Cyanobacterial organic matter (COM) positive feedback aggravates lake eutrophication by changing the phosphorus release characteristics of sediments

Jinglong Wang; Qinyi Chen; Shun Huang; Zhicong Wang; Dunhai Li

doi:10.1016/j.scitotenv.2023.164540

Cyanobacterial organic matter (COM) positive feedback aggravates lake eutrophication by changing the phosphorus release characteristics of sediments

Sci Total Environ. 2023 Sep 20:892:164540. doi: 10.1016/j.scitotenv.2023.164540. Epub 2023 Jun 1.

Authors

Jinglong Wang¹, Qinyi Chen¹, Shun Huang¹, Zhicong Wang², Dunhai Li³

Affiliations

¹ Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
² Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China. Electronic address: wangzc@ihb.ac.cn.
³ Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.

PMID: 37270020
DOI: 10.1016/j.scitotenv.2023.164540

Abstract

Phosphorus is a key nutrient that causes eutrophication in lakes. Our investigation of 11 eutrophic lakes found that the concentrations of soluble reactive phosphorus (SRP) in the water column and EPC₀ in sediments decreased with aggravated eutrophication. There was a significant negative correlation between the SRP concentrations and eutrophication parameters such as chlorophyll a (Chl-a), total phosphorus (TP) and algal biomass (P < 0.001). In addition, SRP concentrations were significantly affected by EPC₀ (P < 0.001), while EPC₀ was significantly affected by the content of cyanobacterial organic matter (COM) in sediments (P < 0.001). Based on these findings, we hypothesized that COM can alter the phosphorus release characteristics of sediments, including the phosphorus adsorption parameters of sediment (PAPS) and the phosphorus release rate of sediment (PRRS), thereby stabilizing SRP concentrations at lower levels and rapidly replenishing them when depleted by phytoplankton, which in turn benefits cyanobacteria due to their low SRP adaptation strategies. Simulation experiments were conducted to confirm this hypothesis by adding higher plant OM and COM to sediments. The results showed that all types of OM could significantly increase the maximum phosphorus adsorption capacity (Q_max), but only COM could reduce sediment EPC₀ and promote PRRS (P < 0.001). Changes in these parameters (i.e., Q_max, EPC₀, and PRRS) resulted in a larger SRP adsorption quantity and faster SRP release rate at low SRP concentrations. This promotes the competitive edge of cyanobacteria due to they have a higher affinity for phosphorus than other algae. As an important component of cyanobacteria, EPS can change the phosphorus release characteristics (i.e., PAPS and PRRS) by reducing sediment particle size and increasing sediment surface functional groups. This study revealed the positive feedback effect of COM accumulation in sediments on lake eutrophication from the perspective of phosphorus release characteristics of sediments, which provides a basic reference for the risk assessment of lake eutrophication.

Keywords: Cyanobacterial bloom; Cyanobacterial organic matter; Lake eutrophication; Phosphorus cycle in lake; Phosphorus release characteristics.

MeSH terms

Animals
China
Chlorophyll A
Cyanobacteria*
Eutrophication
Feedback
Geologic Sediments / microbiology
Lakes / microbiology
Phosphorus / analysis
Porcine Reproductive and Respiratory Syndrome*
Swine
Water Pollutants, Chemical* / analysis

Substances

Phosphorus
Chlorophyll A
Water Pollutants, Chemical