Anthropogenic Perturbations to the Atmospheric Molybdenum Cycle

Daniela Varrica, Maria Grazia Alaimo, Fabrice Lambert, Yuan-Wen Kuang, Yu-Cheng Chen, Shankararaman Chellam, Roy M. Harrison, Philip K. Hopke, Yasser Morera-Gómez, Francisco Barraza, Sergio Rodríguez, David D. Cohen, Chad Milando, Michelle Y. Wong, Andres Alastuey, Harrison, Sagar D. Rathod, David Connelly, Longlei Li, James LiangYangjunjie Xu, Natalie M. Mahowald, Remi Losno, Patricia Smichowski, Willy Maenhaut, Xavier Querol, Manuel Castro Carneiro, Robert W. Howarth, Darió Gómez, Roxanne Marino, Maria Inês Couto Monteiro, Jenny Hand, Yi-Hua Xiao, David D. Cohen, Christoph Hueglin

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Molybdenum (Mo) is a key cofactor in enzymes used for nitrogen (N) fixation and nitrate reduction, and the low availability of Mo can constrain N inputs, affecting ecosystem productivity. Natural atmospheric Mo aerosolization and deposition from sources such as desert dust, sea-salt spray, and volcanoes can affect ecosystem function across long timescales, but anthropogenic activities such as combustion, motor vehicles, and agricultural dust have accelerated the natural Mo cycle. Here we combined a synthesis of global atmospheric concentration observations and modeling to identify and estimate anthropogenic sources of atmospheric Mo. To project the impact of atmospheric Mo on terrestrial ecosystems, we synthesized soil Mo data and estimated the global distribution of soil Mo using two approaches to calculate turnover times. We estimated global emissions of atmospheric Mo in aerosols (<10 μm in diameter) to be 23 Gg Mo yr−1, with 40%–75% from anthropogenic sources. We approximated that for the top meter of soil, Mo turnover times range between 1,000 and 1,000,000 years. In some industrialized regions, anthropogenic inputs have enhanced Mo deposition 100-fold, lowering the soil Mo turnover time considerably. Our synthesis of global observational data, modeling, and a mass balance comparison with riverine Mo exports suggest that anthropogenic activity has greatly accelerated the Mo cycle, with potential to influence N-limited ecosystems.
Original languageEnglish
Number of pages25
JournalGlobal Biogeochemical Cycles
Publication statusPublished - 2021

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • General Environmental Science
  • Atmospheric Science


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