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A summary of 14C data from atmospheric sampling and measurements on wood from annual tree rings for the period 1945-1997 AD is presented and evaluated. Atmospheric records are characterized by different distributions of bomb-test 14C between the Northem and Southem Hemispheres, latitude dependence, and seasonal fluctuations. Radiocarbon data from tree rings are summarised and plotted against atmospheric records from similar latitudes. In some cases, discrepancies are found. Possible reasons for this include: 1) the use of stored carbohydrate from the previous year, 2) different 14C levels in the air around subcanopy trees due to respiration of CO2, 3) regional and local effects of anthropogenic CO2 and 14C sources, 4) sampling of wood material too close to ring boundaries, and 5) insufficient pretreatment of tree ring sampies for dating. But in cases where trees were carefully selected and the sampies adequately pretreated, radiocarbon data from tree rings show excellent agreement with direct atmospheric sampling records.
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A summary of 14C data from atmospheric sampling and measurements on wood from annual tree rings for the period 1945-1997 AD is presented and evaluated. Atmospheric records are characterized by different distributions of bomb-test 14C between the Northem and Southem Hemispheres, latitude dependence, and seasonal fluctuations. Radiocarbon data from tree rings are summarised and plotted against atmospheric records from similar latitudes. In some cases, discrepancies are found. Possible reasons for this include: 1) the use of stored carbohydrate from the previous year, 2) different 14C levels in the air around subcanopy trees due to respiration of CO2, 3) regional and local effects of anthropogenic CO2 and 14C sources, 4) sampling of wood material too close to ring boundaries, and 5) insufficient pretreatment of tree ring sampies for dating. But in cases where trees were carefully selected and the sampies adequately pretreated, radiocarbon data from tree rings show excellent agreement with direct atmospheric sampling records.
All Time | Past Year | Past 30 Days | |
---|---|---|---|
Abstract Views | 24 | 0 | 0 |
Full Text Views | 453 | 78 | 21 |
PDF Views & Downloads | 246 | 68 | 14 |