Phosphorus Flow Patterns in the Chaohu Watershed from 1978 to 2012

Area of Science:

• Environmental Science
• Ecosystem Dynamics
• Biogeochemical Cycles

Background:

• Phosphorus (P) cycling is crucial for watershed management and preventing eutrophication.
• Historical P data is vital for understanding and mitigating environmental impacts.
• The Chaohu watershed faces challenges related to P management and water quality.

Purpose of the Study:

• To quantify phosphorus (P) cycling in the Chaohu watershed from 1978 to 2012.
• To identify the primary sources and accumulation patterns of legacy P.
• To inform sustainable P management strategies and eutrophication mitigation.

Main Methods:

• Utilized a bottom-up model based on substance flow analysis.
• Quantified P inputs, outputs, and storage within the watershed.
• Analyzed changes in P accumulation across cultivated land, uncultivated land, and surface water.

Main Results:

• Annual P inputs increased fivefold, driven by intensive agriculture.
• Approximately 75% of P inputs were stored within the watershed annually.
• Significant legacy P buildup occurred in cultivated land, uncultivated land, and surface water.
• Fertilizer application and phosphogypsum abandonment were key legacy P sources.
• Animal husbandry contributed substantially (63-66%) to P inputs in surface water.
• The contribution of animal food-P to urban and rural residents increased significantly.

Conclusions:

• Watershed-scale legacy P buildup is driven by intensified P flows and storage.
• Sustainable P management requires reducing fertilizer application and improving agricultural technologies.
• Understanding historical P dynamics is essential for effective eutrophication control.