Lin Peng

Atmospheric isotope serves as an effective source tracer for tracking the pollutants fate. Its precise source apportionment capability is constrained by the comprehensive assessment of isotope fractionation. This study aimed to propose a Computational Quantum Chemistry (CQC)-based Atmospheric Isotope Fractionation Prediction (AIFP) framework. It can quantify the isotope fractionation mechanisms. This framework utilizes CQC to perform a pipeline for reaction mechanism determination, atmospheric species geometry calculation, and parameter post-processing. It integrates the isotope-substitution method with the fractionation model to establish isotope fractionation standard equations in complex atmospheric chemical systems, providing a theoretical basis for atmospheric isotope tracing. This framework was applied to investigate sulfur (34S) fractionation and sulfate (pSO42–) formation. This application developed a localized 34S fractionation parameter scheme, revealing that pSO42– pollution is driven by NO2 and TMI oxidation. These oxidants account for 58.3 ± 1.0% of its pollution, highlighting the critical role of controlling the transformation conditions of key oxidants in haze pollution mitigation. Our framework extends the atmospheric isotope application, providing a rapid and efficient isotope fractionation prediction framework.

Atmospheric particulate nitrate (pNO₃^–) is a global pollutant, yet its sources remain poorly constrained and debated. While isotope analysis is a powerful tool for source tracing, its application is hampered by an incomplete understanding of isotopic fractionation, particularly the poorly constrained fractionation during gas-particle partitioning. Here, we integrate isotope with computational quantum chemistry to quantify fractionation during gas-particle partitioning. The results indicate that partitioning process induces ¹⁵N (4.8 to 5.2‰) and ¹⁸O fractionation (−0.8 to −4.9‰), which introduces uncertainties into pNO₃^– pollution causes identification. Isotope-based insights show distinct patterns on a global scale: while the NO₂ + OH pathway dominate pNO₃^– generation overall, formation via N₂O₅ hydrolysis and NO₃ + VOCs pathways is more pronounced in East Asia than others. This highlights the significant roles of higher humid climate and VOCs loads in this region. Furthermore, our analysis indicates an approximately 11.3% underestimation of pNO₃^– from agricultural and biogenic soil, potentially because partitioning processes promotes its formation. It also reveals greater contributions from industrial and combustion sources in East Asia versus North America, underscoring the necessity for reduction targeting these sources. These findings demonstrate that gas-particle partition plays a crucial role in regulating particulate nitrate isotopes.

Perfluorocarbons (PFCs) are one of the seven types of greenhouse gases regulated under the climate convention, and their emissions have drawn international attention. Existing studies have conducted atmospheric observations and source analyses of these substances at multiple global background sites (such as those in the AGAGE network), and estimated global and regional emissions using inversion models and other methods based on observational data. China and India, as the world's top one and top four greenhouse gas emitters, respectively, and the top two aluminum producers, warrant particular attention regarding their PFCs emissions. However, while China has some atmospheric background monitoring stations such as Shanghai Dongtan, Shenzhen Xichong, and Zhejiang Shanghuang, there is still little research on background observations in the Qinghai-Tibet Plateau region, especially the southern Himalayas. Moreover, South Asian regions, like India, lack background monitoring stations and few observational studies have been developed in the past five years. This study conducted a three-year atmospheric background observation experiment for three perfluorocarbons (PFCs, including PFC-116, PFC-218, PFC-318) at the Medog background station, located 30 km outside Medog County on the southern Himalayas. From August to November 2021 and July to October 2022, 229 valid instantaneous atmospheric samples (1–3 per day) were collected using Summa canisters and manual pressurization equipment, analyzed with Medusa. From June to August 2024, continuous observations were conducted using the Tianji ODS system, 434 valid samples were in-situ collected, 12 atmospheric samples daily. Based on the 663 valid samples, this study employed the Robust Extraction of Baseline Signal algorithm to analyze background concentrations of each substance and compared them with simulated background concentrations base on the AGAGE12-BOX model by Rigby et al. (currently updated only to December 2023). The results show that the observed background concentration of PFC-116 deviates from the simulated values by less than ±5%; For PFC-218, observed background concentrations also remained within ±5% of simulated values for most periods, except in August 2021 and early September 2021 when they exceeded 12-BOX simulation results by 10%–15%. However, PFC-318 background concentrations were elevated by at least 40% compared to 12-BOX simulations throughout the sampling period. During the study period, polluted information were only caught for PFC-116 in November 2021, accounting for 72% of samples with 16.8% concentration enhancement. Back Trajectory analysis indicated pollution information primarily originated from regions southwest of the sampling site, including Northeast India etc., while clean samples mainly derived from local sources, Tibet in northern China, and Bangladesh in the south. This study fills a gap in atmospheric background PFC observations over the southern Himalayas of the Tibetan Plateau and provides preliminary insights into PFC pollution sources from South Asian regions like Northeast India. Future work will build on these findings to conduct emission inversion studies for South Asian regions including India, offering scientific support for clarifying global PFC emissions.

