The re-measurement of mercury (Hg) concentrations in archived environmental samples (soils, peats) after several years of storage indicated that there is no statistical difference between new measurements and original data. As a result, archived samples can be used to evaluate historical soil mercury contamination.
Navrátil T., Burns D. A., Nováková T., Kaňa J., Rohovec J., Roll M., Ettler V. (2018): Stability of mercury concentration measurements in archived soil and peat samples. Chemosphere 208, 707-711. (DOI)