Trace metal and total suspended solids concentrations in freshwater: the importance of small-scale temporal variation

The temporal variation in the concentrations of particulate trace metals (C u, Pb and Zn) and total suspended solids (TSS) was examined in three rivers that drain into the Port Jackson estuary, Australia, using a nested, hiera rchical sampling design. Sampling was conducted between March and June 1999 , under low flow conditions. The sampling design incorporated four temporal scales (hours, days, weeks and months). It was considered that hours, days , weeks and months were representative of such time scales and could be ana lyzed as random, nested sources of variation in an analysis of variance (AN OVA). Significant variation was found at temporal scales ranging from hours , within the same day, to months. The amount and scales of variation differ ed between particulate trace metals and TSS concentrations and between rive rs. In many cases, differences between small-scale were as important as dif ferences between months. The results suggest that higher anthropogenic infl uences cause higher variability at small temporal scale. Results indicate t he need for nested sampling designs to be incorporated into studies of temp oral variation in order to unconfound small-scale temporal variation. The c onclusions of this study are likely to be applicable to other water quality variables and pollutants.