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A large fraction of fine particulate matter (PM2.5) and ozone (O3) in the troposphere originates from secondary formation through photochemical processes, which remarkably contributes to the deterioration of regional air quality in China. The photochemical reactions initiated by hydroxyl radicals (OH) play vital roles in secondary PM2.5 and O3 formation. In contrast, the OH levels in polluted areas are underestimated by current chemical transport models (CTMs) because of the strongly unknown daytime sources of tropospheric nitric acid (HONO), which has been recognized as the dominant source of primary OH in polluted areas of China. In this study, the atmospheric HONO levels at two urban sites were found to be significantly underestimated by the WRF-Chem model based on available information on HONO sources. The HONO levels could be well reproduced by the WRF-Chem model after incorporating two new potential HONO sources from the photochemical reactions of NOx, as proposed in our previous study based on chamber experiment results. Comparing the simulations with available information of HONO sources, the simulated levels of atmospheric OH, secondary inorganic and organic aerosols (SIA and SOA), PM2.5 and daily maximum 8-h average (MDA8) O3 were evidently elevated or were closer to the observations over the North China Plain (NCP), with elevation percentages of 0.48-20.1 %, and a decrement percentage of -5.79 % for pNO3-. Additionally, the compensating errors in modeling PM2.5 and the gap in MDA8 O3 levels between observation and simulation in 2 + 26 cities became evidently smaller. The results of this study indicated that the empirical parameterization of two new potential HONO sources through photochemical reactions of NOx improved the model performance in modeling PM2.5 and O3 by narrowing the gap in daytime HONO levels between simulation and observation, although their detailed chemical mechanisms are still unknown and should be further investigated and explicitly parameterized.
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In this study, the chemical mechanisms of O3 and nitrate formation as well as the control strategy were investigated based on extensive observations in Tai'an city in the NCP and an observation-constrained box model. The results showed that O3 pollution was severe with the maximum hourly O3 concentration reaching 150 ppb. Higher O3 concentration was typically accompanied by higher PM2.5 concentrations, which could be ascribed to the common precursors of VOCs and NOx. The modeled averaged peak concentrations of OH, HO2, and RO2 were relatively higher compared to previous observations, indicating strong atmospheric oxidation capacity in the study area. The ROx production rate increased from 2.8 ppb h-1 to 5 ppb h-1 from the clean case to the heavily polluted case and was dominated by HONO photolysis, followed by HCHO photolysis. The contribution of radical-self combination to radical termination gradually exceeded NO2 + OH from clean to polluted cases, indicating that O3 formation shifted to a more NOx-limited regime. The O3 production rate increased from 14 ppb h-1 to 22 ppb h-1 from clean to heavily polluted cases. The relative incremental reactivity (RIR) results showed that VOCs and NOx had comparable RIR values during most days, which suggested that decreasing VOCs or NOx was both effective in alleviating O3 pollution. In addition, HCHO, with the largest RIR value, made important contribution to O3 production. The Empirical Kinetic Modeling Approach (EKMA) revealed that synergistic control of O3 and nitrate can be achieved by decreasing both NOx and VOCs emissions (e.g., alkenes) with the ratio of 3:1. This study emphasized the importance of NOx abatement for the synergistic control of O3 and nitrate pollution in the Tai'an area as the sustained emissions control has shifted the O3 and nitrate formation to a more NOx-limited regime.
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Gaseous nitrous acid (HONO) is identified as a critical precursor of hydroxyl radicals (OH), influencing atmospheric oxidation capacity and the formation of secondary pollutants. However, large uncertainties persist regarding its formation and elimination mechanisms, impeding accurate simulation of HONO levels using chemical models. In this study, a deep neural network (DNN) model was established based on routine air quality data (O3, NO2, CO, and PM2.5) and meteorological parameters (temperature, relative humidity, solar zenith angle, and season) collected from four typical megacity clusters in China. The model exhibited robust performance on both the train sets [slope = 1.0, r2 = 0.94, root mean squared error (RMSE) = 0.29 ppbv] and two independent test sets (slope = 1.0, r2 = 0.79, and RMSE = 0.39 ppbv), demonstrated excellent capability in reproducing the spatiotemporal variations of HONO, and outperformed an observation-constrained box model incorporated with newly proposed HONO formation mechanisms. Nitrogen dioxide (NO2) was identified as the most impactful features for HONO prediction using the SHapely Additive exPlanation (SHAP) approach, highlighting the importance of NO2 conversion in HONO formation. The DNN model was further employed to predict the future change of HONO levels in different NOx abatement scenarios, which is expected to decrease 27-44% in summer as the result of 30-50% NOx reduction. These results suggest a dual effect brought by abatement of NOx emissions, leading to not only reduction of O3 and nitrate precursors but also decrease in HONO levels and hence primary radical production rates (PROx). In summary, this study demonstrates the feasibility of using deep learning approach to predict HONO concentrations, offering a promising supplement to traditional chemical models. Additionally, stringent NOx abatement would be beneficial for collaborative alleviation of O3 and secondary PM2.5.
