  The Climate Change Institute W. M. Keck Laser Ice Facility laser ablation
inductively coupled plasma spectrometer (LA-ICP-MS) yields a sample every 121
micrometers, a resolution on the scale of ice crystal triple junctions and
grain boundaries in ice cores. Recent publications suggest that these features
can allow amplification of impurity concentrations, and allow migration through
veins potentially obscuring climate signals preserved in polar ice. LA-ICP-MS
data reveal that such features modify these signals by less than 6% in the case
of Na, Ca, and Fe based on the examination of GISP2 ice deposited at the
beginning of the Holocene.
