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Abstract Atmospheric organic aerosol (OA) are considered as a significant contributor to the light absorption of OA, but its relationship with abundance, composition and sources are not understood well. In this study, the abundance, chemical structural characteristics, and light absorption property of HULIS and other low-to-high polar organics in PM0.95 collected in Tomakomai Experimental Forest (TOEF) were investigated with consideration of their possible sources. HULIS were the most abundant (51%), and correlation analysis revealed that biogenic secondary organic aerosols significantly contribute to HULIS. The mass spectra obtained using a high-resolution aerosol mass spectrometer (HR-AMS) showed that HULIS and highly polar water-soluble organic matter (HP-WSOM) were substantially oxygenated organic aerosol fractions, whereas water-insoluble organic matter (WISOM) had a low O/C ratio and more hydrocarbon-like structures. The WISOM fraction was the predominant light-absorbing organics. HULIS and WISOM showed a noticeable seasonal change in mass absorption efficiency (MAE365), which was highest in winter. Further, HULIS were shown to be less absorbing than those reported for urban sites. The findings in this study provide insights into the contribution of biogenic secondary OA on aerosol property and radiative forcing under varying contributions from other types of OA.

Purpose: To report a case of subarachnoid hemorrhage-negative Terson syndrome following intracranial artery treatment with flow diverter stents. Observations: A 40-year-old Asian woman presented with floaters in her right eye after treatment of an intracranial aneurysm with flow diverter stents. Vitreous hemorrhage and sub-inner limiting membrane (sub-ILM) hemorrhage were present in her right eye. On fluorescein angiography, contrast perfusion and vascular occlusion were not noted. Magnetic resonance imaging (MRI) did not show any evidence of subarachnoid hemorrhage (SAH). We hypothesize that the bleeding was due to Terson syndrome associated with intracranial treatment with the flow diverter stents. During follow-up, the vitreous hemorrhage and sub-ILM hemorrhage disappeared, and the floaters in her vision improved. Conclusions and Importance: This is the first reported case of vitreous hemorrhage and sub-ILM hemorrhage that should be considered to be Terson syndrome, after flow diverter stents treatment in the absence of SAH.

Abstract To better understand the impact of East Asian pollutants on the molecular composition of marine organic aerosols, we conducted long-term (2001–2013) observations of water-soluble dicarboxylic acids and related compounds in total suspended particulate samples collected at Chichijima Island in the western North Pacific (WNP). Seasonal variations of all the diacids and related compounds showed maxima in winter and spring and minima in summer, except for azelaic acid (C9), which maximized in summer to autumn. The overall annual concentrations of the total diacids, ω-oxoacids and α-dicarbonyls showed an increase during 2001–2013. We found a significant (p 0.05) acids, and methylglyoxal (MeGly). In contrast, phthalic acid (p < 0.05) and glyoxal (Gly) showed a decrease in their trends. We also found a significant decrease in the trend of the Gly/MeGly mass ratios. These results demonstrate that the enhanced concentrations of diacids over the WNP are majorly attributed to the aqueous-phase photooxidation of biogenic volatile organic compounds from East Asia followed by long-range atmospheric transport. Further, positive matrix factorization analysis showed a biogenic photochemical contribution (42%) was the dominant source of oxalic acid in the WNP.

Abstract Biogenic organic aerosols can affect cloud condensation nuclei (CCN) properties, and subsequently impact climate change. Large uncertainties exist in how the difference in the types of terrestrial biogenic sources and the abundance of organics relative to sulfate affect CCN properties. For the submicron water-soluble aerosols collected for two years in a cool-temperate forest in northern Japan, we show that the hygroscopicity parameter κCCN (0.44 ± 0.07) exhibited a distinct seasonal trend with a minimum in autumn (κCCN = 0.32–0.37); these κCCN values were generally larger than that of ambient particles, including water-insoluble fractions. The temporal variability of κCCN was controlled by the water-soluble organic matter (WSOM)-to-sulfate ratio (R2 > 0.60), where the significant reduction of κCCN in autumn was linked to the increased WSOM/sulfate ratio. Positive matrix factorization analysis indicates that α-pinene-derived secondary organic aerosol (SOA) substantially contributed to the WSOM mass (~75%) in autumn, the majority of which was attributable to emissions from litter/soil microbial activity near the forest floor. These findings suggest that WSOM, most likely α-pinene SOA, originated from the forest floor can significantly suppress the aerosol CCN activity in cool-temperate forests, which have implications for predicting climate effects by changes in biogenic emissions in future.

We present the case of an 86-year-old woman who developed a blowout fracture after Descemet's stripping automated endothelial keratoplasty (DSAEK). Sixteen months after DSAEK, she suffered a blow to her left eye caused by a fall. Computed tomography confirmed the presence of a blowout fracture of the inferior wall of the left orbit with soft tissue prolapsing into the orbit. The patient complained of no abnormal symptoms, and her operated cornea was intact and clear. There was no abnormal finding in both the anterior and posterior segments. This case highlights that the DSAEK technique provides adequate tectonic stability of the globe throughout the traumatic event in contrast to penetrating keratoplasty, which can lead to devastating vision damage after trauma.

