. There would have been ecological effect s and important changes in the uptake of some chemicals onto ice. If a cidic sulfate particles were neutralized and removed from the atmosphe re, which remains uncertain, then there are atmospheric chemistry and radiative effects that require further investigation.