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Sample records for aerosol iron solubility

  1. Dry season aerosol iron solubility in tropical northern Australia

    NASA Astrophysics Data System (ADS)

    Winton, V. Holly L.; Edwards, Ross; Bowie, Andrew R.; Keywood, Melita; Williams, Alistair G.; Chambers, Scott D.; Selleck, Paul W.; Desservettaz, Maximilien; Mallet, Marc D.; Paton-Walsh, Clare

    2016-10-01

    Marine nitrogen fixation is co-limited by the supply of iron (Fe) and phosphorus in large regions of the global ocean. The deposition of soluble aerosol Fe can initiate nitrogen fixation and trigger toxic algal blooms in nitrate-poor tropical waters. We present dry season soluble Fe data from the Savannah Fires in the Early Dry Season (SAFIRED) campaign in northern Australia that reflects coincident dust and biomass burning sources of soluble aerosol Fe. The mean soluble and total aerosol Fe concentrations were 40 and 500 ng m-3 respectively. Our results show that while biomass burning species may not be a direct source of soluble Fe, biomass burning may substantially enhance the solubility of mineral dust. We observed fractional Fe solubility up to 12 % in mixed aerosols. Thus, Fe in dust may be more soluble in the tropics compared to higher latitudes due to higher concentrations of biomass-burning-derived reactive organic species in the atmosphere. In addition, biomass-burning-derived particles can act as a surface for aerosol Fe to bind during atmospheric transport and subsequently be released to the ocean upon deposition. As the aerosol loading is dominated by biomass burning emissions over the tropical waters in the dry season, additions of biomass-burning-derived soluble Fe could have harmful consequences for initiating nitrogen-fixing toxic algal blooms. Future research is required to quantify biomass-burning-derived particle sources of soluble Fe over tropical waters.

  2. Speciation and water soluble fraction of iron in aerosols from various sources

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Kurisu, M.; Uematsu, M.

    2015-12-01

    Iron (Fe) is an essential micronutrient and has been identified as a limiting factor for phytoplankton growth in high-nitrate low-chlorophyll (HNLC) regions of the ocean. In the North Pacific, three sources of iron (Fe) transported via. atmosphere can be suggested: (i) mineral dust from East Asia, (ii) anthropogenic Fe, and (iii) aerosols from volcanic origin. Considering these different sources, Fe can be found and transported in a variety of chemical forms, both water-soluble and -insoluble. It is generally believed that only the soluble fraction of Fe can be considered as bioavailable for phytoplankton. To assess the biogeochemical impact of the atmospheric input, attempt was made to determine Fe species by X-ray absorption spectroscopy (XAS) and its water solubility, in particular to compare the three sources. Iron species, chemical composition, and soluble Fe concentration in aerosol collected at Tsukuba (Japan) through a year were investigated to compare the contributions of mineral dust and anthropogenic components. It was found that the concentration of soluble Fe in aerosol is correlated with those of sulfate and oxalate which originate from anthropogenic sources, suggesting that soluble Fe is mainly derived from anthropogenic sources. XAS analysis showed that main Fe species in aerosols in Tsukuba were illite, ferrihydrite, hornblende, and Fe(III) sulfate. Moreover, soluble Fe fraction is closely correlated with that of Fe(III) sulfate. In spite of supply of high concentrations of Fe in mineral dust from East Asia, it was found that anthropogenic fraction is important due to its high water solubility by the presence of Fe(III) sulfate. Marine aerosol samples originated from volcanic ash were collected in the western North Pacific during KH-08-2 cruise (August, 2008). XAS analysis suggested that Fe species of volcanic ashes changed during the long-range transport, while dissolution experiment showed that Fe solubility of the marine aerosol is larger than

  3. The Effect of Particle Size on Iron Solubility in Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Marcotte, A. R.; Majestic, B. J.; Anbar, A. D.; Herckes, P.

    2012-12-01

    The long range transport of mineral dust aerosols, which contain approximately 3% iron by mass, results in an estimated 14-16 Tg of iron deposited into the oceans annually; however, only a small percentage of the deposited iron is soluble. In high-nutrient, low chlorophyll ocean regions iron solubility may limit phytoplankton primary productivity. Although the atmospheric transport processes of mineral dust aerosols have been well studied, the role of particle size has been given little attention. In this work, the effect of particle size on iron solubility in atmospheric aerosols is examined. Iron-containing minerals (illite, kaolinite, magnetite, goethite, red hematite, black hematite, and quartz) were separated into five size fractions (10-2.5, 2.5-1, 1-0.5, 0.5-0.25, and <0.25μm) and extracted into buffer solutions simulating environments in the transport of aerosol particles for 150 minutes. Particle size was confirmed by scanning electron microscopy (SEM). Soluble iron content of the extracted mineral solutions was determined by inductively coupled plasma-mass spectrometry (ICP-MS). Extracted mineral solutions were also analyzed for Fe(II) and Fe(III) content using a ferrozine/UV-VIS method. Preliminary results show that differences in solution composition are more important than differences in size. When extracted into acetate and cloudwater buffers (pH 4.25-4.3), < 0.3% of the Fe in iron oxides (hematite, magnetite, and goethite) is transferred to solution as compared to ~0.1-35% for clays (kaolinite and illite). When extracted into a marine aerosol solution (pH 1.7), the percentage of Fe of the iron oxides and clays transferred to solution increases to approximately 0.5-3% and 5-70%, respectively. However, there is a trend of increased %Fe in the minerals transferred to solution in the largest and smallest size fractions (~0.01-0.3% and ~0.5-35% for iron oxides and clays, respectively), and decreased %Fe in the minerals transferred to solution in the mid

  4. Influence of measurement uncertainties on fractional solubility of iron in mineral aerosols over the oceans

    NASA Astrophysics Data System (ADS)

    Meskhidze, Nicholas; Johnson, Matthew S.; Hurley, David; Dawson, Kyle

    2016-09-01

    The atmospheric supply of mineral dust iron (Fe) plays a crucial role in the Earth's biogeochemical cycle and is of specific importance as a micronutrient in the marine environment. Observations show several orders of magnitude variability in the fractional solubility of Fe in mineral dust aerosols, making it hard to assess the role of mineral dust in the global ocean biogeochemical Fe cycle. In this study we compare the operational solubility of mineral dust aerosol Fe associated with the flow-through leaching protocol to the results of the global 3-D chemical transport model GEOS-Chem. According to the protocol, aerosol Fe is defined as soluble by first deionized water leaching of mineral dust through a 0.45 μm pore size membrane followed by acidification and storage of the leachate over a long period of time prior to analysis. To estimate the uncertainty in soluble Fe results introduced by the flow-through leaching protocol, we prescribe an average 50% (range of 30-70%) fractional solubility to sub-0.45 μm sized mineral dust particles that may inadvertently pass the filter and end up in the acidified (at pH ∼ 1.7) leachate for a couple of month period. In the model, the fractional solubility of Fe is either explicitly calculated using a complex mineral aerosol Fe dissolution equations, or prescribed to be 1% and 4% often used by global ocean biogeochemical Fe cycle models to reproduce the broad characteristics of the presently observed ocean dissolved iron distribution. Calculations show that the fractional solubility of Fe derived through the flow-through leaching is higher compared to the model results. The largest differences (∼40%) are predicted to occur farther away from the dust source regions, over the areas where sub-0.45 μm sized mineral dust particles contribute a larger fraction of the total mineral dust mass. This study suggests that different methods used in soluble Fe measurements and inconsistences in the operational definition of

  5. Constraints on soluble aerosol iron flux to the Southern Ocean at the Last Glacial Maximum

    PubMed Central

    Conway, T.M.; Wolff, E.W.; Röthlisberger, R.; Mulvaney, R.; Elderfield, H.E.

    2015-01-01

    Relief of iron (Fe) limitation in the Southern Ocean during ice ages, with potentially increased carbon storage in the ocean, has been invoked as one driver of glacial–interglacial atmospheric CO2 cycles. Ice and marine sediment records demonstrate that atmospheric dust supply to the oceans increased by up to an order of magnitude during glacial intervals. However, poor constraints on soluble atmospheric Fe fluxes to the oceans limit assessment of the role of Fe in glacial–interglacial change. Here, using novel techniques, we present estimates of water- and seawater-soluble Fe solubility in Last Glacial Maximum (LGM) atmospheric dust from the European Project for Ice Coring in Antarctica (EPICA) Dome C and Berkner Island ice cores. Fe solubility was very variable (1–42%) during the interval, and frequently higher than typically assumed by models. Soluble aerosol Fe fluxes to Dome C at the LGM (0.01–0.84 mg m−2 per year) suggest that soluble Fe deposition to the Southern Ocean would have been ≥10 × modern deposition, rivalling upwelling supply. PMID:26204562

  6. Constraints on soluble aerosol iron flux to the Southern Ocean at the Last Glacial Maximum.

    PubMed

    Conway, T M; Wolff, E W; Röthlisberger, R; Mulvaney, R; Elderfield, H E

    2015-01-01

    Relief of iron (Fe) limitation in the Southern Ocean during ice ages, with potentially increased carbon storage in the ocean, has been invoked as one driver of glacial-interglacial atmospheric CO2 cycles. Ice and marine sediment records demonstrate that atmospheric dust supply to the oceans increased by up to an order of magnitude during glacial intervals. However, poor constraints on soluble atmospheric Fe fluxes to the oceans limit assessment of the role of Fe in glacial-interglacial change. Here, using novel techniques, we present estimates of water- and seawater-soluble Fe solubility in Last Glacial Maximum (LGM) atmospheric dust from the European Project for Ice Coring in Antarctica (EPICA) Dome C and Berkner Island ice cores. Fe solubility was very variable (1-42%) during the interval, and frequently higher than typically assumed by models. Soluble aerosol Fe fluxes to Dome C at the LGM (0.01-0.84 mg m(-2) per year) suggest that soluble Fe deposition to the Southern Ocean would have been ≥10 × modern deposition, rivalling upwelling supply.

  7. Constraints on soluble aerosol iron flux to the Southern Ocean at the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Conway, T. M.; Wolff, E. W.; Röthlisberger, R.; Mulvaney, R.; Elderfield, H. E.

    2015-07-01

    Relief of iron (Fe) limitation in the Southern Ocean during ice ages, with potentially increased carbon storage in the ocean, has been invoked as one driver of glacial-interglacial atmospheric CO2 cycles. Ice and marine sediment records demonstrate that atmospheric dust supply to the oceans increased by up to an order of magnitude during glacial intervals. However, poor constraints on soluble atmospheric Fe fluxes to the oceans limit assessment of the role of Fe in glacial-interglacial change. Here, using novel techniques, we present estimates of water- and seawater-soluble Fe solubility in Last Glacial Maximum (LGM) atmospheric dust from the European Project for Ice Coring in Antarctica (EPICA) Dome C and Berkner Island ice cores. Fe solubility was very variable (1-42%) during the interval, and frequently higher than typically assumed by models. Soluble aerosol Fe fluxes to Dome C at the LGM (0.01-0.84 mg m-2 per year) suggest that soluble Fe deposition to the Southern Ocean would have been >=10 × modern deposition, rivalling upwelling supply.

  8. The impact of particle size, relative humidity, and sulfur dioxide on iron solubility in simulated atmospheric marine aerosols.

    PubMed

    Cartledge, Benton T; Marcotte, Aurelie R; Herckes, Pierre; Anbar, Ariel D; Majestic, Brian J

    2015-06-16

    Iron is a limiting nutrient in about half of the world's oceans, and its most significant source is atmospheric deposition. To understand the pathways of iron solubilization during atmospheric transport, we exposed size segregated simulated marine aerosols to 5 ppm sulfur dioxide at arid (23 ± 1% relative humidity, RH) and marine (98 ± 1% RH) conditions. Relative iron solubility increased as the particle size decreased for goethite and hematite, while for magnetite, the relative solubility was similar for all of the fine size fractions (2.5-0.25 μm) investigated but higher than the coarse size fraction (10-2.5 μm). Goethite and hematite showed increased solubility at arid RH, but no difference (p > 0.05) was observed between the two humidity levels for magnetite. There was no correlation between iron solubility and exposure to SO2 in any mineral for any size fraction. X-ray absorption near edge structure (XANES) measurements showed no change in iron speciation [Fe(II) and Fe(III)] in any minerals following SO2 exposure. SEM-EDS measurements of SO2-exposed goethite revealed small amounts of sulfur uptake on the samples; however, the incorporated sulfur did not affect iron solubility. Our results show that although sulfur is incorporated into particles via gas-phase processes, changes in iron solubility also depend on other species in the aerosol.

  9. Online Measurements of Water-Soluble Iron in Ambient Aerosols: A new Technique

    NASA Astrophysics Data System (ADS)

    Rastogi, N.; Oakes, M.; Weber, R. J.; Majestic, B. J.; Shafer, M. M.; Snyder, D. C.; Schauer, J. J.

    2008-05-01

    Water-soluble iron, i.e. Fe(II) (hereafter, WS-Fe), is a redox active metal that can act as a catalyst in the production of reactive oxygen species (ROS). In atmospheric aerosol particles, WS-Fe may significantly impact human health and the atmospheric oxidative capacity. Further, WS-Fe acts as a critical nutrient for marine organisms and has been hypothesized to limit phytoplankton productivity in high nitrate, low-chlorophyll ocean regions. In order to assess the role of aerosol WS-Fe on human health, atmospheric chemistry and ocean biogeochemistry, it is necessary to understand its major sources, transport, transformation processes and sinks. Filter-based measurements with several (6-24) hours integration time are predominately used to quantify WS-Fe in aerosols but provide limited insight into acute exposures that could be higher than daily averages, or sources having high temporal variability. Generally, mineral dust and its processing with acidic pollutants, is considered the dominant source of WS-Fe, however, recent studies have reported combustion emissions are also a possible source. A time-resolved data set may help in identifying WS-Fe sources, atmospheric transformations and possible sinks. We have developed a new system for online quantitative analyses of WS-Fe present in ambient aerosols with a 12-minute integration time. It mainly consists of Particle-Into-Liquid Sampler (PILS), a liquid waveguide capillary cell (LWCC) and a portable UV-Visible spectrophotometer. The complete system is automated so that first the liquid sample (water-extract of ambient aerosols from PILS) is mixed with ferrozine (complexing reagent) by pumping them simultaneously (10:1) through a serpentine reactor and a 100 turn mixing coil using a peristaltic pump. After holding the mixed solution in the mixing coil for three minutes, the sample is pumped through the LWCC and held there for two minutes to acquire the absorbance of the solution at 562 nm (for Fe

  10. Fractional iron solubility of aerosol particles enhanced by biomass burning and ship emission in Shanghai, East China.

    PubMed

    Fu, H B; Shang, G F; Lin, J; Hu, Y J; Hu, Q Q; Guo, L; Zhang, Y C; Chen, J M

    2014-05-15

    In terms of understanding Fe mobilization from aerosol particles in East China, the PM2.5 particles were collected in spring at Shanghai. Combined with the backtrajectory analysis, the PM2.5/PM10 and Ca/Al ratios, a serious dust-storm episode (DSE) during the sampling was identified. The single-particle analysis showed that the major iron-bearing class is the aluminosilicate dust during DSE, while the Fe-bearing aerosols are dominated by coal fly ash, followed by a minority of iron oxides during the non-dust storm days (NDS). Chemical analyses of samples showed that the fractional Fe solubility (%FeS) is much higher during NDS than that during DSE, and a strong inverse relationship of R(2)=0.967 between %FeS and total atmospheric iron loading were found, suggested that total Fe (FeT) is not controlling soluble Fe (FeS) during the sampling. Furthermore, no relationship between FeS and any of acidic species was established, suggesting that acidic process on aerosol surfaces are not involved in the trend of iron solubility. It was thus proposed that the source-dependent composition of aerosol particles is a primary determinant for %FeS. Specially, the Al/Fe ratio is poorly correlated (R(2)=0.113) with %FeS, while the apparent relationship between %FeS and the calculated KBB(+)/Fe ratio (R(2)=0.888) and the V/Fe ratio (R(2)=0.736) were observed, reflecting that %FeS could be controlled by both biomass burning and oil ash from ship emission, rather than mineral particles and coal fly ash, although the latter two are the main contributors to the atmospheric Fe loading during the sampling. Such information can be useful improving our understanding on iron solubility on East China, which may further correlate with iron bioavailability to the ocean, as well as human health effects associated with exposure to fine Fe-rich particles in densely populated metropolis in China. PMID:24607631

  11. Fractional iron solubility of aerosol particles enhanced by biomass burning and ship emission in Shanghai, East China.

    PubMed

    Fu, H B; Shang, G F; Lin, J; Hu, Y J; Hu, Q Q; Guo, L; Zhang, Y C; Chen, J M

    2014-05-15

    In terms of understanding Fe mobilization from aerosol particles in East China, the PM2.5 particles were collected in spring at Shanghai. Combined with the backtrajectory analysis, the PM2.5/PM10 and Ca/Al ratios, a serious dust-storm episode (DSE) during the sampling was identified. The single-particle analysis showed that the major iron-bearing class is the aluminosilicate dust during DSE, while the Fe-bearing aerosols are dominated by coal fly ash, followed by a minority of iron oxides during the non-dust storm days (NDS). Chemical analyses of samples showed that the fractional Fe solubility (%FeS) is much higher during NDS than that during DSE, and a strong inverse relationship of R(2)=0.967 between %FeS and total atmospheric iron loading were found, suggested that total Fe (FeT) is not controlling soluble Fe (FeS) during the sampling. Furthermore, no relationship between FeS and any of acidic species was established, suggesting that acidic process on aerosol surfaces are not involved in the trend of iron solubility. It was thus proposed that the source-dependent composition of aerosol particles is a primary determinant for %FeS. Specially, the Al/Fe ratio is poorly correlated (R(2)=0.113) with %FeS, while the apparent relationship between %FeS and the calculated KBB(+)/Fe ratio (R(2)=0.888) and the V/Fe ratio (R(2)=0.736) were observed, reflecting that %FeS could be controlled by both biomass burning and oil ash from ship emission, rather than mineral particles and coal fly ash, although the latter two are the main contributors to the atmospheric Fe loading during the sampling. Such information can be useful improving our understanding on iron solubility on East China, which may further correlate with iron bioavailability to the ocean, as well as human health effects associated with exposure to fine Fe-rich particles in densely populated metropolis in China.

  12. Influence of Atmospheric Processes on the Solubility and Composition of Iron in Saharan Dust.

    PubMed

    Longo, Amelia F; Feng, Yan; Lai, Barry; Landing, William M; Shelley, Rachel U; Nenes, Athanasios; Mihalopoulos, Nikolaos; Violaki, Kalliopi; Ingall, Ellery D

    2016-07-01

    Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet-chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated the aerosol iron in Mediterranean samples. In Atlantic samples, iron(II and III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation state became more reduced, and aerosol acidity increased. Atmospheric processing including acidic reactions and photoreduction likely influence the form of iron minerals and oxidation state in Saharan dust aerosols and contribute to increases in aerosol-iron solubility. PMID:27286140

  13. The Speciation and Solubility of Aerosol Iron and Aluminum in the Northwest Pacific Ocean: Results From the 2002 NSF/IOC Cruise

    NASA Astrophysics Data System (ADS)

    Buck, C. S.; Landing, W. M.; Resing, J.; Lebon, G. T.

    2002-12-01

    As part of the 2002 NSF/IOC cruise in the northwest Pacific, we collected separate 10-hour aerosol samples during both the day and night aboard the R/V Melville leaving Osaka, Japan on May 1, 2002 and arriving in Honolulu, HI on June 5, 2002. The goal of this research was to measure the solubility and speciation of Fe and Al in Asian continental dust. Four replicate samples were collected using an automatic sector-controlled aerosol sampling system that collected only when the wind was \\pm90o off the bow of the ship and exceeded 0.5 m/sec. The aerosols were collected on 47 mm PCTE and polypropylene filters for roughly 10-hour periods, filtering as much as 35 m3 of air through each filter. The filters were changed twice each day for a total of 60 samples. The filters were quickly leached with 100 mL of either freshly collected 0.2μm filtered surface seawater at natural pH or 100 mL of unacidified ultrapure water. Seawater filtrates were analyzed for soluble Fe(II) using the FeLume chemiluminescent system. These samples were also analyzed for total soluble Fe using the ICP-MS isotope dilution method upon returning to FSU. The ultrapure water filtrate samples were frozen until they could be analyzed at FSU for major anions using ion chromotography. A replicate PCTE filter was analyzed for total Fe (and other elements) using energy-dispersive X-ray fluorescence at the NOAA/PMEL laboratory. Soluble total aerosol Fe concentrations ranged from 8-130 pmol/m3 of filtered air. The concentrations of soluble Fe(II) ranged from 0.35-95 pmol/m3 and total soluble Al ranged from 20-600 pmol/m3. We will also compare total Fe and Al solubilities in seawater and ultrapure water.

  14. Iron solubility driven by speciation in dust sources to the ocean

    USGS Publications Warehouse

    Schroth, A.W.; Crusius, J.; Sholkovitz, E.R.; Bostick, B.C.

    2009-01-01

    Although abundant in the Earths crust, iron is present at trace concentrations in sea water and is a limiting nutrient for phytoplankton in approximately 40% of the ocean. Current literature suggests that aerosols are the primary external source of iron to offshore waters, yet controls on iron aerosol solubility remain unclear. Here we demonstrate that iron speciation (oxidation state and bonding environment) drives iron solubility in arid region soils, glacial weathering products (flour) and oil combustion products (oil fly ash). Iron speciation varies by aerosol source, with soils in arid regions dominated by ferric (oxy)hydroxides, glacial flour by primary and secondary ferrous silicates and oil fly ash by ferric sulphate salts. Variation in iron speciation produces systematic differences in iron solubility: less than 1% of the iron in arid soils was soluble, compared with 2-3% in glacial products and 77-81% in oil combustion products, which is directly linked to fractions of more soluble phases. We conclude that spatial and temporal variations in aerosol iron speciation, driven by the distribution of deserts, glaciers and fossil-fuel combustion, could have a pronounced effect on aerosol iron solubility and therefore on biological productivity and the carbon cycle in the ocean. ?? 2009 Macmillan Publishers Limited.

  15. Sources, solubility, and acid processing of aerosol iron and phosphorous over the South China Sea: East Asian dust and pollution outflows vs. Southeast Asian biomass burning

    NASA Astrophysics Data System (ADS)

    Hsu, S.-C.; Gong, G.-C.; Shiah, F.-K.; Hung, C.-C.; Kao, S.-J.; Zhang, R.; Chen, W.-N.; Chen, C.-C.; Chou, C. C.-K.; Lin, Y.-C.; Lin, F.-J.; Lin, S.-H.

    2014-08-01

    Iron and phosphorous are essential to marine microorganisms in vast regions in oceans worldwide. Atmospheric inputs are important allochthonous sources of Fe and P. The variability in airborne Fe deposition is hypothesized to serve an important function in previous glacial-interglacial cycles, contributing to the variability in atmospheric CO2 and ultimately the climate. Understanding the mechanisms underlying the mobilization of airborne Fe and P from insoluble to soluble forms is critical to evaluate the biogeochemical effects of these elements. In this study, we present a robust power-law correlation between fractional Fe solubility and non-sea-salt-sulfate / Total-Fe (nss-sulfate / FeT) molar ratio independent of distinct sources of airborne Fe of natural and/or anthropogenic origins over the South China Sea. This area receives Asian dust and pollution outflows and Southeast Asian biomass burning. This correlation is also valid for nitrate and total acids, demonstrating the significance of acid processing in enhancing Fe mobilization. Such correlations are also found for P, yet source dependent. These relationships serve as straightforward parameters that can be directly incorporated into available atmosphere-ocean coupling models that facilitate the assessment of Fe and P fertilization effects. Although biomass burning activity may supply Fe to the bioavailable Fe pool, pyrogenic soils are possibly the main contributors, not the burned plants. This finding warrants a multidisciplinary investigation that integrates atmospheric observations with the resulting biogeochemistry in the South China Sea, which is influenced by atmospheric forcings and nutrient dynamics with monsoons.

  16. Multiple sources of soluble atmospheric iron to Antarctic waters

    NASA Astrophysics Data System (ADS)

    Winton, V. H. L.; Edwards, R.; Delmonte, B.; Ellis, A.; Andersson, P. S.; Bowie, A.; Bertler, N. A. N.; Neff, P.; Tuohy, A.

