sup 210 Pb and sup 137 Cs chronology of sediments from small, shallow Arctic lakes

Journal Article · Tue May 01 04:00:00 EDT 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90167-J· OSTI ID:5981939

Hermanson, M H ^[1]

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1. Univ. of Wisconsin, Milwaukee (USA)

Arctic environmental conditions present special difficulties with the use of nuclides {sup 210}Pb and {sup 137}Cs for measuring lake sediment chronology. Fluxes of these nuclides are lower in the Arctic than in mid-latitudes, shortening the history that can be resolved. Ice prevents atmospheric input of nuclides to sediment during much of the year and can cause redistribution of sediment in shallow lakes. Results from analyses of seven sediment cores from two lakes on the Belcher Islands in southeastern Hudson Bay show that sediment redistribution by ice is a major process in one of the lakes. In order to measure and undisturbed sedimentation rate, it is necessary that a total input or flux of {sup 137}Cs and {sup 210}Pb be measured or estimated. Total unsupported {sup 210}Pb in the area, 14.8 dpm/cm{sup 2}, is the average of measurements in three cores from two lakes that have consistent total {sup 137}Cs inventories closest to the estimated {sup 137}Cs flux. Cores from undisturbed sites have slower sedimentation rates, and {sup 137}Cs appears in layers dated before the early 1950s when it would have first appeared in sediment. {sup 210}Pb measurements of undisturbed sedimentation rates in the lakes range from 0.0044 to 0.0180 g/cm{sup 2}/a. The sedimentation rate in a lake used for raw sewage oxidation doubled after the beginning of sewage input. Rates at sites where sediment is redistributed range from 0.0259 to 0.0309 g/cm{sup 2}/a with similarly higher total {sup 137}Cs and unsupported {sup 210}Pb values. Dates of sediment layers measured using the constant rate of supply model are verified by {sup 210}Pb profile discontinuities corresponding to major storms in 1958 and in 1940.

• OSTI ID: 5981939
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:5; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ALKALI METAL ISOTOPES
ALPHA DECAY RADIOISOTOPES
ARCTIC REGIONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CESIUM 137
CESIUM ISOTOPES
CHEMISTRY
DEPOSITION
EVEN-EVEN NUCLEI
GEOCHEMISTRY
GEOLOGIC HISTORY
HEAVY NUCLEI
ISOTOPE DATING
ISOTOPES
LAKES
LEAD 210
LEAD ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
POLAR REGIONS
RADIOISOTOPES
SEDIMENTS
SURFACE WATERS
VARIATIONS
YEARS LIVING RADIOISOTOPES