Tropical aerosols of PM2.5 and PM10 were collected at a rural site in Morogoro, Tanzania (East Africa), and analysed for stable carbon isotopic composition (δ13C) of dicarboxylic acids (C2–C9), glyoxylic acid (ωC2) and glyoxal (Gly) using gas chromatography/isotope ratio mass spectrometer. PM2.5 samples showed that δ13C of oxalic (C2) acid are largest (mean, −18.3±1.7‰) followed by malonic (C3, −19.6±1.0‰) and succinic (C4, −21.8±2.2‰) acids, whereas those in PM10 are a little smaller: −19.9±3.1‰ (C2), −20.2±2.7‰ (C3) and −23.3±3.2‰ (C4). The δ13C of C2–C4 diacids showed a decreasing trend with an increase in carbon numbers. The higher δ13C values of oxalic acid can be explained by isotopic enrichment of 13C in the remaining C2 due to the atmospheric decomposition of oxalic acid or its precursors. δ13C of ωC2 and Gly that are precursors of oxalic acid also showed larger values (mean, −22.5‰ and −20.2‰, respectively) in PM2.5 than those (−26.7‰ and −23.7‰) in PM10. The δ13C values of ωC2 and Gly are smaller than those of C2 in both PM2.5 and PM10. On the other hand, azelaic acid (C9; mean, −28.5‰) is more depleted in 13C, which is consistent with the previous knowledge; that is, C9 is produced by the oxidation of unsaturated fatty acids emitted from terrestrial higher plants. A significant enrichment of 13C in oxalic acid together with its negative correlations with relative abundance of C2 in total diacids and ratios of water-soluble organic carbon and organic carbon further support that a photochemical degradation of oxalic acid occurs during long-range transport from source regions.

In this paper, we report for the first time the δ13C and δ15N data for PM2.5 and PM10 aerosols collected in Tanzania during May–August 2011 together with total carbon (TC) and nitrogen (TN) contents. Mean TC concentrations were 6.5±2.1 µg m−3 in PM2.5 and 9.2±3.5 µg m−3 in PM10. δ13C of TC ranged from −26.1 to −20.6‰ with a mean of −23.6‰ in PM2.5 and from −24.4 to −22.4‰ with a mean of −23.6‰ in PM10. We found substantially greater δ13C values in PM2.5 samples during dry season as well as strong positive correlation between levoglucosan (and nss-K+) and TC in PM2.5. These results suggest a significant contribution from burning of C4 plants to fine organic aerosol formation. TN contents showed a mean of 0.7±0.3 µg m−3 in PM2.5 and 0.8±0.2 µg m−3 in PM10. δ15N ranged from +13.4 to +22.1‰ with a mean of +16.2±2.7‰ in PM2.5 and +10.4 to +18.7‰ with a mean of +13.7±2.2‰ in PM10. δ15N showed higher ratios in fine particles than coarse particles in both wet and dry season. The relatively high δ15N values suggest isotopic enrichment of 15N in aerosols via exchange reaction between NH3 (gas) and NH4+ (particle). We found a strong correlation between TN and NH4+(r2=0.94 in PM2.5 and r2=0.86 in PM10) and NO3- (r 2=0.48 in PM2.5 and r2=0.55 in PM10). We also found that organic nitrogen is less significant than inorganic nitrogen in the Morogoro aerosols. Based on stable carbon isotopic composition, contributions of burning C3 plants to TC were estimated to range from 42 to 74% in PM2.5 and from 39 to 64% in PM10, whereas those of C4 ranged from 26 to 58% in PM2.5 and from 36 to 61% in PM10. These results suggest that burning activities of C3 and C4 plants contribute to organic aerosol formation in Tanzania.

Fatty alcohols (FAs) are major components of surface lipids in plant leaves and serve as surface-active organic aerosols (OAs), which can act as primary biological aerosol particles (PBAPs). To elucidate the origin and formation of secondary fatty alcohols (SFAs) in atmospheric aerosols, their mass size distribution in aerosol samples obtained from a deciduous forest canopy was measured in spring, summer, and autumn. The SFAs showed the highest concentration in spring (growing season), with n-nonacosan-10-ol being the most abundant. In spring and summer, the size peak of n15 nonacosan-10-ol was in particle size range >10.0 µm, whereas it was in the 1.9-3.0 µm range in autumn. The size distribution of n-nonacosan-10-ol did not show any significant correlation with that of the known biogenic tracers of pollen, soil, and fungal spores in spring and summer. The overall results, together with SFAs measured in plant leaves, as well as the literature, suggest that SFAs originate mostly from plant waxes, and that leaf senescence status is likely an important factor controlling the size distribution of SFAs. This study provides new insights into the possible sources of PBAPs and their effects on the ice nucleation activity of aerosols based on seasonal changes in particle size. [ABSTRACT FROM AUTHOR]

Fatty alcohols (FAs) are major components of surface lipids (waxes) and can act as surface-active organic aerosols in the atmosphere, influencing chemical reactions, particle lifetimes, and the formation of cloud droplets and ice nuclei. However, studies on the composition and source of the FAs in atmospheric aerosols are very limited. In this study, we identified five secondary FAs (SFAs) with C27 and C29 from aerosol samples collected throughout one year at two different deciduous forest sites in Japan. Fatty diols, such as n-heptacosan-5,10-diol, were identified in atmospheric aerosols for the first time. Among the identified SFAs, n-nonacosan-10-ol was the most abundant compound, followed by n-nonacosan-5-10-diol at both of the forest sites. Concentrations of the SFAs exhibited distinct seasonal variation, with pronounced peaks during the growing season at each forest site. The SFAs showed significant correlation with sucrose, which is used as a molecular tracer of pollen. A significant fraction of the SFAs was attributed to the submicrometer particles in the growing season. The results indicate that they originated mostly from plant wax and could be used as useful tracers for primary biological aerosol particles. [ABSTRACT FROM AUTHOR]