Nickel content of antarctic snow: Implications of the influx rate of extraterrestrial dust

The concentration of Na, Mg, K, Ca, Cl, and Ni has been measured in firn samples collected in the vicinity of King Baudouin Base (70°S, 24°E) and Amundsen-Scott Station (90°S). The Ni content is of the order of a few ppb at both stations. About 35% of the Ni was probably present in the firn as soluble salts. Arguments are presented in support of an extraterrestrial origin for nearly all the Ni found in the south pole samples. The rate of Ni deposition at the south pole is of the order of 10−8 g/cm²/yr. Under the assumption of a Ni abundance of 1.3% (chondrite average), the influx rate of extraterrestrial matter over the entire earth's surface should lie between 3 and 10 million tons per year depending on the assumption made in the extrapolation.