Start Analytical and sampling constraints of 210pb dating

Analytical and sampling constraints of 210pb dating

Science of the total environment ISSN 0048-9697 CODEN STENDL 2011, vol.

The Constant Rate of Supply (CRS) model is the most versatile and widely used method for establishing ²¹⁰Pb chronologies but, when using this model, care must be taken to account for limitations imposed by sampling and analytical factors.

The origin and magnitude of this effect are considered below, firstly for an idealized, theoretical ²¹⁰Pb profile and secondly for a freshwater lake sediment core.

A brief consideration is presented of the implications of this potential artefact for sampling and analysis. Although carefully collected, accuracy cannot be guaranteed. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

The concentrations of radionuclides 32Si, 7Be, 210Pb and 137Cs have been measured in snow samples from the shelf ice near the Indian Station, Dakshin Gangotri, East Antarctica.

The annual fallout of cosmic-ray produced 32Si — the first measurement of its kind in Antarctica — has been estimated to be 2·34 × 10−5 dpm cm−2y−1 which corresponds to a global production rate of 32Si of 0·75 × 10−4 atoms cm−2y−1 if the half-life of 32Si is 140 y.

The fallout of the other natural radionuclides 7Be and 210Pb are estimated to be 4·2 and 1·86 × 10−2 dpm cm−2 y−1, respectively.

Based on the depth profile of 210Pb and 137Cs concentrations in the shallow ice core samples, the accumulation rate of ice has been estimated to be 13·5 g cm−2 y−1 (0·3 my−1) over the past few decades.

The origin and magnitude of this effect are considered below, firstly for an idealised, theoretical Pb profile and secondly for a freshwater lake sediment core.

A brief consideration is presented of the implications of this potential artefact for sampling and analysis.

Pb dating provides a valuable, widely used means of establishing recent chronologies for sediments and other accumulating natural deposits.

The Constant Rate of Supply (CRS) model is the most versatile and widely used method for establishing Pb chronologies but, when using this model, care must be taken to account for limitations imposed by sampling and analytical factors.