    2016-03-01

    The Ross Sea, Antarctica, is a highly productive region of the Southern Ocean. Significant new sources of iron (Fe) are required to sustain phytoplankton blooms in the austral summer. Atmospheric deposition is one potential source. The fractional solubility of Fe is an important variable determining Fe availability for biological uptake. To constrain aerosol Fe inputs to the Ross Sea region, fractional solubility of Fe was analyzed in a snow pit from Roosevelt Island, eastern Ross Sea. In addition, aluminum, dust, and refractory black carbon (rBC) concentrations were analyzed, to determine the contribution of mineral dust and combustion sources to the supply of aerosol Fe. We estimate exceptionally high dissolved Fe (dFe) flux of 1.2 × 10-6 g m-2 y-1 and total dissolvable Fe flux of 140 × 10-6 g m-2 y-1 for 2011/2012. Deposition of dust, Fe, Al, and rBC occurs primarily during spring-summer. The observed background fractional Fe solubility of ~0.7% is consistent with a mineral dust source. Radiogenic isotopic ratios and particle size distribution of dust indicates that the site is influenced by local and remote sources. In 2011/2012 summer, relatively high dFe concentrations paralleled both mineral dust and rBC deposition. Around half of the annual aerosol Fe deposition occurred in the austral summer phytoplankton growth season; however, the fractional Fe solubility was low. Our results suggest that the seasonality of dFe deposition can vary and should be considered on longer glacial-interglacial timescales.

  17. Iron speciation in aerosol dust influences iron bioavailability over glacial-interglacial timescales

    NASA Astrophysics Data System (ADS)

    Spolaor, A.; Vallelonga, P.; Cozzi, G.; Gabrieli, J.; Varin, C.; Kehrwald, N.; Zennaro, P.; Boutron, C.; Barbante, C.

    2013-04-01

    Iron deposition influences primary production and oceanic sequestration of atmospheric carbon dioxide (CO2). Iron has two oxidation states, Fe(II) and Fe(III), with Fe(II) being more soluble and available for oceanic phytoplankton uptake. The past proportions of soluble iron in aerosol dust remain unknown. Here we present iron speciation (Fe2+ and Fe3+) in the Antarctic Talos Dome ice core over millennial time scales. We demonstrate that iron speciation over the last 55 kyr is linked to increasing quantities of fine dust (FD) (0.7-5 µm) and intensified long-range dust transport. We propose that Fe(II) and Fe2+ production is principally enhanced in FD by photoreduction, although pH and organic complexation may also contribute to the speciation dynamics. During the Last Glacial Maximum, Fe2+ concentrations in dust increased by up to seven times more than interglacial levels, while Fe3+ only doubled. Cold and dusty climatic periods may increase the percentage of biologically available Fe(II) and Fe2+ deposited in the nutrient-limited Southern Ocean, allowing greater phytoplankton uptake and perhaps increased CO2 drawdown.

  18. Photochemical Activation of Chlorine by Iron and Iron Oxide Aerosol

    NASA Astrophysics Data System (ADS)

    Wittmer, J.; Zetzsch, C.

    2015-12-01

    The photochemical activation of chlorine by dissolved iron in sea-salt aerosol droplets and by highly dispersed Fe2O3 aerosol particles (mainly hematite, specific surface > 100 m2/g), exposed to gaseous HCl, was investigated in humidified air in a Teflon simulation chamber. Employing the radical-clock technique, we quantified the production of gaseous atomic Cl. When the artificial sea salt aerosols contained suspended Fe2O3 alone at pH 6, no significant Cl production could be observed, even if the dissolution of iron was forced by "weathering" (repeatedly freezing and thawing for five times). Adjusting the pH in the stock suspension to 2.6, 2.2, and 1.9 and equilibrating for one week resulted in a quantifiable amount of dissolved iron (0.03, 0.2, and 0.6 mmol/L, respectively) and in gaseous Cl production rates of ~1.6, 6, and 8 × 1021 atoms cm-2 h-1, respectively. Exposing the pure Fe2O3 aerosol in the absence of salt to various gaseous HCl concentrations resulted in rates ranging from 8 × 1020 Cl atoms cm-2 h-1 (at ~4 ppb HCl) to 5 × 1022 Cl atoms cm-2 h-1 (at ~350 ppb HCl) and confirmed the uptake and conversion of HCl to atomic Cl (at HCl to Cl conversion yields of 2-5 % mol/mol, depending on the relative humidity). The relevance for environmental processes in the atmosphere will be discussed.

  19. Chemical characterizations of soluble aerosols in southern China.

    PubMed

    Wu, Dui; Tie, Xuexi; Deng, Xuejiao

    2006-07-01

    Soluble aerosols are measured at Guangdong and Hainan Provinces of southern China. The measured chemical composition of aerosols includes F-, Cl-, NO3-, SO4=, Na+, NH4+, K+, Ca2+, and Mg2+. The locations of measurements include a mega city (Guangzhou), a medium city along the coastline (Haiko), a small city along the coastline (Shanya), and a remote island site in the South China Sea (Yongxing island). The results reveal that aerosols in this region are complex and heterogeneous. Sulfate aerosol (SO4=) has the highest concentrations in Guangzhou (approximately 41% of total soluble aerosol mass), suggesting that anthropogenic activities (e.g., coal burning) play important roles in controlling aerosol concentrations in Guangzhou. By contrast, the concentrations of chlorine (Cl-) and sodium (Na+) are higher in Yongxing than in Guangzhou, indicating that the sea salt is the dominant aerosol in this marine environment site. In the medium (Haiko) and small (Shanya) city sites, the effects of anthropogenic and marine activities on aerosols fall in between the values in the mega city and the remote island site. The measured ratio of Cl-/Na+ shows that the ratio is less than 1.16 in all observation sites. The ratio in the Guangzhou city, the Haiko city, the Shanya city, and the Yongxing island is 0.52, 0.91, 0.24, and 0.53, respectively, indicating that significantly heterogeneous chemical reactions occur on sea salt particles. Unlike those in Europe and North America, there are high concentrations of calcium (Ca+) in all observation sites. The percentage of calcium mass to the measured total soluble aerosols mass is 21, 32, 34, and 30 at Guangzhou, Haiko, Sanya, and Yongxing, respectively. The calculations show that calcium plays an important role in neutralizing aerosols. The calculated "cation/anion" (summation operator[ion+]/summation operator[ion-]) ratio is 2.5, 2.5, 3.2, and 2.1, at Guangzhou, Haiko, Shanya, and Yongxing, respectively. The high "cation/anion" ratios

  20. The impact of changing surface ocean conditions on the dissolution of aerosol iron

    NASA Astrophysics Data System (ADS)

    Fishwick, Matthew P.; Sedwick, Peter N.; Lohan, Maeve C.; Worsfold, Paul J.; Buck, Kristen N.; Church, Thomas M.; Ussher, Simon J.

    2014-11-01

    The proportion of aerosol iron (Fe) that dissolves in seawater varies greatly and is dependent on aerosol composition and the physicochemical conditions of seawater, which may change depending on location or be altered by global environmental change. Aerosol and surface seawater samples were collected in the Sargasso Sea and used to investigate the impact of these changing conditions on aerosol Fe dissolution in seawater. Our data show that seawater temperature, pH, and oxygen concentration, within the range of current and projected future values, had no significant effect on the dissolution of aerosol Fe. However, the source and composition of aerosols had the most significant effect on the aerosol Fe solubility, with the most anthropogenically influenced samples having the highest fractional solubility (up to 3.2%). The impact of ocean warming and acidification on aerosol Fe dissolution is therefore unlikely to be as important as changes in land usage and fossil fuel combustion. Our experimental results also reveal important changes in the size distribution of soluble aerosol Fe in solution, depending on the chemical conditions of seawater. Under typical conditions, the majority (77-100%) of Fe released from aerosols into ambient seawater existed in the colloidal (0.02-0.4 µm) size fraction. However, in the presence of a sufficient concentration of strong Fe-binding organic ligands (10 nM) most of the aerosol-derived colloidal Fe was converted to soluble Fe (<0.02 µm). This finding highlights the potential importance of organic ligands in retaining aerosol Fe in a biologically available form in the surface ocean.

  1. Water soluble organic constituents in Arctic aerosols and snow pack

    SciTech Connect

    Li, Shaomeng ); Winchester, J.W. )

    1993-01-08

    Eight water-soluble organic anions were measured in 70 aerosol samples and 10 snow samples at Barrow, Alaska in March-April, 1989. The ranking of the ions in aerosols according to total (coarse + fine aerosol) median concentrations was acetate (44 ng m[sup [minus]3]), oxalate (27), benzoate (23), formate (22), propionate (6), methanesulfonate (5), lactate (4), and pyruvate (4). When added up, the median organic anion mass was 156 ng m[sup [minus]3]. The organic anions/nssSO[sub 4][sup =] mass ratio had a median of 0.18 and 0.07 in the coarse (>1 [mu]m) and fine (<1 [mu]m) size fractions, respectively, but can be very high on occasions. On average, the organic anions made up more than 10% of the water-soluble aerosol mass. A similar ranking in concentration was also found for the organic ions in the snow pack samples. The organic anion/nssSO[sub 4][sup =] mass ratio in these samples was >0.5, substantially higher than in aerosols. 18 refs., 2 tabs.

  2. Cloud condensation nuclei activation of limited solubility organic aerosol

    NASA Astrophysics Data System (ADS)

    Huff Hartz, Kara E.; Tischuk, Joshua E.; Chan, Man Nin; Chan, Chak K.; Donahue, Neil M.; Pandis, Spyros N.

    The cloud condensation nuclei (CCN) activation of 19 organic species with water solubilities ( Csat) ranging from 10 -4 to 10 2 g solute 100 g -1 H 2O was measured. The organic particles were generated by nebulization of an aqueous or an alcohol solution. Use of alcohols as solvents enables the measurement of low solubility, non-volatile organic CCN activity and reduces the likelihood of residual water in the aerosol. The activation diameter of organic species with very low solubility in water ( Csat<0.3 g 100 g -1 H 2O) is in agreement with Köhler theory using the bulk solubility (limited solubility case) of the organic in water. Many species, including 2-acetylbenzoic acid, aspartic acid, azelaic acid, glutamic acid, homophthalic acid, phthalic acid, cis-pinonic acid, and salicylic acid are highly CCN active in spite of their low solubility (0.3 g 100 g -1 H 2O< Csat<1 g 100 g -1 H 2O), and activate almost as if completely water soluble. The CCN activity of most species is reduced, if the particles are produced using non-aqueous solvents. The existence of the particles in a metastable state at low RH can explain the observed enhancement in CCN activity beyond the levels suggested by their solubility.

  3. Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, A.; Shi, Z.

    2015-08-01

    Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. Here, we, for the first time, interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. We firstly examined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). We then constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water, by using acidity as a master variable. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean (i.e., 1-2 orders of magnitude lower Fe solubility in North African- than combustion-influenced aerosols). The model results show a positive relationship between Fe solubility and water soluble organic carbon (WSOC)/Fe molar ratio, which is consistent with previous field measurements. We estimated that deposition of soluble Fe to the ocean increased from 0.05-0.07 Tg Fe yr-1 in preindustrial era to 0.11-0.12 Tg Fe yr-1 in present days, due to air pollution. Over the High Nitrate Low Chlorophyll (HNLC) regions of the ocean, the modeled Fe solubility remains low for

  4. Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, A.; Shi, Z.

    2016-01-01

    Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. In this study, for the first time, we interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. Firstly, we determined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). Then, by using acidity as a master variable, we constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean (i.e., 1-2 orders of magnitude lower Fe solubility in northern-African- than combustion-influenced aerosols). The model results show a positive relationship between Fe solubility and water-soluble organic carbon (WSOC)/Fe molar ratio, which is consistent with previous field measurements. We estimated that deposition of soluble Fe to the ocean increased from 0.05-0.07 Tg Fe yr-1 in the preindustrial era to 0.11-0.12 Tg Fe yr-1 in the present day, due to air pollution. Over the high-nitrate, low-chlorophyll (HNLC) regions of the ocean, the modeled Fe

  5. Factors controlling the solubility of trace metals in atmospheric aerosols over the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Nikolaou, Panagiota; Mihalopoulos, Nikolaos; Kanakidou, Maria

    2015-04-01

    Atmospheric input of aerosols is recognized, as an important source of nutrients, for the oceans. The chemical interactions between aerosols and varying composition of air masses lead to different coating of their surfaces with sulfate, nitrate and organic compounds, increasing their solubility and their role as a carrier of nutrients and pollutants in ecosystems. Recent works have highlighted that atmospheric inputs of nutrients and trace metals can considerably influence the marine ecosystem functioning at semi-enclosed or enclosed water bodies such as the eastern Mediterranean. The current work aims to determine the sources and the factors controlling the variability of nutrients in the eastern Mediterranean. Special focus has been given on trace elements solubility, considered either as key nutrients for phytoplankton growth such as iron (Fe), phosphorus (P) or inhibitors such as copper (Cu). This has been accomplished by analyzing size segregated aerosol samples collected at the background site of Finokalia in Crete for an entire year. Phosphorus concentrations indicate important increases in air masses influenced both by anthropogenic activities in the northeast European countries and by dust outbreaks. The last is confirmed by the correlation observed between total P and dust concentrations and by the air mass backward trajectories computed by running the NOAA Hysplit Model (Hybrid Single - Particle Langrangian Integrated Trajectory (http://www.arl.noaa.gov/ready/hysplit4.html). Overall 73% of total P has been found to be associated with anthropogenic sources. The solubility of P and Fe has been found to be closely related to the acidity (pH) and dust amount in aerosols. The aerosol pH was predicted using thermodynamic modeling (ISORROPIA-II), meteorological observations (RH, T), and gas/particle observations. More specifically P and Fe solubility appears to be inversely related to the crustal elements levels, while it increases in acidic environment. The

  6. The Impacts of Increasing Soluble Iron and Nitrogen Deposition on Ocean Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, A.; Moore, J. K.; Mahowald, N. M.; Luo, C.; Doney, S. C.; Lindsay, K.; Zender, C. S.

    2008-12-01

    We present results from sensitivity studies with the Biogeochemical Elemental Cycling (BEC) ocean model to increasing atmospheric inorganic N and soluble iron deposition since the pre-industrial era. Increasing soluble iron deposition results from increased atmospheric processing in the presence of anthropogenic pollutants and soluble iron from combustion sources. Increasing iron inputs raised nitrogen fixation by ~11% globally, with the majority of the increase in the sub-tropical north and south Pacific, and increased production and export in the high nutrient low chlorophyll (HNLC) regions. Increasing inorganic N inputs impacted coastal and open ocean regions close to major source areas in South and East Asia, North America and Europe. N2-fixation decreased by ~6% compared to the control because the diazotrophs (N2-fixers) were out-competed by diatoms and small phytoplankton. Net global nitrogen fixation, increased by ~5% compared to the control, in the simulation with increasing iron and nitrogen inputs. Global primary production increased by 2%, 0.4% and 2.4% under increasing Fe, inorganic N, and combined Fe and N inputs relative to the pre-industrial. This resulted in an increase in sinking POC export at 103m by 2.5%, 0.5%, and 3.2% leading to a reduction in atmospheric pCO2 by 1.8ppm, 0.5ppm and 2.2ppm under the three different cases relative to our control. Our results suggest that increasing combustion iron sources and aerosol Fe solubility along with atmospheric anthropogenic nitrogen deposition are significantly perturbing marine biogeochemical cycling and could partially explain the observed trend towards increased P limitation at Station Aloha in the sub-tropical North Pacific.

  7. Staining of minerals and solubility of iron in tissues.

    PubMed

    Klavins, J V; Pickett, J P; Wessely, Z

    1976-01-01

    Iron deposits in ethionine induced aortic siderosis of rats, in splenic deposits in sickle cell anemia and siderocalcific vessels in cerebral arteriosclerosis were completely removed by exposure to 20 percent hydrochloric acid for 30 min. This contrasted with idiopathic hemochromatosis and idiopathic pulmonary hemosiderosis in which the iron containing organs had to be exposed to 40 percent hydrochloric acid for two hours. The more soluble iron appeared colorless in unstained tissues, purplish blue with hematoxylin and eosin, turquoise blue with Perls' stain, violet blue with gallocyanin and dark-drown with sodium rhodizonate. The less soluble iron was golden yellow in unstained tissues. It appeared golden yellow with hematoxylin and eosin and sodium rhodizonate, but it stained greenish blue with Perls' method and dark brown with gallocyanin. Lead and copper were capable of deposition in some tissues in vitro in the presence of iron and/or calcium but not when these minerals were removed. This phenomenon may be of importance in certain pathological conditions, e.g. hemochromatosis, where on preexisting tissue-iron-complexes there is a secondary deposition of copper.

  8. Atmospheric processing outside clouds increases soluble iron in mineral dust.

    PubMed

    Shi, Zongbo; Krom, Michael D; Bonneville, Steeve; Benning, Liane G

    2015-02-01

    Iron (Fe) is a key micronutrient regulating primary productivity in many parts of the global ocean. Dust deposition is an important source of Fe to the surface ocean, but most of this Fe is biologically unavailable. Atmospheric processing and reworking of Fe in dust aerosol can increase the bioavailable Fe inputs to the ocean, yet the processes are not well understood. Here, we experimentally simulate and model the cycling of Fe-bearing dust between wet aerosol and cloud droplets. Our results show that insoluble Fe in dust particles readily dissolves under acidic conditions relevant to wet aerosols. By contrast, under the higher pH conditions generally relevant to clouds, Fe dissolution tends to stop, and dissolved Fe precipitates as poorly crystalline nanoparticles. If the dust-bearing cloud droplets evaporated again (returning to the wet aerosol stage with low pH), those neo-formed Fe nanoparticles quickly redissolve, while the refractory Fe-bearing phases continue to dissolve gradually. Overall, the duration of the acidic, wet aerosol stage ultimately increases the amount of potentially bioavailable Fe delivered to oceans, while conditions in clouds favor the formation of Fe-rich nanoparticles in the atmosphere.

  9. The relationship between dissolved humic acids and soluble iron in estuaries

    NASA Technical Reports Server (NTRS)

    Fox, L. E.

    1984-01-01

    Dissolved humic acid and soluble iron appear to be chemically unassociated in estuaries despite their coincident removal. This conclusion is supported by differences in the aggregation kinetics of soluble iron and dissolved humic acid, the inability of extracted humic acid to stabilize laboratory preparations of ferric hydroxide, and decreasing ratios of humic acid carbon to soluble iron along the axes of some estuaries.

  10. Investigating water soluble organic aerosols: Sources and evolution

    NASA Astrophysics Data System (ADS)

    Hecobian, Arsineh N.

    Many studies are being conducted on the different properties of organic aerosols (OA-s) as it is first emitted into the atmosphere and the consequent changes in these characteristics as OA-s age and secondary organic aerosol (SOA) is produced and in turn aged. This thesis attempts to address some of the significant and emerging issues that deal with the formation and transformation of water-soluble organic aerosols in the atmosphere. First, a proven method for the measurement of gaseous sulfuric acid, negative ion chemical ionization mass spectrometry (CIMS), has been modified for fast and sensitive measurements of particulate phase sulfuric acid (i.e. sulfate). The modifications implemented on this system have also been the subject of preliminary verifications for measurements of aerosol phase oxalic acid (an organic acid). Second, chemical and physical characteristics of a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS experiment are presented here. A statistical summary of the emission (or enhancement) ratios relative to carbon monoxide is presented for various gaseous and aerosol species. Extensive investigations of fire plume evolutions were undertaken during the second part of this field campaign. For four distinct Boreal fires, where plumes were intercepted by the aircraft over a wide range of down-wind distances, emissions of various compounds and the effect of aging on them were investigated in detail. No clear evidence of production of secondary compounds (e.g., WSOC and OA) was observed. High variability in emissions between the different plumes may have obscured any clear evidence of changes in the mass of various species with increasing plume age. Also, the lack if tropospheric oxidizing species (e.g., O3 and OH) may have contributed to the lack of SOA formation. Individual intercepts of smoke plumes in this study were segregated by source regions. The normalized excess mixing

  11. Solubility of aerosol trace elements: sources and deposition fluxes in the Canary Region

    NASA Astrophysics Data System (ADS)

    Gelado-Caballero, María Dolores; López-García, Patricia; Patey, Matthew; Prieto, Sandra; Collado, Cayetano; Santana, Desire; Hernández-Brito, Joaquín

    2013-04-01

    To date there have been no long-term aerosol studies in the Canary Basin, and current estimates of soluble fluxes of Al, Mn, Fe, P and N for the region are based on limited data available from several oceanographic research cruises which have crossed the region during large transects of the Atlantic Ocean. In this study, aerosol samples have been collected at two stations on the island of Gran Canaria regularly since 2006 (Taliarte, at sea level, and Pico de la Gorra, at 1930 m altitude). Samples have been analysed for total and soluble trace metals (Al, Mn, Fe, Co, Cu and Ti). The high temporal resolution of this dataset represents a valuable contribution to the understanding of aerosol deposition of trace metals to the region. Solubility measurements from acetate buffer leaching experiments showed the same tendency in the percentage of soluble metals in the samples: a higher percentage solubility of metals in anthropogenic aerosols and at low dust loading. Moreover, categorisation of aerosol samples with a continental African origin according to air-mass back-trajectories (North of Africa, Central and Western Sahara and Sahel) showed a decreasing tendency in the percentage of soluble Al and Fe to the south. In addition, factors that can affect the percentage solubility values for crustal elements and comparisons with different methods were studied. Freezing the samples stored affects the measurements of Al and Fe solubility. This last result is important for the design of future aerosol sampling programmes and aerosol solubility experiments. Flux estimates for aerosol-derived soluble metals reveal that phosphate is highly depleted relative to Fe and N when compared with Redfield values. It appears that aerosol deposition is an important source of N and trace metals (Fe, Co, Mn and Al) to the NE subtropical Atlantic Ocean. This work has been supported by the European Commission FEDER funds (PCT MAC 2007-2013, ESTRAMAR Mac/3/C177).

  12. Iron Speciation and Mixing in Single Aerosol Particles from the Asian Continental Outflow

    SciTech Connect

    Moffet, Ryan C.; Furutani, Hiroshi; Rodel, Tobias; Henn, Tobias R.; Sprau, Peter; Laskin, Alexander; Uematsu, Mitsuo; Gilles, Marry K.

    2012-04-04

    Bioavailable iron from atmospheric aerosol is an essential nutrient that can control oceanic productivity, thereby impacting the global carbon budget and climate. Particles collected on Okinawa Island during an atmospheric pollution transport event from China were analyzed using complementary single particle techniques to determine the iron source and speciation. Comparing the spatial distribution of iron within ambient particles and standard Asian mineral dust, it was determined that field-collected atmospheric Fe-containing particles have numerous sources, including anthropogenic sources such as coal combustion. Fe-containing particles were found to be internally mixed with secondary species such as sulfate, soot, and organic carbon. The mass weighted average Fe(II) fraction (defined as Fe(II)/[Fe(II)+Fe(III)]) was determined to be 0.33 {+-} 0.08. Within the experimental uncertainty, this value lies close to the range of 0.26-0.30 determined for representative Asian mineral dust. Previous studies have indicated that the solubility of iron from combustion is much higher than that from mineral dust. Therefore, chemical and/or physical differences other than oxidation state may help explain the higher solubility of iron in atmospheric particles.

  13. Crystallinity and solubility behavior of iron-containing fluoridated hydroxyapatites.

    PubMed

    Okazaki, M; Takahashi, J; Kimura, H

    1986-09-01

    Iron-containing fluoridated hydroxyapatites with various fluoride contents were synthesized at 80 degrees C and pH 7.4 using FeCl2 X nH2O as a source of iron. The Fe2+ uptake of fluoridated apatites was independent of fluoride concentration in the solution. a-Axis dimensions of Fe-containing apatites decreased with the degree of fluoridation in addition to the decrease related to the substitution of Fe2+ ions. All Fe-containing fluoridated apatites were less well crystallized than Fe-free fluoridated apatites previously reported, although with increasing degree of fluoridation, the crystallinity behavior of the former apatites appeared analogous to that of the latter apatites. In contrast to this inhibited crystallinity behavior, the apparent solubility of Fe-containing fluoridated apatites decreased more than that of Fe-free fluoridated apatites at low fluoride content.