As China's emission reduction efforts enter a plateau phase due to the slow decline of secondary pollutants, existing strategies face diminishing returns. Atmospheric Oxidation Capacity (AOC), a key driver of secondary pollutant formation, represents a critical yet underutilized target for more effective control. In this study, the Atmospheric Oxidation Capacity Path Tracing (AOCPT) approach was proposed to quantitatively trace AOC to its precursors and sources. It facilitates coordinated control by integrating three core modules. It employs a Radiation Equivalent Oxidation Capacity (REOC) method to quantify precursor species contributions. Meanwhile, it utilizes a Relative Incremental AOC (RIA) metric derived from a coupled box-receptor model to assess source impacts. Finally, a modified source apportionment technique was applied to resolve the respective contributions of both precursor species and sources to AOC. Successfully applied in a field study in Changzhi, China. The AOCPT identified industrial processes (26.8 %) and diesel vehicle emissions (24.1 %) as the dominant AOC sources, driven largely by trans-2-butene. Notably, conventional sensitivity analyses based on ozone (O₃)-targeted strategies were found to underestimate the contributions of these two sources by 28.7 % and 48.5 %, respectively. Furthermore, while O₃-targeted abatement inadvertently enhanced secondary organic aerosols (SOA), an AOC-centric strategy enabled the co-mitigation of both pollutants. By enabling the precise regulation of AOC through direct quantification of precursor and source roles, the AOCPT approach facilitates the synergistic control of secondary pollutants. It provides a robust technical pathway and theoretical foundation to overcome current challenges in air quality management.

As China's emission reduction efforts enter a plateau phase due to the slow decline of secondary pollutants, existing control strategies face diminishing returns. Atmospheric Oxidation Capacity (AOC), a key driver of secondary pollutant formation, represents a critical yet underutilized target for more effective control. The Atmospheric Oxidation Capacity Path Tracing (AOCPT) approach was proposed in this study. This approach quantitatively traces AOC to its precursors and sources, thereby facilitating the coordinated control of secondary pollution, by integrating three modules: a Radiation Equivalent Oxidation Capacity (REOC) method to quantify precursor species contributions, a Relative Incremental AOC (RIA) metric derived from a coupled box-receptor model to assess source impacts, and a modified source apportionment technique to resolve the respective contributions of both precursor species and sources to AOC. Successfully validated in a field study in Changzhi, China, AOCPT identified industrial processes (26.8 %) and diesel vehicle emissions (24.1 %) as the dominant AOC sources in a case city, driven largely by their trans-2-butene emissions (49.3 % and 20.6 % of total trans-2-butene, respectively). Crucially, secondary organic aerosols (SOA) were inadvertently enhanced by ozone (O₃)-targeted abatement, an AOC-centric strategy enables the co-mitigation of both pollutants. By enabling the precise regulation of AOC through direct quantification of precursor and source roles, the AOCPT approach facilitates the synergistic control of secondary pollutants. It provides a robust technical pathway and theoretical foundation to overcome current challenges in air quality management.

As China's emission reduction efforts enter a plateau phase due to the slow decline of secondary pollutants, existing control strategies face diminishing returns. Atmospheric Oxidation Capacity (AOC), a key driver of secondary pollutant formation, represents a critical yet underutilized target for more effective control. The Atmospheric Oxidation Capacity Path Tracing (AOCPT) approach was proposed in this study. This approach quantitatively traces AOC to its precursors and sources, thereby facilitating the coordinated control of secondary pollution, by integrating three modules: a Radiation Equivalent Oxidation Capacity (REOC) method to quantify precursor species contributions, a Relative Incremental AOC (RIA) metric derived from a coupled box-receptor model to assess source impacts, and a modified source apportionment technique to resolve the respective contributions of both precursor species and sources to AOC. Successfully validated in a field study in Changzhi, China, AOCPT identified industrial processes (26.8 %) and diesel vehicle emissions (24.1 %) as the dominant AOC sources in a case city, driven largely by their trans-2-butene emissions (49.3 % and 20.6 % of total trans-2-butene, respectively). Crucially, secondary organic aerosols (SOA) were inadvertently enhanced by ozone (O₃)-targeted abatement, an AOC-centric strategy enables the co-mitigation of both pollutants. By enabling the precise regulation of AOC through direct quantification of precursor and source roles, the AOCPT approach facilitates the synergistic control of secondary pollutants. It provides a robust technical pathway and theoretical foundation to overcome current challenges in air quality management.

