Perchlorate record from Greenland ice cores

Perchlorate is a long-lived environmental contaminant, released from human activities but increasingly recognized to have a natural source as well. The project was undertaken to measure perchlorate in previously-collected Greenland ice cores, with specific objectives (1) to obtain a robust (continuous and annual resolution) 300-year record of perchlorate in the environment using ice core samples from Greenland, (2) to quantify the magnitude and variability of the natural, probably atmospheric perchlorate source in the Northern Hemisphere environment using the pre-1850 part of the record, (3) to estimate the relative contributions of natural and anthropogenic sources to perchlorate in the current environment, and (4) to improve our understanding of the natural formation process of environmentally important substances. A Summit, Greenland ice core was sampled and analyzed for perchlorate concentration. The ice core was previously dated with annual layer counting based on seasonal variations of chemical species in snow/ice. The perchlorate record covers the time period of 1700-2006.