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Peat bogs in northern Alberta, Canada reveal decades of declining atmospheric Pb contamination
Author(s) -
Shotyk William,
Appleby Peter G.,
Bicalho Beatriz,
Davies Lauren,
Froese Duane,
GrantWeaver Iain,
Krachler Michael,
Magnan Gabriel,
MullanBoudreau Gillian,
Noernberg Tommy,
Pelletier Rick,
Shan Bob,
Bellen Simon,
Zaccone Claudio
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl070952
Subject(s) - bog , peat , ombrotrophic , environmental science , macrofossil , deposition (geology) , atmosphere (unit) , contamination , physical geography , environmental chemistry , hydrology (agriculture) , geology , oceanography , sediment , ecology , archaeology , geography , geomorphology , chemistry , holocene , meteorology , biology , geotechnical engineering
Peat cores were collected from six bogs in northern Alberta to reconstruct changes in the atmospheric deposition of Pb, a valuable tracer of human activities. In each profile, the maximum Pb enrichment is found well below the surface. Radiometric age dating using three independent approaches ( 14 C measurements of plant macrofossils combined with the atmospheric bomb pulse curve, plus 210 Pb confirmed using the fallout radionuclides 137 Cs and 241 Am) showed that Pb contamination has been in decline for decades. Today, the surface layers of these bogs are comparable in composition to the “cleanest” peat samples ever found in the Northern Hemisphere, from a Swiss bog ~ 6000 to 9000 years old. The lack of contemporary Pb contamination in the Alberta bogs is testimony to successful international efforts of the past decades to reduce anthropogenic emissions of this potentially toxic metal to the atmosphere.