Qualitative estimates of soil disturbance in the vicinity of CANDU stations, utilizing measurements of Cs-137 and Pb-210 in soil cores

Anthropogenically derived C-14 has been used to trace recent carbon input i n a study of carbon accumulation and turnover in Canadian soils. III order to do so, documentation of the undisturbed nature of the soil horizons samp led was of prime concern. Although all the sites chosen for coring were cur rently uncultivated, detailed information on long-term land usage was not a vailable. To overcome this problem,Cs-137 profiles were measured in all the cores used in the study. Pb-210 measurements were also made in cases where total Cs-137 deposition was lower than predicted. For some sample sites, t he data obtained showed correlated losses of both radionuclides, indicating that land disturbance and/or erosion had indeed occurred in these areas ov er the past 50 years, hence invalidating the use of those cores for carbon cycling studies. In a few cases a marked lack of correlation between these two radionuclides has made it accessary to hypothesize that chemical, rathe r than physical, processes have been partially responsible for the observed anomalies. Since results of this nature raise doubts about the reliability of the Cs-137 method for identification of land disturbance, further inves tigation is warranted. (C) 2001 Elsevier Science Ltd. All rights reserved.