Hotspots of nitrogen deposition in the world’s urban areas: a global data synthesis

• Published in: Frontiers in ecology and the environment 2020-03, Vol.18 (2), p.92-100
• Main Authors: Decina, Stephen M, Hutyra, Lucy R, Templer, Pamela H
• Format: Article
• Language: English
• Subjects: Ammonia; Deposition; Nitrates; Nitrogen; REVIEWS; Rural areas; Urban areas
• ISSN: 1540-9295; 1540-9309
• DOI: 10.1002/fee.2143

Human activities have altered the global nitrogen (N) cycle, elevating rates of atmospheric N deposition up to tenfold above pre-industrial levels, with consequences for ecosystem function and human health. To date, most N deposition studies have been carried out in rural areas; however, there has been a recent surge of N deposition studies conducted in urban ecosystems due to the increased recognition that humans are greatly altering the N cycle in these environments. We synthesized data from 174 publications over a period of 40 years that examined rates of N deposition in urban and nearby rural areas worldwide. Results of this meta-analysis help to quantify urban N deposition, demonstrate that total N deposition in cities is predominately composed of chemically reduced – as opposed to oxidized – forms of N like ammonia, and identify regional hotspots of urban N deposition, particularly in China. These findings highlight the need to examine and address the N cycle in cities as the world continues to urbanize.