Using sediment resuspension to immobilize sedimentary phosphorus.

Area of Science:

• Environmental Science
• Limnology
• Water Chemistry

Background:

• Phosphorus (P) cycling in sediment-water systems is crucial for lake eutrophication.
• Sediment resuspension events can alter nutrient dynamics in shallow lakes like Taihu Lake.
• Understanding the transformation of internal phosphorus under disturbance is key to managing water quality.

Purpose of the Study:

• To investigate the transformation of internal phosphorus in response to sediment resuspension.
• To evaluate the impact of different disturbance intensities on phosphorus fractions and related parameters.
• To determine the effect of sediment resuspension on phosphorus retention capacity in the sediment-water system.

Main Methods:

• Laboratory-simulated experiments using sediments and overlying water from Taihu Lake.
• Analysis of particulate phosphorus (PP), dissolved inorganic phosphorus (DIP), and algal-available phosphorus (AAP).
• Evaluation of phosphorus fractions, suspended particle characteristics, dissolved oxygen (DO), pH, and ammonia nitrogen (NH4+-N).

Main Results:

• Sediment resuspension increased dissolved oxygen (DO) and decreased pH and ammonia nitrogen (NH4+-N) in overlying water.
• Disturbance promoted the formation of insoluble crystalline metal compounds, increasing refractory P in sediments.
• Enhanced P retention was evidenced by increased maximum P adsorption (Qmax) and decreased P saturation (DPS) and equilibrium P concentration (EPC0).

Conclusions:

• Sediment resuspension improves the redox environment in the sediment-water system.
• The process significantly enhances the sediment's capacity for long-term phosphorus retention.
• Sediment resuspension offers a potential strategy for managing phosphorus in shallow lake ecosystems.