Temperature and Cyanobacterial Bloom Biomass Influence Phosphorous Cycling in Eutrophic Lake Sediments

Abstract

Cyanobacterial blooms frequently occur in freshwater lakes, subsequently, substantial amounts of decaying cyanobacterial bloom biomass (CBB) settles onto the lake sediments where anaerobic mineralization reactions prevail. Coupled Fe/S cycling processes can influence the mobilization of phosphorus (P) in sediments, with high releases often resulting in eutrophication. To better understand eutrophication in Lake Taihu (PRC), we investigated the effects of CBB and temperature on phosphorus cycling in lake sediments. Results indicated that added CBB not only enhanced sedimentary iron reduction, but also resulted in a change from net sulfur oxidation to sulfate reduction, which jointly resulted in a spike of soluble Fe(II) and the formation of FeS/FeS2. Phosphate release was also enhanced with CBB amendment along with increases in reduced sulfur. Further release of phosphate was associated with increases in incubation temperature. In addition, CBB amendment resulted in a shift in P from the Fe-adsorbed P and the relatively unreactive Residual-P pools to the more reactive Al-adsorbed P, Ca-bound P and organic-P pools. Phosphorus cycling rates increased on addition of CBB and were higher at elevated temperatures, resulting in increased phosphorus release from sediments. These findings suggest that settling of CBB into sediments will likely increase the extent of eutrophication in aquatic environments and these processes will be magnified at higher temperatures.

Internal phosphorus loading in Canadian fresh waters: a critical review and data analysis

“…When Chen et al (2014) incubated sediments from Lake Taihu, China, at 4, 15, 25, or 32°C, greater phosphate concentrations in sediment pore waters were observed at higher incubation temperatures. Likewise, 2 m aquatic mesocosms that were heated (+4°C) had significantly higher concentrations of SRP than those of mesocosms at ambient temperatures (Feuchtmayr et al 2009).…”

Identifying the Chemical Composition of Decomposed Residues From Cyanobacterial Bloom Biomass by Pyrolysis‐GC/MS

“…The overlying water quickly shifted to anoxic/anaerobic conditions (on day 1) after algae addition, and the conditions were maintained during the whole incubation test. The test conditions adopted herein were according to a previous report, which indicated that algae bloom sedimentation induced anoxic/anaerobic conditions of overlying water . Finally, 24 beakers were prepared and experiments were performed in triplicate.…”

“…Temperature is one of the most important factors controlling the mineralization of organic carbon in lake sediment , and warmer water temperature results in a greater level of mineralization in lakes . Mineralization of settled CBB in sediment causes phosphorus regeneration and nitrogen liberation in aquatic systems, and even induces the formation of black water agglomerates .…”

Impact of nitrogen deposition on forest and lake food webs in nitrogen‐limited environments

“…Under conditions of increased N r deposition and increased N run-off into lakes, pelagic primary production in these oligotrophic clear-water and humic lakes will quickly switch from N to P limitation without affecting light availability or nutrient limitation of benthic algae (M. Jansson, personnel communication). However, P release rates from sediments will likely increase with increasing water temperatures, generally leading to higher P cycling rates (Chen et al, 2014;North et al, 2014). This may in turn intensify N limitation of benthic algae and even change nutrient cycling of both benthic and pelagic ecosystems.…”