Improvements in methods of analyzing dust concentrations, and influence of the storage processes on dust concentrations in polar snow and ice samples

Abstract

We sought to improve the analytical methods employed when operating a laser particle counter and to evaluate the influence of the storage processes on dust concentrations in polar snow and ice samples. We corrected the particle size ranges and threshold voltage using the new calibration curve, confirmed the analytical precision and dust concentrations of blank of wipers using in a clean room, and managed any variations in the laser sensor's sensitivity by measuring standard particles. The 15 ml glass screw bottles without packing (liner of cap of bottles) yielded the lowest dust concentration of the blank among two types of bottles and nine types of packing for dust analysis. Storage of samples of the Dome Fuji ice core (Antarctica) in a refrigerator for 1 year resulted in just a 4% decrease in dust concentration, which is within the analytical precision of the laser particle counter. Storage in a freezer resulted in an increase in dust concentrations and a decrease in the ratio of large particles more than 0.98 μm in particle diameter in the samples, suggesting a change in dust particle size during storage and an influence by the materials of the storage bottles. The addition of dispersants to the Antarctic snow samples is not clearly suitable when analyzing dust concentrations after sample storage by refrigeration or freezing．