A life cycle assessment approach for nitrogen footprint quantification: the reactive nitrogen indicator

Area of Science:

• Environmental Science
• Biogeochemistry
• Sustainable Agriculture

Background:

• Perturbations in nitrogen and phosphorus biogeochemical cycles pose global environmental and social risks.
• Accurate quantification of reactive nitrogen emissions is crucial for environmental impact assessment.
• Existing methods for calculating the nitrogen footprint lack alignment with standardized life cycle assessment (LCA) procedures.

Purpose of the Study:

• To propose an innovative and standardized method for quantifying reactive nitrogen emissions.
• To align the calculation of the nitrogen footprint with ISO 14040 and ISO 14044 standards.
• To provide a reproducible and complete approach for assessing nitrogen-related environmental impacts of product systems.

Main Methods:

• Developed a novel quantification method for reactive nitrogen emissions based on the nitrogen footprint indicator.
• Ensured methodological alignment with ISO 14040 and ISO 14044 standards for Life Cycle Assessment (LCA).
• Applied the method to agricultural and livestock supply chains using secondary inventory data.

Main Results:

• Successfully applied the proposed method to quantify reactive nitrogen emissions in selected agricultural and livestock products.
• Validated the method by comparing results with existing literature on nitrogen footprint accounting, showing good agreement.
• Demonstrated the method's reproducibility, ease of application, and completeness.

Conclusions:

• The proposed method offers a standardized and reliable approach to quantifying reactive nitrogen emissions.
• Its alignment with LCA principles and ISO standards makes it a valuable tool for environmental impact assessment.
• The method is broadly applicable to any product system for calculating reactive nitrogen emissions.