Triple Junction and Grain Boundary Influences on Climate Signals in Polar Ice

TL;DR

This study uses high-resolution LA-ICP-MS to analyze how ice crystal features like triple junctions and grain boundaries affect impurity signals in polar ice cores, finding minimal impact on climate signal preservation.

Contribution

It provides the first detailed quantification of impurity signal modification by ice crystal features at high spatial resolution.

Findings

Impurity modifications are less than 6% for Na, Ca, and Fe.

Triple junctions and grain boundaries have limited influence on climate signals.

High-resolution analysis can distinguish impurity migration effects.

Abstract

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.