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Poluentes Atmosféricos , Aprendizado Profundo , Ácido Nitroso , Ácido Nitroso/química , Poluentes Atmosféricos/análise , China , Monitoramento Ambiental/métodos , Poluição do ArRESUMO
Severe ozone (O3) pollution has been a major air quality issue and affects environmental sustainability in China. Conventional mitigation strategies focusing on reducing volatile organic compounds and nitrogen oxides (NOx) remain complex and challenging. Here, through field flux measurements and laboratory simulations, we observe substantial nitrous acid (HONO) emissions (FHONO) enhanced by nitrogen fertilizer application at an agricultural site. The observed FHONO significantly improves model performance in predicting atmospheric HONO and leads to regional O3 increases by 37%. We also demonstrate the significant potential of nitrification inhibitors in reducing emissions of reactive nitrogen, including HONO and NOx, by as much as 90%, as well as greenhouse gases like nitrous oxide by up to 60%. Our findings introduce a feasible concept for mitigating O3 pollution: reducing soil HONO emissions. Hence, this study has important implications for policy decisions related to the control of O3 pollution and climate change.
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Ácido Nitroso , Ozônio , Solo , Ácido Nitroso/química , Solo/química , Poluição do Ar/prevenção & controle , Poluentes Atmosféricos , China , Mudança Climática , Óxido NitrosoRESUMO
Interfacial active water molecule-induced parasitic reactions and stochastic Zn2+ transport-caused dendrite issue significantly impede the implementation of aqueous Zn-ion batteries. Herein, three positively charged amino acids, namely arginine, histidine, and lysine, were utilized as adsorption-type electrolyte additives to enhance the stability and reversibility of Zn anodes. Combined theoretical and experimental analyses verified that these amino acid cations can synergistically modulate the interfacial microenvironment and promote orientational Zn deposition. The adsorbed amino acid cations reconfigured the interfacial electric double layer structure, forming SO42-- and H2O-poor interfaces, thereby retarding hydrogen evolution and corrosion side reactions. Simultaneously, the preferential adsorption of the amino acid cations at specific facets induced crystallographic orientational Zn deposition along unterminated facets. Three deposition architectures, namely planar texture, subvertical alignment, and vertical erection, were obtained, all effectively inhibiting dendrite formation. Consequently, symmetric cells with the three amino acid cations exhibited high stripping/plating reversibility of over 2000 cycles at 5 mA cm-2. Moreover, MnO2-based full cells exhibited markedly improved stabilities compared with their additive-free counterparts.
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Radiation resistance has always been one of the main obstacles to tumor radiotherapy. Therefore, understanding the mechanisms underlying radiotherapy resistance is a focus of research. In this study, we induced two radiation-resistant cell lines to mimic the radiation resistance of NSCLC and investigated the mechanisms of radiotherapy resistance. Cell radiosensitivity was analyzed by single-cell gel electrophoresis, colony formation and tumor sphere formation assays. A wound healing assay was used to analyze cell migration. Western blotting and siRNA were used to identify the potential mechanism. In animal model experiments, xenograft tumors were used to verify the difference between radiotherapy-resistant and nonresistant NSCLC models after radiotherapy. Our results showed that NSCLC radiation-resistant cells exhibited more radioresistance and migratory abilities under low-dose irradiation. The expression of LIMK2 and p-CFL1 were upregulated in NSCLC radiation-resistant cells. Knockdown of LIMK2 significantly enhanced the radiosensitivity of NSCLC-resistant cells. In vivo, low-dose radiotherapy suppressed tumor growth, induced apoptosis and upregulated the expression of LIMK2 in xenograft tumors. However, radiotherapy had little effect on the NSCLC radiation resistance model. In conclusion, NSCLC radiation-resistant cells exhibit more radioresistance and migratory ability under low-dose irradiation. Strikingly, knockdown of LIMK2 enhanced the radiosensitivity of NSCLC-resistant cells.