  14. Atmospheric transport of mineral dust from the Indo-Gangetic Plain: Temporal variability, acid processing, and iron solubility

    NASA Astrophysics Data System (ADS)

    Srinivas, Bikkina; Sarin, M. M.; Rengarajan, R.

    2014-08-01

    transport of chemical constituents from the Indo-Gangetic Plain (IGP) to the Bay of Bengal is a conspicuous seasonal feature that occurs during the late NE-monsoon (December-March). With this perspective, aerosol composition and abundance of mineral dust have been studied during November 2009 to March 2010 from a sampling site (Kharagpur: 22.3°N, 87.3°E) in the IGP, representing the atmospheric outflow to the Bay of Bengal. The chemical composition of PM2.5 suggests the dominance of nss-SO42- (6.9-24.3 µg m-3); whereas the abundance of mineral dust varied from 3 to 18 µg m-3. The concentration of aerosol iron (FeTot) and its fractional solubility (Fews % = Fews/FeTot *100, where Fews is the water-soluble fraction of FeTot) varied from 60 to 1144 ng m-3 and from 6.7 to 26.5%, respectively. A striking similarity in the temporal variability of total inorganic acidity (TIA = NO3- + nss-SO42-) and Fews (%) provides evidence for acid processing of mineral dust (alluvium) during atmospheric transport from the IGP. The contribution of TIA to water-soluble inorganic species [(nss-SO42- + NO3-)/ΣWSIS], mass ratios of Ca/Al and Fe/Al, and abundance of dust (%) and Fews (%) in the IGP-outflow are similar to the aerosol composition over the Bay of Bengal. With the rapid increase in anthropogenic activities over south and south-east Asia, the enhanced fractional solubility of aerosol iron (attributed to acid processing of mineral dust) has implications to further increase in the air-sea deposition of Fe to the Ocean surface.

  15. On the fractional solubility of copper in marine aerosols: Toxicity of aeolian copper revisited

    NASA Astrophysics Data System (ADS)

    Sholkovitz, Edward R.; Sedwick, Peter N.; Church, Thomas M.

    2010-10-01

    Paytan et al. (2009) argue that the atmospheric deposition of aerosols lead to copper concentrations that are potentially toxic to marine phytoplankton in a large area of tropical and subtropical North Atlantic Ocean. A key assumption in their model is that all marine aerosols (mineral dust and anthropogenic particles) have a high (40%) fractional solubility of copper. Our data show that the fractional solubility of copper for Saharan dust over the Sargasso Sea and Bermuda is significantly lower (1-7%). In contrast, anthropogenic aerosols with non-Saharan sources have significantly higher values (10-100%). Hence, the potential Cu toxicity in the tropical and subtropical North Atlantic should be re-estimated, given the low fractional solubility of Cu in the Saharan dust that dominates aerosol deposition to this region.

  16. Atmospheric Processing of Volcanic Glass: Effects on Iron Solubility and Redox Speciation.

    PubMed

    Maters, Elena C; Delmelle, Pierre; Bonneville, Steeve

    2016-05-17

    Volcanic ash from explosive eruptions can provide iron (Fe) to oceanic regions where this micronutrient limits primary production. Controls on the soluble Fe fraction in ash remain poorly understood but Fe solubility is likely influenced during atmospheric transport by condensation-evaporation cycles which induce large pH fluctuations. Using glass powder as surrogate for ash, we experimentally simulate its atmospheric processing via cycles of pH 2 and 5 exposure. Glass fractional Fe solubility (maximum 0.4%) is governed by the pH 2 exposure duration rather than by the pH fluctuations, however; pH 5 exposure induces precipitation of Fe-bearing nanoparticles which (re)dissolve at pH 2. Glass leaching/dissolution release Fe(II) and Fe(III) which are differentially affected by changes in pH; the average dissolved Fe(II)/Fetot ratio is ∼0.09 at pH 2 versus ∼0.18 at pH 5. Iron release at pH 2 from glass with a relatively high bulk Fe(II)/Fetot ratio (0.5), limited aqueous Fe(II) oxidation at pH 5, and possibly glass-mediated aqueous Fe(III) reduction may render atmospherically processed ash a significant source of Fe(II) for phytoplankton. By providing new insight into the form(s) of Fe associated with ash as wet aerosol versus cloud droplet, we improve knowledge of atmospheric controls on volcanogenic Fe delivery to the ocean. PMID:27128877

  17. Novel insights about salting-effects and reactivity of soluble molecules in aqueous aerosols

    NASA Astrophysics Data System (ADS)

    Volkamer, Rainer

    2014-05-01

    Organic carbon in the atmosphere modifies the lifetime of climate active gases such as O3, and CH4 (oxidative capacity), and forms aerosols that affect Earth's radiation balance. Water soluble organic carbon (WSOC) molecules are well established to form secondary organic aerosol (SOA) in cloud water. However, the chemistry and rate of SOA formation in aqueous aerosol is less well known, and is typically ignored in atmospheric models. Aqueous particles provide a very different chemical environment than clouds, i.e., they are the most concentrated aqueous salt solution that can be found on Earth. As a result of high ionic strength, phase separations of inorganic and organic phases, mass transfer limitations and viscosity effects affect the chemistry in aqueous particles, which proceeds via essentially different reaction pathways than in clouds. Of particular importance in this context is the Henry's law partitioning coefficient. Laboratory experiments show activity coefficients of 1/500 for Henry's law partitioning coefficients of glyoxal in concentrated aqueous aerosol- salt solutions. This salting-in mechanism is investigated in laboratory experiments, and shown to be a major driver in the rate of secondary organic aerosol (SOA) formation from the multiphase chemistry of soluble species like glyoxal. This solicited talk will summarize and discuss new experimental findings from simulation chamber experiments, and bulk reactor experiments to assess the Setschenow salting behavior of soluble molecules in different aqueous seed types, and study the effect of anthropogenic triggers such as sulfate and ammonium for the reactivity of multiphase reactions in the aerosol aqueous phase.

  18. Source apportionment of aerosol iron in the marine environment using iron isotope analysis

    NASA Astrophysics Data System (ADS)

    Mead, Chris; Herckes, Pierre; Majestic, Brian J.; Anbar, Ariel D.

    2013-11-01

    (Fe) is a critical nutrient for phytoplankton. In the open ocean, this demand coupled with scarce supply often makes Fe the limiting factor in phytoplankton growth. The largest source, by mass, of Fe to the open ocean is windblown soil dust, but this Fe is much less soluble than Fe from other aerosol sources. Therefore, to fully understand how Fe reaches this ecosystem, it is necessary to understand the range of sources of aerosol Fe. To do this, we collected size-segregated aerosol samples from Bermuda and analyzed them to determine their Fe isotope composition. From this analysis, we found clear evidence in the fine size fraction (< 2.5 µm) of an important non-soil-dust Fe source. Our isotope analysis of multiple oil and coal fly ashes shows that those materials cannot explain our finding. We suggest biomass burning as the most likely source.

  19. Magnesium solubility in metallic iron during core formation

    NASA Astrophysics Data System (ADS)

    Badro, J.; Siebert, J.; Nimmo, F.

    2015-12-01

    Terrestrial core formation occurred by gravitational segregation of immiscible metal and silicate melts in an extensively molten proto-Earth. This stripped the bulk silicate Earth of most of its siderophile elements, which were concentrated in the core. The process occurs by virtue of partitioning through a redox reaction (e.g. [1]) whereby iron in the metal exchanges for a bonded siderophile element in the mantle. By performing metal-silicate equilibration experiments at extreme pressures and temperatures using the laser-heated diamond anvil cell, we find that the major lithophile component of the silicate Earth, namely MgO, can also become soluble in the metal. At close to 5000 K, our experiments show that up to 1.2 % MgO can be incorporated in the metal. We show that Mg incorporation in the metal isn't a redox reaction as with siderophile element partitioning, but rather a direct solubility of the MgO component as temperatures approach the metal-silicate solvus; in that respect, our results are fully consistent with the recently calculated Fe-MgO solvus [2]. This confirms that significant amounts of magnesium could have been added to the early core, provided that a giant impact had generated the necessary temperature increase. The subsequent exsolution of MgO driven by core cooling would have provided a significant buoyancy source, likely sufficient to drive core convection and producing an ancient magnetic field [3]. [1] J. Wade and B. J. Wood, Earth Planet. Sci. Lett., 236, 78-95 (2005) [2] S. M. Wahl and B. Militzer, Earth Planet. Sci. Lett. 410, 25-33 (2015) [3] D. J. Stevenson, DI11C-03, Fall AGU 2012.

  20. Speciation of water soluble iron in size segregated airborne particulate matter using LED based liquid waveguide with a novel dispersive absorption spectroscopic measurement technique.

    PubMed

    Chan, K L; Jiang, S Y N; Ning, Z

    2016-03-31

    In this study, we present the development and evaluation of a dispersive absorption spectroscopic technique for trace level soluble ferrous detection. The technique makes use of the broadband absorption spectra of the ferrous-ferrozine complex with a novel spectral fitting algorithm to determine soluble ferrous concentrations in samples and achieves much improved measurement precision compared to conventional methods. The developed method was evaluated by both model simulations and experimental investigations. The results demonstrated the robustness of the method against the spectral fluctuation, wavelength drift and electronic noise, while achieving excellent linearity (R(2) > 0.999) and low detection limit (0.06 μg L(-1)) for soluble ferrous detection. The developed method was also used for the speciation of soluble iron in size segregated atmospheric aerosols. The measurement was carried out during Spring and Summer in typical urban environment in Hong Kong. The measured total iron concentrations are in good agreement compared to conventional Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) measurements. Investigation on ambient particulate matter samples shows the size dependent characteristic of iron speciation in the atmosphere with a more active role of fine particles in transforming between ferrous and ferric. The method demonstrated in this study provides a cost and time effective approach for the speciation of iron in ambient aerosols. PMID:26965332

  1. Connecting the solubility and CCN activation of complex organic aerosols: A theoretical study using the Solubility Basis Set (SBS)

    NASA Astrophysics Data System (ADS)

    Rastak, Narges; Riipinen, Ilona; Pandis, Spyros

    2015-04-01

    INTRODUCTION Organic aerosol particles often consist of thousands of compounds with different properties. One of these properties is solubility, which affects the hygroscopic growth and CCN activation of the organic particles. Here we investigate the CCN activation behavior of complex organic aerosols accounting for the distribution of solubilities present in these mixtures. METHODS We considered a monodisperse population of spherical aerosol particles consisting of an internal mixture of organic compounds. When exposed to water vapor, these particles were assumed to grow reaching a thermodynamic equilibrium between the water vapor and the particle phase. The composition of the organic and aqueous phases was determined on one hand by the equilibrium between the aqueous phase and water vapor, and on the other hand by the equilibrium of the aqueous phase with the organic insoluble phase. We modelled the mixtures with the help of a solubility basis set (SBS, analogous to the volatility basis set VBS, Donahue et al. 2006, 2011, 2012), describing the mixture with n surrogate compounds with varying solubilities. We varied the range and shape of the solubility distribution, and the number of components n in the distribution, we also assumed two different kinds of interactions between the organic compounds in the insoluble phase 1) ideal mixture, where organics limit each other's dissolution; 2) unity activity, where organics behave as pure compounds and do not influence each other's dissolution. Critical supersaturations and the dissolution behavior at the point of CCN activation were calculated utilizing the Köhler theory for all organic mixtures (denoted here as the "full model"). The full model predictions were compared with the three simplified models: 1) assuming complete dissolution of all compounds; 2) treating the organic mixture solubility with the hygroscopicity parameter κ and 3) assuming a fixed soluble fraction ɛ for each mixture. RESULTS AND CONCLUSIONS

  2. Soluble Iron in Alveolar Macrophages Modulates Iron Oxide Particle-Induced Inflammatory Response via Prostaglandin E2 Synthesis

    EPA Science Inventory

    Ambient particulate matter (PM)-associated metals have been shown to play an important role in cardiopulmonary health outcomes. To study the modulation of inflammation by PM-associated soluble metal, we investigated intracellular solubility of radiolabelled iron oxide (59

  3. Detection of Remarkably Low Isotopic Ratio of Iron in Anthropogenic Aerosols and Evaluation of its Contribution to the Surface Ocean

    NASA Astrophysics Data System (ADS)

    Kurisu, M.; Iizuka, T.; Sakata, K.; Uematsu, M.; Takahashi, Y.

    2015-12-01

    It has been reported that phytoplankton growth in the High Nutrient-Low Chlorophyll (HNLC) regions is limited by dissolved iron (DFe) concentration (e.g., Martin and Fitzwater, 1988). Aerosol is known as one of the dominant sources of DFe to the ocean and classified into two origins such as anthropogenic and natural. A series of recent studies showed that Fe in anthropogenic aerosols is more soluble than that in natural aerosols (Takahashi et al., 2013) and has lower isotopic ratio (Mead et al., 2013). However, the difference between Fe isotopic ratio (δ56Fe: [(56Fe/54Fe)sample/(56Fe/54Fe)IRMM-14]-1) of two origins reported in Mead et al. (2013) is not so large compared with the standard deviation. Therefore, the aim of this study is to determine Fe species and δ56Fe in anthropogenic aerosols more accurately and to evaluate its contribution to the ocean surface. Iron species were determined by X-ray absorption fine structure (XAFS) analysis, while δ56Fe in size-fractionated aerosols were measured by MC-ICP-MS (NEPTUNE Plus) after chemical separation using anion exchange resin. Dominant Fe species in the samples were, ferrihydrite, hematite, and biotite. It was also revealed that coarse particles contained a larger amount of biotite and that fine particles contained a larger amount of hematite, which suggested that anthropogenic aerosols were emitted during combustion processes. In addition, results of Fe isotopic ratio analysis suggested that δ56Fe of coarse particles were around +0.25‰, whereas that of fine particles were -0.5 ˜ -2‰, which was lower than the δ56Fe in anthropogenic aerosol by Mead et al. (2013). The size-fractionated sampling made it possible to determine the δ56Fe in anthropogenic aerosol. Soluble component in fine particles extracted by simulated rain water also showed much lower δ56Fe (δ56Fe = -3.9±0.12‰), suggesting that anthropogenic Fe has much lower isotopic ratio. The remarkably low δ56Fe may be caused by the

  4. Preparation and characterization of iron-containing liposomes: their effect on soluble iron uptake by Caco-2 cells.

    PubMed

    Hermida, Laura G; Roig, Anna; Bregni, Carlos; Sabés-Xamaní, Manuel; Barnadas-Rodríguez, Ramon

    2011-09-01

    The aim of this work was to study the iron uptake of Caco-2 cells incubated with five different formulations of liposomes containing iron. The vesicles were also characterized before, during, and after in vitro digestion. Caco-2 cells were incubated with digested and nondigested liposomes, and soluble iron uptake was determined. Nondigested liposomes made with chitosan (CHI) or the cationic lipid, DC-Cholesterol (DC-CHOL), generated the highest iron uptake. However, these two formulations were highly unstable under in vitro digestion, resulting in nonmeasurable iron uptake. Digested conventional liposomes composed of soybean phosphatidylcholine (SPC), hydrogentated phosphatidylcholine (HSPC), or HSPC and cholesterol (CHOL) presented the highest iron-uptake values. These liposomal formulations protected iron from oxidation and improved iron uptake from intestinal cells, compared to an aqueous solution of ferrous sulphate. PMID:20854064

  5. Iron-containing atmospheric aerosols in the Chernobyl fallout

    NASA Astrophysics Data System (ADS)

    Rusanov, V.; Gushterov, V.; Winkler, H.; Trautwein, A. X.

    2005-11-01

    Mössbauer spectroscopy was applied to determine the composition and the iron concentration in the atmospheric aerosols contaminated in Sofia, Bulgaria after the Chernobyl accident. The results confirm the major conclusion of the Kopcewiczs for Poland, i.e. that in the initial filters, collected during the contaminating fallout (30.04 05.05.1986), the iron concentration was highest, 3.69 μg/m3 and that magnetite Fe3O4 was present. For the following days a change in the chemical composition including the presence of α-Fe2O3, α-FeOOH and γ-FeOOH as well as the absence of magnetite, was detected. Input of industrial iron contamination was negligible since the nearby steel plant had worked at minimum power due to official holidays. Unfortunately, Mössbauer spectroscopy studies only, do not allow a definite conclusion about an increase of the isotope abundance of 57Fe in the Chernobyl fallout.

  6. Aerosol water soluble organic nitrogen and carbon over the remote Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Pollard, Liam; Baker, Alex; Jickels, Tim

    2014-05-01

    Nitrogen is a limiting or co-limiting nutrient in large parts of the world's oceans particularly in oligotrophic regions such as gyres. In the open ocean there are two pathways by which new nutrient nitrogen can enter the oligotrophic system: biological nitrogen fixation and atmospheric deposition. Aerosol matter contributes to the latter route via dry and wet deposition, therefore it is important to understand and quantify the nitrogen containing material in aerosols and establish its major sources. Until recently, the organic nitrogen component of aerosol nitrogen was largely ignored, however, it is now known to contribute between 25-30 % of total water soluble nitrogen in aerosols, globally. This organic nitrogen is known to be chemically complex, shows high spatial and temporal variability and a large proportion of it has been shown to be bioavailable. It is important that this material is further quantified and characterised (including its carbon component) to determine its biogeochemical impact. Data gathered from fine and coarse mode aerosol samples collected on three Atlantic cruises (AMT21, AMT22 and ANT26-4) will be presented. Bulk and water soluble organic carbon and nitrogen data will be shown alongside major ion and inorganic nitrogen data. Potential sources of organic nitrogen and carbon material will be evaluated using a combination of inter-component correlations with known tracers and air-parcel back trajectories, allowing estimates of the anthropogenic impact on nutrient deposition to the remote Atlantic Ocean to be made.

  7. Solubility of HOBr in Acidic Solution and Implications for Liberation of Halogens Via Aerosol Processing

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, R. R.; Rammer, T. A.; Ashbourn, S. F. M.

    2004-01-01

    Halogen species are known to catalytically destroy ozone in several regions of the atmosphere. In addition to direct catalytic losses, bromine compounds can indirectly enhance ozone loss through coupling to other radical families. Hypobromous acid (HOBr) is a key species in the linkage of BrOx to ClOx and HOx. The aqueous- phase coupling reaction HOBr + HCI (right arrow) BrCl + H2O may provide a pathway for chlorine activation on sulfate aerosols at temperatures warmer than those required for polar stratospheric cloud formation. We have measured t h e solubility of HOBr in 45 - 70 wt% sulfuric acid solutions. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, H* = 10(exp 4) - 10(exp 7) mol dm(exp -3) atm(exp -1). The expected inverse dependence of H* on temperature was observed, but only a weak dependence on acidity was found. The solubility of HOBr is comparable to that of HBr, indicating that equilibrium concentrations of HOBr could equal or exceed those of HBr in upper tropospheric and lower stratospheric aerosols. Despite the high solubility of HOBr, aerosol volumes are not large enough to sequester a significant fraction of inorganic bromine from the gas phase. Our measurements of HOBr uptake in aqueous sulfuric acid in the presence of other brominated gases show the evolution of gaseous products including Br2O and Br2.

  8. Water-soluble material on aerosols collected within volcanic eruption clouds ( Fuego, Pacaya, Santiaguito, Guatamala).

    USGS Publications Warehouse

    Smith, D.B.; Zielinski, R.A.; Rose, W.I.; Huebert, B.J.

    1982-01-01

    In Feb. and March of 1978, filter samplers mounted on an aircraft were used to collect the aerosol fraction of the eruption clouds from three active Guatemalan volcanoes (Fuego, Pacaya, and Santiaguito). The elements dissolved in the aqueous extracts represent components of water-soluble material either formed directly in the eruption cloud or derived from interaction of ash particles and aerosol components of the plume. Calculations of enrichment factors, based upon concentration ratios, showed the elements most enriched in the extracts relative to bulk ash composition were Cd, Cu, V, F, Cl, Zn, and Pb.-from Authors

  9. Bioavailability an in vitro solubility of iron in green leafy vegetables

    SciTech Connect

    Miller, J.

    1986-03-05

    Bioavailability, measured by hemoglobin repletion in anemic rats, of iron in turnip greens, spinach, and broccoli was compared with its solubility in water, in 0.1 and 1.0 N HCl, and in 0.1 M acetic, citric and tartaric acids. Both in vivo and in vitro tests were conducted with raw plant materials and with vegetables that had been heat processed. Turnip greens were canned and spinach and broccoli were cooked in boiling water. Bioavailability of iron in turnip greens was significantly increased by heat processing and the RBV of canned greens was 70-90% of the standard FeSO/sub 4/. The RBV of spinach was about 50% and that of broccoli was about 80%, and the bioavailability of iron in neither of these vegetables was altered significantly by cooking. In vitro solubility of iron of raw turnip greens in water, the organic acids, and 0.1 N HCl was poor and was increased by heat treatment. Iron of raw spinach was somewhat more soluble in these media than that of raw turnip greens, but cooking had the effect of decreasing the proportion of iron on spinach that could be solubilized by the aqueous solutions. Thus, the in vitro solubility of iron in the green leafy vegetables was predictive of biological availability of this iron the anemic rats.

  10. Surface tension depression by low-solubility organic material in aqueous aerosol mimics

    NASA Astrophysics Data System (ADS)

    Schwier, Allison; Mitroo, Dhruv; McNeill, V. Faye

    2012-07-01

    Surface-active material, including long-chain fatty acids (LCFAs), comprises a significant fraction of organic aerosol mass. Surface-active species are thought to form a film at the gas-aerosol interface, with implications for aerosol heterogeneous chemistry and cloud formation. However, LCFA phase behavior and surface-bulk partitioning has not been characterized under most conditions typical of tropospheric aerosol water (i.e. acidic, high ionic content), making it challenging to predict surface film formation in aerosols. In this study, we present measurements of the surface tension of aqueous solutions containing the slightly soluble LCFAs oleic and stearic acid. The effect of varying pH, organic concentration, and inorganic salt content was tested for each system. We observe surface tension depression compared to water of up to ˜30 and 45% for aqueous solutions containing stearic or oleic acid at pH 0-8 and high inorganic salt concentrations (NaCl and (NH4)2SO4). This suggests that surface film formation is favorable for these species in atmospheric aerosols.

  11. Soluble iron dust export in the high altitude Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Ravelo-Pérez, L. M.; Rodríguez, S.; Galindo, L.; García, M. I.; Alastuey, A.; López-Solano, J.

