Impacts of hydrodynamic disturbance on sediment resuspension, phosphorus and phosphatase release, and cyanobacterial growth in Lake Tai

Abstract

The objective of this study was to link hydrodynamic disturbance with sediment resuspension, phosphorus release, and algal growth in Lake Tai, a typical shallow lake located in the south of the Yangtze River Delta in China. With this regard, a sediment-water-algae laboratory experiment was conducted and extrapolated to the real situation in terms of field observations. The results show that the algal growth rate synchronically increased with dissolved total phosphorus (DTP) release rate. The DTP decreased with increase of bottom flow velocity, indicating that the phosphorus release rate was lower than its transfer rate into algal biomass. While all levels of hydrodynamic disturbances could increase sediment resuspension and phosphorus release, a low to moderate disturbance was beneficial, but a strong disturbance was harmful for algal growth. Also, a low to moderate disturbance caused the dissolved alkaline phosphatase activity (DAPA) to increase with time, which provided the enzyme for hydrolyzing a variety of organic phosphorus compounds from bed sediment into algae-needed nutritional DTP. The experiment proved to be an efficient means to understanding eutrophication mechanisms of large shallow lakes such as Lake Tai.

Parameter uncertainty and sensitivity analysis of water quality model in Lake Taihu, China

“…In our previous research, field observations with using of advanced devices were conducted on the lake to find behaviours of sediments settling and resuspension (Gao et al 2017). Diffusive exchange of dissolved phase nutrients between water column and interstitial waters was investigated in many studies as well (Yu et al 2016;Huang et al 2015;Qiu et al 2015;Kaiming et al 2014). Thus, we set the model with fixed benthic flux rates spatially by recent researches to simulate the processes of sediment instead (i.e.…”

Thematic Issue: Water of the Taihu Lake

“…Zhang et al (2015) presented the dataset of dissolved organic nitrogen (DON) in 17 lakes in Eastern China, and analyzed the different DON concentration patterns in nonriver-connected lakes and in river-isolated lakes, as well as in summer and in winter. Huang et al (2015a, b) studied the eutrophication mechanisms in Lake Taihu through a sediment-water-algae laboratory experiment, and linked hydrodynamic disturbance with sediment resuspension, phosphorus release, and algal growth in Lake Taihu. Wang et al (2015) presented a statistical approach which considered the nonstationarity caused by step change in time series, and used this approach to analyze the data from the past decades to examine temporal trends of TN and TP in four Chinese lakes, including Lake Dongting, Lake Poyang, Lake Chaohu and Lake Taihu.…”

Using sedimentary phosphorus/nitrogen as indicators of shallow lake eutrophication: concentrations or accumulation fluxes

“…OP (organic phosphorus) and Fe-P (phosphorus bound to Fe, Al and Mn oxides and hydroxides) increments accounted for most of the increase in TP between older sediments and newer deposits in Taihu (Yuan et al 2014;Zhu et al 2013) and other shallow lakes (Chen et al 2014). Meanwhile, surface sediments with higher P/Fe ratios released more soluble reactive phosphorus (SRP) and explained larger P release rates in shallow lakes (Jensen et al 1992) and P fixed in organic forms constitute major fractions that are potentially mobile and eventually may be released to the lake water (Søndergaard et al 2001) and quickly transfer into algal biomass likely causing eutrophication (Huang et al 2015). In this study, P/Fe ratio was positively correlated with TOC (Pearson coefficient, 0.463; P \ 0.05), giving evidence that sedimentary organic carbon may have responsible for sedimentary P/Fe ratio increments in CL after 1980 and organic phosphorus makes a larger fraction of P in sediment in the past decades, so the potential release risk of phosphorus in sediment of CL is likely to continue increasing and may threaten the overlying water of Taihu in future.…”