Modeling global oceanic nitrogen deposition from food systems and its mitigation potential by reducing overuse of fertilizers

Growing population and consumption pose unprecedented demands on food production. However, ammonia emissions mainly from food systems increase oceanic nitrogen deposition contributing to eutrophication. Here, we developed a long-term oceanic nitrogen deposition dataset (1970 to 2018) with updated ammonia emissions from food systems, evaluated the impact of ammonia emissions on oceanic nitrogen deposition patterns, and discussed the potential impact of nitrogen fertilizer over-use. Based on the chemical transport modeling approach, oceanic ammonia-related nitrogen deposition increased by 89% globally between 1970 and 2018, and now, it exceeds oxidized nitrogen deposition by over 20% in coastal regions including China Sea, India Coastal, and Northeastern Atlantic Shelves. Approximately 38% of agricultural nitrogen fertilizer was excessive, which corresponds to 15% of global oceanic ammonia-related nitrogen deposition. Policymakers and water quality managers need to pay increasingly more attention to ammonia associated with food production if the goal of reducing coastal nitrogen pollution is to be achieved for Sustainable Development Goals.

Automated summary

Growing population and consumption increase demands on food production, leading to increased ammonia emissions from food systems and subsequent oceanic nitrogen deposition. This study developed a long-term oceanic nitrogen deposition dataset and evaluated the impact of ammonia emissions on nitrogen deposition patterns. It was found that oceanic ammonia-related nitrogen deposition has increased globally by 89% between 1970 and 2018, exceeding oxidized nitrogen deposition in coastal regions. Excessive use of nitrogen fertilizer corresponds to 15% of global oceanic ammonia-related nitrogen deposition. Policymakers and water quality managers should focus on reducing ammonia emissions from food production to achieve Sustainable Development Goals for coastal nitrogen pollution reduction.