    2016-05-01

    Every summer huge amounts of desert dust particles are exported from the hyperarid subtropical Sahara to the North Atlantic the so-called Saharan Air Layer (SAL), a dry, warm and dust-laden corridor that expands from the North African coast (1-5 km.a.s.l.) to the Americas above the marine boundary layer. Because of the potential impact of the dust deposited on the ocean on marine biogeochemistry and climate, we studied the Fe solubility (in seawater) of atmospheric aerosols samples directly collected in the SAL off the North African coast, i.e. the fresh aerosols recently exported from the Sahara in the SAL. The aerosol sampling was performed at ˜2400 m.a.s.l. in Izaña observatory in Tenerife island. In the total aerosols, we found low Fe concentrations and high fractional Fe solubility (FFS ˜2%) in the North Atlantic free troposphere airflows and high Fe concentrations and low FFS (˜0.7%) within the SAL; the resulting FFS versus total dust (or total Fe) plot shows a hyperbolic trend attributed to the conservative mixing of 'fine combustion aerosols' and 'lithogenic mineral dust'. We then focused on the soluble Fe in the SAL. Our results indicate that ˜70% of soluble Fe is associated with the dissolution of submicron dust particles, probably involving Fe-bearing clays. We found a FFS of submicron dust (˜6%) higher than that typically observed in submicron particles of soil dust samples (<1%). The correlation between FFS and the ammonium-sulphate/dust ratio and the low variability in the Fe/Al ratio in the dust samples, suggests that the increase in the FFS of submicron dust aerosols (with respect to soil dust particles) may be related to the presence of acid pollutants mixed with dust. Previous studies had focused on dust processing and changes of Fe solubility during the trans-Atlantic transport of dust in the SAL. We found that submicron dust exported off the coast of North Africa may have already experienced acid processing over the Sahara, i.e. before

  12. Water soluble ions in aerosols (TSP) : Characteristics, sources and seasonal variation over the central Himalayas, Nepal

    NASA Astrophysics Data System (ADS)

    Tripathee, Lekhendra; Kang, Shichang; Zhang, Qianggong; Rupakheti, Dipesh

    2016-04-01

    Atmspheric pollutants transported from South Asia could have adverse impact on the Himalayan ecosystems. Investigation of aerosol chemistry in the Himalayan region in Nepal has been limited on a temporal and spatial scale to date. Therefore, the water-soluble ionic composition of aerosol using TSP sampler was investigated for a year period from April 2013 to March 2014 at four sites Bode, Dhunche, Lumbini and Jomsom characterized as an urban, rural, semi-urban and remote sites in Nepal. During the study period, the highest concentration of major cation was Ca2+ with an average concentration of 8.91, 2.17, 7.85 and 6.42 μg m-3 and the highest concentration of major anion was SO42- with an average of 10.96, 4.06, 6.85 and 3.30 μg m-3 at Bode, Dhunche, Lumbini and Jomsom respectively. The soluble ions showed the decrease in concentrations from urban to the rural site. Correlations and PCA analysis suggested that that SO42-, NO3- and NH4+ were derived from the anthropogenic sources where as the Ca2+ and Mg2+ were from crustal sources. Our results also suggest that the largest acid neutralizing agent at our sampling sites in the central Himalayas are Ca2+ followed by NH4+. Seasonal variations of soluble ions in aerosols showed higher concentrations during pre-monsoon and winter (dry-periods) due to limited precipitation amount and lower concentrations during the monsoon which can be explained by the dilution effect, higher the precipitation lower the concentration. K+ which is regarded as the tracer of biomss burning had a significant peaks during pre-monsoon season when the forest fires are active around the regions. In general, the results of this study suggests that the atmospheric chemistry is influenced by natural and anthropogenic sources. Thus, soluble ionic concentrations in aerosols from central Himalayas, Nepal can provide a useful database to assess atmospheric environment and its impacts on human health and ecosystem in the southern side of central

  13. Basin scale survey of marine humic fluorescence in the Atlantic: Relationship to iron solubility and H2O2

    NASA Astrophysics Data System (ADS)

    Heller, M. I.; Gaiero, D. M.; Croot, P. L.

    2013-01-01

    Iron (Fe) is a limiting nutrient for phytoplankton productivity in many different oceanic regions. A critical aspect underlying iron limitation is its low solubility in seawater as this controls the distribution and transport of iron through the ocean. Processes which enhance the solubility of iron in seawater, either through redox reactions or organic complexation, are central to understanding the biogeochemical cycling of iron. In this work we combined iron solubility measurements with parallel factor (PARAFAC) data analysis of Coloured Dissolved Organic Matter (CDOM) fluorescence along a meridional transect through the Atlantic (PS ANT XXVI-4) to examine the hypothesis that marine humic fluorescence is a potential proxy for iron solubility in the surface ocean. PARAFAC analysis revealed 4 components (C1-4), two humic like substances (C2&4) and two protein-like (C1&3). Overall none of the 4 components were significantly correlated with iron solubility, though humic-like components were weakly correlated with iron solubility in iron replete waters. Our analysis suggests that the ligands responsible for maintaining iron in solution in the euphotic zone are sourced from both remineralisation processes and specific ligands produced in response to iron stress and are not easily related to bulk CDOM properties. The humic fluorescence signal was sharply attenuated in surface waters presumably most likely due to photo bleaching, though there was only a weak correlation with the transient photo product H2O2, suggesting longer lifetimes in the photic zone for the fluorescent components identified here.

  14. Chemical compositions of past soluble aerosols reconstructed from NEEM (Greenland) and Dome C (Antarctica) ice cores

    NASA Astrophysics Data System (ADS)

    Oyabu, Ikumi; Iizuka, Yoshinori; Fukui, Manabu; Fischer, Hubertus; Schüpbach, Simon; Gfeller, Gideon; Mulvaney, Robert; Hansson, Margareta

    2015-04-01

    Polar ice core preserve past atmospheric aerosols, which is a useful proxy for understanding the interaction between climate changes and atmospheric aerosols. One useful technique for reconstructing past soluble aerosols from ice core is the determination of dissolved ion species. However, since salts and acids melt into ions, chemical compositions of soluble aerosols in the ice cores have not been cleared. To clarify the temporal variations in the chemical compositions of past soluble aerosols, this study investigated chemical compositions of soluble particles preserved in the NEEM (Greenland) and Dome C (Antarctica) ice cores using new method 'ice-sublimation method'. The ice-sublimation method can extract soluble salts particles as a solid state without melting. The ice core samples are selected from the sections from the last termination (the Last Glacial Maximum (LGM) to Holocene) of Dome C (inland Antarctica) and NEEM ice cores. Using ice-sublimation method, soluble salts particles were extracted. Chemical components of extracted particles were analysed by scanning electron microscope and energy dispersive spectroscopy, and micro-Raman spectroscopy. The major components of soluble salts particles in the Dome C ice core are CaSO4, Na2SO4 and NaCl. The CaSO4 and NaCl fractions were high in the first half of the last termination, whereas the Na2SO4 fraction is high in the latter half of the last termination. The major components of soluble salts particles in the NEEM ice core are CaCO3, CaSO4, NaCl and Na2SO4. The fractions of CaCO3, CaSO4 and NaCl were high in LGM, whereas those of NaCl and Na2SO4 were high in Holocene. The changes in the salts compositions in Dome C ice core are mainly controlled by concentration of terrestrial material (Ca2+). In the first half of the last termination, most of the terrestrial material (CaCO3) reacted with H2SO4 but some of sea-salt (NaCl) was not reacted with H2SO4 due to high Ca2+ concentration. As a result, the CaSO4 and Na

  15. Soluble species in the Arctic summer troposphere - acidic gases, aerosols, and precipitation

    SciTech Connect

    Talbot, R.W.; Vijgen, A.S.; Harriss, R.C. Old Dominion Univ., Norfolk, VA )

    1992-10-01

    The large-scale spatial distribution from 0.15-to 6 km altitude in the North American Arctic troposphere of several soluble acidic gases and major aerosol species during the summertime is reported. The distribution is found to be compositionally consistent on a large spatial scale. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases while acidic sulfate aerosols dominate the particulate phase. There appears to be a surface source of NH3 over the pack ice which may originate from decay of dead marine organisms on the ice surface, evolution from surface ocean waters in open ice leads, or release from rotting sea ice. At low altitude over the pack ice this NH34 appears to partially neutralize aerosol acidity. Over sub-Arctic tundra in southeastern Alaska, inputs of marine biogenic sulfur from the Bering Sea appear to be an important source of boundary layer aerosol SO4(2-). The rainwater acidity over the tundra is typical of remote regions. 61 refs.

  16. Soluble species in the Arctic summer troposphere - Acidic gases, aerosols, and precipitation

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

    1992-01-01

    The large-scale spatial distribution from 0.15-to 6 km altitude in the North American Arctic troposphere of several soluble acidic gases and major aerosol species during the summertime is reported. The distribution is found to be compositionally consistent on a large spatial scale. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases while acidic sulfate aerosols dominate the particulate phase. There appears to be a surface source of NH3 over the pack ice which may originate from decay of dead marine organisms on the ice surface, evolution from surface ocean waters in open ice leads, or release from rotting sea ice. At low altitude over the pack ice this NH34 appears to partially neutralize aerosol acidity. Over sub-Arctic tundra in southeastern Alaska, inputs of marine biogenic sulfur from the Bering Sea appear to be an important source of boundary layer aerosol SO4(2-). The rainwater acidity over the tundra is typical of remote regions.

  17. Fluorescent water-soluble organic aerosols in the High Arctic atmosphere

    PubMed Central

    Fu, Pingqing; Kawamura, Kimitaka; Chen, Jing; Qin, Mingyue; Ren, Lujie; Sun, Yele; Wang, Zifa; Barrie, Leonard A.; Tachibana, Eri; Ding, Aijun; Yamashita, Youhei

    2015-01-01

    Organic aerosols are ubiquitous in the earth’s atmosphere. They have been extensively studied in urban, rural and marine environments. However, little is known about the fluorescence properties of water-soluble organic carbon (WSOC) or their transport to and distribution in the polar regions. Here, we present evidence that fluorescent WSOC is a substantial component of High Arctic aerosols. The ratios of fluorescence intensity of protein-like peak to humic-like peak generally increased from dark winter to early summer, indicating an enhanced contribution of protein-like organics from the ocean to Arctic aerosols after the polar sunrise. Such a seasonal pattern is in agreement with an increase of stable carbon isotope ratios of total carbon (δ13CTC) from −26.8‰ to −22.5‰. Our results suggest that Arctic aerosols are derived from a combination of the long-range transport of terrestrial organics and local sea-to-air emission of marine organics, with an estimated contribution from the latter of 8.7–77% (mean 45%). PMID:25920042

  18. Soluble Nutrient and Trace Metal Fluxes from Aerosol Dry Deposition to Elkhorn Slough, CA

    NASA Astrophysics Data System (ADS)

    Gray, E. T.; Paytan, A.; Haskins, J.

    2009-12-01

    Atmospheric deposition has been widely recognized as a source of pollutants and nutrients to coastal ecosystems. Specifically, deposition includes nitrogen compounds, sulfur compounds, mercury, pesticides, phosphate, trace metals and other toxic compounds that can travel great distances in aerosols. These components can come from both natural (volcanoes, mineral dust, forest fires) and anthropogenic (fossil fuels, chemical byproducts, incineration of waste) sources. These pollutants may affect ecosystem health and water quality with environmental impacts such as eutrophication, contaminated fish and harmful algal blooms. In this study we focus on dry deposition to Elkhorn Slough, California. Size fractionated aerosol samples (PM 2.5 and PM 10) collected continuously over a seven day period using a cascade impactor are used along with a deposition model to determine the soluble nutrient and trace metal fluxes on the Elkhorn Slough ecosystem. Atmospheric deposition inputs will be compared to other sources and their potential impact evaluated.

  19. Characteristics of the water-soluble components of aerosol particles in Hefei, China.

    PubMed

    Deng, Xue-liang; Shi, Chun-e; Wu, Bi-wen; Yang, Yuan-jian; Jin, Qi; Wang, Hong-lei; Zhu, Song; Yu, Caixia

    2016-04-01

    Size-classified daily aerosol mass concentrations and concentrations of water-soluble inorganic ions were measured in Hefei, China, in four representative months between September 2012 and August 2013. An annual average mass concentration of 169.09 μg/m(3) for total suspended particulate (TSP) was measured using an Andersen Mark-II cascade impactor. The seasonal average mass concentration was highest in winter (234.73 μg/m(3)) and lowest in summer (91.71 μg/m(3)). Water-soluble ions accounted for 59.49%, 32.90%, 48.62% and 37.08% of the aerosol mass concentration in winter, spring, summer, and fall, respectively, which indicated that ionic species were the primary constituents of the atmospheric aerosols. The four most abundant ions were NO3(-), SO4(2-), Ca(2+) and NH4(+). With the exception of Ca(2+), the mass concentrations of water-soluble ions were in an intermediate range compared with the levels for other Chinese cities. Sulfate, nitrate, and ammonium were the dominant fine-particle species, which were bimodally distributed in spring, summer and fall; however, the size distribution became unimodal in winter, with a peak at 1.1-2.1 μm. The Ca(2+) peak occurred at approximately 4.7-5.8 μm in all seasons. The cation to anion ratio was close to 1.4, which suggested that the aerosol particles were alkalescent in Hefei. The average NO3(-)/SO4(2-) mass ratio was 1.10 in Hefei, which indicated that mobile source emissions were predominant. Significant positive correlation coefficients between the concentrations of NH4(+) and SO4(2-), NH4(+) and NO3(-), SO4(2-) and NO3(-), and Mg(2+) and Ca(2+) were also indicated, suggesting that aerosol particles may be present as (NH4)2SO4, NH4HSO4, and NH4NO3. PMID:27090692

  20. Anthropogenic Influence on Secondary Aerosol Formation and Total Water-Soluble Carbon on Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Gioda, Adriana; Mateus, Vinicius; Monteiro, Isabela; Taira, Fabio; Esteves, Veronica; Saint'Pierre, Tatiana

    2013-04-01

    On a global scale, the atmosphere is an important source of nutrients, as well as pollutants, because of its interfaces with soil and water. Important compounds in the gaseous phase are in both organic and inorganic forms, such as organic acids, nitrogen, sulfur and chloride. In spite of the species in gas form, a huge number of process, anthropogenic and natural, are able to form aerosols, which may be transported over long distances. Sulfates e nitrates are responsible for rain acidity; they may also increase the solubility of organic compounds and metals making them more bioavailable, and also can act as cloud condensation nuclei (CCN). Aerosol samples (PM2.5) were collected in a rural and industrial area in Rio de Janeiro, Brazil, in order to quantify chemical species and evaluate anthropogenic influences in secondary aerosol formation and organic compounds. Samples were collected during 24 h every six days using a high-volume sampler from August 2010 to July 2011. The aerosol mass was determined by Gravimetry. The water-soluble ionic composition (WSIC) was obtained by Ion Chromatography in order to determine the major anions (NO3-, SO4= and Cl-); total water-soluble carbon (TWSC) was determined by a TOC analyzer. The average aerosol (PM2.5) concentrations ranged from 1 to 43 ug/m3 in the industrial site and from 4 to 35 ug/m3 in the rural area. Regarding anions, the highest concentrations were measured for SO42- (10.6 μg/m3-12.6 μg/m3); where the lowest value was found in the rural site and the highest in the industrial. The concentrations for NO3- and Cl- ranged from 4.2 μg/m3 to 9.3 μg/m3 and 3.1 μg/m3 to 6.4 μg /m3, respectively. Sulfate was the major species and, like nitrate, it is related to photooxidation in the atmosphere. Interestingly sulfate concentrations were higher during the dry period and could be related to photochemistry activity. The correlations between nitrate and non-sea-salt sulfate were weak, suggesting different sources for these

  1. COMPARISON OF MINERAL AND SOLUBLE IRON FENTON'S CATALYSTS FOR THE TREATMENT OF TRICHLOROETHYLENE. (R826163)

    EPA Science Inventory

    Abstract

    Contaminant degradation, stoichiometry, and role of hydroxyl radicals (OH·) in four Fenton's systems were investigated using trichloroethylene (TCE) as a model contaminant. A standard Fenton's system, a modified soluble iron system with a...

  2. Atmospheric Processing of Iron-Containing Mineral Dust Aerosol: A Major Source of Bioavailable Iron to Ocean Life

    NASA Astrophysics Data System (ADS)

    Rubasinghege, G. R. S.; Hurub, O. A.

    2015-12-01

    In the present day, it has become more apparent that redox reactions involving mineral dust are of great interest, especially for Fe-containing mineral dust, as they transported and deposited into certain regions of the ocean that dissolved iron is often a limiting nutrient for ocean life. Given that heterogeneous reactions of Fe-containing mineral dust with acidic gases and their precursors, i.e. HNO3, dimethyl sulfide( DMS), lead to lower pH environments, the amount of bioavailable iron can increase as they are transported through the atmosphere. The current work focuses on chemical and photochemical processing of Fe-containing mineral dust particles in the presence of HNO3, SO2 and DMS under atmospherically relevant conditions. Here, various spectroscopic methods are combined with dissolution measurements to investigate atmospheric processing of iron containing aerosol dust, with a specific focus on mineralogy and environmental conditions, i.e. pH, relative humidity, temperature and solar flux. Ilmenite (FeTiO3) is used as one of the proxies for Fe-containing minerals that have enough complexity to mimic the mineral dust, yet simple enough to know the details of the reaction pathways. During these studies, above factors are found to play significant roles in the dissolution of iron from mineral dust aerosol. More importantly, data suggest that presence of titanium in the lattice structure of ilmenite enhances iron dissolution, at least by 3-fold in a comparison with hematite. Further, growth and activity of ocean diatoms (Cyclotella meneghiniana) are monitored in the presence of Fe-containing mineral dust under the same conditions. Here, diatoms are added to the reactors containing pre-dissolved iron from a prior 48hr reaction. Results show a high correlation between the growth of diatoms and the amount of bioavailable from iron containing minerals. The current study thus highlights these important, yet unconsidered, factors in the atmospheric processing of iron

  3. Uncertainties in the measurements of water-soluble organic nitrogen in the aerosol

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kiyoshi; Yamato, Koki

    2016-11-01

    In order to evaluate the positive and negative artifacts in the measurements of the water-soluble organic nitrogen (WSON) in the aerosols by filter sampling, comparative experiments between the filter sampling and denuder-filter sampling were conducted during both the warm and cold seasons. The results suggest that the traditional filter sampling underestimates the concentrations of the particulate WSON due to its volatilization loss, but this effect on the ratio of the WSON to the water-soluble total nitrogen (WSTN) was small probably because inorganic nitrogen species were also lost during the filter sampling. Approximately 32.5% of the WSON in the PM2.5 was estimated to be lost during the filter sampling. The denuder-filter sampling also demonstrated the existence of the WSON in the gas phase with approximately quarter concentrations of the WSON in the PM2.5. On the other hand, the filter sampling would overestimate the gaseous WSON concentration due to the loss of the WSON from the aerosol collection filter.

  4. Case Study of Water-Soluble Metal Containing Organic Constituents of Biomass Burning Aerosol

    SciTech Connect

    Chang-Graham, Alexandra L.; Profeta, Luisa T. M.; Johnson, Timothy J.; Yokelson, Robert J.; Laskin, Alexander; Laskin, Julia

    2011-02-15

    Natural and prescribed biomass fires are a major source of aerosols that may persist in the atmosphere for several weeks. Biomass burning aerosols (BBA) can be associated with long-range transport of water-soluble N-, S-, P-, and metal-containing species. In this study, BBA samples were collected using a particle-into-liquid sampler (PILS) from laboratory burns of vegetation collected on military bases in the southeastern and southwestern United States. The samples were then analyzed using high resolution electrospray ionization mass spectrometry (ESI/HR-MS) that enabled accurate mass measurements for hundreds of species with m/z values between 70 and 1000 and assignment of elemental formulas. Mg, Al, Ca, Cr, Mn, Fe, Ni, Cu, Zn, and Ba-containing organometallic species were identified. The results suggest that the biomass may have accumulated metal-containing species that were re-emitted during biomass burning. Finally, further research into the sources, dispersion, and persistence of metal-containing aerosols, as well as their environmental effects, is needed.

  5. Mossbauer study of iron-containing atmospheric aerosol in relation to the air pollution.

    NASA Astrophysics Data System (ADS)

    Kopcewicz, B.; Kopcewicz, M.

    2003-04-01

    Observation and monitoring of the aerosol background in the troposphere is very important for atmospheric physics. It is the first step in studying antropogenic components and their impact on the climate. Iron (both Fe(II) and Fe(III)) plays an important role in the multiphase atmospheric chemistry of S(IV) as a catalyst as well as an oxidant, and a photolytic source of OH radical. In order to assess the extent in which the iron content in the troposphere may change and to which extent that change may be attributed to human activity, it is necessary to have a complete picture of the distribution of iron concentration and its variation. For these purposes the Mössbauer spectroscopy was applied to analyze the iron compounds present in atmospheric aerosol. In this presentation we show results of measurements performed on the atmospheric aerosol collected in Poznan and Lodz (industrial cites in central Poland), Mikolajki (lake district, North-East Poland) and Kasprowy Wierch (mountain observatory, 1985 m a.s.l.). Depending to the sampling period and sampling site the significant changes in the iron concentration and chemical properties of the collected aerosol were observed. As a significant part of air pollution, especially in winter months, iron appeared in the form of iron sulfides, which were products of coal combustion. Also, iron oxyhydroxides and iron oxides, mostly hematite (bulk) and in the form of ultra fine particles in superparamagnetic state were observed. Results obtained from Mössbauer measurements were discussed in relation to the concentration of general air pollution.

  6. Organic aerosols associated with the generation of reactive oxygen species (ROS) by water-soluble PM2.5.

    PubMed

    Verma, Vishal; Fang, Ting; Xu, Lu; Peltier, Richard E; Russell, Armistead G; Ng, Nga Lee; Weber, Rodney J

    2015-04-01

    We compare the relative toxicity of various organic aerosol (OA) components identified by an aerosol mass spectrometer (AMS) based on their ability to generate reactive oxygen species (ROS). Ambient fine aerosols were collected from urban (three in Atlanta, GA and one in Birmingham, AL) and rural (Yorkville, GA and Centerville, AL) sites in the Southeastern United States. The ROS generating capability of the water-soluble fraction of the particles was measured by the dithiothreitol (DTT) assay. Water-soluble PM extracts were further separated into the hydrophobic and hydrophilic fractions using a C-18 column, and both fractions were analyzed for DTT activity and water-soluble metals. Organic aerosol composition was measured at selected sites using a high-resolution time-of-flight AMS. Positive matrix factorization of the AMS spectra resolved the organic aerosol into isoprene-derived OA (Isop_OA), hydrocarbon-like OA (HOA), less-oxidized oxygenated OA, (LO-OOA), more-oxidized OOA (MO-OOA), cooking OA (COA), and biomass burning OA (BBOA). The association of the DTT activity of water-soluble PM2.5 (WS_DTT) with these factors was investigated by linear regression techniques. BBOA and MO-OOA were most consistently linked with WS_DTT, with intrinsic water-soluble activities of 151 ± 20 and 36 ± 22 pmol/min/μg, respectively. Although less toxic, MO-OOA was most widespread, contributing to WS_DTT activity at all sites and during all seasons. WS_DTT activity was least associated with biogenic secondary organic aerosol. The OA components contributing to WS_DTT were humic-like substances (HULIS), which are abundantly emitted in biomass burning (BBOA) and include highly oxidized OA from multiple sources (MO-OOA). Overall, OA contributed approximately 60% to the WS_DTT activity, with the remaining probably from water-soluble metals, which were mostly associated with the hydrophilic WS_DTT fraction. PMID:25748105

  7. Volcanic and atmospheric controls on ash iron solubility: A review

    NASA Astrophysics Data System (ADS)

    Ayris, Paul; Delmelle, Pierre

    2012-01-01

    The ash material produced by volcanic eruptions carries important information about the underground magma eruptive conditions and subsequent modifications in the volcanic plume and during atmospheric transport. Volcanic ash is also studied because of its impacts on the environment and human health. In particular, there is a growing interest from a multidisciplinary scientific community to understand the role that ash deposition over open ocean regions may play as a source of bioavailable Fe for phytoplankton production. Similar to aeolian mineral dust, the processes that affect the mineralogy and speciation of Fe in ash may promote solubilisation of Fe in ash, and thus may increase the amount of volcanic Fe supplied to ocean surface waters. Our knowledge of these controls is still very limited, a situation which has hindered quantitative interpretation of experimental Fe release measurements. In this review, we identify the key volcanic and atmospheric controls that are likely to modulate ash Fe solubility. We also briefly discuss existing data on Fe release from ash and make some recommendations for future studies in this area.

  8. Water-soluble Organic Components in Aerosols Associated with Savanna Fires in Southern Africa: Identification, Evolution and Distribution

    NASA Technical Reports Server (NTRS)

    Gao, Song; Hegg, Dean A.; Hobbs, Peter V.; Kirchstetter, Thomas W.; Magi, Brian I.; Sadilek, Martin

    2003-01-01

    During the SAFARI 2000 field campaign, both smoke aerosols from savanna fires and haze aerosols in the boundary layer and in the free troposphere were collected from an aircraft in southern Africa. These aerosol samples were analyzed for their water-soluble chemical components, particularly the organic species. A novel technique, electrospray ionization-ion trap mass spectrometry, was used concurrently with an ion chromatography system to analyze for carbohydrate species. Seven carbohydrates, seven organic acids, five metallic elements, and three inorganic anions were identified and quantified. On the average, these 22 species comprised 36% and 27% of the total aerosol mass in haze and smoke aerosols, respectively. For the smoke aerosols, levoglucosan was the most abundant carbohydrate species, while gluconic acid was tentatively identified as the most abundant organic acid. The mass abundance and possible source of each class of identified species are discussed, along with their possible formation pathways. The combustion phase of a fire had an impact on the chemical composition of the emitted aerosols. Secondary formation of sulfate, nitrate, levoglucosan, and several organic acids occurred during the initial aging of smoke aerosols. It is likely that under certain conditions, some carbohydrate species in smoke aerosols, such as levoglucosan, were converted to organic acids during upward transport.

