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Polar stratospheric clouds (PSCs), of which the surface is a dynamic liquid water layer and might consist of aqueous HNO 3 and H 2 O 2 , is a well-known key meteorological condition contributing to the ozone hole in the polar stratosphere. PSCs has been considered to provide abundant surface for the heterogeneous reactions causing the formation of the Cl 2 and HOCl, which are further photolyzed into Cl and ClO radicals leading to the ozone destruction. Here we demonstrated that the sunlight drives the massive and stable production of OH radicals in aqueous HNO 3 and its main photo-induced byproduct HNO 2. We also found that the photo-generated OH radicals in aqueous HNO 3 , HNO 2 and H 2 O 2 have the remarkable capability to react with the dissolved HCl, Cl− and Br− to form halogen radicals. In addition, we observed that the H 2 O 2 can react with dissolved HCl and Br− in darkness to form and release Cl 2 and Br 2 gases, which could further be photolyzed into reactive halogen radicals whenever sunlight is available. All these findings suggest that, except for the well-known heterogeneous reactions, photochemical reactions involving the aqueous HNO 3 and H 2 O 2 on and within PSCs surface might constitute another important halogen activation pathway for ozone destruction. This study may shed deeper insights into the mechanism of halogen radicals resulting in ozone depletion in polar stratosphere. [Display omitted] • Photo-generated OH radicals were determined in sunlight-irradiated HNO 3 and HNO 2. • The OH radicals react with dissolved inorganic halides to form halogen radicals. • The H 2 O 2 reacts with HCl and Br− to form and release Cl 2 and Br 2 gases in darkness. • Mechanism on photo-generation of halogen radicals on/within PSCs surface were proposed. [ABSTRACT FROM AUTHOR]

Abstract: The FeNi alloy nanoparticles (FeNi and BFeNi) supported on natural halloysite nanotubes (HNTs) were prepared for catalytic decomposition of toxic phosphine (PH3) to yellow phosphorus and hydrogen. The Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma, scanning electron microscope, and hydrogen temperature-programmed reduction tests were carried out to characterize the physicochemical properties of HNTs and the prepared nano-catalysts. Nearly 100% PH3 was decomposed into yellow phosphorus and hydrogen at 420°C with prepared FeNi/HNTs catalysts. Metallic Ni and Fe3O4 could be the catalytic active sites in FeNi/HNTs for PH3 decomposition under the low temperature. The boron (B) additives decrease the catalytic activity of FeNi/HNTs for PH3 decomposition due to the formation of the spinal NiFe2O4 and Fe2B which replace the active Fe3O4 and metallic Ni in catalysts. The developed FeNi/HNTs are low-cost and effective catalysts for air-pollution control and recycle of the hazardous waste PH3 gas in industry. [Copyright &y& Elsevier]

This study aimed to characterize PM 2.5 -bound trace elements in Northern Zhejiang Province (NZP), one of the most economically prosperous regions in China, and assess the associated health risks for the general populations. A year-long sampling campaign was conducted at four sites representative of urban, suburban, and rural areas of NZP. The average of the sum of twenty trace elements in PM 2.5 was 2.8 ± 0.4 μg m−3, dominated by K, Al, Fe, Mg, Zn, and V (>100 ng m−3). The highest total elements' concentration occurred in winter, followed by autumn, spring, and summer. Enrichment factors and principal component analysis (PCA) revealed that the major sources of trace elements in NZP were fossil fuel combustion, biomass burning, crustal dust, traffic, and industrial emissions. Elevated concentrations of certain elements reflected featured sources in different areas, e.g., V and Ni from heavy oil combustion in the port city, and Cu, Fe and Ba from traffic emissions in urban areas. Arsenic (As) represented the major non-cancer risk driver as its hazard quotient was 8.7. The cumulative cancer risk from all the carcinogenic elements was 1.7 × 10−3 in NZP, exceeding the upper limit (10−4) of the acceptable risk range. As and Cr contributed 33% and 66%, respectively, and thus were regarded as cancer risk drivers. The high health risks from PM 2.5 -bound elements warrant future actions to control their emissions in this region. Priorities should target industrial operations and coal combustion emissions, as informed by the risk drivers. [Display omitted] • Trace element levels exhibited a seasonality of winter > autumn > spring > summer. • Elements were mostly anthropogenic except for Mg, Sr, and Fe. • Shipping emissions dominated the port city. • Arsenic was the non-cancer risk driver with a hazard quotient of 8.7. • The cumulative cancer risk was 1.7 × 10−3, with chromium and arsenic as drivers. [ABSTRACT FROM AUTHOR]

Photolysis of pesticides has been widely investigated for evaluating their environmental behavior and agricultural effectiveness after crop spraying. However, little information about the effects of the water-soluble substances in atmosphere on photodegradation of pesticides is available. In current study, we found that photolysis of applied dithianon fungicides on real plant leaves was much faster than that in sealed stock aqueous suspensions under simulated sunlight. To simulate the natural conditions, for the first time, photodegradation of dithianon in air-saturated solutions containing typical dissolved atmospheric substances (DAS) including CO 2 (HCO 3 −/CO 3 2−), NO 2 (NO 3 −), Fe3+ (Fe3+-complexes), and humic-like substances (HULIS) exposed to simulated solar irradiations were carried out in lab-scale. Fulvic acid (FA) was used as a surrogate for atmospheric HULIS in this study. The dithianon photodegradation was significantly enhanced in the presence of DAS and the photo-generated reactive species such as ·OH, 1O 2 , CO 3 ·- and 3FA∗ play important roles according to the results of reactive species quenching, electron spin resonance spectroscopy, and laser flash photolysis experiments. Moreover, the photodegraded intermediates and final products of dithianon on plant leaves have been identified by HPLC-MS analysis, and its possible photodegradation pathways were proposed. This work indicated that, except for direct photolysis, indirect photosensitive degradation induced by the dissolved photo-active substances in atmosphere should be considered for evaluating the degradation of the applied pesticides on crops. Image 1 • Dithianon photolysis on plant leaves was faster than that in sealed aqueous solution. • Dissolved atmospheric substances accelerate the photodegradation of dithianon. • · OH, 1O 2 , CO 3 · - and 3HULIS ∗ play key roles for indirect photolysis of dithianon. • Photodegradation pathways of dithianon fungicides on plant leaves were proposed. [ABSTRACT FROM AUTHOR]