The quantification of element pools and their changes in time is an importa
nt part of the analysis of ecosystems. This quantification is more difficul
t in soils with rock fragments because of their heterogeneity and because o
f the difficult analysis of the rock fraction for the pool substance. Repea
ted sampling and geostatistical analysis were used to quantify spatial hete
rogeneity in rock fragment content. Cs-137 measurements were used to quanti
fy fine-earth contamination of dry-sieved and washed rock fragments because
they are nondestructive and allowed for Pu239 + 240, C and N were repeated
analysis of the same sample after different treatments. determined fur com
parison. They are typical for substances that are difficult to be determine
d directly in lock fragments and they also occur mainly in topsoils.
Small distance heterogeneity may cause an error in rock fragment content of
10% with similar errors biasing the determination of other pools. After dr
y-sieving, up to 10% of the Cs-137 pool may still adhere to the rock fragme
nts. Washing could remove a further 9% but 1% still remained on the rock fr
agments. These fractions will normally be ignored in analyses, which cannot
be applied to the rock fragment fraction. Pu, C and N were distributed sim
ilarly to Cs-137 between the fine Cs-137 technique therefore allows an easy
and less earth from dry-sieving and the wash-off. The laborious estimation
of the part of other element pools associated with rock fragments than dir
ect measurement, which in many cases is difficult. Where the Cs-137 techniq
ue is used to estimate past erosion, since the: beginning of nuclear bomb t
esting, errors of several 100 t ha(-1) soil loss may result if heterogeneit
y and Cs contamination of rock fragments are ignored. (C) 2000 Elsevier Sci
ence B.V. All rights reserved.