  9. Characterization of water-soluble organic matter in urban aerosol by 1H-NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Chalbot, Marie-Cecile G.; Chitranshi, Priyanka; Gamboa da Costa, Gonçalo; Pollock, Erik; Kavouras, Ilias G.

    2016-03-01

    The functional and 13C isotopic compositions of water-soluble organic carbon (WSOC) in atmospheric aerosol were determined by nuclear magnetic resonance (1H-NMR) and isotope ratio mass spectrometry (IRMS) in an urban location in the Southern Mississippi Valley. The origin of WSOC was resolved using the functional distribution of organic hydrogen, δ13C ratio, and positive matrix factorization (PMF). Three factors were retained based on NMR spectral bins loadings. Two factors (factors 1 and 3) demonstrated strong associations with the aliphatic region in the NMR spectra and levoglucosan resonances. Differences between the two factors included the abundance of the aromatic functional group for factor 1, indicating fresh emissions and, for factor 3, the presence of resonances attributed to secondary ammonium nitrate and low δ13C ratio values that are indicative of secondary organic aerosol. Factors 1 and 3 added 0.89 and 1.08 μgC m-3, respectively, with the highest contribution in the summer and fall. Factor 2 retained resonances consistent with saccharides and was attributed to pollen particles. Its contribution to WSOC varied from 0.22 μgC m-3 in winter to 1.04 μgC m-3 in spring.

  10. Influence of sugar cane burning on aerosol soluble ion composition in Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Allen, A. G.; Cardoso, A. A.; da Rocha, G. O.

    2004-09-01

    Seasonal variability in the major soluble ion composition of atmospheric particulate matter in the principal sugar cane growing region of central São Paulo State indicates that pre-harvest burning of sugar cane plants is an important influence on the regional scale aerosol chemistry. Samples of particulate matter were collected between April 1999 and February 2001 in coarse (> 3.5 μm) and fine (< 3.5 μm) fractions, and analysed for HCOO-, CH3COO-, C2O42- , SO42-, NO3-, Cl-, Na+, K+, NH4+, Mg2+ and Ca2+. Results indicated that the principal sources of the aerosols investigated were local or regional in nature (scale of tens to a few hundreds of km), and that differences between air masses of varying origins were small. Fine particles were typically acidic, containing secondary nitrates, sulphates and organic species. Coarse fraction concentrations were mainly influenced by physical parameters (wind speed, movement of vehicles and surface condition) affecting rates of re-suspension, although secondary nitrate and sulphate were also present in the larger particles. Concentrations of all measured species except sodium and chloride were higher during the burning season. Although concentrations were lower than often found in polluted urban environments, the massive increases during much of the year, due to a single anthropogenic activity (sugar cane burning) are indicative of a very large perturbation of the lower troposphere in the region relative to the natural condition. These aerosols are suspected of promoting respiratory disease. They also represent an important mechanism for the tropospheric transport of species relevant to surface acidification (sulphates, nitrates, ammonium and organic acids) and soil nutrient status (potassium, nitrogen, ammonium, calcium), so their impact on fragile natural ecosystems (following deposition) needs to be considered.

  11. SOLUBILITY OF IRON IN METALLIC HYDROGEN AND STABILITY OF DENSE CORES IN GIANT PLANETS

    SciTech Connect

    Wahl, Sean M.; Wilson, Hugh F.; Militzer, Burkhard

    2013-08-20

    The formation of the giant planets in our solar system, and likely a majority of giant exoplanets, is most commonly explained by the accretion of nebular hydrogen and helium onto a large core of terrestrial-like composition. The fate of this core has important consequences for the evolution of the interior structure of the planet. It has recently been shown that H{sub 2}O, MgO, and SiO{sub 2} dissolve in liquid metallic hydrogen at high temperature and pressure. In this study, we perform ab initio calculations to study the solubility of an innermost metallic core. We find dissolution of iron to be strongly favored above 2000 K over the entire pressure range (0.4-4 TPa) considered. We compare with and summarize the results for solubilities on other probable core constituents. The calculations imply that giant planet cores are in thermodynamic disequilibrium with surrounding layers, promoting erosion and redistribution of heavy elements. Differences in solubility behavior between iron and rock may influence evolution of interiors, particularly for Saturn-mass planets. Understanding the distribution of iron and other heavy elements in gas giants may be relevant in understanding mass-radius relationships, as well as deviations in transport properties from pure hydrogen-helium mixtures.

  12. Soluble trace metals in aerosols over the tropical south east Pacific offshore of Peru

    NASA Astrophysics Data System (ADS)

    Baker, A. R.; Thomas, M.; Bange, H. W.; Plasencia Sánchez, E.

    2015-10-01

    Bulk aerosol samples collected during cruise M91 of FS Meteor off the coast of Peru in December 2012 were analysed for their soluble trace metal (Fe, Al, Mn, Ti, Zn, V, Ni, Cu, Co, Cd, Pb, Th) and major ion (including NO3- and NH4+) content. These data are among the first recorded for trace metals in this relatively poorly studied region of the global marine atmosphere. To the north of ∼ 13° S, the concentrations of several elements (Fe, Ti, Zn, V, Ni, Pb) appear to be related to distance from the coast. At the south of the transect (∼ 15-16° S), elevated concentrations of Fe, Cu, Co and Ni were observed. These may be related to the activities of the large smelting facilities in the south of Peru or northern Chile. Calculated dry deposition fluxes (3370-17 800 and 16-107 nmol m-2 d-1 for inorganic nitrogen and soluble Fe respectively) indicated that atmospheric input to the waters of the Peru upwelling system contains an excess of Fe over N, with respect to phytoplankton requirements. This may be significant as primary production in these waters has been reported to be limited by Fe availability, but atmospheric deposition is unlikely to be the dominant source of Fe to the system.

  13. Anaemia in Systemic Lupus Erythematosus Based on Iron Studies and Soluble Transferrin Receptor Levels

    PubMed Central

    Agarwal, Preeti; Wakhlu, Anupam; Kumar, Ashutosh; Mehrotra, Raj; Mittal, Saumya

    2016-01-01

    Introduction Haematological alterations such as anaemia, neutropenia and thrombocytopenia are frequent in Systemic Lupus Erythematosus (SLE). Ferritin being an acute phase reactant can be falsely elevated in lupus cases. Aim To evaluate the haematological alterations and to re-categorise the types of anemia by soluble transferrin receptor levels in diagnosed cases of SLE. Materials and Methods A sample of 30 newly diagnosed ANA positive SLE patients was taken. Complete blood counts, ESR, reticulocyte count, coagulation studies, diluted Russel Viper Venom Test (dRVVT), mixing studies, serological tests, high sensitivity CRP along with iron profile, transferrin saturation, soluble transferrin receptor (sol TFR) levels, anti-beta2 glycoprotein1, direct and indirect Coomb’s test were estimated in cases diagnosed as SLE. Clinical symptoms were co-related with and Systemic Lupus Erythaematosus Disease Activity Index (SLEDAI) was estimated. Results Anaemia was the most prevalent haematological alteration followed by thrombocytopenia. Further sub typing of anaemia was done by serum ferritin levels and using sol TFR assays. Ferritin is an acute phase reactant; it underestimated iron deficiency in patients of SLE. When sol TFR was used; patients with pure Anaemia of Chronic Disease (ACD) reduced from 68% to 26%, those with pure IDA reduced from 32% to 16% and a group with co-existing IDA & ACD (58%) was defined {Agreement=53%, p=0.09} by sol TFR which co-related with clinical response to Iron therapy in these patients. CRP was significantly raised in association with disease activity. Fever (p<0.0001), arthritis (p<0.03) were significantly related and CRP was elevated (p<0.04) in cases with high SLEDAI (severe flare). Conclusion Thus, in SLE, anaemia is the most frequent hematological alteration; iron deficiencies supercede in contrast to ACD and further autoimmune haemolytic anaemia. Sol TFR emerged as a better parameter to detect iron deficiency in patients of non

  14. Soluble trace metals in aerosols over the tropical south-east Pacific offshore of Peru

    NASA Astrophysics Data System (ADS)

    Baker, A. R.; Thomas, M.; Bange, H. W.; Plasencia Sánchez, E.

    2016-02-01

    Bulk aerosol samples collected during cruise M91 of FS Meteor off the coast of Peru in December 2012 were analysed for their soluble trace metal (Fe, Al, Mn, Ti, Zn, V, Ni, Cu, Co, Cd, Pb, Th) and major ion (including NO3- and NH4+) content. These data are among the first recorded for trace metals in this relatively poorly studied region of the global marine atmosphere. To the north of ˜ 13° S, the concentrations of several elements (Fe, Ti, Zn, V, Ni, Pb) appear to be related to distance from the coast. At the south of the transect ( ˜ 15-16° S), elevated concentrations of Fe, Cu, Co, and Ni were observed, and we calculated dry deposition fluxes of soluble Cu approximately an order of magnitude higher than a recent model-based estimate of total Cu deposition to the region. The model did not take account of emissions from the large smelting facilities in the south of Peru and northern Chile, and our results may indicate that these facilities constitute an important source of trace metals to the region. Calculated dry deposition fluxes (3370-17800 and 16-107 nmol m-2 d-1 for inorganic nitrogen and soluble Fe respectively) indicated that atmospheric input to the waters of the Peru upwelling system contains an excess of Fe over N, with respect to phytoplankton requirements. This may be significant as primary production in these waters has been reported to be limited by Fe availability, but atmospheric deposition is unlikely to be the dominant source of Fe to the system.

  15. Fine Iron Aerosols Are Internally Mixed with Nitrate in the Urban European Atmosphere.

    PubMed

    Dall'Osto, Manuel; Beddows, D C S; Harrison, Roy M; Onat, Burcu

    2016-04-19

    Atmospheric iron aerosol is a bioavailable essential nutrient playing a role in oceanic productivity. Using aerosol time-of-flight mass spectrometry (ATOFMS), the particle size (0.3-1.5 μm), chemical composition and mixing state of Fe-containing particles collected at two European urban sites (London and Barcelona) were characterized. Out of the six particle types accounting for the entire Fe-aerosol population, that arising from long-range transport (LRT) of fine Fe-containing particles (Fe-LRT, 54-82% across the two sites) was predominant. This particle type was found to be internally mixed with nitrate and not with sulfate, and likely mostly associated with urban traffic activities. This is in profound contrast with previous studies carried out in Asia, where the majority of iron-containing particles are mixed with sulfate and are of coal combustion origin. Other minor fine iron aerosol sources included mineral dust (8-11%), traffic brake wear material (1-17%), shipping/oil (1-6%), biomass combustion (4-13%) and vegetative debris (1-3%). Overall, relative to anthropogenic Asian Fe-sulfate dust, anthropogenic European dust internally mixed with additional key nutrients such as nitrate is likely to play a different role in ocean global biogeochemical cycles. PMID:27002272

  16. Soluble metals in the atmosphere and their biological implications. A study to identify important aerosol components by statistical analysis of PIXE data.

    PubMed

    Winchester, J W

    1990-01-01

    Multivariate statistical analysis has been applied to time series measurements of aerosol elemental composition from PIXE analysis of filter samples, and principal components have been resolved that represent distinct particle types in an external mixture in the atmosphere. In this study, it is argued that a combination of chemical and statistical analyses of the data may be more powerful in determining chemical species in atmospheric aerosols than studied that employ mainly direct chemical analysis of chemical species in unresolved mixtures of aerosol particle samples. Sulfur is generally associated with mineral dust elements. It is reasoned that the association may represent sulfuric acid coatings on particles that can lead to mineral dissolution and solubilization of significant amounts of aluminum, iron, and other metals. Upon wet or dry deposition to the surface, the fluxes of these metals in biologically-available form may be sufficient to affect primary productivity in the world ocean and cause ecological damage in lakes. As a consequence, the fluxes of biogenic trace gases to the atmosphere may be changed, possibly leading to changes in the tropospheric concentration of ozone. The inputs to lakes of soluble aluminum, which is toxic to fish, may be partly by deposition directly from the atmosphere, thus not limited to leaching of soils by acid deposition. Human inhalation of soluble aluminum and other solubilized mineral metals may account, in part, for the observed geographic pattern of deaths attributed to chronic obstructive pulmonary disease (COPD) that show high rates in cities of the Western US and the southeast region, but low in most of the midwest and northeast.

  17. Regulation of cell surface transferrin receptor-2 by iron-dependent cleavage and release of a soluble form.

    PubMed

    Pagani, Alessia; Vieillevoye, Maud; Nai, Antonella; Rausa, Marco; Ladli, Meriem; Lacombe, Catherine; Mayeux, Patrick; Verdier, Frédérique; Camaschella, Clara; Silvestri, Laura

    2015-04-01

    Transferrin receptor-2 is a transmembrane protein whose expression is restricted to hepatocytes and erythroid cells. Transferrin receptor-2 has a regulatory function in iron homeostasis, since its inactivation causes systemic iron overload. Hepatic transferrin receptor-2 participates in iron sensing and is involved in hepcidin activation, although the mechanism remains unclear. Erythroid transferrin receptor-2 associates with and stabilizes erythropoietin receptors on the erythroblast surface and is essential to control erythrocyte production in iron deficiency. We identified a soluble form of transferrin receptor-2 in the media of transfected cells and showed that cultured human erythroid cells release an endogenous soluble form. Soluble transferrin receptor-2 originates from a cleavage of the cell surface protein, which is inhibited by diferric transferrin in a dose-dependent manner. Accordingly, the shedding of the transferrin receptor-2 variant G679A, mutated in the Arginine-Glycine-Aspartic acid motif and unable to bind diferric transferrin, is not modulated by the ligand. This observation links the process of transferrin receptor-2 removal from the plasma membrane to iron homeostasis. Soluble transferrin receptor-2 does not affect the binding of erythropoietin to erythropoietin receptor or the consequent signaling and partially inhibits hepcidin promoter activation only in vitro. Whether it is a component of the signals released by erythropoiesis in iron deficiency remains to be investigated. Our results indicate that membrane transferrin receptor-2, a sensor of circulating iron, is released from the cell membrane in iron deficiency. PMID:25637053

  18. Determination of total and non-water soluble iodine in atmospheric aerosols by thermal extraction and spectrometric detection (TESI).

    PubMed

    Gilfedder, B S; Chance, R; Dettmann, U; Lai, S C; Baker, A R

    2010-09-01

    Iodine has recently been of interest in atmospheric chemistry due to its role in tropospheric ozone depletion, modification of the HO/HO(2) ratio and aerosol nucleation. Gas-phase iodine chemistry is tightly coupled to the aerosol phase through heterogeneous reactions, which are dependent on iodine concentrations and speciation in the aerosol. To date, the only method available for total iodine determination in aerosols is collection on filters by impaction and quantification by neutron activation analysis (NAA). NAA is not widely available to all working groups and is costly to commission. Here, we present a method to determine total iodine concentrations in aerosol impact filter samples by combustion of filter sub-samples (approximately 5 cm(2)) at 1,000 degrees C, trapping in deionised water and quantification by UV/Vis spectroscopy. Both quartz and cellulose filters were analysed from four separate sampling campaigns. The method proved to be sensitive (3sigma = 6 ng absolute iodine approximately 3 pmol m(-3)) precise (RSD approximately 5%) and accurate, as determined by external and standard addition calibrations. Total iodine concentrations ranged from 10 pmol m(-3) over the Southern Ocean to 100 pmol m(-3) over the tropical Atlantic, in agreement with previous estimates. The soluble iodine concentration (extracted with water and measured by ICP-MS) was then subtracted from the total iodine to yield non-water-soluble iodine (NSI). The NSI fraction ranged from 20% to 53% of total iodine, and thus can be significant in some cases.

  19. Comparison of mineral and soluble iron Fenton's catalysts for the treatment of trichloroethylene.

    PubMed

    Teel, A L; Warberg, C R; Atkinson, D A; Watts, R J

    2001-03-01

    Contaminant degradation, stoichiometry, and role of hydroxyl radicals (OH*) in four Fenton's systems were investigated using trichloroethylene (TCE) as a model contaminant. A standard Fenton's system, a modified soluble iron system with a pulse input of hydrogen peroxide, and two modified mineral-catalyzed systems (pH 3 and 7) were studied. In the standard Fenton's system, which had the most efficient reaction stoichiometry, 78% of the TCE was degraded; however, chloride analysis indicated that no more than two of the three chlorines were displaced per TCE molecule degraded. Although the modified soluble iron system was characterized by 91% TCE degradation, chloride analysis also indicated that no more than two of the chlorines were lost from the TCE. In the goethite system of pH 3, > 99% of the TCE was degraded. Near-complete release of chloride suggested that the TCE may have been mineralized. Only 22% degradation of TCE was achieved in the pH 7 goethite system. and there was minimal release of chloride. The mineral-catalyzed reactions exhibited the least efficient reaction stoichiometry of the four systems. Experiments using hydroxyl radical scavengers showed that the standard Fenton's system degraded TCE entirely by hydroxyl radical mechanisms, while approximately 10-15% of the degradation achieved in the modified soluble iron and goethite-catalyzed systems at pH 3 was mediated by non-hydroxyl radical mechanisms. In the goethite system at pH 7, only non-hydroxyl radical mechanisms were found. The goethite-catalyzed system at pH 3 effectively degraded the parent compound and may have the potential to mineralize contaminants when used for in situ soil and groundwater remediation and ex situ waste stream treatment in packed-bed reactors.

  20. Disproportionation of hydroxylamine by water-soluble iron(III) porphyrinate compounds.

    PubMed

    Bari, Sara E; Amorebieta, Valentín T; Gutiérrez, María M; Olabe, José A; Doctorovich, Fabio

    2010-01-01

    The reactions of hydroxylamine (HA) with several water-soluble iron(III) porphyrinate compounds, namely iron(III) meso-tetrakis-(N-ethylpyridinium-2yl)-porphyrinate ([Fe(III)(TEPyP)](5+)), iron(III) meso-tetrakis-(4-sulphonatophenyl)-porphyrinate ([Fe(III)(TPPS)](3-)), and microperoxidase 11 ([Fe(III)(MP11)]) were studied for different [Fe(III)(Porph)]/[HA] ratios, under anaerobic conditions at neutral pH. Efficient catalytic processes leading to the disproportionation of HA by these iron(III) porphyrinates were evidenced for the first time. As a common feature, only N(2) and N(2)O were found as gaseous, nitrogen-containing oxidation products, while NH(3) was the unique reduced species detected. Different N(2)/N(2)O ratios obtained with these three porphyrinates strongly suggest distinctive mechanistic scenarios: while [Fe(III)(TEPyP)](5+) and [Fe(III)(MP11)] formed unknown steady-state porphyrinic intermediates in the presence of HA, [Fe(III)(TPPS)](3-) led to the well characterized soluble intermediate, [Fe(II)(TPPS)NO](4-). Free-radical formation was only evidenced for [Fe(III)(TEPyP)](5+), as a consequence of a metal centered reduction. We discuss the catalytic pathways of HA disproportionation on the basis of the distribution of gaseous products, free radicals formation, the nature of porphyrinic intermediates, the Fe(II)/Fe(III) redox potential, the coordinating capabilities of each complex, and the kinetic analysis. The absence of NO(2)(-) revealed either that no HAO-like activity was operative under our reaction conditions, or that NO(2)(-), if formed, was consumed in the reaction milieu.

  1. Speciation of Water-Soluble Organic Carbons in Aerosols from two collecting methods: PILS and filters

    NASA Astrophysics Data System (ADS)

    Kim, J.; Yoon, H.; Ahn, Y.; Shin, J.; Lee, M.; Park, M.

    2013-12-01

    Total suspended particles aerosol sampling for collection of 24 h by high volume air sampler at Campus of Korea University in metropolitan city Seoul. To measure WSOC, an aliquot (2 cm2) of quartz fiber filter ( 20.3 × 25.4 cm) was extracted 5 mL Milli-Q water with hot water (80 °C) and room temperature water (25 °C) under ultrasonication (10 min, three times). Hot water extracted method was comparison with PILS samples. WSOC was quantified using a total organic carbon (TOC) analyzer. For speciation analysis of organic compounds, the extracts were concentrated to dryness using freeze dryer and then derivatized with MSTFA (N-Methyl-N-trimethy- silyltrifluoroacetamide+1% trimethylchlorosilane) and analyzed with GC-MS scan mode. In extracted with hot water, total carbon concentrations were higher than room temperature extracts. Organic compounds widely recognized to be generated from anthropogenic sources with a low solubility at ambient temperature organic were detected in both samples obtained from PILS and hot water extraction. It is demonstrating that difference between total carbon concentration and composition of sampling obtain from two different systems (i.e. PILS and filter) in analytical procedure of WSOCs. Acknowledgement This research was susported by Center for Women In Science, Engineering Technology(WISET) commissioned by the Ministry of Science, ICT & Future Planning and the National Research Foundation of korea. The authors also acknowledge the support made by a grant from the Korea Basic Science Institute.

  2. High-Resolution Electrospray Ionization Mass Spectrometry Analysis of Water- Soluble Organic Aerosols Collected with a Particle into Liquid Sampler

    SciTech Connect

    Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

    2010-10-01

    This work demonstrates the utility of a particle-into-liquid sampler (PILS) a technique traditionally used for identification of inorganic ions present in ambient or laboratory aerosols for the analysis of water soluble organic aerosol (OA) using high resolution electrospray ionization mass spectrometry (HR ESI-MS). Secondary organic aerosol (SOA) was produced from 0.5 ppm mixing ratios of limonene and ozone in a 5 m3 Teflon chamber. SOA was collected simultaneously using a traditional filter sampler and a PILS. The filter samples were later extracted with either water or acetonitrile, while the aqueous PILS samples were analyzed directly. In terms of peak intensities, types of detectable compounds, average O:C ratios, and organic mass to organic carbon ratios, the resulting high resolution mass spectra were essentially identical for the PILS and filter based samples. SOA compounds extracted from both filter/acetonitrile extraction and PILS/water extraction accounted for >95% of the total ion current in ESI mass spectra. This similarity was attributed to high solubility of limonene SOA in water. In contrast, significant differences in detected ions and peak abundances were observed for pine needle biomass burning organic aerosol (BBOA) collected with PILS and filter sampling. The water soluble fraction of BBOA is considerably smaller than for SOA, and a number of unique peaks were detectable only by the filter/acetonitrile method. The combination of PILS collection with HR-ESI-MS analysis offers a new approach for molecular analysis of the water-soluble organic fraction in biogenic SOA, aged photochemical smog, and BBOA.

  3. Micro-scale (μg) radiocarbon analysis of water-soluble organic carbon in aerosol samples

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-lin; Liu, Jun-wen; Salazar, Gary A.; Li, Jun; Zotter, Peter; Zhang, Gan; Shen, Rong-rong; Schäfer, Klaus; Schnelle-Kreis, Jürgen; Prévôt, André S. H.; Szidat, Sönke

    2014-11-01

    Radiocarbon (14C) measurement of water-soluble organic carbon (WSOC) in ambient aerosols is a quantitative tool for unambiguously distinguishing fossil and non-fossil sources. In this study, a fast and reliable method for measuring 14C in micro-scale (μg) WSOC aerosol samples is successfully developed, which includes three steps: (1) extraction (2) freeze drying, and (3) online 14C analysis of CO2 from WSOC combustion. Procedure blanks are carefully assessed by measuring high-purity water and reference materials. Accurate 14C results could be obtained for WSOC with only 10 μg C, and thus the potential applications are substantially broadened because much less filter material is needed compared to previous reported methods. This method is applied to aerosols samples collected during winter from Switzerland and China. The results demonstrate that non-fossil sources are important if not dominant contributors of WSOC. These non-fossil components are consistently enriched in WSOC compared to bulk OC and water-insoluble OC for all samples, due to high water solubility of primary and secondary biomass burning aerosols. However, the presence of fossil WSOC is still considerable indicating a substantial contribution of secondary OC (SOC) formed from precursors emitted by fossil emissions. Larger fossil contributions to WSOC is found in China than in Switzerland and previously reported values in Europe, USA and South Asia, which may be attributed to higher fossil-derived SOC formation in China.

  4. Speciation of water-soluble organic carbon compounds in boundary layer aerosols during the LBA/CLAIRE/SMOCC-2002 campaign

    NASA Astrophysics Data System (ADS)

    Claeys, M.; Pashynska, V.; Vermeylen, R.; Vas, G.; Cafmeyer, J.; Maenhaut, W.; Artaxo, P.

