Emerging nitrogen-driven urban atmosphere control on aerosol iron dissolution for biogeochemical cycles
Abstract
Iron (Fe) is a critical micronutrient regulating marine productivity and the global carbon cycle, yet its atmospheric dissolution mechanisms remain debated for biogeochemical cycle. The prevailing “iron-sulfur coupling” paradigm has traditionally explained proton-promoted dissolution. However, disproportionate declines in sulfur dioxide relative to nitrogen oxides emissions have created a “low-sulfur, high-nitrogen” atmosphere over East Asia, raising questions about the role of nitric acid. Here, we develop a data-driven framework to elucidate nitric acid–driven Fe dissolution using the nitrate-to-sulfate acidification capacity ratio ( R N/S ). Results show that nitrate now dominates urban aerosol Fe dissolution, contributing ∼1.5 times more than sulfate, challenging the long-standing paradigm. Global simulations further estimate that nitrate contributes to ∼68% of the enhancement in Fe solubility in PM 2.5 (particulate matter with a diameter of 2.5 μm) dust relative to preindustrial levels. These findings reveal an emerging nitrogen-driven control on Fe mobilization, emphasizing the need to incorporate species-dependent acid chemistry into models to accurately represent global Fe cycling and its climate feedbacks.
// Source
Authors: Guochen Wang, Xiyao Chen, Kan Huang, W. J. Guan, Minkang Zhi, Qi Yuan, Keliang Li, Liang Xu, Ziwei Liu, Ruifeng Zhang, Yuntao Wang, Shixian Zhai, Pingqing Fu, Akinori Ito, Weijun Li
Institutions: Ocean University of China, Shanghai Jiao Tong University, Zhejiang University, Chinese University of Hong Kong, Quality Research, Tianjin University, Zhejiang Ocean University, Hangzhou Normal University, Japan Agency for Marine-Earth Science and Technology, China Jiliang University, Ministry of Natural Resources, Zhejiang Normal University, Second Institute of Oceanography