Does external phosphorus loading diminish the effect of sediment dredging on internal phosphorus loading? An in-situ...

Area of Science:

• Environmental Science
• Limnology
• Water Quality Management

Background:

• Eutrophic lakes suffer from excessive phosphorus (P) loading, impacting water quality.
• Sediment dredging is a common method to mitigate internal P loading.
• The long-term efficacy of dredging can be compromised by external P sources, with unclear mechanisms.

Purpose of the Study:

• To investigate the impact of external loading (suspended particle matter, SPM) on the effectiveness of sediment dredging for internal P loading control.
• To elucidate the migration and transformation processes of P under combined dredging and SPM input scenarios.
• To identify key factors influencing phosphorus flux at the sediment-water interface (SWI).

Main Methods:

• One-year in-situ simulation experiments were conducted.
• Studied P migration and transformation under dredging and SPM input.
• Analyzed P flux across the SWI, considering environmental factors.

Main Results:

• Dredging significantly reduced internal P loading and P mobility.
• Dredging enhanced sediment P adsorption, retention, and improved the SWI oxidation environment.
• SPM input inhibited dredging's positive effects, increasing P resupply and release risks.
• Temperature, dissolved oxygen, and P resupply capacity (R) were key factors for P flux.

Conclusions:

• Sediment dredging is effective in reducing internal P loading and improving lake conditions.
• Controlling SPM input is crucial for the long-term success of dredging in eutrophic lakes.
• Implementing measures like buffer zones and wetlands to manage SPM is recommended post-dredging.