    2003-04-01

    The water-soluble, hygroscopic aerosol fraction is of climatic interest because of its role as cloud condensation nuclei (CCN) and the associated effects on cloud formation and cloud properties. As part of the LBA/CLAIRE/SMOCC experiment in Amazonia, September-November 2002, aerosol samples were collected using various types of samplers. The campaign spanned from the peak of the burning season, with high smoke concentrations, to fairly clean conditions in the early rainy season. Separate day and night samples were collected, and the collection time per sample varied from 12 hours in September to up to 48 hours in November. Fine (< 2.5 μm) and coarse (> 2.5 μm) aerosol size fractions were obtained using a Hi-Vol dichotomous sampler, and the samples were analysed for organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and various water-soluble organic carbon compounds. The latter compounds included the anhydrosugars, levoglucosan, mannosan, and galactosan, which are markers for wood combustion, the polyols, arabitol and mannitol, which originate from the natural forest environment, as well as the hydroxydicarboxylic acid, malic acid, which is a late product in the photochemistry of fatty acids and n-alkanes. Preliminary results including the mass concentrations of OC, EC, WSOC and the water-soluble organic compounds will be presented. By far the major water-soluble organic carbon compound in the fine size fraction was levoglucosan, showing concentrations in the range of 1-6 μg m-3 in the peak of the burning season (17-24 September).

  5. Enhanced Yields of Iron-Oxidizing Bacteria by In Situ Electrochemical Reduction of Soluble Iron in the Growth Medium

    PubMed Central

    Blake, Robert C.; Howard, Gary T.; McGinness, Stephen

    1994-01-01

    An electrochemical apparatus for culturing chemolithotrophic bacteria that respire aerobically on ferrous ions is described. Enhanced yields of the bacteria were achieved by the in situ electrochemical reduction of soluble iron in the growth medium. When subjected to a direct current of 30 A for 60 days, a 45-liter culture of Thiobacillus ferrooxidans grew from 6 × 107 to 9.5 × 109 cells per ml. Growth of the bacterium within the electrolytic bioreactor was linear with time. A final cell density corresponding to 4.7 g of wet cell paste per liter was achieved, and a total of 320 g of wet cell paste was harvested from one culture. The apparatus was designed to deliver protons concomitantly with electrons; therefore, the pH of the culture remained stable at 1.6 ± 0.1 for the duration of growth. This laboratory-scale apparatus may be readily adapted to pilot or production scale. It is thus anticipated that abundant numbers of iron-oxidizing bacteria may be obtained for both fundamental and applied studies. PMID:16349344

  6. Water-Soluble Organic Species in Biomass Burning Aerosols in Southern Africa: Their Chemical Identification and Spatial Distribution

    NASA Astrophysics Data System (ADS)

    Gao, S.; Hegg, D. A.; Hobbs, P. V.; Kirchstetter, T. W.; Magi, B.

    2001-12-01

    During the SAFARI-2000 field campaign, 14 aerosol samples were collected from an aircraft in plumes from biomass fires (under both flaming and smoldering conditions), at various distances from the fire source. Also collected were 36 aerosol samples in haze layers ranging from the surface to 16,000 feet, some of which could be associated with specific fires. The samples were collected on teflon membrane filters (lower size limit of about 30nm in diameter) which were analyzed for total aerosol mass loading and chemical composition using several analytical techniques. Particular effort was made to speciate the water-soluble portion of the aerosol organics. Seven organic acids and seven carbohydrate species (and their possible stereoisomers) were identified and quantified, along with three inorganic anions and five inorganic cations. The identified organic species accounted for up to 32% of the total aerosol mass; compared with concurrent total carbon and organic carbon measurements, the identified organics constituted at least 5% to 30% of the mass of the total aerosol organics. A number of conspicuous spatial distribution patterns were observed for these species. For instance, using K+ to correct for dilution, it was found that gluconate, oxalate, succinate, and glutarate, along with sulfate and nitrate, all increased significantly in mass concentration from the fire source going downwind. This suggests secondary formation of these species during aerosol aging. On the other hand, formate and acetate showed decreasing trends downwind, probably due to the loss of these volatile species to the gas phase. Another striking pattern is that anhydrosugars (e.g. levoglucosan) had the highest aerosol mass fraction near smoldering fires but a very low fraction in the haze layers, whereas, dicarboxylic acids showed an almost opposite trend. This implies possible chemical reaction processes converting intermediate organic products, such as levoglucosan, to smaller products like

  7. Reconciling kinetic and equilibrium observations of iron(III) solubility in aqueous solutions with a polymer-based model

    NASA Astrophysics Data System (ADS)

    Rose, Andrew L.; David Waite, T.

    2007-12-01

    Due to hydrolysis reactions, iron(III) forms oxyhydroxide precipitates in natural waters that minimise its availability to living organisms. Thermodynamic studies have established equilibrium concentrations of dissolved iron at various pH values, however these studies offer no insight into the kinetics of iron(III) polymerisation and subsequent precipitation. In recent work, the kinetics of iron(III) precipitation and dissolution of the precipitate have been investigated, but there are apparent discrepancies between the equilibrium solubility of iron(III) calculated from the kinetic parameters and its solubility measured by separation of the solid and dissolved phases at equilibrium. In this work, we reconcile kinetic and thermodynamic measurements using a polymer-based mechanistic model of the processes responsible for iron(III) precipitation in aqueous solutions based on a variety of previously published experimental data. This model is used to explain the existence of a solubility limit, including the effect of precipitate ageing on its solubility. We suggest that the model provides a unified approach for examining aqueous systems containing dissolved, solid-phase and surface species.

  8. The ambient organic aerosol soluble in water: Measurements, chemical characterization, and an investigation of sources

    NASA Astrophysics Data System (ADS)

    Sullivan, Amy P.

    This thesis characterizes the ambient fine organic carbon (OC) aerosol and investigates its sources through the development and deployment of new analytical measurement techniques. Recognizing that OC is highly chemically complex, the approach was to develop methods capable of quantitatively measuring a large chemical fraction of the aerosol instead of specific chemical speciation. The focus is on organic compounds that are soluble in water (WSOC) since little is known about its chemical nature. The results from this thesis show that WSOC has mainly two sources: biomass burning and secondary organic aerosol (SOA). In urban areas, WSOC increases with plume age, and tracks other photochemically produced compounds. Chemical analysis of WSOC suggests that in urban Atlanta, the SOA is mainly small-chain aliphatic compounds indirectly linked to vehicle emissions. A method was first developed for quantitative on-line measurements of WSOC by extending the application of the Particle-into-Liquid Sampler (PILS) from inorganic to organic aerosol measurements. In this approach a PILS captures ambient particles into a flow of purified water, which is then forced through a liquid filter and the carbonaceous content quantified on-line by a Total Organic Carbon (TOC) analyzer. An instrument was first developed for ground-based measurements and then modified for airborne deployment. Ground-based measurements at the St. Louis - Midwest Supersite during the summer of 2003 showed that the fraction of OC that is water-soluble can have a highly diurnal pattern with WSOC to OC ratios reaching 0.80 during the day and lows of 0.40 during the night. During extended periods under stagnation pollution events, this pattern was well correlated with ozone concentrations. The results are consistent with formation of SOA. Airborne PILS-TOC measurements from the NOAA WP-3D during the New England Air Quality Study/Intercontinental Transport and Chemical Transformation (NEAQS/ITCT) 2004 program

  9. Water-soluble organic carbon, dicarboxylic acids, ketoacids, and α-dicarbonyls in the tropical Indian aerosols

    NASA Astrophysics Data System (ADS)

    Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.

    2010-06-01

    Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2-C12), ketocarboxylic acids (C2-C9), and α-dicarbonyls (glyoxal and methylglyoxal), together with analyses of total carbon (TC) and water-soluble organic carbon (WSOC). Their distributions were characterized by a predominance of oxalic acid followed by terephthalic (t-Ph), malonic, and succinic acids. Total concentrations of diacids (227-1030 ng m-3), ketoacids (16-105 ng m-3), and dicarbonyls (4-23 ng m-3) are comparative to those from other Asian megacities such as Tokyo and Hong Kong. t-Ph acid was found as the second most abundant diacid in the Chennai aerosols. This feature has not been reported previously in atmospheric aerosols. t-Ph acid is most likely derived from the field burning of plastics. Water-soluble diacids were found to contribute 0.4%-3% of TC and 4%-11% of WSOC. Based on molecular distributions and backward air mass trajectories, we found that diacids and related compounds in coastal South Indian aerosols are influenced by South Asian and Indian Ocean monsoons. Organic aerosols are also suggested to be significantly transported long distances from North India and the Middle East in early winter and from Southeast Asia in late winter, but some originate from photochemical reactions over the Bay of Bengal. In contrast, the Arabian Sea, Indian Ocean, and South Indian continent are suggested as major source regions in summer. We also found daytime maxima of most diacids, except for C9 and t-Ph acids, which showed nighttime maxima in summer. Emissions from marine and terrestrial plants, combined with land/sea breezes and in situ photochemical oxidation, are suggested especially in summer as an important factor that controls the composition of water-soluble organic aerosols over the southeast coast of India. Regional emissions from anthropogenic sources are also important in megacity Chennai, but their influence is

  10. Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

    NASA Astrophysics Data System (ADS)

    Asa-Awuku, A.; Sullivan, A. P.; Hennigan, C. J.; Weber, R. J.; Nenes, A.

    2008-02-01

    In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH4)2SO4) in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH4)2SO4. From our analysis, average thermodynamic properties (i.e, molar volume) are determined for samples using our newly developed Köhler Theory Analysis (KTA) method. The molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol-1 and 780±231 g mol-1, respectively. KTA also suggests that the relative proportion (in moles) of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

  11. Investigation of molar volume and surfactant characteristics of water-soluble organic compounds in biomass burning aerosol

    NASA Astrophysics Data System (ADS)

    Asa-Awuku, A.; Nenes, A.; Sullivan, A. P.; Hennigan, C. J.; Weber, R. J.

    2007-03-01

    In this study, we characterize the CCN activity of the water-soluble organics in biomass burning aerosol. The aerosol after collection upon filters is dissolved in water using sonication. Hydrophobic and hydrophilic components are fractionated from a portion of the original sample using solid phase extraction, and subsequently desalted. The surface tension and CCN activity of these different samples are measured with a KSV CAM 200 goniometer and a DMT Streamwise Thermal Gradient CCN Counter, respectively. The measurements show that the strongest surfactants are isolated in the hydrophobic fraction, while the hydrophilics exhibit negligible surface tension depression. The presence of salts (primarily (NH4)2SO4) in the hydrophobic fraction substantially enhances surface tension depression; their synergistic effects considerably enhance CCN activity, exceeding that of pure (NH4)2SO4. For our analysis, average thermodynamic properties (i.e., molar volume) are determined for samples using our newly developed Köhler Theory Analysis (KTA) method. We have found that, the molar mass of the hydrophilic and hydrophobic aerosol components is estimated to be 87±26 g mol-1 and 780±231 g mol-1, respectively. KTA also suggests that the relative proportion (in moles) of hydrophobic to hydrophilic compounds in the original sample to be 1:3. For the first time, KTA is applied to an aerosol with this level of complexity and displays its potential for providing physically-based constraints for GCM parameterizations of the aerosol indirect effect.

  12. The Role of Dimethyl Sulfoxide in the Reductive Dissolution of Iron in Marine Aerosols

    NASA Astrophysics Data System (ADS)

    Key, J. M.; Johansen, A. M.

    2003-12-01

    Very little is known about the effects of atmospheric iron (Fe) deposition from aeolian dusts into the remote oceans and the role it plays as a key nutrient for photosynthesis in marine phytoplankton in high nutrient low chlorophyll (HNLC) waters. Several in situ iron fertilization studies in HNLC regions have reported increases in chlorophyll a concentrations, nutrient and carbon uptake, and the release of various biogenic gases which have the potential to directly and indirectly impact global climate. Of particular interest in the present study is the indirect effect of dimethyl sulfoxide (DMSO) as part of a positive feedback cycle that may exist between such biogenically derived reduced sulfur compounds and crustal derived iron in the atmosphere over remote oceanic regions. To determine whether DMSO can lead to larger atmospheric concentrations of bioavailable iron in the form of Fe(II), photochemical simulation experiments were carried out using synthetic ferrihydrite (Fe5HO8ṡ4H2O) in the presence of DMSO. During these experiments DMSO oxidation products, such as methane sulfonic acid (MSA), methane sulfinic acid (MSIA), and sulfate (SO42-), were quantified by means of ion chromatography (IC), while Fe(II) was determined spectrophotometrically by complexation with ferrozine. Preliminary results suggest that current ambient DMSO levels are too low to play a significant role in the reductive dissolution of iron hydroxide in aerosol particles. However, increased DMSO levels may enhance bioavailability of iron, thus potentially closing the gap in the positive feedback cycle.

  13. A case of anaemia in a neonatal warthog (Phacochoerus aethiopicus) and evaluation of serum-soluble iron in warthogs.

    PubMed

    Kenny, D E; Braselton, W E; Taylor, R A; Morgan, T; Hesky, R B

    2002-09-01

    A 38-day-old male warthog (Phacochoerus aethiopicus) with marked anaemia (haematocrit = 14 %) presented to the Denver Zoological Gardens hospital with ataxia, tachypnoea, suspected stunted growth and cardiomegaly. The piglet demonstrated some features consistent with both iron deficiency anaemia and autoimmune haemolytic anaemia. Serum-soluble iron was below the level of detection (< 8.96 micromol/l). Iron deficiency anaemia is a well recognised entity in domestic swine reared on concrete and denied access to soil. Fifteen captive warthogs were subsequently evaluated for serum soluble iron content (mean = 21.62 +/- 4.36 micromol/l as well as 5 neonatal warthog piglets that required hand-rearing. Only 1 of 5 neonatal warthog piglets had measurable serum soluble iron (9.50 micromol/l). These data suggest that warthogs are similar to domestic swine and are born with low iron stores. Some form of iron supplementation should be considered for captive neonatal warthog piglets, especially if they are reared on concrete. PMID:12515305

  14. Sources of Water-soluble Organic Aerosol in the Southeastern United States - Evidence of SOA Formed Through Heterogeneous Reactions

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Weber, R. J.

    2010-12-01

    Recent laboratory studies suggest partitioning of semi-volatile organic compounds (SVOCs) to liquid water followed by heterogeneous chemical transformation as a possible route to forming secondary organic aerosol (SOA). This paper will present results from observational studies of SOA formation using Water-Soluble Organic Carbon (WSOC) fraction of SOA, soluble brown carbon (e.g., light absorption spectra), organic acids and a number of aerosol source tracers in the Southeastern U.S., a region known for extensive biogenic and anthropogenic VOC emissions. Based on 24-h integrated filter measurements at 15 sites in the southeast throughout the year of 2007, a PMF analysis identified a factor characterized by the co-abundance of WSOC (58 percent of the total), oxalate (51 percent) and brown carbon (Abs365) (44 percent), which is consistent with the aqueous phase SOA formation mechanism in which water-soluble organic products from gas-phase photochemistry dissolve in liquid (fog/cloud droplets or particle water) and react further to form oligomers, light absorbing compounds, and light-weight organic acids, with oxalic acid being the most abundant one [Hecobian et al., 2010; Zhang et al., 2010]. The temporal variability of this factor correlated well with ambient temperature, possibly owing to the large impact from biogenic emissions, which are dependent on temperature and known to be significant over the southeast. PMF analysis of other data sets collected in Atlanta with online instruments during summer support these findings; as do other studies based on different data sets and data-analysis methods [Hennigan et al., 2008a; Hennigan et al., 2008b; Hennigan et al., 2008c; Hennigan et al., 2009]. Overall, we find that WSOC is largely secondary (roughly 75 to 85 percent) and estimate that 65 to 75 percent of the secondary WSOC formed in the southeast involves some form of aqueous phase chemical process. Hecobian, A., X. Zhang, M. Zheng, N. Frank, E. S. Edgerton, and R. J

  15. Seasonal cycles of water-soluble organic nitrogen aerosols in a deciduous broadleaf forest in northern Japan

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzo; Fu, PingQing; Ono, Kaori; Tachibana, Eri; Kawamura, Kimitaka

    2014-02-01

    The seasonal variations in aerosol water-soluble organic nitrogen (WSON) concentrations measured in a deciduous forest canopy over an approximately 30 month period were investigated for possible sources in the forest. The WSON concentrations (average 157 ± 127 ng N m-3) and WSON/water-soluble total nitrogen mass fractions (average 20 ± 11%) in the total suspended particulate matter exhibited a clear seasonal cycle with maxima in early summer. The WSON mass was found to reside mostly in the fine-mode size range (Dp < 1.9 µm) during the summer months. WSON was positively correlated with oxidation products of α-pinene and isoprene with similar size distributions, suggesting that secondary formation from biogenic hydrocarbon precursors is a plausible source for WSON in summer. In contrast, the majority of WSON in autumn was associated with coarse fraction (Dp > 1.9 µm), which was similar to the size distributions of sugar compounds, indicating that the major WSON sources in autumn are associated with primary biological emissions. The vertical differences in WSON concentrations suggest that the water-soluble organic aerosol is enriched with nitrogen below the canopy level relative to the forest floor. The WSON concentration increased with enhanced hydrogen ion concentrations in aerosol in the early summer, indicating that aerosol acidity associated with anthropogenic sources outside the forest likely plays an important role in the formation of WSON in that season. The study suggests that multiple sources of WSON within the forest canopy may dominate over others in specific seasons, providing insights into WSON formation processes in forest environments.

  16. Size distributions of aerosol and water-soluble ions in Nanjing during a crop residual burning event.

    PubMed

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; Kang, Hanqing

    2012-01-01

    To investigate the impact on urban air pollution by crop residual burning outside Nanjing, aerosol concentration, pollution gas concentration, mass concentration, and water-soluble ion size distribution were observed during one event of November 4-9, 2010. Results show that the size distribution of aerosol concentration is bimodal on pollution days and normal days, with peak values at 60-70 and 200-300 nm, respectively. Aerosol concentration is 10(4) cm(-3) x nm(-1) on pollution days. The peak value of spectrum distribution of aerosol concentration on pollution days is 1.5-3.3 times higher than that on a normal day. Crop residual burning has a great impact on the concentration of fine particles. Diurnal variation of aerosol concentration is trimodal on pollution days and normal days, with peak values at 03:00, 09:00 and 19:00 local standard time. The first peak is impacted by meteorological elements, while the second and third peaks are due to human activities, such as rush hour traffic. Crop residual burning has the greatest impact on SO2 concentration, followed by NO2, O3 is hardly affected. The impact of crop residual burning on fine particles (< 2.1 microm) is larger than on coarse particles (> 2.1 microm), thus ion concentration in fine particles is higher than that in coarse particles. Crop residual burning leads to similar increase in all ion components, thus it has a small impact on the water-soluble ions order. Crop residual burning has a strong impact on the size distribution of K+, Cl-, Na+, and F- and has a weak impact on the size distributions of NH4+, Ca2+, NO3- and SO4(2-).

  17. Concentrations and Fluxes of Water-Soluble Reactive Nitrogen Gases and Aerosol Compounds Above a Forest Canopy

    NASA Astrophysics Data System (ADS)

    Wolff, V.; Trebs, I.; Moravek, A.; Zhu, Z.; Meixner, F. X.

    2008-12-01

    In summer 2007 we measured concentration gradients of NH3, HNO3, HONO and related aerosol species NH4+ and NO3- as well as SO2, and aerosol SO42- above a spruce canopy in south-east Germany (50° 09"N, 11° 52"E, 775m asl). Measurements were performed as part of an intensive observation period within the framework of the EGER (ExchanGE processes in mountainous Regions) project. NH3, HNO3, HONO, SO2, aerosol NH4+, aerosol NO3-, and aerosol SO42- were measured using the Gradient Analyzer for Aerosols and Gases, mounted on a tower. Water-soluble gases and aerosol species were collected simultaneously at two different heights by two rotating wet-annular denuders and two Steam-Jet Aerosol Collectors, respectively. Samples were analysed on-line via ion chromatography and flow injection analysis. To our knowledge this was the first time that these gas and aerosol species were measured simultaneously and with high time resolution (30 min) above a forest canopy. Data accuracy and precision is provided by a rigorous data screening, including the use of an internal standard, careful error estimation and repeated in- field blanks. Gradient precision of the measurements are derived from extended periods of side-by-side sampling of the sample boxes (n = 257). NH3 mixing ratios reached their maximum in the late afternoon with 2 to 3 ppb and their minimum in morning hours with 0.25 ppb, whereas aerosol NH4+ mirrored this behaviour with maximum values late night and early morning with 4 up to 8 ppb and minimum values in the afternoon, around 0.5 ppb and less. HNO3 and aerosol NO3- diel cycles also mirrored each other, HNO3 maxima during late afternoon ( above 1 ppb) and minimum during night and early morning with less than 0.2 ppb and aerosol NO3- maxima during night ( around 2 ppb, up to 6 ppb) and minima during afternoons with 0.5 ppb. Patterns of aerosol NH4+ and aerosol NO3- in the time series are apparently closely related. NH3 gradients indicate bidirectional fluxes, whereas

  18. Attributes of aerosol bound water soluble ions and carbon, and their relationships with AOD over the Brahmaputra Valley

    NASA Astrophysics Data System (ADS)

    Bhuyan, Pranamika; Barman, Nivedita; Bora, Jayanta; Daimari, Rebecca; Deka, Pratibha; Hoque, Raza Rafiqul

    2016-10-01

    The present study is a ground based investigation of chemical properties of aerosol as PM10 and its relationship with the upper air optical properties. A total of 161 aerosol samples collected during 2010-2014 were characterized for water soluble ions viz. SO42-, NO3-, Cl-, F-, NH4+, K+, Ca2+, Mg2+and Na+ and water soluble carbon factions - water soluble organic carbon (WSOC) and water soluble inorganic carbon (WSIC). The entire study period was subdivided into four distinct seasons -pre-monsoon, monsoon, post-monsoon and winter to assess the characteristics of chemical species in different times of the year contributing to the particulate loading over the study site. To understand the relationship between chemical species and optical properties, aerosol optical depth (AOD) data of the study area have been retrieved from MODIS satellite data at 550 nm. Mean mass concentration of PM10 was found to be 49.3 ± 37 μg/m3 for the whole study period with an explicit seasonal variation and winter maximum of mass concentration. Also, secondary ions have strong influence on the total aerosol loading in the region. Vivid seasonal variability was found in the concentrations of ions and carbons. The winter season showed maximum loading of ionic and carbonaceous species and the presence of crustal derived ions - Ca2+ and Mg2+ - remained uniform all through the seasons. The anions were found to be dominant over the cations during the study period. Interestingly, K+, originating mostly from biomass burning emissions, also play important neutralizing role together with NH4+. Significant relationships between AOD with PM10 and attributes were observed. Strong correlation of anthropogenic (SO42-, NO3-, NH4+), biomass burning (K+) and organic carbon fraction of PM10 with AOD was observed, which indicated the influence of these fractions on the attenuation of incoming light over the study region. HYSPLIT backward trajectories of air masses, which were computed for the study area

  19. Dissolution behaviour of ferric pyrophosphate and its mixtures with soluble pyrophosphates: Potential strategy for increasing iron bioavailability.

    PubMed

    Tian, Tian; Blanco, Elena; Smoukov, Stoyan K; Velev, Orlin D; Velikov, Krassimir P

    2016-10-01

    Ferric pyrophosphate (FePP) is a widely used iron source in food fortification and in nutritional supplements, due to its white colour, that is very uncommon for insoluble Fe salts. Although its dissolution is an important determinant of Fe adsorption in human body, the solubility characteristics of FePP are complex and not well understood. This report is a study on the solubility of FePP as a function of pH and excess of pyrophosphate ions. FePP powder is sparingly soluble in the pH range of 3-6 but slightly soluble at pH<2 and pH>8. In the presence of pyrophosphate ions the solubility of FePP strongly increases at pH 5-8.5 due to formation a soluble complex between Fe(III) and pyrophosphate ions, which leads to an 8-10-fold increase in the total ionic iron concentration. This finding is beneficial for enhancing iron bioavailability, which important for the design of fortified food, beverages, and nutraceutical products. PMID:27132828

  20. Insights Into Water-Soluble Organic Aerosol Sources From Carbon-13 Ratios of Size Exclusion Chromatography Fractions

    NASA Astrophysics Data System (ADS)

    Ruehl, C. R.; Chuang, P. Y.; McCarthy, M. D.

