Mobility and diagenesis of Pb and sup 210 Pb in peat

Journal Article · Sat Dec 01 00:00:00 EST 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90288-V· OSTI ID:5970294

Urban, N R; Eisenreich, S J ^[1]; Grigal, D F ^[2]; Schurr, K T ^[3]

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1. Univ. of Minnesota, Minneapolis (USA)
2. Univ. of Minnesota, St. Paul (USA)
3. Environmental Protection Agency, Seattle, WA (USA)

Peatlands long have been considered to preserve the record of atmospheric deposition of anthropogenic contaminants such as Pb. In the past two decades, {sup 210}Pb has been widely used to data recent strata of peat and to calculate accumulation rates. The assumption that Pb and {sup 210}Pb are immobile and not subject to diagenesis in peat has been questioned but not rigorously tested. The authors attempted to determine if Pb is mobile in peatlands and if Pb profiles are altered by diagenic processes by constructing a mass balance for Pb about a small peatland, by comparing inventories, concentrations, and accumulation rates of Pb and {sup 210}Pb in peatlands across northeastern North America, and by examining the relationship between concentrations of Pb in bog waters and peat in numerous sites. The results clearly demonstrate that Pb and {sup 210}Pb are mobilized by the organic-rich waters of peatlands. Profiles of Pb and {sup 210}Pb at depths below the water table do not preserve the record of atmospheric deposition, and inventories of Pb and {sup 210}Pb are depleted in peatland hollows. Concentrations of Pb in bog waters are regulated by the concentration of Pb in the peat and the concentration of dissolved organic carbon. The mass balance for one bog indicated that over the specific three-year period of study more than 30% of inputs of Pb were not retained within the peat. As a result of this mobility, dates based on {sup 210}Pb can be biased and inaccurate by as much as 30 years. Dates based on {sup 210}Pb should be verified by other techniques, especially when the inventory of {sup 210}Pb is less than that expected from local rates of deposition.

• OSTI ID: 5970294
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 54:12; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
58 GEOSCIENCES
PEAT
CHEMICAL COMPOSITION
DIAGENESIS
ISOTOPE DATING
CONCENTRATION RATIO
DEPOSITION
ELEMENT ABUNDANCE
GEOCHEMISTRY
LEAD
LEAD 210
MASS BALANCE
ABUNDANCE
AGE ESTIMATION
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMISTRY
ELEMENTS
ENERGY SOURCES
EVEN-EVEN NUCLEI
FOSSIL FUELS
FUELS
HEAVY NUCLEI
ISOTOPES
LEAD ISOTOPES
METALS
NUCLEI
ORGANIC MATTER
RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
010600* - Coal
Lignite
& Peat- Properties & Composition
580000 - Geosciences