Lead isotope analysis dating

Service DHI offers dating of sediment cores by means of the 210Pb method and may assist with sampling in both marine and freshwater systems.

The sediment samples must remain totally undisturbed during sampling to obtain the best possible dating.

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In addition to the mentioned rates, the dating may also give a picture of the stability of the sediments and thus tell whether the chronology of the layers is intact or whether the activity of the benthic fauna has changed the chronology by bioturbation.

Local changes of current conditions may also cause changes of the chronology of the layers.

Scope of application Dating of sediment is used to calculate sedimentation rate and accumulation rates for different substances.

A number of studies have focused on the accumulation of heavy metals during the past 100 years.

The 210Pb dating may be supplemented with dating of the caesium 137Cs isotope.

This isotope was released in huge quantities in connection with the atmospheric nuclear explosions in 1963 and later by the Tjernobyl accident in 1986.

Furthermore, the 210Pb method may be used to carry out a sensitivity analysis to estimate the suitability of the sediment to repeated monitoring of, for instance of changes in the flux of contaminants in the sediments.

CATEGORY: geology DEFINITION: Atoms of the same element that have different atomic masses due to having different numbers of neutrons in the nuclei, but which still have similar chemical properties.

Human remains are analyzed for a measurement of the ratio between 13C and 12C isotopes in ancient human bone collagen.

in which the proportion of carbon isotopes is counted directly (as contrasted with the indirect Geiger counter method) using an accelerator mass spectrometer.

In the water phase 210Pb is adsorbed to particulate matter and together they are deposited in the sediment. The remaining amount of 210Pb at a certain depth will reveal the age of the given sediment layer.

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