    2008-12-01

    Many sources of organic aerosols have been identified and quantified, and much of this work has used individual (mosty water-insoluble) compounds as tracers of primary sources. However, most organic aerosol cannot be molecularly characterized, and the water-soluble organic carbon (WSOC) in many aerosols is thought to originate from gaseous precursors (i.e., it is secondary in nature). It can therefore be difficult to infer aerosol sources, particularly of background (i.e., aged) aerosols, and of the relatively high-MW component of aerosols. The stable isotope ratios (δ13C) of organic aerosols have been used to distinguish between sources, with lighter values (-30‰ to -25‰) interpreted as having originated from fossil fuel combustion and C4 biogenic emission, and heavier values (-25‰ to - 20‰) indicating a marine or C3 biogenic source. Most published measurements were of either total suspended particulates or PM2.5, however, and it is unknown to what extent these fractions differ from submicron WSOC. We report δ13C for submicron WSOC collected at a variety of sites, ranging from marine to polluted to background continental. Bulk marine organic δ13C ranged from -30.4 to - 27.6‰, slightly lighter than previously published results. This could be due to the elimination of supermicron cellular material or other biogenic primary emissions from the sample. Continental WSOC δ13C ranged from -19.1 to -29.8‰, with heavier values (-19.8 ± 1.0‰) in Oklahoma and lighter values at Great Smoky Mountain National Park in Tennessee (-25.8 ± 2.6‰) and Illinois (-24.5 ± 1.0‰). This likely results from the greater proportional of C3 plant material in the Oklahoma samples. In addition to bulk samples, we used size exclusion chromatography (SEC) to report δ13C of organic aerosols as a function of hydrodynamic diameter. Variability and magnitude of hydrodynamic diameter was greatest at low SEC pH, indicative of the acidic character of submicron WSOC. Tennessee

  1. Multifunctional iron-carbon nanocomposites through an aerosol-based process for the in situ remediation of chlorinated hydrocarbons.

    PubMed

    Zhan, Jingjing; Kolesnichenko, Igor; Sunkara, Bhanukiran; He, Jibao; McPherson, Gary L; Piringer, Gerhard; John, Vijay T

    2011-03-01

    Spherical iron-carbon nanocomposites were developed through a facile aerosol-based process with sucrose and iron chloride as starting materials. These composites exhibit multiple functionalities relevant to the in situ remediation of chlorinated hydrocarbons such as trichloroethylene (TCE). The distribution and immobilization of iron nanoparticles on the surface of carbon spheres prevents zerovalent nanoiron aggregation with maintenance of reactivity. The aerosol-based carbon microspheres allow adsorption of TCE, thus removing dissolved TCE rapidly and facilitating reaction by increasing the local concentration of TCE in the vicinity of iron nanoparticles. The strongly adsorptive property of the composites may also prevent release of any toxic chlorinated intermediate products. The composite particles are in the optimal range for transport through groundwater saturated sediments. Furthermore, those iron-carbon composites can be designed at low cost, the process is amenable to scale-up for in situ application, and the materials are intrinsically benign to the environment.

  2. An automated analyzer to measure surface-atmosphere exchange fluxes of water soluble inorganic aerosol compounds and reactive trace gases.

    PubMed

    Thomas, Rick M; Trebs, Ivonne; Otjes, René; Jongejan, Piet A C; Ten Brink, Harry; Phillips, Gavin; Kortner, Michael; Meixner, Franz X; Nemitz, Eiko

    2009-03-01

    Here, we present a new automated instrument for semicontinuous gradient measurements of water-soluble reactive trace gas species (NH3, HNO3, HONO, HCl, and SO2) and their related aerosol compounds (NH4+, NO3-, Cl-, SO4(2-)). Gas and aerosol samples are collected simultaneously at two heights using rotating wet-annular denuders and steam-jet aerosol collectors, respectively. Online (real-time) analysis using ion chromatography (IC) for anions and flow injection analysis (FIA) for NH4+ and NH3 provide a half-hourly averaged gas and aerosol gradients within each hour. Through the use of syringe pumps, IC preconcentration columns, and high-quality purified water, the system achieves detection limits (3sigma-definition) under field conditions of typically: 136/207,135/114, 29/ 22,119/92, and 189/159 ng m(-3) for NH3/NH4+, HNO3/NO3-, HONO/ NO2-, HCl/Cl- and SO2/SO4(2-), respectively. The instrument demonstrates very good linearity and accuracy for liquid and selected gas phase calibrations over typical ambient concentration ranges. As shown by examples from field experiments, the instrument provides sufficient precision (3-9%), even at low ambient concentrations, to resolve vertical gradients and calculate surface-atmosphere exchange fluxes undertypical meteorological conditions of the atmospheric surface layer using the aerodynamic gradient technique. PMID:19350912

  3. Prevention of Acid Mine Drainage Through Complexation of Ferric Iron by Soluble Microbial Growth Products

    NASA Astrophysics Data System (ADS)

    Pandey, S.; Yacob, T. W.; Silverstein, J.; Rajaram, H.; Minchow, K.; Basta, J.

    2011-12-01

    Acid mine drainage (AMD) is a widespread environmental problem with deleterious impacts on water quality in streams and watersheds. AMD is generated largely by the oxidation of metal sulfides (i.e. pyrite) by ferric iron. This abiotic reaction is catalyzed by conversion of ferrous to ferric iron by iron and sulfur oxidizing microorganisms. Biostimulation is currently being investigated as an attempt to inhibit the oxidation of pyrite and growth of iron oxidizing bacteria through addition of organic carbon. This may stimulate growth of indigenous communities of acidophilic heterotrophic bacteria to compete for oxygen. The goal of this research is to investigate a secondary mechanism associated with carbon addition: complexation of free Fe(III) by soluble microbial growth products (SMPs) produced by microorganisms growing in waste rock. Exploratory research at the laboratory scale examined the effect of soluble microbial products (SMPs) on the kinetics of oxidation of pure pyrite during shaker flask experiments. The results confirmed a decrease in the rate of pyrite oxidation that was dependent upon the concentration of SMPs in solution. We are using these data to verify results from a pyrite oxidation model that accounts for SMPs. This reactor model involves differential-algebraic equations incorporating total component mass balances and mass action laws for equilibrium reactions. Species concentrations determined in each time step are applied to abiotic pyrite oxidation rate expressions from the literature to determine the evolution of total component concentrations. The model was embedded in a parameter estimation algorithm to determine the reactive surface area of pyrite in an abiotic control experiment, yielding an optimized value of 0.0037 m2. The optimized model exhibited similar behavior to the experiment for this case; the root mean squared of residuals for Fe(III) was calculated to be 7.58 x 10-4 M, which is several orders of magnitude less than the actual

  4. Water Soluble Organic Nitrogen in atmospheric aerosol samples from urban, sub-urban and pristine areas of Venezuela

    NASA Astrophysics Data System (ADS)

    Canelon, R.; Giuliante, A.; Aguiar, G.; Ghneim, T.; Perez, T.

    2007-12-01

    Concentrations of water soluble organic nitrogen (WSON) were determined in atmospheric total suspended particles (TSP) collected between September of 2005 and May of 2006, in an urban continental (Caracas, 10° 29' 09'' N, 66° 53' 48'' W), an urban coastal (Catia la mar, 10° 35' 47'' N, 67° 01' 45'' W), a sub-urban coastal (Osma, 10° 32' N, 67° 28' W), a suburban continental (Altos de Pipe, 10° 23' 41'' N, 63° 59' 10'' W), a pristine coastal (Isla de Aves, 15° 40' N, 63° 36' W) and a pristine continental (La Gran Sabana National Park, 5° 41' 30'' N, 61° 34' 20'' W) areas of Venezuela. TSP samples were collected using a Hi-Vol airborne particle sampler. TSP were impacted on a fiberglass filter pretreated under 400° C for 4 hours to minimize organic nitrogen contamination. Ultra sound water extractions of the sample filters were performed and their NH4+, NO2- and NO3- concentrations were determined by ion exchange liquid chromatography. The water extracts were UV digested and the nitrogen inorganic ions were analyzed after the UV exposure. WSON concentrations were calculated by the difference between the inorganic nitrogen concentrations before and after UV digestion. Ninety five percent of the aerosol samples collected in the suburban and pristine areas showed a WSON concentration range from 0.03 to 0.6 μg/m3 whereas in urban areas the range was 0.21 to 1.09 μg/m3. These concentration values are on the same order of magnitude than the previously found in other tropical and subtropical areas. The contribution of aerosol WSON to the total soluble nitrogen in the coastal urban, sub-urban and pristine areas ranged from 23 to 67%, while in Caracas was smaller (38±8%, n=5). Therefore, aerosol WSON provides an important source of nitrogen to these pristine and suburban ecosystems, which could potentially have implications on the nutrient cycling. There was a statistically significant linear correlation between the aerosol WSON and the water soluble inorganic

  5. Solubility relationships of aluminium and iron minerals associated with acid mine drainage

    SciTech Connect

    Sullivan, P.J.; Yelton, J.L. ); Reddy, K.J. )

    1988-06-01

    The ability to properly manage the oxidation of pyritic minerals and associated acid mine drainage is dependent upon understanding the chemistry of the disposal environment. One accepted disposal method is placing pyritic-containing materials in the groundwater environment. The objective of this study was to examine solubility relationships of Al and Fe minerals associated with pyritic waste disposed in a low leaching aerobic saturated environment. Two eastern oil shales were used in this oxidizing equilibration study, a New Albany Shale (unweathered, 4.6 percent pyrite), and a Chattanooga Shale (weathered, 1.5 percent pyrite). Oil shale samples were equilibrated with distilled-deionized water from 1 to 180 d with a 1:1 solid-to-solution ratio. The suspensions were filtered and the clear filtrates were analyzed for total cations and anions. Ion activities were calculated from total concentrations. Below pH 6.0, depending upon SO{sub 4}{sup 2{minus}} activity, Al{sup 3+} solubility was controlled by AlOHSO{sub 4} (solid phase) for both shales. The results of this study indicate that below pH 6.0, Al{sup 3+} and Fe{sup 3+} solubilities, are limited by basic Al and Fe sulfate solid phases (AlOHSO{sub 4(s)} and FeHSO{sub 4(s)}). The results from this study further indicate that the acidity in oil shale waters is produced from the hydrolysis of Al{sup 3+} and Fe{sup 3+} activities in solution. These results indicate a fundamental change in the stoichiometric equations used to predict acidity from iron sulfide oxidation. The results of this study also indicate that water quality predictions associated with acid mine drainage can be based on fundamental thermodynamic relationships. As a result, waste management decisions can be based on waste-specific/site test methods.

  6. [Characteristics of aerosol water-soluble inorganic ions in three types air-pollution incidents of Nanjing City].

    PubMed

    Zhang, Qiu-Chen; Zhu, Bin; Su, Ji-Feng; Wang, Hong-Lei

    2012-06-01

    In order to compare aerosol water-soluble inorganic species in different air-pollution periods, samples of PM10, PM2.1, PM1.1 and the main water-soluble ions (NH4+, Mg2+, Ca2+, Na+, K+, NO2(-), F(-), NO3(-), Cl(-), SO4(2-)) were measured, which were from 3 air-pollution incidents (continued pollution in October 16-30 of 2009, sandstorm pollution in April 27-30 of 2010, and crop burning pollution in June 14 of 2010. The results show that aerosol pollution of 3 periods is serious. The lowest PM2.1/PM10 is only 0.27, which is from sandstorm pollution period, while the largest is 0. 7 from crop burning pollution period. In continued pollution periods, NO3(-) and SO4(2-) are the dominant ions, and the total anions account for an average of 18.62%, 32.92% and 33.53% of PM10, PM2.1 and PM1.1. Total water-soluble ions only account for 13.36%, 23.72% and 28.54% of PM10, PM2.1 and PM1.1 due to the insoluble species is increased in sandstorm pollution period. The mass concentration of Ca2+ in sandstorm pollution period is higher than the other two pollution periods, and which is mainly in coarse particles with diameter larger than 1 microm. All the ten water-soluble ions are much higher in crop burning pollution especially K+ which is the tracer from crop burning. The peak mass concentrations of NO3(-), SO4(2-) and NH4+ are in 0.43-0.65 microm. PMID:22946180

  7. Depleted iron stores and iron deficiency anemia associated with reduced ferritin and hepcidin and elevated soluble transferrin receptors in a multiethnic group of preschool-age children.

    PubMed

    Weiler, Hope A; Jean-Philippe, Sonia; Cohen, Tamara R; Vanstone, Catherine A; Agellon, Sherry

    2015-09-01

    Iron deficiency anemia is prevalent in subgroups of the Canadian population. The objective of this study was to examine iron status and anemia in preschool-age children. Healthy children (n = 430, 2-5 years old, Montreal, Quebec, Canada) were sampled from randomly selected daycares. Anthropometry, demographics, and diet were assessed. Biochemistry included hemoglobin, ferritin, soluble transferrin receptors (sTfR), ferritin index, markers of inflammation (C-reactive protein, interleukin 6 (IL-6), and tumour necrosis factor alpha (TNFα)), and hepcidin. Iron deficiency and anemia cutoffs conformed to the World Health Organization criteria. Differences among categories were tested using mixed-model ANOVA or χ(2) tests. Children were 3.8 ± 1.0 years of age, with a body mass index z score of 0.48 ± 0.97, and 51% were white. Adjusted intakes of iron indicated <1% were at risk for deficiency. Hemoglobin was higher in white children, whereas ferritin was higher with greater age and female sex. Inflammatory markers and hepcidin did not vary with any demographic variable. The prevalence of iron deficiency was 16.5% (95% confidence interval (CI), 13.0-20.0). Three percent (95% CI, 1.4-4.6) of children had iron deficiency anemia and 12.8% (95% CI, 9.6-16.0) had unexplained anemia. Children with iron deficiency, with and without anemia, had lower plasma ferritin and hepcidin but higher sTfR, ferritin index, and IL-6, whereas those with unexplained anemia had elevated TNFα. We conclude that iron deficiency anemia is not very common in young children in Montreal. While iron deficiency without anemia is more common than iron deficiency with anemia, the correspondingly reduced circulating hepcidin would have enabled heightened absorption of dietary iron in support of erythropoiesis.

  8. Water Soluble Ions in Bulk Aerosol During the WINTER 2015 Campaign.

    NASA Astrophysics Data System (ADS)

    Dibb, J. E.; Scheuer, E. M.; Brown, S. S.; Campuzano Jost, P.; Fibiger, D. L.; Guo, H.; Jimenez, J. L.; Lopez-Hilfiker, F.; McDuffie, E. E.; Schroder, J. C.; Sullivan, A.; Thornton, J. A.; Veres, P. R.; Weber, R. J.

    2015-12-01

    Aerosol samples were collected on filters from the NCAR C-130 during the WINTER campaign using an inlet believed to transmit particles up to 4 micron in diameter. Filter integration times were nominally 7 minutes. Aqueous extracts of the filter samples were analyzed by ion chromatography for 5 anions and 5 cations, we focus primarily on chloride and nitrate due to their roles coupling chlorine and nitrogen oxide chemistry. Comparison to measurements of submicron aerosol (by PILS and AMS) indicates that there was significant coarse chloride in the boundary layer on all WINTER flights, including the 7 flights over the continent. Significant super micron chloride at altitudes above 2 km was seen in just 3 of the filter samples from the entire mission, all of these were well inland. During the 6 flights over the Atlantic ocean we observed displacement of chloride from the dominant seasalt aerosol at times, but evidence for coarse mode nitrate or sulfate aerosol to explain this is less clear. While coarse aerosol chloride mixing ratios were sufficient to support observed production of nitryl chloride, no correlations between these compounds were observed on any flights. However, nitrate was positively correlated with nitryl chloride, as expected, on all flights when the latter exceeded several 100's of pptv for extended periods. Aerosol nitrate was also positively correlated with dinitrogen pentoxide when mixing ratios of the latter exceeded ~500 pptv for significant portions of a flight. On the WINTER flights in February aerosol nitrate was often more abundant than nitric acid, this was less often the case for the flights in March. This change in partitioning of nitrate between gas and particle phases reflects an increasing trend of nitric acid and a small decrease in abundance of aerosol nitrate through the campaign.

  9. Aircraft observations of water-soluble dicarboxylic acids in the aerosols over China

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Qing Fu, Ping; Boreddy, Suresh K. R.; Watanabe, Tomomi; Hatakeyama, Shiro; Takami, Akinori; Wang, Wei

    2016-05-01

    Vertical profiles of dicarboxylic acids, related organic compounds and secondary organic aerosol (SOA) tracer compounds in particle phase have not yet been simultaneously explored in East Asia, although there is growing evidence that aqueous-phase oxidation of volatile organic compounds may be responsible for the elevated organic aerosols (OA) in the troposphere. Here, we found consistently good correlation of oxalic acid, the most abundant individual organic compounds in aerosols globally, with its precursors as well as biogenic-derived SOA compounds in Chinese tropospheric aerosols by aircraft measurements. Anthropogenically derived dicarboxylic acids (i.e., C5 and C6 diacids) at high altitudes were 4-20 times higher than those from surface measurements and even occasionally dominant over oxalic acid at altitudes higher than 2 km, which is in contrast to the predominance of oxalic acid previously reported globally including the tropospheric and surface aerosols. This indicates an enhancement of tropospheric SOA formation from anthropogenic precursors. Furthermore, oxalic acid-to-sulfate ratio maximized at altitudes of ˜ 2 km, explaining aqueous-phase SOA production that was supported by good correlations with predicted liquid water content, organic carbon and biogenic SOA tracers. These results demonstrate that elevated oxalic acid and related SOA compounds from both the anthropogenic and biogenic sources may substantially contribute to tropospheric OA burden over polluted regions of China, implying aerosol-associated climate effects and intercontinental transport.

  10. Saharan dust aerosol over the central Mediterranean Sea: optical columnar measurements vs. aerosol load, chemical composition and marker solubility at ground level

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Sferlazzo, D. M.; Becagli, S.; Bommarito, C.; Calzolai, G.; Chiari, M.; di Sarra, A.; Ghedini, C.; Gómez-Amo, J. L.; Lucarelli, F.; Meloni, D.; Monteleone, F.; Nava, S.; Pace, G.; Piacentino, S.; Rugi, F.; Severi, M.; Traversi, R.; Udisti, R.

    2013-08-01

    This study aims at the determination of the mineral contribution to PM10 in the central Mediterranean Sea on the basis of 7 yr of PM10 chemical composition daily measurements made on the island of Lampedusa (35.5° N, 12.6° E). Aerosol optical depth measurements are carried out in parallel while sampling with a multi-stage impactor, and observations with an optical particle counter were performed in selected periods. Based on daily samples, the total content and soluble fraction of selected metals are used to identify and characterize the dust events. The total contribution is determined by PIXE (particle-induced X-ray emission) while the composition of the soluble fraction by ICP-AES (inductively coupled plasma atomic emission spectroscopy) after extraction with HNO3 at pH 1.5. The average PM10 concentration at Lampedusa calculated over the period June 2004-December 2010 is 31.5 μg m-3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceed the daily threshold value established by the European Commission for PM (50 μg m-3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases with crustal content exceeding the 75th percentile of the crustal oxide content distribution were identified as dust events. Using this threshold we identify 175 events; 31.6% of them (55 events) present PM10 higher than 50 μg m-3, with dust contributing by 33% on average. The annual average crustal contribution to PM10 is 5.42 μg m-3, reaching a value as high as 67.9 μg m-3, 49% of PM10, during an intense Saharan dust event. The crustal aerosol amount and contribution to PM10 shows a very small seasonal dependence; conversely, the dust columnar burden displays an evident annual cycle, with a strong summer maximum (monthly

  11. Can land use intensification in the Mallee, Australia increase the supply of soluble iron to the Southern Ocean?

    NASA Astrophysics Data System (ADS)

    Bhattachan, Abinash; D'Odorico, Paolo

    2014-08-01

    The supply of soluble iron through atmospheric dust deposition limits the productivity of the Southern Ocean. In comparison to the Northern Hemisphere, the Southern Hemisphere exhibits low levels of dust activity. However, given their proximity to the Southern Ocean, dust emissions from continental sources in the Southern Hemisphere could have disproportionate impact on ocean productivity. Australia is the largest source of dust in the Southern Hemisphere and aeolian transport of dust has major ecological, economic and health implications. In the Mallee, agriculture is a major driver of dust emissions and dust storms that affect Southeastern Australia. In this study, we assess the dust generating potential of the sediment from the Mallee, analyze the sediment for soluble iron content and determine the likely depositional region of the emitted dust. Our results suggest that the Mallee sediments have comparable dust generating potential to other currently active dust sources in the Southern Hemisphere and the dust-sized fraction is rich in soluble iron. Forward trajectory analyses show that this dust will impact the Tasman Sea and the Australian section of the Southern Ocean. This iron-rich dust could stimulate ocean productivity in future as more areas are reactivated as a result of land-use and droughts.

  12. Can land use intensification in the Mallee, Australia increase the supply of soluble iron to the Southern Ocean?

    PubMed

    Bhattachan, Abinash; D'Odorico, Paolo

    2014-01-01

    The supply of soluble iron through atmospheric dust deposition limits the productivity of the Southern Ocean. In comparison to the Northern Hemisphere, the Southern Hemisphere exhibits low levels of dust activity. However, given their proximity to the Southern Ocean, dust emissions from continental sources in the Southern Hemisphere could have disproportionate impact on ocean productivity. Australia is the largest source of dust in the Southern Hemisphere and aeolian transport of dust has major ecological, economic and health implications. In the Mallee, agriculture is a major driver of dust emissions and dust storms that affect Southeastern Australia. In this study, we assess the dust generating potential of the sediment from the Mallee, analyze the sediment for soluble iron content and determine the likely depositional region of the emitted dust. Our results suggest that the Mallee sediments have comparable dust generating potential to other currently active dust sources in the Southern Hemisphere and the dust-sized fraction is rich in soluble iron. Forward trajectory analyses show that this dust will impact the Tasman Sea and the Australian section of the Southern Ocean. This iron-rich dust could stimulate ocean productivity in future as more areas are reactivated as a result of land-use and droughts. PMID:25109703

  13. Can land use intensification in the Mallee, Australia increase the supply of soluble iron to the Southern Ocean?

    PubMed

    Bhattachan, Abinash; D'Odorico, Paolo

    2014-08-11

    The supply of soluble iron through atmospheric dust deposition limits the productivity of the Southern Ocean. In comparison to the Northern Hemisphere, the Southern Hemisphere exhibits low levels of dust activity. However, given their proximity to the Southern Ocean, dust emissions from continental sources in the Southern Hemisphere could have disproportionate impact on ocean productivity. Australia is the largest source of dust in the Southern Hemisphere and aeolian transport of dust has major ecological, economic and health implications. In the Mallee, agriculture is a major driver of dust emissions and dust storms that affect Southeastern Australia. In this study, we assess the dust generating potential of the sediment from the Mallee, analyze the sediment for soluble iron content and determine the likely depositional region of the emitted dust. Our results suggest that the Mallee sediments have comparable dust generating potential to other currently active dust sources in the Southern Hemisphere and the dust-sized fraction is rich in soluble iron. Forward trajectory analyses show that this dust will impact the Tasman Sea and the Australian section of the Southern Ocean. This iron-rich dust could stimulate ocean productivity in future as more areas are reactivated as a result of land-use and droughts.

  14. Effects of aerosol collection and extraction procedures on the optical properties of water-soluble organic compounds

    NASA Astrophysics Data System (ADS)

    Mladenov, N.; Alados-Arboledas, L.; Olmo Reyes, F. J.; Reche, I.

