Physics
Scientific paper
Nov 1981
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1981gecoa..45.2109n&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 45, Issue 11, pp.2109-2121
Physics
18
Scientific paper
Concentrations of Pb and K were determined in a series of veneer layers chiseled in sequence from the outside toward the center of each of the five 1500-5500yr old ice core sections that had been drilled in Greenland and Antarctic ice. They were analogs of very old ice samples analyzed earlier by et al . (1977) and et al . (1975), who reported high concentrations of Pb in them. Lead contamination, existing at exterior concentrations of about 10 6 ng/kg ice, had intruded to the centers of the cores, establishing interior values of at least 1.4 ng/kg ice in three electromechanically drilled Camp Century core sections taken from fluid filled drill holes. Corresponding Pb concentration changes were 3 × 10 4 ng/kg ice to 1.2 ng/kg ice in two thermally drilled New Byrd Station core sections taken from non-fluid filled drill holes. Contamination made the lowest center concentrations serve only as upper limits to the original concentrations of Pb in the ice. Potassium concentrations decreased from exterior values of about 5 × 10 5 ng/kg ice to an interior value of 2 × 10 3 ng/kg ice in the Camp Century core sections and from 8 × 10 4 ng/kg ice to 9 × 10 2 ng/kg ice in New Byrd Station core sections. Potassium contamination effects were not large within the central portions of the cores. These data verify earlier findings by et al . (1969) and extend to a broader geographical significance the general validity of their observation of a ~ 300-fold increase of Pb concentrations in the Greenland ice sheet during the past 3000 yr. Our findings refute claims by et al . (1977) and et al . (1975) that 100-fold excesses of natural Pb exist in 800 yr old Greenland ice above levels contributed by silicate dusts. Our new data also show that average Pb concentrations of 26 ng Pb/kg ice, claimed by and (1979) to be natural and present for 60 yr in snow strata in Antarctica, did not exist in old Antarctic ice, and that Pb concentrations have increased at least 10-fold in that ice during the past century. Virtually all of the present day ~300-fold excess of Pb above natural levels in Greenland ice can be shown to be caused by industrial Pb emissions to the atmosphere on the basis of the following factors: (1) the historic increase of Pb in snow strata coincides with the historic increase of industrial Pb production and atmospheric emissions (2) mass inventories of industrial emissions can account for the excess Pb in polar snow (3) new quantitative measurements of Pb emissions from volcanic plumes by and (1978), et al . (1981), and et al . (1981), and from sea spray by and (1981) and and (1981). show that these natural sources cannot account for 99% of the excess Pb above contributions by silicate dusts observed today in the atmosphere; and (4) the historic increase of Pb in snow strata is paralleled by analogous increases of excess Pb shown by isotopic tracers to be industrial in water-laid sediments in a remote continental region ( et al ., 1980). It is now known, however, that snows display about a 10-fold greater excess of industrial Pb above crustal silicate concentrations than exists in the air above the snows.
Ng Amy
Patterson Clair
No associations
LandOfFree
Natural concentrations of lead in ancient Arctic and Antarctic ice does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Natural concentrations of lead in ancient Arctic and Antarctic ice, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Natural concentrations of lead in ancient Arctic and Antarctic ice will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-744190