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Hydrochar from agricultural wastes is regarded as a prospective and low-cost material to activate peroxymonosulfate (PMS) for degrading pollutants. Herein, a novel in-situ N-doped hydrochar composite (RHCM4) was synthesized using montmorillonite and waste reed straw rich in nitrogen as pyrolysis catalyst and carbon source, respectively. The fabricated RHCM4 possessed excellent PMS activation performance for decomposing quinclorac (QC), a refractory herbicide, with a high removal efficiency of 100.0% and mineralization efficiency of 75.1%. The quenching experiments and electron spin resonance (ESR) detection disclosed free radicals (â¢OH, â¢SO4-, and â¢O2-) and non-radicals (1O2) took part in the QC degradation process. Additionally, the catalytic mechanisms were analyzed in depth with the aid of various characterizations. Moreover, the QC degradation intermediates and pathways were clarified by density functional theory calculations and HPLC-MS. Importantly, phytotoxicity experiments showed that RHCM4/PMS could efficaciously mitigate the injury of QC to Solanaceae crops (pepper, tomato, and tobacco). These findings give a new idea for enhancing the catalytic activity of hydrochar from agricultural wastes and broaden its application in the field of agricultural environment.
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Solanaceae , Estudos Prospectivos , Peróxidos , VerdurasRESUMO
This study aims to investigate the status and influencing factors of two-way social support among old adults. A cross-sectional study of 408 convenient samples of old adults was conducted using socio-demographic questionnaire, Brief 2-Way Social Support Scale, Modified Barthel index, General Well-being Schedule, Family APGAR Index, and Lubben Social Network Scale 6. The two-way social support score for old adults in China was (43.74±7.86), with the receiving and giving social support scoring (22.80±4.06) and (20.94±4.52), respectively. The multiple linear regression analysis revealed that family care, residence place, socioeconomic status, and social network were associated with both receiving and giving social support. Chronic diseases and religious beliefs were related to receiving social support, while gender, general well-being, and residence form were related to giving social support. Tailored interventions based on the distinct influencing factors are needed to enhance old adults' social support both as recipients and providers.
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Apoio Social , Humanos , Estudos Transversais , Fatores Socioeconômicos , China , Inquéritos e QuestionáriosRESUMO
The widespread application of copper (Cu) -based fertilizers and pesticides could increase the accumulation of Cu in kiwifruit. According to a global survey, red- and yellow-fleshed kiwifruit contained more elevated amounts of Cu than green-fleshed kiwifruit due to weaker disease resistance and higher use of Cu pesticides. Intriguingly, our research revealed that external and endogenous ascorbic acid (AsA) reduced the phenotypic and physiological injury of Cu toxicity in kiwifruit. Cu stress assays and transcriptional analysis have shown that Cu treatment for 12 h significantly increased the AsA content in kiwifruit leaves and up-regulated key genes involved in AsA biosynthesis, such as GDP-L-galactose phosphorylase3 (GGP3) and GDP-mannose-3',5'-epimerase (GME). Overexpressing GGP3 in transgenic kiwifruit significantly increased the endogenous AsA content of kiwifruit, which was beneficial in mitigating Cu toxicity by decreasing levels of reactive oxygen species, malondialdehyde, and electrolyte leakage, as well as reducing damage to the chloroplast structure and photosystem II. This study presented a novel strategy to ameliorate plant Cu stress by increasing the endogenous antioxidant (AsA) content through transgenesis.
