Detecting and analyzing soil phosphorus loss associated with critical source areas using a remote sensing approach

Area of Science:

• Environmental Science
• Remote Sensing
• Water Quality Management

Background:

• Managing soil phosphorus (P) loss is vital to prevent water body eutrophication.
• Existing studies primarily focus on local scales, limiting regional understanding of P loss CSAs.
• Long-term variations in CSAs and their driving factors remain under-investigated.

Purpose of the Study:

• To develop and apply a regional-scale approach for detecting critical source areas (CSAs) of soil P loss.
• To analyze the spatial and temporal variability of CSAs over a 15-year period (2000-2014).
• To identify key factors influencing the long-term variation of CSAs at a regional scale.

Main Methods:

• Utilized a novel regional-scale approach integrating data from ASTER, TM/ETM, and MODIS satellite sensors.
• Incorporated five key factors driving soil P loss: precipitation, slope, soil erosion, land use, and soil total phosphorus.
• Analyzed 15 years of data (2000-2014) in a representative intensive agricultural region of China.

Main Results:

• The average area of critical phosphorus source areas (CPSAs) was 15,056 km², representing 13.8% of the total study area.
• CPSA area fluctuated significantly, ranging from 1.2% to 23.0% over the 15-year period.
• CSAs for P loss exhibited spatially variable and more dispersed long-term distribution patterns, with precipitation identified as a primary driver of variation.

Conclusions:

• The developed regional-scale method effectively detects and monitors CSAs for soil P loss.
• Precipitation significantly influences the spatial and temporal dynamics of CSAs at a regional scale.
• This approach offers scientific guidance for managing regional soil P loss and preventing eutrophication, with potential for global application.