Cerium in Ice Cores as a Tracer of Mineral Dust

Abstract

The rare earth element (REE) cerium (Ce) is examined as a potential tracer for mineral dust. Mineral dust trapped in ice cores provides a record of dust levels and atmospheric conditions in the past. Previous studies of mineral dust in ice cores have counted insoluble microparticles or used Ca$^{2+}$ and Al as tracers. With the development of continuous flow analysis (CFA) for ice cores, higher temporal resolution of ice cores is possible. Measurement of Ce by inductively coupled plasma mass spectrometer (ICPMS) is easily incorporated into the CFA method and promises more detailed records than using more common elements as tracers. Higher resolution records enable better evaluation of the correlation of dust records between ice cores.A potential problem with the use of Ce as a dust tracer is the possibility of an anthropogenic input of Ce. One ice core in Greenland (NEEM) and one ice core in West Antarctica (WAIS-WDC05A) were examined for an anthropogenic Ce signal. The ice core in Greenland shows a general increase in Ce concentrations starting in the 1890s and decreasing in the 1970s, suggesting a Ce source related to the Industrial Revolution. The use of Ce as a dust tracer in the Arctic during this time period is therefore compromised. The ice core in Antarctica showed no increase during the same time period; therefore, Ce can be used as a dust tracer in Antarctica.Cerium data from four ice cores in West Antarctica and seven ice cores from East Antarctica were evaluated for the similarity of dust deposition between the sites. Composite cores of the records in West and East Antarctica show a remarkably similar rise in dust deposition continent-wide between 1870 and 1945, followed by a decrease in deposition to 1980. This continent-wide signal contrasts with a more regional signal predicted by some global climate models.