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Atmospheric humic-like substances (HULIS) are not only an unresolved mixture of macro-organic compounds but also powerful chelating agents in atmospheric particulate matters (PMs); impacting on both the properties of aerosol particles and health effects by generating reactive oxygen species (ROS). Currently, the interests of HULIS are intensively shifting to the investigations of HULIS-metal synergic effects and kinetics modeling studies, as well as the development of HULIS quantification, findings of possible HULIS sources and generation of ROS from HULIS. In light of HULIS studies, we comprehensively review the current knowledge of isolation and physicochemical characterization of HULIS from atmospheric samples as well as HULIS properties (hygroscopic, surface activity, and colloidal) and possible sources of HULIS. This review mainly highlights the generation of reactive oxygen species (ROS) from PMs, HULIS and transition metals, especially iron. This review also summarized the mechanism of iron-organic complexation and recent findings of OH formation from HULIS-metal complexes. This review will be helpful to carry out the modeling studies that concern with HULIS-transition metals and for further studies in the generation of ROS from HULIS-metal complexes., (Copyright © 2017. Published by Elsevier B.V.)

It is well accepted that diesel exhaust particles (DEPs) are highly associated with improper function of organ systems. In this study, DEP toxicity was performed by using in vitro human BEAS-2B cell line and in vivo animal model, namely, Caenorhabditis elegans (C. elegans). The potential toxicity of DEP was assessed by the apical endpoints of BEAS-2B cell line and reflections of C. elegans under exposure scenarios of 0~50 μg mL–1 DEP. With the increase of DEP exposure concentration, microscopic accumulations in the cytoplasm of cell line and intestine of C. elegans were observed. Such invasion of DEP impaired the behaviors of C. elegans as well as its un-exposed offspring and caused significant impeded locomotion. Moreover, the disorders of dopaminergic function were observed simultaneously under DEP exposure, specifically manifested by the decreased transcriptional expression of dat-1. The stress responses instructed by the expression of hsp-16.2 were also increased sharply in TJ375 strain of C. elegans at DEP concentrations of 1 and 10 μg mL–1. In the case of cellular reactions to DEP exposure, the injuries of membrane integrity and the decreased viability of cell line were simultaneously identified, and reactive oxygen species (ROS), damaged DNA fragment, and upregulated apoptosis were monotonically elevated in cell lines with the increase of DEP concentrations. This study provided a systematic insight into toxicity of DEP both in vivo and vitro, demonstrating that DEP exposure could disturb the stability of cell system and further threat the stability of organism. [ABSTRACT FROM AUTHOR]

Humic-like substances (HULIS), the most ubiquitous class of water-soluble organic compounds in the atmosphere could enhance the generation of reactive oxygen species (ROS), and play a significant role in impacting aerosol chemistry and health effects. In this study, twenty-three PM2.5 samples were collected in the atmosphere of suburban Shanghai from November 29 to December 17, 2015, and March 17 to April 30, 2016, during haze and non-haze days. The mean concentrations of HULIS in spring both in haze and non-haze days (2.34 ± 0.70 µg/m3 and 1.94 ± 0.88 µg/m3) were relatively higher than in that of winter (1.93 ± 0.95 µg/m3 and 1.31 ± 0.28 µg/m3). The ammonium, sulfate, and nitrate are the dominant ionic species in both winter and spring during haze days in suburban Shanghai. Correlation results revealed that HULIS formation was highly associated with the biomass burning (K) and secondary aerosols formation (SIA: NH4+, SO42−, NO3−) and also well-correlated with F− and ca.2+ ions, crustal elements (Al and Fe) and anthropogenic pollution metals (As, Se, Rb, Sr, and Pb), suggesting that HULIS-C formation might be from biomass burning and secondary aerosol processes and also mixed formation (marine, crustal and industrial emissions) sources. From the coinciding results of the clustering analysis and weighted-CWT model, the principal potential source regions were the short transports from the Yangtze River Delta (YRD) regions, local regions, marine areas (the Bohai Sea, the Yellow Sea, the East China Sea) and also the long-range transports from northwestern in those seasons. [ABSTRACT FROM AUTHOR]

The photodegradation reactions of two typical β2-adrenoceptor agonists, salbutamol (SAL) and terbutaline (TBL), alone, and in the presence of Aldrich humic acid (AHA) or Suwannee River fulvic acid (SRFA) were investigated by steady-state photolysis experiments, laser flash photolysis (LFP), kinetic modeling and quantum calculation. AHA and SRFA (2–20 mgC L−1) accelerated the phototransformation of both SAL and TBL. For SAL, an inhibiting effect of oxygen on the photodegradation was observed that is fully consistent with the main involvement of excited triplet states of HS (3HS*). On the contrary, oxygen drastically enhanced the photodegradation of TBL showing that 3HS* were negligibly involved in the reaction. The involvement of singlet oxygen was also ruled out because of the low reaction rate constant measured between TBL and singlet oxygen. Quantum calculations were therefore performed to explore whether oxygenated radicals could through addition reactions explain the differences of reactivity of TBL and SAL in oxygen medium. Interestingly, calculations showed that in the presence of oxygen, the addition of phenoxyl on TBL led to the formation of adducts and to the loss of TBL while the same addition reaction on SAL partly regenerated the starting compound and at the end degraded SAL less efficiently. This study is of high relevance to understand the processes involved in SAL and TBL phototransformation and the photoreactivity of HS. Moreover, our findings suggest that TBL might be a promising probe molecule to delineate the role of oxygenated radicals. Image 1 • HS-mediated photodegradations of Salbutamol and Terbutaline were compared. • Oxygen affected the reactions very differently. • 3HS* is responsible for Salbutamol photodegradation but not for that of terbutaline. • Quantum calculations were performed to test the effect of phenoxyl radicals. • Oxygenated radicals might be involved in the terbutaline phototransformation. [ABSTRACT FROM AUTHOR]

