Internal loadings of nutrients play important roles in the eutrophication of shallow lakes. The effective removal of sediments rich in nutrients is of great importance for lake management and the abatement of eutrophication. In this study, grooves were installed in the bottom of Lake Chaohu. Approximately 8.5 months later, the chlorophyll a, organic matter, and total nitrogen contents in the sediment inside the grooves were 1.5-3.0 times, 1.2-1.8 times, and 1.3-1.6 times higher, respectively, than those in the surrounding sediments, and the total phosphorus contents in the bottom grooves were slightly lower than those in the surrounding sediments. The thicknesses of the sediments with high chlorophyll a, organic matter, total nitrogen, and total phosphorus contents in the grooves were 5-15 times greater than those of the surrounding sediments with high pollution contents. Internal pollution was captured in the grooves. The active hydrodynamic process was an important factor related to the effectiveness of this method and is conducive to the transport of polluted sediments to the bottom grooves where they are collected. Bottom grooves have broad application potential for the removal of sediments rich in nutrients from shallow-water lakes; these grooves can be widely used in areas that experience large disturbances from wind waves, have water flows gathering in or entering the lake, or have thin sediments with high pollution contents. This study provides scientific guidance for the control and management of internal pollution in shallow lakes.
Keywords: Bottom grooves; Lake currents; Sediments; Shallow lake; Wind waves.