Abstract12 – University of Copenhagen

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Centre for Ice and Climate > Publications > Scientific papers > Abstracts > Abstract12

Climatic implications of background acidity and other chemistry derived from electrical studies of the Greenland ice core project ice core.

Journal of Geophysical Research, Vol. 102, No. C12, p. 26,325-26,332, 1997

E.W. Wolff
British Antarctic Survey, Natural Environment Research Council, Cambridge, England.
J.C. Moore
Arctic Centre, University of Lapland, Rovaniemi, Finland.
H.B. Clausen and C.U. Hammer
Departement of Geophysics, The Niels Bohr Institute of Astronomy, Physics and Geophysics, University of Copenhagen .

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 conductivity method (ECM) technique responds only to acidity, while dielectric profiling (DEP) responds to acid, ammonium and chloride. Detailed chemistry on a section of glacioal-age ice allows us to confirm the calibration factor for chloride in DEP. Acidity dominates the DEP variability in the Holocene, Allerod/Bolling, and larger interstadials; ammonium dominates in the Younger Dryas, while chloride is the major contributor in cold periods including smaller interstadials. From the electrical signals plotted on a linear timescale we can deduce the background (nonvolcanic) acidity of the ice, varying from always acidic in the Holocene to always alkaline in the cold periods. In the interstadials, the ice is close to nautral, with most of it acidic in larger interstadials, most of it alkaline in smaller ones, and rapid alternations within interstadials. It is not clear whether neutralization of individual acidic particles occurred in the atmosphere or whether acid and alkaline particles coexisted until deposition in the snowpack. The changes in acidity observed at GRIP apply at least to all of Greenland and probably to much of North America. There would have been ecological effects and important changes in the uptake of some chemicals onto ice. If acidic sulfate particles were neutralized and removed from the atmosphere, which remains uncertain, then there are atmospheric chemistry and radiative effects that require further investigation.