In recent years, the atmospheric sciences community has grappled with the complex chemical interactions that drive the Earth’s air quality and influence climate dynamics. A groundbreaking study by Yang, Huang, Zhao, and colleagues, published in the prestigious journal Nature Communications in 2025, unveils a previously underappreciated mechanism pivotal to the atmospheric formation of organic nitrates. Their research highlights the multiphase reactions between organic peroxides and nitrite ions, which fundamentally reshape our understanding of atmospheric chemistry and the sources of organic nitrates in the troposphere.
Organic nitrates hold tremendous significance in atmospheric chemistry due to their role in modulating the oxidative capacity of the atmosphere and their potential to influence aerosol formation—key determinants in climate forcing and human health. Traditional pathways for organic nitrate formation have focused primarily on gas-phase reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOx). However, the work of Yang et al. challenges this convention by elucidating the role of multiphase processes, particularly chemical transformations occurring within or on the surfaces of aqueous aerosols and droplets.
At the crux of their study is the interaction between organic peroxides—a broad class of oxygen-containing organic compounds characterized by the peroxide functional group—and nitrite ions (NO₂⁻). Nitrite, itself an intermediary nitrogen species, is abundant in atmospheric aqueous phases, such as cloud droplets, fog, and wet aerosols. Previous research has recognized the importance of multiphase reactions for sulfate and nitrate formation, yet the detailed mechanisms by which organic nitrates form in these microenvironments remained poorly constrained. Yang and colleagues address this gap by employing a combination of laboratory experiments, advanced spectroscopic analyses, and atmospheric modeling.
The experimental design underpinning their investigation involved simulating atmospheric aqueous aerosol conditions under controlled laboratory settings. They introduced organic peroxides into solutions containing nitrite ions and monitored the formation of organic nitrates over time. Sophisticated mass spectrometry and infrared spectroscopy techniques were deployed to characterize reaction intermediates and products, providing molecular-level insights into the reaction pathways. Their findings robustly demonstrate that organic peroxides and nitrite engage in multiphase redox reactions, leading to the efficient production of organic nitrates.
One of the remarkable revelations of this study is the mechanistic pathway through which these reactions proceed. Detailed kinetic analyses showed that nitrite can act as both a nucleophile and an oxidant when interacting with organic peroxides. This dual functionality facilitates the cleavage of peroxide bonds and subsequent formation of nitrate esters on organic frameworks. Such processes are markedly accelerated at the liquid–air interfaces of aerosols, highlighting the importance of interfacial chemistry. This underscores the complexity of aerosol chemistry, where compartmentalization within microdroplets can drastically alter reaction kinetics compared to bulk solutions.
Beyond the laboratory, the authors integrated their mechanistic findings into atmospheric chemical transport models to assess environmental impacts. Simulations incorporating multiphase organic peroxide-nitrite reactions predicted significantly enhanced formation rates of organic nitrates in polluted urban atmospheres, particularly under humid conditions where aqueous aerosols are prevalent. This introduces an important revision to current atmospheric models that typically underrepresent or exclude these multiphase pathways. Consequently, the revised models suggest greater atmospheric burdens of organic nitrates, with implications for secondary organic aerosol (SOA) formation, atmospheric oxidation cycles, and nitrogen deposition patterns.
The environmental ramifications of these discoveries are far-reaching. Organic nitrates are known to act as reservoirs for reactive nitrogen oxides, modulating their availability for ozone production and other photochemical processes. By establishing a novel source of organic nitrates, the study provides insight into how urban pollution and climate-induced changes in aerosol water content could amplify regional air quality issues. Moreover, organic nitrates contribute to SOA mass, which influences radiative forcing by scattering or absorbing sunlight. Therefore, accurate representation of their sources is essential for predicting future climate scenarios and formulating effective pollution mitigation strategies.
Furthermore, the identification of this multiphase pathway sheds light on the intricate linkages between atmospheric redox chemistry and nitrogen cycling. Organic peroxides, often formed through photochemical oxidation of VOCs, serve as reactive intermediates that couple with inorganic nitrogen species such as nitrite in ways previously unaccounted for. Such cross-domain interactions exemplify the emergent complexity inherent in atmospheric chemistry, where multiple reactive species and phases converge. This discovery highlights the need for interdisciplinary approaches combining field observations, laboratory experiments, and theoretical modeling to unravel the full scope of atmospheric transformations.
Importantly, the findings also raise questions regarding the fate and transport of organic nitrates post-formation. Their chemical stability, propensity to undergo hydrolysis or photolysis, and potential to deposit onto ecosystems influence both local and regional environmental dynamics. The study prompts further investigations into the lifecycle of these compounds once formed within aerosols, encompassing their role in particulate matter toxicity, feedstock for further oxidation, and interaction with cloud microphysical properties.
The research by Yang et al. also opens avenues for reevaluating mitigation policies targeting nitrogen oxide emissions and VOC precursors. Traditional control strategies focus on reducing NOx to limit ozone and particulate pollution. However, the recognition that nitrite in aqueous phases actively participates in forming organic nitrates suggests alternative pathways that may sustain reactive nitrogen cycling, even under lowered NOx emissions. This nuance invites policymakers to consider multiphase chemistry when devising air quality regulations, emphasizing the interconnectedness of anthropogenic emissions and atmospheric chemical cascades.
Moreover, the study’s methodological advances stand as exemplary in atmospheric research. By coupling real-time spectroscopic measurements with kinetic modeling, the authors provide a robust framework for exploring complex heterogeneous reactions. Their approach serves as a template for future studies aiming to dissect other multiphase processes that remain elusive due to analytical challenges. The precision in detecting transient intermediates reinforces the potential for uncovering additional cryptic reactions in atmospheric chemistry.
One cannot overlook the role of such fundamental research in advancing global climate science. The atmospheric oxidative capacity governs the lifetime of greenhouse gases and pollutants, thereby influencing planetary temperature regulation. Organic nitrates, by sequestering nitrogen oxides and affecting aerosol properties, interact with this oxidative framework. The elucidation of their formation via multiphase reactions enriches scientific understanding critical for refining climate prediction models, thereby enhancing the fidelity of forecasts that inform international climate agreements.
In light of these findings, future research trajectories are clear. Expanding field measurements to confirm the prevalence of these reactions in diverse atmospheric environments is a pivotal next step. Additionally, exploring the interplay between organic peroxide structure, nitrite concentration, and ambient conditions can unravel the reaction’s variability. Exploring interactions with other aqueous-phase constituents, such as sulfate, ferrous iron, or dissolved organic matter, could add layers of complexity and realism to the current mechanistic picture.
Finally, Yang and colleagues’ study exemplifies the continuous evolution of atmospheric chemistry as a discipline, blending chemistry, physics, and environmental science to address pressing global challenges. It reminds the scientific community and society at large that even well-studied atmospheric components such as organic nitrates harbor hidden dimensions that can profoundly influence air quality, climate regulation, and human well-being. By illuminating these multiphase chemical pathways, the research propels a new era of discovery, encouraging innovative approaches to safeguard the atmosphere for future generations.
Subject of Research: Multiphase reactions between organic peroxides and nitrite ions in atmospheric aqueous aerosols leading to the formation of organic nitrates.
Article Title: Multiphase reactions of organic peroxides and nitrite as a source of atmospheric organic nitrates.
Article References:
Yang, Y., Huang, L., Zhao, M. et al. Multiphase reactions of organic peroxides and nitrite as a source of atmospheric organic nitrates. Nat Commun 16, 5437 (2025). https://doi.org/10.1038/s41467-025-60696-3
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