Distributions and sources of low-molecular-weight monocarboxylic acids in gas and particles from a deciduous broadleaf forest in northern Japan

To better understand the distributions and sources of low-molecular-weight (LMW) monocarboxylic acids (monoacids) in the forest atmosphere, we conducted simultaneous collection of gaseous and particulate samples at a deciduous broadleaf forest site in northern Japan. LMW normal (C1–C10), branched (iC4–iC6), hydroxyl (glycolic and lactic) and aromatic (benzoic) monoacids were detected in the gas and particle phases. The dominant LMW monoacids in gas phase were formic (mean: 953&thinsp;ng&thinsp;m−3) and acetic (528&thinsp;ng&thinsp;m−3) acids followed by propionic (37&thinsp;ng&thinsp;m−3) or isopentanoic (42&thinsp;ng&thinsp;m−3) acid. In the particle phase, isopentanoic (159&thinsp;ng&thinsp;m−3) was dominant, followed by acetic (104&thinsp;ng&thinsp;m−3) and formic (71&thinsp;ng&thinsp;m−3) or lactic (65&thinsp;ng&thinsp;m−3) acids. Concentrations of LMW monoacids did not show correlations with anthropogenic tracers such as nss-SO42- and NO3-, indicating that anthropogenic contribution is not important. Concentrations of C1–C6 monoacids in the gas phase showed positive correlations (r2=0.21–0.91) with isobutyric acid (iC4), which may be produced by microbial activity in soil. The forest soil may be a source of gaseous C1–C6 monoacids in the forest atmosphere. Acetic acid in the particle phase positively correlated with nonanoic acid (C9) (r2=0.63), suggesting that formation of acetic and nonanoic acids is associated with the oxidation of biogenic unsaturated fatty acids in the aerosol phase, in addition to photochemical oxidation of biogenic volatile organic compounds. The particle-phase fractions (Fp) of formic and acetic acids showed negative correlation with ambient temperature (C1: r2=0.49, C2: r2=0.60) but showed positive correlation with relative humidity (C1: r2=0.30, C2: r2=0.55) in daytime, suggesting that these meteorological parameters are important for the gas and particle portioning of monoacids in the forest atmosphere.</p

3′-[Hy­droxy(4-oxo-4H-chromen-3-yl)meth­yl]-2-oxospiro­[indoline-3,2′-pyrrolidine]-3′-carbonitrile

In the title compound, C23H19N3O4, the pyran ring adopts a half-chair conformation, while the pyrrolidine (with a C atom as the flap atom) and the five-membered ring in the indoline (with a C atom as the flap atom) ring system adopt slight envelope conformations. The pyrrolidine ring makes dihedral angles of 83.3 (1) and 60.4 (1)° with the mean plane through all non-H atoms of the indoline and chromene ring systems, respectively. In the crystal, mol­ecules are connected by two unique N—H⋯O and O—H⋯O hydrogen-bonding inter­actions, which form centrosymmetric patterns described by graph-set motifs R 2 2(18) and R 2 2(14). These two motifs combine to form a hydrogen-bonded chain which propagates in the a-axis direction. The crystal structure is also stablized by C—H⋯O inter­actions and by aromatic π–π stacking inter­actions between the pyran and benzene rings of neighbouring mol­ecules [centroid–centroid distance = 3.755 (1) Å and slippage = 1.371 (2) Å]

Role of Mitochondrial Electron Transport Chain Complexes in Capsaicin Mediated Oxidative Stress Leading to Apoptosis in Pancreatic Cancer Cells

We evaluated the mechanism of capsaicin-mediated ROS generation in pancreatic cancer cells. The generation of ROS was about 4–6 fold more as compared to control and as early as 1 h after capsaicin treatment in BxPC-3 and AsPC-1 cells but not in normal HPDE-6 cells. The generation of ROS was inhibited by catalase and EUK-134. To delineate the mechanism of ROS generation, enzymatic activities of mitochondrial complex-I and complex-III were determined in the pure mitochondria. Our results shows that capsaicin inhibits about 2.5–9% and 5–20% of complex-I activity and 8–75% of complex-III activity in BxPC-3 and AsPC-1 cells respectively, which was attenuable by SOD, catalase and EUK-134. On the other hand, capsaicin treatment failed to inhibit complex-I or complex-III activities in normal HPDE-6 cells. The ATP levels were drastically suppressed by capsaicin treatment in both BxPC-3 and AsPC-1 cells and attenuated by catalase or EUK-134. Oxidation of mitochondria-specific cardiolipin was substantially higher in capsaicin treated cells. BxPC-3 derived ρ0 cells, which lack mitochondrial DNA, were completely resistant to capsaicin mediated ROS generation and apoptosis. Our results reveal that the release of cytochrome c and cleavage of both caspase-9 and caspase-3 due to disruption of mitochondrial membrane potential were significantly blocked by catalase and EUK-134 in BxPC-3 cells. Our results further demonstrate that capsaicin treatment not only inhibit the enzymatic activity and expression of SOD, catalase and glutathione peroxidase but also reduce glutathione level. Over-expression of catalase by transient transfection protected the cells from capsaicin-mediated ROS generation and apoptosis. Furthermore, tumors from mice orally fed with 2.5 mg/kg capsaicin show decreased SOD activity and an increase in GSSG/GSH levels as compared to controls. Taken together, our results suggest the involvement of mitochondrial complex-I and III in capsaicin-mediated ROS generation and decrease in antioxidant levels resulting in severe mitochondrial damage leading to apoptosis in pancreatic cancer cells