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Cobre , Praguicidas , Cobre/toxicidade , Ácido Ascórbico/farmacologia , Bioensaio , CloroplastosRESUMO
The differentiation of pluripotent stem cells (PSCs) into diverse functional cell types provides a promising solution to support drug discovery, disease modeling, and regenerative medicine. However, functional cell differentiation is currently limited by the substantial line-to-line and batch-to-batch variabilities, which severely impede the progress of scientific research and the manufacturing of cell products. For instance, PSC-to-cardiomyocyte (CM) differentiation is vulnerable to inappropriate doses of CHIR99021 (CHIR) that are applied in the initial stage of mesoderm differentiation. Here, by harnessing live-cell bright-field imaging and machine learning (ML), we realize real-time cell recognition in the entire differentiation process, e.g., CMs, cardiac progenitor cells (CPCs), PSC clones, and even misdifferentiated cells. This enables non-invasive prediction of differentiation efficiency, purification of ML-recognized CMs and CPCs for reducing cell contamination, early assessment of the CHIR dose for correcting the misdifferentiation trajectory, and evaluation of initial PSC colonies for controlling the start point of differentiation, all of which provide a more invulnerable differentiation method with resistance to variability. Moreover, with the established ML models as a readout for the chemical screen, we identify a CDK8 inhibitor that can further improve the cell resistance to the overdose of CHIR. Together, this study indicates that artificial intelligence is able to guide and iteratively optimize PSC differentiation to achieve consistently high efficiency across cell lines and batches, providing a better understanding and rational modulation of the differentiation process for functional cell manufacturing in biomedical applications.
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Atmospheric HONO acts as a major source for OH radicals in polluted areas, playing an important role in formation of secondary pollutants. However, the atmospheric HONO sources remain unclear. Here we propose that the heterogeneous reaction of NO2 on aerosols during aging processes acts as the dominant source for nocturnal HONO. Based on the nocturnal variations of HONO and related species in Tai'an city of China, we firstly developed new method to estimate the localized HONO dry deposition velocity (v(HONO)). The estimated v(HONO) of 0-0.077 m/s was in a good agreement with the reported ranges. Additionally, we set up a parametrization to reflect the HONO formation from the aged air parcels based on the variation of HONO/NO2 ratio. The detailed variation of nocturnal HONO could be well reproduced by a complete budget calculation coupled with above parameterizations, with the difference between the observed and calculated HONO levels being <5 %. The results also revealed the average contribution of HONO formation from aged air parcels to atmospheric HONO could achieve to be ~63 % in average.
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Recently, deteriorating ozone (O3) pollution in China brought the precise diagnosis of O3 sensitive chemistry to the forefront. As a dominant precursor of OH radicals, atmospheric nitrous acid (HONO) plays an important role in O3 production. However, its measurement unavailability in many regions especially for second- and third-tier cities may lead to the misjudgment of the O3 sensitivity regime derived from observation-based models. Here, we systematically assess the potential impact of HONO on diagnosing the sensitivity of O3 production using a 0-dimension box model based on a comprehensive summer urban field campaign. The results indicated that the default mode (only the NO + OH reaction is included) in the model could underestimate â¼87% of observed HONO levels, leading to an obvious decrease (â¼19%) of net O3 production in the morning, which was in line with the previous studies. The unconstrained HONO in the model was found to significantly push O3 production toward the VOC-sensitive regime. Additionally, it is unrealistic to change NO x but constrain HONO in the model due to the dependence of HONO formation on NO x . Assuming that HONO varied proportionally with NO x , a stronger NO x -sensitive condition could be achieved. Therefore, effective reduction of NO x should be given more attention together with VOC emission control for O3 mitigation.
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Drug resistance and relapse of T-cell acute lymphoblastic leukemia (T-ALL) remain significant concerns for physicians; hence, the development and screening of effective targeted drugs remain important. Considering that STAT3 is emerging as a potential therapeutic target for T-ALL, T-ALL cell lines (MOLT-4 and CUTLL1) were treated with BP-1-102, a small-molecule inhibitor that blocks STAT3 phosphorylation. Cell Counting Kit-8 assay and colony formation assay results showed that BP-1-102 inhibited T-ALL cell proliferation and colony formation. Flow cytometry and morphological results demonstrated that BP-1-102 dramatically induced apoptosis and caused cell cycle arrest at the G0/G1 phase in T-ALL cell lines. Western blotting results indicated that BP-1-102 suppressed the JAK2/STAT3/c-Myc pathway activity in T-ALL cell lines. In conclusion, BP-1-102 suppressed the JAK2/STAT3/c-Myc signaling pathway in T-ALL cells and exerted various antitumor effects, representing a promising targeted antitumor inhibitor.
