Metal contamination of sediments can be an issue for minesites discharging water. Water sampling of receiving waters is
frequently undertaken. Sampling and analysis of sediment is less common. The variability of receiving environments
makes the formulation of a generic sediment sampling strategy virtually impossible. Each situation needs to be carefully
assessed before sampling is undertaken. This paper outlines the approach taken for one such survey.
The main factors that need to be considered in a survey of surficial sediments are sample representativeness and sample
variability. A simple data set from one site within a regional survey is used to illustrate the importance of these factors. The
metal content of sediment is shown to vary significantly over small spatial scales.
The variability associated with the spatial distribution of samples within a site is shown to be the most significant source of
variability in the study. This variability could bias the results of a study if not planned for in the sampling methodology.
Taking multiple samples from within each site (sub-site samples) and combining the data gives a more representative
indicator of overall conditions than a single sample. The optimum number of sub-site samples to be taken from each
sampling site was found to be 15.
It is shown that a composite of sub-site samples can give a good indication of the average site metal content,
while considerably reducing the sample preparation and analysis effort.