Water-level fluctuation enhances sediment and trace metal mobility in lake littoral

Abstract Water-level fluctuation (WLF) is a widespread management action in lakes and reservoirs whose impacts on contaminant fate have seldom been investigated. We used near shore hourly measurements (n = 2122) of turbidity (contaminant proxy) water velocity (sediment resuspension to track high-frequency dynamics during 0.6 m change level observed autumn 2017 large French lake. Simultaneously, discrete trace metal highlighted that trapped sediment was more contaminated finer than surficial supporting suspended particles (measured by turbidity) were preferential medium for mobility. General additive models involving tensor products revealed the enhancement wind-speed river discharge effects with draw down. The decrease explained deviances over time-lags indicated short time-scale response external forcing. Three four major turbid events occurred at lowest water-level concomitant as well precipitation and/or flood suggesting complex interplay among in-lake watershed processes controlling mobility WLF. These results shed light WLF can affect lake littoral hydrodynamic cascading up Sediment may be an overlooked feature increasing contamination risk exposure organisms ecological consequences due number regulated ecosystems.