Dynamic monitoring of resuspension in the multiple eco-types of the littoral zone of a shallow wind-disturbed lake

Abstract

Sedimentation and resuspension processes, are known to govern nutrient cycling and lake metabolic processes, but have not been well studied in littoral zones with multi-ecotypes of shallow wind-disturbed lakes. This time-series study used sediment traps to estimate the spatiotemporal changes in sedimentation and resuspension rates, during the four seasonal continuous deployment periods, in the littoral zone of Lake Taihu. The effect of sedimentation processes on nutrient accumulation was also investigated. Results showed that the sedimentation rates at six observation sites were highly variable, with gross sedimentation rates ranging from 184.83 to 2150.74 g m−2 day−1. Almost 88% of the total observed sedimentation originated from sediment resuspension. Cyanobacterial blooms coupled with the frequently changeable wind conditions in the littoral zone, were the key factors in lacustrine sediment redistribution and a large pool of organic material accumulated during cyanobacterial blooms. Moreover, the contribution of resuspended total phosphorous and total nitrogen to the water column, were 0.22 mg L−1 and 0.46 mg L−1, respectively. The high rate of rapid nutrient cycling observed at the sediment water interface due to resuspension, may be a key factor in maintaining eutrophication in large and shallow lakes, which is of high relevance to the future management of aquatic ecosystems.