The cytotoxicity, apoptosis, reactive oxygen species (ROS) and DNA damage induced by the commercial diesel exhaust particulate matter (PM) (SRM2975) with concentrations ranging from 0.1 μg mL −1 to 20 μg mL −1 were assessed in human umbilical vein endothelial cells (HUVECs) in vitro. An epigenetics-wide investigation of DNA methylation profiles was also performed using a new methylation beadchip (Illumina 850 K) to identify the health effects of traffic-derived nanoparticulate matter (nPM) with a concentration of 20 μg mL −1 . By characterising its physical and chemical properties, we found that SRM2975 is a highly disordered graphitic structure material with a nanometer dimension and a large surface area. Low levels of traffic-derived nPM (≤10 μg mL −1 ) induced cell apoptosis and DNA damage as well as increased intracellular ROS levels (p < 0.001). The HUVECs showed a significantly decreased cell viability following their exposure to traffic-derived nPM with a concentration of 20 μg mL −1 (p < 0.001). A total of 149 significant differential methylated probes between the control and traffic-derived nPM treated-cells were identified, among which 86.6% were hypermethylated. A gene ontology (GO) enrichment analysis of differential methylated genes reported that the majority of the enriched GO terms were related to calcium ion and heart muscle, and further Kyoto encyclopaedia of genes and genomes (KEGG) pathway analysis indicated that the top three enriched pathways were involved in three common subtypes of cardiomyopathy. Overall, these results demonstrated that traffic-derived nPM could induce cytotoxic effects and demonstrate robust associations with cardiomyopathy though differential DNA methylation as well as the physiologic process of ROS, oxidative stress, inflammation, cell death and calcium ion channel. [ABSTRACT FROM AUTHOR]

A novel B,N-decorated carbocatalyst (Fe@BPC-XBN) for peroxymonosulfate (PMS) activation was prepared by a simple pyrolysis method using the iron-based metal organic frameworks (Fe-MOF), boric acid and boron nitride (BN) as precursors. Fe@BPC-20BN removed 93.3% of bisphenol A (BPA) in 90 min compared to 64.9%, 82.1% and 83.5% with Fe@PC, Fe@BPC and Fe@PC-20BN, respectively, with 0.15 g/L catalyst and 1 mM PMS at initial pH of 7. The solo B-doping with boron acid on the Fe-MOF derived porous carbon enhanced its catalytic capacity; moreover, B, N co-doping with BN and boron acid as precursors further promoted the catalytic performance. The addition of BN not only provided more B, N catalytic centers but also improved the stability of the carbocatalyst. In addition, hydroxyl radicals, sulfate radicals, superoxide radicals, and singlet oxygen species were involved in the degradation of BPA. Fe species, –BCO 2 /–BC 2 O, pyridinic N, and pyrrolic N groups on the carbon matrix played the important roles in the BPA degradation. The outstanding catalytic performance of Fe@BPC-20BN could be attributed to the synergistic effects between iron nanoparticles and the B/N codoped carbon matrix. This study gives new insights into the design and preparation of high-efficient B,N-decorated carbocatalysts for environmental remediation. [Display omitted] • The promoting effect of B-doping on PMS activation of the catalyst was observed. • The modification of BN improved the stability of carbocatalyst. • •OH, SO 4 •−, O 2 •−, and 1O 2 species were involved in the degradation of BPA. • The Fe species, –BCO 2 /–BC 2 O, pyridinic N, and pyrrolic N groups were active sites. [ABSTRACT FROM AUTHOR]

Humic-like substances (HULIS) were isolated from PM 2.5 in Shanghai. The oxidative potential and the cytotoxicity of the isolated HULIS and its Fe(II) binary mixtures were evaluated by using cell-free Dithiothreitol (DTT) and cellular 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Our data showed that HULIS-C contents in spring during hazy and non-hazy days were relatively higher than in winter. Cell-free DTT and bioassay (reactive oxygen species (ROS) and MTT) results showed that higher ROS values were released from individual HULIS or SRFA (Suwannee River Fulvic Acid) compounds than HULIS-Fe(II) complexes and Fe(II) alone. In addition, DTT and ROS correlation results were in line with each other and the oxidative potentials of HULIS and its binary mixtures were strongly inter-correlated with carbonaceous components (WSOC, OC) in PM 2.5. Dose-dependent MTT results revealed that cell mortality positively correlated with the mass concentrations of HULIS (10–50 μg/ml). In the HULIS-Fe(II) system, the ROS generation ability depended on the mixing time of HULIS-C with Fe(II), thus suggesting that the organic-metal complexation time and the Fenton reaction induced by Fe (II) play a role in the cell mortality rate. Image 1 • Higher reactive oxygen species from HULIS-Fe(II) complexation than Fe (II) alone. • Reactive oxygen species generation depending on the mixing time with Fe(II). • Oxidative potentials of HULIS and its binary mixtures strongly inter-correlated with WSOC/ OC. [ABSTRACT FROM AUTHOR]