Temporal Variation in Concentrations of Heavy Metals in Marine Sediments

Temporal changes in the distribution of heavy-metal pollutants have been examined in many studies. Without knowledge of the presence or absence of variation at shorter time-scales, however, comparisons among longer intervals are always potentially confounded. Temporal variation in the distribution of copper, lead and zinc in the sediments of Botany Bay, Australia is described, using a nested, hierarchical sampling design. Significant variation was found at temporal scales from days to several months. The implications of short-term variation for environmental sampling, and the means of overcoming problems associated with it, are discussed. The conclusions of the present study are applicable to other variables and to other environments.