An experimental study on using rare earth elements to trace phosphorous losses from nonpoint sources.

Area of Science:

• Environmental Science
• Water Quality Management
• Geochemistry

Background:

• Freshwater eutrophication is a major environmental issue driven by excessive phosphorus (P) inputs.
• Managing P sources and transport is crucial for mitigating eutrophication.
• Agricultural nonpoint source pollution is a significant contributor to P loading in freshwater systems.

Purpose of the Study:

• To investigate the characteristics of rare earth elements (REEs) and P losses in surface runoff.
• To determine the transport pathways (water vs. sediment) of REEs and P.
• To explore the potential of using REEs as tracers for agricultural nonpoint P losses.

Main Methods:

• Simulated rainfall experiments were conducted to induce surface runoff.
• Concentrations of REEs (La, Nd, Sm) and P were measured in runoff water and sediments.
• Statistical analysis was used to correlate REE and P losses.

Main Results:

• The majority of REEs (La: 94%, Nd: 93%, Sm: 96%) and P (96%) were transported with sediments in the runoff.
• Total amounts of REEs and P losses in the runoff were significantly correlated.
• REEs and P exhibited similar transport behavior, predominantly associated with sediment fractions.

Conclusions:

• REEs and P losses in surface runoff are strongly linked, particularly in sediment transport.
• Exogenous REEs show potential as effective tracers for agricultural nonpoint P losses.
• This finding offers a novel approach for monitoring and managing P pollution to combat freshwater eutrophication.