A 12-year observation of water-soluble ions in TSP aerosols collected at a remote marine location in the western North Pacific : an outflow region of Asian dust

In order to characterize the long-term trend of remote marine aerosols, a 12-year observation was conducted for water-soluble ions in TSP (total suspended particulate) aerosols collected from 2001 to 2012 in the Asian outflow region at Chichijima Island in the western North Pacific. We found a clear difference in chemical composition between the continentally affected and marine background air masses over the observation site. Asian continental air masses are delivered from late autumn to spring, whereas marine air masses were dominated in summer. Concentrations of non-sea salt (nss-) SO42-, NO3-, NH4+, nss-K+ and nss-Ca2+ are high in winter and spring and low in summer. On the other hand, MSA(-) (methanesulfonate) exhibits higher concentrations during spring and winter, probably due to springtime dust bloom or due to the direct continental transport of MSA(-) to the observation site. We could not find any clear decadal trend for Na+, Cl-, Mg2+ and nss-Ca2+ in all seasons, although there exists a clear seasonal trend. However, concentrations of nss-SO42- continuously decreased from 2007 to 2012, probably due to the decreased SO2 emissions in East Asia especially in China. In contrast, nss-K+ and MSA(-) concentrations continuously increased from 2001 to 2012 during winter and spring seasons, demonstrating that biomass burning and/or terrestrial biological emissions in East Asia are being increasingly transported from the Asian continent to the western North Pacific. This study also demonstrates that Asian dusts can act as an important source of nutrients for phytoplankton and thus sea-to-air emission of dimethyl sulfide over the western North Pacific

Hygroscopic properties of particles nebulized from water extracts of aerosols collected at Chichijima Island in the western North Pacific: An outflow region of Asian dust

We present 2 year measurements of hygroscopic properties of water-soluble matter (WSM) extracted from marine aerosols from remote Chichijima Island in the western North Pacific during 2001-2002. Hygroscopic growth factors (g) of WSM were measured by a hygroscopicity tandem differential mobility analyzer with initial dry particle diameter of 100 nm. The observed g at 90% relative humidity (RH), g(90%), ranged from 1.42 to 1.89 with an average of 1.790.11. The g values are significantly lower than that of seawater (2.1) and slightly lower than those previously reported for marine aerosols (>1.8), probably due to the atmospheric processing associated with chlorine depletion; mean Cl-/Na+ molar ratio (1.100.23) was smaller than seawater (1.18), and organometal interaction (e.g., formation of water-insoluble calcium oxalate, g(90%)<1). Inorganic salts accounted for 87-98% of WSM. Na+ and Cl- are two major species, contributing 63% of total inorganic ion mass. The calculated aerosol water content (V-w/V-dry) at 85% RH during hydration experiment ranged from 1 to 3.66 (mean of 2.750.81). V-w/V-dry is negatively correlated with organic mass fraction, indicating that organics may suppress the hygroscopicity of the marine aerosol particles. The declined g(90%) and Cl-/Na+ molar ratio and increased abundance of water-soluble organics in spring demonstrated that the atmospheric mixing of anthropogenic pollutants (e.g., NO3, SOx) and water-soluble organics can decrease the growth factor of marine aerosols. The two case studies of spring aerosols demonstrated that Asian dusts were internally mixed with hygroscopic species in different ways, depending on their transport pathway

Long-term (2001-2012) observation of the modeled hygroscopic growth factor of remote marine TSP aerosols over the western North Pacific : impact of long-range transport of pollutants and their mixing states