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Atmospheric ammonia (NH3) plays an important role in secondary inorganic aerosol formation. Understanding the temporal variations, sources, and environmental influences of NH3 is conducive to better formulate PM2.5 pollution control strategies for policy-makers. Here, we performed a comprehensive field campaign with the measurements of NH3 and related parameters at a rural site of the North China Plain (NCP) in winter of 2017. The results showed that residential coal combustion contributed dominantly to NH3 during the entire observation period, resulting in the obviously high average concentration of NH3 (31.2 ± 24.6 ppbv). The sensitivity tests of pH-NHx during the three different pollution periods suggested that the rural site was always in the NHx-rich atmosphere where high levels of NHx increased the particle pH inefficiently. Nevertheless, the particle pH still elevated by 1.5-2.2 units at the excessive NHx levels during the three pollution periods. In addition, the HONO/NO2 ratios were found to correlate linearly with NH3 concentrations, implying the acceleration effect of NH3 on HONO production from NO2 heterogeneous reactions. After considering the NH3-enhanced uptake coefficient of NO2 in the nocturnal HONO budget, the unknown source of HONO could be fully explained. Therefore, more attentions should be given for effective emission control of NH3 to improve air quality throughout the NCP, especially in the rural areas.
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Poluentes Atmosféricos , Amônia , Amônia/análise , Poluentes Atmosféricos/análise , Dióxido de Nitrogênio , Monitoramento Ambiental , China , Aerossóis/análiseRESUMO
Sulfate aerosol contributes to particulate matter pollution and plays a key role in aerosol radiative forcing, impacting human health and climate change. Atmospheric models tend to substantially underestimate sulfate concentrations during haze episodes, indicating that there are still missing mechanisms not considered by the models. Despite recent good progress in understanding the missing sulfate sources, knowledge on different sulfate formation pathways during polluted periods still involves large uncertainties and the dominant mechanism is under heated debate, calling for more field, laboratory, and modeling work. Here, we review the traditional sulfate formation mechanisms in cloud water and also discuss the potential factors affecting multiphase S(â £) oxidation. Then recent progress in multiphase S(â £) oxidation mechanisms is summarized. Sulfate formation rates by different prevailing oxidation pathways under typical winter-haze conditions are also calculated and compared. Based on the literature reviewed, we put forward control of the atmospheric oxidation capacity as a means to abate sulfate aerosol pollution. Finally, we conclude with a concise set of research priorities for improving our understanding of sulfate formation mechanisms during polluted periods.
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Poluentes Atmosféricos , Humanos , Poluentes Atmosféricos/análise , Sulfatos/análise , Monitoramento Ambiental , Aerossóis/análise , Material Particulado/análise , Óxidos de Enxofre , ChinaRESUMO
Gas-phase hydrogen peroxide (H2O2) plays an important role in atmospheric chemistry as an indicator of the atmospheric oxidizing capacity. It is also a vital oxidant of sulfur dioxide (SO2) in the aqueous phase, resulting in the formation of acid precipitation and sulfate aerosol. However, sources of H2O2 are not fully understood especially in polluted areas affected by human activities. In this study, we reported some high H2O2 cases observed during one summer and two winter campaigns conducted at a polluted rural site in the North China Plain. Our results showed that agricultural fires led to high H2O2 concentrations up to 9 ppb, indicating biomass burning events contributed substantially to primary H2O2 emission. In addition, elevated H2O2 and O3 concentrations were measured after fertilization as a consequence of the enhanced atmospheric oxidizing capacity by soil HONO emission. Furthermore, H2O2 exhibited unexpectedly high concentration under high NOx conditions in winter, which are closely related to multiphase reactions in particles involving organic chromophores. Our findings suggest that these special factors (biomass burning, fertilization, and ambient particles), which are not well considered in current models, are significant contributors to H2O2 production, thereby affecting the regional atmospheric oxidizing capacity and the global sulfate aerosol formation.
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Poluentes Atmosféricos , Peróxido de Hidrogênio , Aerossóis/análise , Poluentes Atmosféricos/análise , Biomassa , China , Monitoramento Ambiental , Fertilização , Humanos , Nitrogênio , Material Particulado/análise , SulfatosRESUMO
Small B-cell lymphoma is the classification of B-cell chronic lymphoproliferative disorders that include chronic lymphocytic leukaemia/small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia. The clinical presentation is somewhat heterogeneous, and its occurrence and development mechanisms are not yet precise and may involve epigenetic changes. Epigenetic alterations mainly include DNA methylation, histone modification, and non-coding RNA, which are essential for genetic detection, early diagnosis, and assessment of treatment resistance in small B-cell lymphoma. As chronic lymphocytic leukemia/small lymphocytic lymphoma has already been reported in the literature, this article focuses on small B-cell lymphomas such as follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, and Waldenstrom macroglobulinemia. It discusses recent developments in epigenetic research to diagnose and treat this group of lymphomas. This review provides new ideas for the treatment and prognosis assessment of small B-cell lymphoma by exploring the connection between small B-cell lymphoma and epigenetics.