As China's emission reduction efforts enter a plateau phase due to the slow decline of secondary pollutants, existing control strategies face diminishing returns. Atmospheric Oxidation Capacity (AOC), a key driver of secondary pollutant formation, represents a critical yet underutilized target for more effective control. The Atmospheric Oxidation Capacity Path Tracing (AOCPT) approach was proposed in this study. This approach quantitatively traces AOC to its precursors and sources, thereby facilitating the coordinated control of secondary pollution, by integrating three modules: a Radiation Equivalent Oxidation Capacity (REOC) method to quantify precursor species contributions, a Relative Incremental AOC (RIA) metric derived from a coupled box-receptor model to assess source impacts, and a modified source apportionment technique to resolve the respective contributions of both precursor species and sources to AOC. Successfully validated in a field study in Changzhi, China, AOCPT identified industrial processes (26.8 %) and diesel vehicle emissions (24.1 %) as the dominant AOC sources in a case city, driven largely by their trans-2-butene emissions (49.3 % and 20.6 % of total trans-2-butene, respectively). Crucially, secondary organic aerosols (SOA) were inadvertently enhanced by ozone (O₃)-targeted abatement, an AOC-centric strategy enables the co-mitigation of both pollutants. By enabling the precise regulation of AOC through direct quantification of precursor and source roles, the AOCPT approach facilitates the synergistic control of secondary pollutants. It provides a robust technical pathway and theoretical foundation to overcome current challenges in air quality management.

As China's emission reduction efforts enter a plateau phase due to the slow decline of secondary pollutants, existing control strategies face diminishing returns. Atmospheric Oxidation Capacity (AOC), a key driver of secondary pollutant formation, represents a critical yet underutilized target for more effective control. The Atmospheric Oxidation Capacity Path Tracing (AOCPT) approach was proposed in this study. This approach quantitatively traces AOC to its precursors and sources, thereby facilitating the coordinated control of secondary pollution, by integrating three modules: a Radiation Equivalent Oxidation Capacity (REOC) method to quantify precursor species contributions, a Relative Incremental AOC (RIA) metric derived from a coupled box-receptor model to assess source impacts, and a modified source apportionment technique to resolve the respective contributions of both precursor species and sources to AOC. Successfully validated in a field study in Changzhi, China, AOCPT identified industrial processes (26.8 %) and diesel vehicle emissions (24.1 %) as the dominant AOC sources in a case city, driven largely by their trans-2-butene emissions (49.3 % and 20.6 % of total trans-2-butene, respectively). Crucially, secondary organic aerosols (SOA) were inadvertently enhanced by ozone (O₃)-targeted abatement, an AOC-centric strategy enables the co-mitigation of both pollutants. By enabling the precise regulation of AOC through direct quantification of precursor and source roles, the AOCPT approach facilitates the synergistic control of secondary pollutants. It provides a robust technical pathway and theoretical foundation to overcome current challenges in air quality management.

As China's emission reduction efforts enter a plateau phase due to the slow decline of secondary pollutants, existing control strategies face diminishing returns. Atmospheric Oxidation Capacity (AOC), a key driver of secondary pollutant formation, represents a critical yet underutilized target for more effective control. The Atmospheric Oxidation Capacity Path Tracing (AOCPT) approach was proposed in this study. This approach quantitatively traces AOC to its precursors and sources, thereby facilitating the coordinated control of secondary pollution, by integrating three modules: a Radiation Equivalent Oxidation Capacity (REOC) method to quantify precursor species contributions, a Relative Incremental AOC (RIA) metric derived from a coupled box-receptor model to assess source impacts, and a modified source apportionment technique to resolve the respective contributions of both precursor species and sources to AOC. Successfully validated in a field study in Changzhi, China, AOCPT identified industrial processes (26.8 %) and diesel vehicle emissions (24.1 %) as the dominant AOC sources in a case city, driven largely by their trans-2-butene emissions (49.3 % and 20.6 % of total trans-2-butene, respectively). Crucially, secondary organic aerosols (SOA) were inadvertently enhanced by ozone (O₃)-targeted abatement, an AOC-centric strategy enables the co-mitigation of both pollutants. By enabling the precise regulation of AOC through direct quantification of precursor and source roles, the AOCPT approach facilitates the synergistic control of secondary pollutants. It provides a robust technical pathway and theoretical foundation to overcome current challenges in air quality management.