Pb and Ba concentrations and the isotopic composition of Pb were determined in Antarctic snow to investigate recent decadal changes in Pb pollution and sources of Pb at a remote Antarctic site.A continuous series of 80 snow samples were collected from a 4-m deep snow pit,covering the period from 1956 to 2007,at Dome Fuji in central East Antarctica(77°18S,39°47E,3785 m a.s.l.)during the 2007/08 Japanese-Swedish IPY Antarctic expedition.Ultraclean procedures and techniques were used during every step from the field sampling to analysis to prevent the possibility of contamination.Pb and Ba concentrations and Pb isotopes were simultaneously measured by means of thermal ionization mass spectrometry(TIMS).Our results show well-defined variations in Pb and Pb isotopic ratios with time.Pb concentrations are at the ultratrace level,ranging from 1.6 to 34 pg/g,with pronounced peaks during the late 1970s and the early 1990s.Concentrations tend to continuously decrease after~1990,reaching the lowest concentration level of~3 pg/g during recent years.The crustal enrichment factors(EFc)show a prominent peak during the late 1970s,which is clearly linked to the rise and fall in the use of leaded gasoline in the Southern Hemisphere.Changes in Pb isotopes(1.132 to 1.222 for 206Pb/207Pb ratio)document the changing origin of anthropogenic Pb over the last 50 years.The 206Pb/207Pb ratios are more radiogenic when the highest EF values are encountered during the late 1970s.Combined with temporal patterns of Pb emission rate in different regions(South America,Southern Africa,and Australia)in the Southern Hemisphere,EFs and the 206Pb/207Pb ratios suggest South America,especially Brazil as a possible major source region of anthropogenic Pb in the late 1970s.During the 1980s,an abrupt decrease in the 206Pb/207Pb ratios is observed likely due to a rapid phase of the use of alcohol as automobile fuel in Brazil in the early 1980s.After the year 2000,a progressive decrease in the Pb concentrations and its EF values is well coupled with continuous increase in the 206Pb/207Pb ratios,indicating a reduction of input of anthropogenic Pb into central Antarctica.Despite these temporal patterns,however,the isotopic signature and EF values reveal that significant input of anthropogenic Pb is still currently underway.