Tracing phosphorus cycle in global watershed using phosphate oxygen isotopes.

Area of Science:

• Earth System Science
• Environmental Chemistry
• Biogeochemistry

Background:

• The Phosphorus (P) cycle is vital for Earth's ecosystems.
• Increased P input into watersheds disrupts ecosystem balance.
• Understanding P sources is critical for environmental management.

Purpose of the Study:

• To explore the effects of internal P loading and external P input in global watersheds.
• To synthesize research progress and isotope data on P dynamics.
• To evaluate methods for tracing the P biogeochemical cycle.

Main Methods:

• Literature review of research progress on P loading.
• Synthesis of experimental isotope data from published studies.
• Integration of observational and experimental findings.

Main Results:

• Both internal P release and external P input substantially contribute to watershed P loadings.
• Internal P is released via sediment resuspension and redox changes.
• Increased fertilizer use drives significant external P input.

Conclusions:

• Improving water quality necessitates managing both internal and external P loadings.
• Phosphate oxygen isotope technology is effective for tracing P biogeochemical cycles.
• Future research should integrate isotope fractionation mechanisms for better P dynamic prediction.