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Leucemia Linfocítica Crônica de Células B , Linfoma de Zona Marginal Tipo Células B , Linfoma Folicular , Linfoma de Célula do Manto , Macroglobulinemia de Waldenstrom , Adulto , Epigênese Genética , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Linfoma de Zona Marginal Tipo Células B/diagnóstico , Linfoma de Zona Marginal Tipo Células B/genética , Linfoma de Zona Marginal Tipo Células B/patologia , Linfoma Folicular/diagnóstico , Linfoma de Célula do Manto/diagnóstico , Linfoma de Célula do Manto/genética , Linfoma de Célula do Manto/patologia , Macroglobulinemia de Waldenstrom/diagnóstico , Macroglobulinemia de Waldenstrom/genética , Macroglobulinemia de Waldenstrom/patologiaRESUMO
B-acute lymphoblastic leukemia (B-ALL) is characterized by clonal expansion of immature B-lymphocytes in the bone marrow, blood, or other tissues. Chromosomal translocations have often been reported in B-ALL, which are important for its prognosis. B-ALL patients with ETV6-RUNX1 fusion have favorable outcomes, but the mechanisms remain to be clarified. In the present study, we crossed the selected WGCNA module genes and differential expression genes to obtain core genes, and random forest algorithm, a type of supervised learning analysis, was conducted to evaluate the importance of those core genes in distinguishing B-ALL samples with ETV6-RUNX2 fusion with extracting 5 genes as gene markers for ETV6-RUNX2 fusion. Moreover, we calculated the immune infiltration profiles and screened out the ETV6-RUNX2 association immune cells using the CIBERSORT algorithm. In conclusion, combined with various solid informatics methods, we depicted the underlying molecular and immune mechanism of ETV6-RUNX2 fusion and providing potential biological targets for diagnosing and treating B-ALL in the future.
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Subunidade alfa 2 de Fator de Ligação ao Core/genética , Proteínas de Fusão Oncogênica/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/mortalidade , Proteínas Proto-Oncogênicas c-ets/genética , Proteínas Repressoras/genética , Biomarcadores Tumorais/genética , Biologia Computacional , Regulação Leucêmica da Expressão Gênica , Redes Reguladoras de Genes , Humanos , Estimativa de Kaplan-Meier , Leucemia-Linfoma Linfoblástico de Células Precursoras B/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras B/imunologia , Prognóstico , Microambiente Tumoral/genética , Microambiente Tumoral/imunologia , Variante 6 da Proteína do Fator de Translocação ETSRESUMO
Atmospheric hydrogen peroxide (H2O2), as an important oxidant, plays a key role in atmospheric sulfate formation, affecting the global radiation budget and causing acid rain deposition. The disproportionation reactions of hydroperoxyl radicals (HO2) in both gas and aqueous phases have long been considered as dominant sources for atmospheric H2O2. However, these known sources cannot explain the significant formation of H2O2 in polluted areas under the conditions of high NO levels and low ambient relative humidity (RH). Here, we show that under relatively dry conditions during daytime, atmospheric fine particles directly produce abundant gas-phase H2O2. The formation of H2O2 is verified to be by a reaction between the particle surface -OH group and HO2 radicals formed by photooxidation of chromophoric dissolved organic matters (CDOMs), which is slightly influenced by the presence of high NO levels but remarkably accelerated by water vapor and O2. In contrast to aqueous-phase chemistry, transition metal ions (TMIs) are found to significantly suppress H2O2 formation from the atmospheric fine particles. The H2O2 formed from relatively dry particles can be directly involved in in situ SO2 oxidation, leading to sulfate formation. As CDOMs are ubiquitous in atmospheric fine particles, their daytime photochemistry is expected to play important roles in formation of H2O2 and sulfate worldwide.