Possible changes of the isotopic composition of ice wedge as a result of self-diffusion
The subject of this research is the assessment of changes of the isotopic composition of ice wedge as a result of self-diffusion. The author offers a relatively simple method of considering the impact of the process of self-diffusion upon redistribution of paleo-isotopic composition that allows accurately and quickly estimating the changes in the values δ18О and δ2H values in ice wedges at different periods of the quaternary (1000 years, 10,000 years, 100,000 years, and 1,000,000 years). The patterns of diffusion process in physico-chemical systems are described by two differential forms of Fick's diffusion laws, which are transformed into Gaussian integral, using six-digit Chambers charts for calculation of the threshold values δ18О. The article applies the experimentally determined real values of self-diffusion coefficient in the ice – D=(2–10)×10-15 m2/s. The values of the Gaussian integral are calculated for time intervals, at different distances between samples with different concentration; for the period of 1,000 years its values in all cases exceed 0.99. For longer time intervals, these values change significantly. The calculated probabilistic values of changes in the concentration of heavy oxygen isotopes in ice wedge under the impact of self-diffusion at different distances and concentration gradients are noticeable only for the time period of over 100,000 years.