Interpreting sediment trap data in relation to the dominant sediment redistribution process in a lake

Abstract

The total sedimentation rate (primary and secondary sedimentation) was measured in 5 lakes, using a time series sediment trap. The sediment trap had 12 sample bottles which were programmed to open at intervals from 3 to 12 hours, giving total deployment times from 36 hrs to 6 days. The variation of total sedimentation rate during deployment in each lake was large, yet the mean total primary sedimentation rate for each lake was similar to annual primary sedimentation rates estimated by dated sediment cores taking into account the expected sediment redistribution process which causes secondary sedimentation. The results of this study emphasise the value of sediment traps for measuring the total sedimentation rate (and the secondary sedimentation rate, when the primary is known from sediment cores) when they are correctly designed and the data analysed in relation to the dominant sediment redistribution process in the lake. In many investigations, inaccuracies which sediment trap sedimentation rates have been associated with may not be due to any specific design flaw of the sediment trap. They may instead reflect the ability of the trap to measure the total sedimentation rate including specific short term events that are not represented in dated sediment cores.