Sediment phosphorus buffering in streams at baseflow: A meta-analysis

Area of Science:

• Environmental Science
• Aquatic Chemistry
• Water Quality Management

Background:

• Phosphorus pollution is a major threat to surface water quality.
• Understanding factors controlling phosphorus (P) concentrations in streams is crucial.
• The sediment P buffer plays a significant role in regulating streamwater P.

Purpose of the Study:

• To synthesize literature on the sediment P buffer's control on stream P concentrations.
• To conduct a global meta-analysis of sediment equilibrium phosphate concentration (EPC0).
• To understand streamwater-sediment P interactions at baseflow.

Main Methods:

• Global meta-analysis of 45 studies with >900 paired observations of dissolved reactive P (DRP) and EPC0.
• Analysis of factors moderating P exchange, including sediment and stream characteristics.
• Evaluation of methodological influences on EPC0 determination.

Main Results:

• Sediments rarely reach equilibrium with streamwater, frequently having the potential to remove or release P (83% of observations).
• P exchange potential is influenced by sediment properties (sorption affinity, pH, P concentration, particle size) and stream conditions.
• Other factors like hydrology, sediment surface chemistry, hyporheic exchange, and biota affect P exchange realization.

Conclusions:

• Sediments are dynamic P buffers, but equilibrium is uncommon.
• Understanding sediment P dynamics is vital for effective management of P pollution and eutrophication.
• Standardized measurement and reporting of EPC0 are needed for improved inter-study comparison and application.