Chemical composition, oxidative potential and identifying the sources of outdoor PM2.5 after the improvement of air quality in Beijing

Oxidative Potential of Metal-Containing Nanoparticles in Coal Fly Ash Generated from Coal-Fired Power Plants in China

“…In addition, as presented in Figure A, the highest OP AA value of 14.6 nmol AA min –1 μg –1 was obtained for sample #32 from the Henan group, which could be attributed to the highest concentrations of Fe, Se, W, and U in <1 μm fractions of this sample. This value is 3 orders of magnitude higher than the highest OP value for atmospheric PM 2.5 in Beijing . The OP AA of <1 μm fractions in sample #28 (9.4 nmol AA min –1 μg –1 ) from the Hebei group were 4 times higher than the average OP AA of <1 μm fractions in all 56 CFA samples.…”

“…Previous studies have confirmed the facilitating effects of these elements in ROS generation and transformation in the lung cells. − It is noted that the TOC also exhibited a positive correlation with OP AA . It is not difficult to understand that TOC stands for the fly ash’s organic components, including environmentally persistent free radicals, which have been demonstrated to potentially interact with antioxidants during inhalation and respiratory deposition. ,, …”

“…The oxidative potential of each <1 μm fraction in CFA samples was assessed using the AA assay. ,, MQ, GS, and ALF were used to simulate the normal conditions of respiratory tract, lung interstitial environment, and alveolar macrophage environment, with the detailed recipes in Table S4. By mixing the extracted <1 μm fractions of CFA samples with three simulated solutions, 160 μL of the mixed solution was placed in a quartz 96-well plate, and 40 μL of 1 mmol L –1 AA solution was spiked into the mixture.…”

“…Extensive studies suggest that NPs can cause adverse cardiorespiratory end points. − Oxidative stress is identified as the dominant mechanism of NPs exposure causing respiratory and chronic cardiopulmonary diseases, mediated by reactive oxygen species (ROS) including hydrogen peroxide (H 2 O 2 ), superoxide (O 2 – ), and hydroxyl radicals (OH – ). − ROS can enter the body by inhalation of ROS-bound particles and through the generation of ROS by cellular redox reactions of soluble transition metals in the inhaled particles. , Oxidative stress caused by excessive ROS concentrations can lead to changes of the redox state in cells, which in turn can trigger or exacerbate inflammation in the respiratory and cardiovascular systems . Oxidation potential (OP) is widely used as a metric for health effects of particles. − Dithiothreitol (DTT) assay and ascorbic acid (AA) assay are two methods widely used for the determination of OP in lung fluids of atmospheric PM, among which the AA assay was proven to be more suitable for metal-containing particles. For example, Lin and Yu found that metals (Fe and Cu) are catalysts for AA oxidation consumption in the reaction system of the AA assay.…”

Oxidative Potential Characterization of Different PM2.5 Sources and Components in Beijing and the Surrounding Region

“…A p and A t are the intercepted membrane area and the total membrane area, respectively. V r and V e are the volumes of the participating and total extraction solutions, respectively [ 22 ].…”