In order to assess the seasonal and annual variability of long-range transported anthropogenic pollutants from East Asia and their effect on the hygroscopicity and precipitation process over the western North Pacific, we conducted long-term calculations of bulk hygroscopicity, g(90%)(ZSR), based on the ZSR model using chemical composition data from 2001-2012 at Chichijima Island. We found that sea-salts (Na+ and Cl-) are the major mass fraction (65%) of the total water-soluble matter followed by SO42- (20%) and WSOM (6%). The seasonal variation of g(90%)(ZSR) was high in summer to autumn and low in winter to spring months, probably due to the influence of the long-range transport of anthropogenic SO42-, dust, and organics from East Asia and their interaction with sea-salts through heterogeneous reactions. On the other hand, annual variations of g(90%)(ZSR) showed a decrease from 2001 to 2006 and then an increase from 2007 to 2012. Interestingly, the annual variations in SO42- mass fractions showed an increase from 2001 to 2006 and then a decrease from 2007 to 2012, demonstrating that SO42- seriously suppresses the hygroscopic growth of sea-salt particles over the western North Pacific. This is further supported by the strong negative correlation between SO42- and g(90%)(ZSR). Based on the MODIS satellite data, the present study demonstrates that long-range transported anthropogenic pollutants from East Asia to the North Pacific can act as efficient cloud condensation nuclei but significantly suppress the precipitation by reducing the size of cloud droplets over the western North Pacific

Hygroscopic behavior of water-soluble matter extracted from biomass burning aerosols collected at a rural site in Tanzania, East Africa

In this study, we present the hygroscopic behavior of water-soluble matter (WSM) extracted from biomass burning derived particulate matter 2.5 (PM2.5) aerosols collected at a rural background site in Tanzania during June-August 2011. Hygroscopic growth factors, g(RH), of WSM were measured by hygroscopic tandem differential mobility analyzer (H-TDMA) with an initial dry particle diameter of 100 nm. We observed that the g(RH) of WSM at 90% relative humidity (RH), g(90%)(WSM), ranged from 1.10 to 1.47 with an average of 1.25 +/- 0.12. The H-TDMA retrieved hygroscopicity parameter of WSM, kappa(WSM), ranged from 0.04 to 0.24 with a mean of 0.11 +/- 0.07. We found that the observed g(90%)(WSM) is positively correlated with PM2.5 mass fractions of K+ (R-2 = 0.61), Cl- (0.54), and organic carbon (0.58). Moreover, it well correlates with levoglucosan (0.67) and total diacids (0.76), implying that although the inorganic fraction may be the most important factor to control the hygroscopicity; biomass burning organics play a significant role in the hygroscopicity of Tanzanian aerosols. The lower growth factors obtained over the sampling site are probably due to the formation of less water-soluble potassium oxalate (K2C2O4) or less hygroscopic K2SO4 particles during atmospheric aging. We observed a moderate correlation (R-2 = 0.33) between PM2.5 mass fraction of WSOC and g(90%)(WSM). The retrieved g(90%)(WSOM) values ranged from 1.0 to 1.25 with a mean of 1.16 +/- 0.05. This study demonstrates that the hygroscopicity of Tanzanian aerosols is largely controlled by the emission of biomass burning products and the subsequent chemical aging during atmospheric transport

Seasonal and longitudinal distributions of atmospheric water-soluble dicarboxylic acids, oxocarboxylic acids, and α-dicarbonyls over the North Pacific

In order to assess the seasonal variability of atmospheric abundances of dicarboxylic acids, oxocarboxylic acids, and -dicarbonyls over the North Pacific and Sea of Japan, aerosol samples were collected along the longitudinal transacts during six cruises between Canada and Japan. The back trajectory analyses indicate that aerosol samples collected in winter and spring are influenced by the East Asian outflow, whereas summer and fall samples are associated with the pristine maritime air masses. Molecular distributions of water-soluble organics in winter and spring samples show the predominance of oxalic acid (C-2) followed by succinic (C-4) and malonic acids (C-3). In contrast, summer and fall marine aerosols are characterized by the predominance of C-3 over C-4. Concentrations of dicarboxylic acids were higher over the Sea of Japan than the North Pacific. With a lack of continental outflow, higher concentrations during early summer are ascribed to atmospheric oxidation of organic precursors associated with high biological activity in the North Pacific. This interpretation is further supported by the high abundances of azelaic acid, which is a photochemical oxidation product of biogenic unsaturated fatty acids, over the Bering Sea in early summer when surface waters are characterized by high biological productivity. We found higher ratios of oxalic acid to pyruvic and glyoxylic acids (C-2/Pyr and C-2/C-2) and glyoxal and methylglyoxal (C-2/Gly and C-2/MeGly) in summer and fall than in winter and spring, suggesting a production of C-2 from the aqueous-phase oxidation of oceanic isoprene. In this study, dicarboxylic acids account for 0.7-38% of water-soluble organic carbon