There is evidence for 10 mechanisms of sediment distribution in small lakes. The sediment accumulation rates measured from a common horizon in cores from 64 sites on Esthwaite Water, U.K., were used to determine the relative importance of these mechanisms on the distribution of sediment in the lake.River inflows generally produced localized effects but there were indications of periodic turbidity flows to the deepest point of the lake from the major inflow. Active sediment focusing processes were the dominant distribution mechanisms, a major resuspension of sediment at autumn overturn probably being the most important. The remaining variance was much greater than observed in similar work elsewhere, suggesting that redistribution of sediment by direct and indirect wave action may be taking placeall over the lakebcd during isothermal periods. The relative contributions of the different processes were corroborated by analysis of previously published sediment trap data.

Pigment concentrations in surface sediments in two lakes were analysed on ten occasions over a year. Statistical analysis showed that mean concentrations varied through the year and the relative contribution of several sources of variability (analytical, spatial, temporal) to the total was estimated. Using this information, the relative cost-effectiveness of several alternative sampling strategies was investigated. Measurement of sedimentary pigment concentrations on single cores on two or three different occasions would reduce the standard error of the mean by 30% and 42% respectively and is very cost effective. However replicate cores taken on a single occasion appeared to be a workable compromise.The data also allowed a comparison of the ability of the different pigment determinands to resolve two lakes of very different trophic status. Total carotenoid concentrations were found to be the most effective.