Integrated assessment of the costs and benefits of reactive nitrogen emission and mitigation: a methodological review and framework proposal

Reactive nitrogen (N r ) emissions represent one of the most pressing challenges at the interface of environment, human health, and climate, yet their assessment remains methodologically fragmented and geographically uneven. This review synthesizes 398 studies from environmental science, environmental economics, agricultural systems, epidemiology, and ecosystem ecology published between 2000-2025 to evaluate the costs and benefits of nitrogen emissions and mitigation strategies. The methodological approaches discussed include emission inventories, cost-benefit analysis, and integrated assessment models that connect environmental and economic outcomes. We found that despite progress achieved through expanding global and regional studies, significant fragmentation persists in nitrogen assessment approaches, limiting the potential to provide generalizable insights and coherent policy recommendations. Moreover, comprehensive cost-benefit assessments of nitrogen management are often underdeveloped, with significant uncertainties and a lack of integration across environmental, economic, and societal dimensions. Building on this analysis, we propose an integrated nitrogen assessment framework (INAF) that systematically connects emission quantification, impact evaluation, mitigation cost and benefit analysis. This framework provides a pathway toward more comprehensive, transparent, and policy-relevant assessments. Our findings emphasize the urgent need for harmonized methodologies, cross-scale integration, and stronger interdisciplinary collaboration. By identifying knowledge gaps and outlining future directions, this review aims to accelerate the development of robust and actionable strategies for sustainable nitrogen management. • Comprehensive review of nitrogen emission and mitigation assessment methods. • Identifies key methodological and data gaps across sectors and scales. • Proposes an integrated assessment framework for Nitrogen. • Supports evidence-based nitrogen management and policy design.