Source tracking aerosols released from land-applied class B biosolids during high-wind events

Area of Science:

• Environmental microbiology
• Molecular biology
• Public health

Background:

• Land application of treated sewage sludge (biosolids) is common.
• Potential for aerosolization and off-site transport of biosolids during high-wind events is a concern.
• Need for sensitive methods to track biosolids in the environment.

Purpose of the Study:

• Develop and validate DNA-based microbial source tracking (MST) methods.
• Assess the unintended aerosolization of biosolids during high-wind events.
• Determine if wind can transport biosolids from land-applied fields.

Main Methods:

• Developed three DNA-based MST methods targeting specific microbial markers in biosolids.
• Validated methods using bulk biosolids and soil samples.
• Applied methods to aerosol samples collected upwind and downwind of biosolids-amended fields during high-wind conditions.

Main Results:

• All three MST methods successfully distinguished biosolids from soil.
• Biosolids markers were detected in 56% of downwind aerosol samples versus 3% of upwind samples during high winds (>5 m/s).
• Biosolid concentrations in downwind aerosols ranged from 0.1 to 2 µg/m³.

Conclusions:

• DNA-based MST is effective for tracking biosolids in aerosols.
• Wind is a significant mechanism for aerosolization and off-site transport of land-applied biosolids.
• Findings highlight potential risks associated with biosolids application and wind events.