    2009-12-01

    Water-soluble organic compounds (WSOC) are routinely collected using active and passive aerosol samplers and, after extraction in water, analyzed using UV-vis absorbance and fluorescence techniques. These analyses provide important information regarding the chemical character and sources of aerosols worldwide. To evaluate the effects of various aerosol collection and processing methods on the optical properties of WSOC, two-dimensional absorption spectra from 200 to 900 nm and three-dimensional fluorescence excitation-emission spectra (EEMs) from 240 to 450 nm excitation and 300 to 560 nm emission were analyzed in samples obtained simultaneously with different procedures. Samples included: milli-Q purified water passed through 140 mm diameter glass fiber and quartz fiber filters used in high volume PM10 aerosol samplers, 47 mm glass fiber filters used for organic matter analyses, and mixed cellulose 0.2 micron and 0.015 micron filters used for bacterial and viral filtration, respectively; milli-Q purified water rinsed in plastic buckets used for passive wet and dry deposition collection; and WSOC samples extracted from filters by soaking, sonication, and agitation. Parallel factor analysis (PARAFAC) modeling of WSOC was performed to quantify the influence of various collection and extraction procedures on fluorescence signatures. All filters examined were found to leach some amount of fluorescent compounds (Figure 1). Mixed cellulose filters, especially those with small pore size, leached substantially more amino acid-like and humic-like material than other filters, whereas leaching from quartz fiber filters used for high volume aerosol collection was minimal (Figure 1). Fluorescence intensities of filter leachates decreased with increased rinsing of filters, indicating that rinsing with purified water prior to filtration is advisable, even for pre-combusted filters. Dissolved organic carbon concentrations of WSOC extracted from filters by sonication, agitation

  15. Functional characterization of the water-soluble organic carbon of size fractionated aerosol in the Southern Mississippi Valley

    NASA Astrophysics Data System (ADS)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-02-01

    The chemical content of the water soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to: (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for the period when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp < 0.96 μm. Non-exchangeable aliphatic (H-C), unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance. The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 0.96 < dp < 1.5 μm to 73.9 ± 12.3 nmol m-3 for particles with dp < 0.49 μm, resulting in molar H / C ratios of 0.48 ± 0.05 to 0.92 ± 0.09 observed in combustion-related organic aerosol. The R-H was the most abundant group representing about 45% of measured total non-exchangeable organic hydrogen concentration followed by H-C-O (27%) and H-C-C= (26%). Levoglucosan, amines, ammonium and methanosulfonate were tentatively identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosol and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative

  16. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    NASA Astrophysics Data System (ADS)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-06-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp < 0.96 μm. Non-exchangeable aliphatic (H-C), unsaturated aliphatic (H-C-C=), oxygenated saturated aliphatic (H-C-O), acetalic (O-CH-O) and aromatic (Ar-H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 1.5 < dp < 3.0 μm to 73.9 ± 12.3 nmol m-3 for particles with dp < 0.49 μm. The molar H / C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R-H was the most abundant group, representing about 45% of measured total non-exchangeable organic hydrogen concentrations, followed by H-C-O (27%) and H-C-C= (26%). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest

  17. Molecular composition of the water-soluble fraction of atmospheric carbonaceous aerosols collected during ACE-Asia

    NASA Astrophysics Data System (ADS)

    Mader, B. T.; Yu, J. Z.; Xu, J. H.; Li, Q. F.; Wu, W. S.; Flagan, R. C.; Seinfeld, J. H.

    2004-03-01

    During the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), samples of carbonaceous aerosols were collected on board the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) De Havilland DHC-6 Twin Otter aircraft. The samples were analyzed to determine their total carbon (TC) and water-soluble organic compound (WSOC) contents as well as to identify the individual compounds comprising the WSOC fraction of the aerosol. The TC concentrations varied from 3.5 to 14.3 μg C m-3; the highest TC levels were observed for samples collected in pollution layers that originated over mainland China. WSOC concentrations ranged from 0.54 to 7.2 μg C m-3, with the WSOC fraction contributing from 10 to 50% of the carbon mass. About 50% of the carbonaceous aerosol mass in pollution layers could be attributed to WSOC. For samples collected in dust layers the WSOC fraction of TC was much lower than that observed in pollution layers. The sum of all the detected organic ions accounted for 6.9-19% of the WSOC. In the six samples collected by the Twin Otter during ACE-Asia, of the organic ions identified in the WSOC fraction, oxalate had the highest concentration. Samples collected from pollution layers exhibited a slightly higher ratio of formate to oxalate as compared to the other samples. Two samples had a relatively high ratio of lactate to oxalate, which might be a signature of some currently unidentified source of carbonaceous aerosol. The sum of the masses of sulfate and nitrate ions exceeded the sum of the masses of the identified organic ions by a factor of 9 to 17. The chemical levoglucosan, a tracer for biomass burning, comprised from 0.1 to 0.4% of TC mass. Comparing this ratio to the ratio measured directly in wood-burning studies it was determined that biomass burning may have represented from ≈2 to 10% of the carbonaceous aerosol collected during ACE-Asia.

  18. Morphology control of lithium iron phosphate nanoparticles by soluble starch-assisted hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoyong; Xu, Ming; Du, Binglin; Zhu, Huali; Xie, Tian; Wang, Wenhua

    2014-12-01

    Lithium iron phosphate (LiFePO4) is a potentially high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and one-dimensional diffusion channel for lithium ions require small particle size and shape control during the synthesis. In this paper, well-crystallized and morphology-controlled LiFePO4 cathode material for lithium-ion batteries is successfully synthesized via a soluble starch-assisted hydrothermal method at 180 °C for 5 h, followed by calcining with phenolic resin at 750 °C for 6 h. In this study, we investigate the effect of five different concentrations of starch solution on controlling morphology of LiFePO4. Interestingly, the nano-sized LiFePO4 particles obtained in 0.075 mol L-1 starch solution exhibit a spheroidal microstructure, while the platelet shape LiFePO4 particles are synthesized in lower or higher concentration of starch solution. The mechanism and process of forming such spheroidal microstructure is discussed. These unique structural and morphological properties of LiFePO4 lead to high specific capacity and stable cycling performance. Analysis of the electrochemical impedance spectroscopy reveals that nano-sized carbon/polyacene coated LiFePO4 cathode materials play an critical role in achieving excellent electrochemical performance.

  19. Iron mobilization in North African dust.

    SciTech Connect

    Ito, A.; Feng, Y.

    2011-01-01

    Iron is an essential nutrient for phytoplankton. Although iron-containing dust mobilized from arid regions supplies the majority of the iron to the oceans, the key flux in terms of the biogeochemical response to atmospheric deposition is the amount of soluble or bioavailable iron. Atmospheric processing of mineral aerosols by anthropogenic pollutants (e.g. sulfuric acid) may transform insoluble iron into soluble forms. Previous studies have suggested higher iron solubility in smaller particles, as they are subject to more thorough atmospheric processing due to a longer residence time than coarse particles. On the other hand, the specific mineralogy of iron in dust may also influence the particulate iron solubility in size. Compared to mineral dust aerosols, iron from combustion sources could be more soluble, and found more frequently in smaller particles. Internal mixing of alkaline dust with iron-containing minerals could significantly reduce iron dissolution in large dust aerosols due to the buffering effect, which may, in contrast, yield higher solubility in smaller particles externally mixed with alkaline dust (Ito and Feng, 2010). Here, we extend the modeling study of Ito and Feng (2010) to investigate atmospheric processing of mineral aerosols from African dust. In contrast to Asian dust, we used a slower dissolution rate for African dust in the fine mode. We compare simulated fractional iron solubility with observations. The inclusion of alkaline compounds in aqueous chemistry substantially limits the iron dissolution during long-range transport to the Atlantic Ocean: only a small fraction of iron (<0.2%) dissolves from illite in coarsemode dust aerosols with 0.45% soluble iron initially. In contrast, a significant fraction (1-1.5%) dissolves in fine-mode dust aerosols due to the acid mobilization of the iron-containing minerals externally mixed with carbonate minerals. Consequently, the model generally reproduces higher iron solubility in smaller particles

  20. Formation of Thick Dense Yttrium Iron Garnet Films Using Aerosol Deposition.

    PubMed

    Johnson, Scooter D; Glaser, Evan R; Kub, Fritz J; Eddy, Charles R

    2015-05-15

    Aerosol deposition (AD) is a thick-film deposition process that can produce layers up to several hundred micrometers thick with densities greater than 95% of the bulk. The primary advantage of AD is that the deposition takes place entirely at ambient temperature; thereby enabling film growth in material systems with disparate melting temperatures. This report describes in detail the processing steps for preparing the powder and for performing AD using the custom-built system. Representative characterization results are presented from scanning electron microscopy, profilometry, and ferromagnetic resonance for films grown in this system. As a representative overview of the capabilities of the system, focus is given to a sample produced following the described protocol and system setup. Results indicate that this system can successfully deposit 11 µm thick yttrium iron garnet films that are  > 90% of the bulk density during a single 5 min deposition run. A discussion of methods to afford better control of the aerosol and particle selection for improved thickness and roughness variations in the film is provided.

  1. The Effects of Particle Size, Relative Humidity, and Sulfur Dioxide on Iron Solubility in Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    Cartledge, B. T.; Marcotte, A.; Anbar, A. D.; Herckes, P.; Majestic, B. J.

    2014-12-01

    The current study focuses on studying how iron (Fe) solubility is affected by particle size, relative humidity, and exposure to sulfur dioxide (SO2). Fe, the most abundant transition metal in atmospheric particulate matter, plays a critical role in the atmospheric sulfur cycle and is a micronutrient for phytoplankton in remote regions of the ocean. To mimic oceanic particles, iron-containing minerals (hematite, magnetite, goethite, and illite) were resuspended with sodium chloride and size-segregated on Teflon filters into five different size fractions: 10-2.5 μm, 2.5-1.0 μm, 1.0-0.5 μm, 0.5-0.25 μm, and <0.25 μm. Mineral phases were then exposed to 5 ppm SO2 in air at marine environment humidity (>80%) and arid environment humidity (24%). Trials with no SO2 ­were also performed as comparisons. Total Fe was determined by using microwave-assisted acid digestion and soluble Fe was determined by extracting the samples in a simulated cloud water buffer (pH 4.25, 0.5 mM acetate, 0.5 mM formate, and 0.2 mM ammonium nitrate). Both total and soluble Fe concentrations were determined via inductively-coupled plasma mass spectrometry (ICP-MS). We found that, as particle size decreased, Fe percent solubility increased for hematite, magnetite, and goethite. The percent solubility of Fe in these mineral phases steadily increased from 0.5-10% as particle size decreased. In contrast, the Fe percent solubility in illite was relatively constant for the largest four size fractions but increased dramatically in the smallest size fraction. The percent solubility of Fe in illite ranged from 5-20% as the particle size decreased. Additionally, increased Fe solubility was linked to increased relative humidity with higher percent solubility generally observed in all mineral phases for the samples exposed at the higher humidity. No correlation was observed for the effects of the SO2 on Fe percent solubility. The likely lack of Fe-SO2 interactions were also supported by synchrotron

  2. Soluble species in the Arctic summer troposphere: Acidic gases, aerosols, and precipitation

    NASA Astrophysics Data System (ADS)

    Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

    1992-10-01

    We report here the distribution of selected acidic gases and aerosol species in the North American Arctic and sub-Arctic summer troposphere. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases and acidic sulfate aerosols dominating the particulate phase. Our data show that the acidic gas and aerosol composition is uniform on a large spatial scale. There appears to be a surface source of NH4+ over the Arctic Ocean pack ice which may reflect release of NH3 from decay of dead marine organisms on the ice surface near ice leads, release from rotting sea ice, or an upward flux from surface ocean waters in open ice leads. This NH3 appears to partially neutralize aerosol acidity in the boundary layer. Over sub-Arctic tundra in southwestern Alaska inputs of marine biogenic sulfur from the nearby Bering Sea appear to be an important source of boundary layer aerosol SO42-. While there were only minor effects on aerosol chemistry over the tundra from sea salt, the rainwater chemistry showed influence from marine aerosols which were apparently incorporated into air masses during frontal passages moving inland from the Bering Sea. The rainwater acidity over the tundra (pH 4.69) is typical of remote regions. The principal acidity components are H2SO4 and carboxylic acids, especially HCOOH. The carboxylic acids appear to have a strong continental biogenic source, but hydrocarbons of marine origin and emissions from forest fires may also be important. The wet deposition fluxes of NO3--N and SO42--S over sub-Arctic tundra during July-August 1988 were 2.1 and 2.4 mmol m-2 yr-1. Wet deposition of NO3- was nearly 3 times higher than the average NOy deposition flux, which is believed to represent primarily dry deposition of HNO3 (Bakwin et al., this issue). Our measurements indicate that the mid-troposphere in the Arctic is generally contaminated with low levels of anthropogenic pollutants even in summer when direct atmospheric coupling

  3. Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

    NASA Astrophysics Data System (ADS)

    Ehn, M.; Petäjä, T.; Aufmhoff, H.; Aalto, P.; Hämeri, K.; Arnold, F.; Laaksonen, A.; Kulmala, M.

    2006-10-01

    Freshly formed atmospheric aerosol particles are neither large enough to efficiently scatter incoming solar radiation nor able to act as cloud condensation nuclei. As the particles grow larger, their hygroscopicity determines the limiting size after which they are important in both of the aforementioned processes. The condensing species resulting in growth alter the hygroscopicity of the particles. We have measured hygroscopic growth of aerosol particles present in a boreal forest, along with the very hygroscopic atmospheric trace gas sulfuric acid. The focus was on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with gaseous phase sulfuric acid concentrations. This correlation had a strong size dependency; the smaller the particle, the more condensing sulfuric acid is bound to alter the GF due to initially smaller mass. In addition, water uptake of nucleation mode particles was monitored during new particle formation events and followed during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that initially more hygroscopic particles transformed into less hygroscopic or even hydrophobic particles. A similar behavior was seen also during days with no particle formation, with GF decreasing during the evenings and increasing during early morning. This can be tentatively explained by day- and nighttime differences in the hygroscopicity of condensable vapors.

  4. Water-soluble organic carbon (WSOC) and its temperature-resolved carbon fractions in atmospheric aerosols in Beijing

    NASA Astrophysics Data System (ADS)

    Tang, Xiong; Zhang, Xiaoshan; Wang, Zhangwei; Ci, Zhijia

    2016-11-01

    Investigation of temperature-resolved carbon fractions of water-soluble organic carbon (WSOC) can improve our understanding of the chemical properties, formation processes and sources of WSOC in aerosols. We developed a method that can examine different temperature-resolved carbon fractions of WSOC and used this method to characterize aerosol samples (n = 102) collected from an urban site in Beijing in 2010-2011. The aerosol composition data including inorganic ions, elements and temperature-resolved carbon fractions of WSOC were used as input of positive matrix factorization (PMF) model to investigate the sources of WSOC. The results showed that the mean concentrations of WSOC were 10.2 μg m- 3 with increased values in winter and decreased values in summer, while WSOC/OC ratios (mean: 51.7%) were higher in spring and summer than in fall and winter. The sampling artifacts of WSOC (18.2%) were higher than those of OC (13.4%). Though WSOC was significantly influenced by biomass burning in spring and winter, the strong correlations between WSOC and other secondary components suggested that WSOC was secondary in nature. Results of temperature-resolved carbon fractions of OC and WSOC showed that WSOC/OC ratios for different carbon fractions had the highest value of 0.92 and lowest value of 0.30. PMF analysis identified four factors, three of which were associated with three organic polar compounds groups (low, medium, and high molecular weight compounds) based on their thermal evolution features, and one of which was attributed to inorganic secondary formation processes. Annually, the contributions of four factors were 20.5%, 46.2%, 12.4% and 20.9%, respectively.

  5. Modeling of the laser pyrolysis process by means of the aerosol theory: Case of iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Bomatí-Miguel, O.; Zhao, X. Q.; Martelli, S.; Di Nunzio, P. E.; Veintemillas-Verdaguer, S.

    2010-01-01

    Laser pyrolysis is a technique in which the interaction between a laser and a gaseous flow of precursors is used to obtain homogeneous nanoparticles. One of the main advantages of using this method is that it generates ultrafine powders in a continuous way with narrow particle-size distribution. The absence of surfactants of potential toxicity makes the product ideal for the preparation of colloidal dispersions for use in biomedical applications. It is of particular interest in the case of the iron nanoparticles due to their high magnetic response. In this paper, a simple coagulation model adapted from the theory of aerosol formation is successfully used in the modeling of the production of iron nanoparticles. The experimental conditions needed to maximize the productivity were obtained as a function of particle size. The main conclusion is that for the production of "large" particle-size nanomaterials (>20 nm), the ruling factors are the pressure and the carrier gas flux. However, the production of small particle-size nanomaterials (<20 nm) depends on the evaporation temperature of the precursor.

  6. Soluble ferric iron as an effective protective agent against UV radiation: Implications for early life

    NASA Astrophysics Data System (ADS)

    Gómez, Felipe; Aguilera, Angeles; Amils, Ricardo

    2007-11-01

    Some recent MER Rover Opportunity results on ancient sedimentary rocks from Mars describe sandstones originated from the chemical weathering of olivine basalts by acidic waters [Squyres, S.W., Knoll, A.H., 2005. Earth Planet. Sci. Lett. 240, 1-10]. The absence of protective components in early Mars atmosphere forced any possible primordial life forms to deal with high doses of UV radiation. A similar situation occurred on the primitive Earth during the development of early life in the Archean [Berkner, L.V., Marshall, L.C., 1965. J. Atmos. Sci. 22 (3), 225-261; Kasting, J.F., 1993. Science 259, 920-926]. It is known that some cellular and/or external components can shield organisms from damaging UV radiation or quench its toxic effects [Olson, J.M., Pierson, B.K., 1986. Photosynth. Res. 9, 251-259; García-Pichel, F., 1998. Origins Life Evol. B 28, 321-347; Cockell, C., Rettberg, P., Horneck, G., Scherer, K., Stokes, M.D., 2003. Polar Biol. 26, 62-69]. The effectiveness of iron minerals for UV protection has also been reported [Phoenix, V.R., Konhauser, K.O., Adams, D.G., Bottrell, S.H., 2001. Geology 29 (9), 823-826], but nothing is known about the effect of iron in solution. Here we demonstrate the protective effect of soluble ferric iron against UV radiation on acidophilic photosynthetic microorganisms. These results offer an interesting alternative means of protection for life on the surface of early Mars and Earth, especially in light of the geochemical conditions in which the sedimentary minerals, jarosite and goethite, recently reported by the MER missions, were formed [Squyres, S.W., Arvidson, R.E., Bell III, J.F., Brückner, J., Cabrol, N.A., Calvin, W., Carr, M.H., Christensen, P.R., Clark, B.C., Crumpler, L., Des Marais, D.J., d'Uston, C., Economou, T., Farmer, J., Farrand, W., Folkner, W., Golombek, M., Gorevan, S., Grant, J.A., Greeley, R., Grotzinger, J., Haskin, L., Herkenhoff, K.E., Hviid, S., Johnson, J., Klingelhöfer, G., Knoll, A.H., Landis, G

  7. Physico-chemical qualification of a universal portable sampler for aerosols and water-soluble gases

    NASA Astrophysics Data System (ADS)

    Roux, Jean-Maxime; Sarda-Estève, Roland

    2015-10-01

    Developing a universal portable air sampler based on electrostatic precipitation. The challenge is to collect micro and nanoparticles, microorganisms as well as toxic molecules with a portable device. Electrostatic precipitation is an efficient and gentle method to collect airborne microorganisms and preserve their cultivability. But the collection of toxic gases required is not possible in such a device. The collection of such gases requires a liquid into which they have to be solubilized. Two concepts are being evaluated. The first one is based on electrospray. The goal is to investigate the collection efficiency of water-soluble gases. The second concept is based on the semi-humid electrostatic precipitator. Their high collection efficiencies for particles were already demonstrated. In the present study they are both tested with water-soluble gases. Concentrations are measured in the liquid solution by Ion Chromatography and in the gas phase by Proton Transfer Reaction Mass Spectrometry.

  8. The effect of low solubility organic acids on the hygroscopicity of sodium halide aerosols

    NASA Astrophysics Data System (ADS)

    Miñambres, L.; Méndez, E.; Sánchez, M. N.; Castaño, F.; Basterretxea, F. J.

    2014-10-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be investigated in this study. The hygroscopic properties of sodium halide sub-micrometre particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles were generated by flowing atomized sodium halide particles (either dry or aqueous) through a heated oven containing the gaseous acid. The obtained results indicate that gaseous organic acids easily nucleate onto dry and aqueous sodium halide particles. On the other hand, scanning electron microscopy (SEM) images indicate that lauric acid coating on NaCl particles makes them to aggregate in small clusters. The hygroscopic behaviour of covered sodium halide particles in deliquescence mode shows different features with the exchange of the halide ion, whereas the organic surfactant has little effect in NaBr particles, NaCl and NaI covered particles experience appreciable shifts in their deliquescence relative humidities, with different trends observed for each of the acids studied. In efflorescence mode, the overall effect of the organic covering is to retard the loss of water in the particles. It has been observed that the presence of gaseous water in heterogeneously nucleated particles tends to displace the cover of hexanoic acid to energetically stabilize the system.

  9. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    PubMed Central

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; da Costa, G. Gamboa; Pollock, E. D.; Kavouras, I. G.

    2016-01-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5 % of particle mass for particles with δp > 0.96 μm and 10 % of particle mass for particles with δp < 0.96 μm. Non-exchangeable aliphatic (H–C), unsaturated aliphatic (H–C–C=), oxygenated saturated aliphatic (H–C–O), acetalic (O–CH–O) and aromatic (Ar–H) protons were determined by proton nuclear magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m−3 for particles with 1.5 < δp < 3.0 μm to 73.9 ± 12.3 nmol m−3 for particles with δp < 0.49 μm. The molar H/C ratios varied from 0.48 ± 0.05 to 0.92 ± 0.09, which were comparable to those observed for combustion-related organic aerosol. The R–H was the most abundant group, representing about 45 % of measured total non-exchangeable organic hydrogen concentrations, followed by H–C–O (27 %) and H–C–C= (26 %). Levoglucosan, amines, ammonium and methanesulfonate were identified in NMR fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from −26.81 ± 0.18 ‰ for the smallest particles to

  10. Lactic acid fermentation stimulated iron absorption by Caco-2 cells is associated with increased soluble iron content in carrot juice.

    PubMed

    Bergqvist, Sharon W; Andlid, Thomas; Sandberg, Ann-Sofie

    2006-10-01

    An in vitro digestion/Caco-2 cell model was applied to explore the impact of lactic acid (LA) fermentation by Lactobacillus pentosus FSC1 and Leuconostoc mesenteroides FSC2 on the Fe bioavailability of carrot juice. The redox state of Fe in fermented carrot juice was also assessed as a crucial factor for absorption. LA fermentation was shown to improve mineral solubility to different extents at simulated physiological conditions: Mn (2-fold); Fe (1.5-1.7-fold); Zn (1.2-fold); Cu (1-fold). Soluble Fe2+ was increased about 16-fold by LA fermentation, and about one third of the Fe2+ remained soluble after in vitro digestion (about 4-5-fold higher than in fresh juice). Data on cell-line studies showed a 4-fold increase in the efficiency of Fe uptake, but not in transepithelial transfer by Caco2 cells, as a result of fermentation. The increases in Fe2+ level and the efficiency of cellular Fe uptake were strain-dependent. To sum up the effect on both Fe solubility and cellular uptake efficiency, the amount of cellularly absorbed Fe from Ln. mesenteroides FSC2-fermented juice was about 20 % higher than that from L. pentosus FSC1-fermented juice (22.7 v. 19.2 microg/l juice per mg protein). To conclude, LA fermentation enhanced Fe absorption by Caco-2 cells from carrot juice because of increases in not only Fe solubility after digestion, but also the efficiency of cellular Fe uptake. The fermentation-improved efficiency of Fe uptake was possibly due to the increased level of soluble Fe2+ rather than a being a strain-specific event.

  11. Decomposition of water-soluble mononitrosyl iron complexes with dithiocarbamates and of dinitrosyl iron complexes with thiol ligands in animal organisms.

    PubMed

    Serezhenkov, Vladimir A; Timoshin, Alexander A; Orlova, Tsvetina R; Mikoyan, Vasak D; Kubrina, Lioudmila N; Poltorakov, Alexander P; Ruuge, Enno K; Sanina, Natalia A; Vanin, Anatoly F

    2008-05-01

    EPR studies have shown that water-soluble mononitrosyl iron complexes with N-methyl-d-glucamine dithiocarbamate (MNIC-MGD) (3 micromol) injected to intact mice were decomposed virtually completely within 1h. The total content of MNIC-MGD in animal urine did not exceed 30 nmol/ml. In the liver, a small amount of MNIC-MGD were converted into dinitrosyl iron complexes (30 nmol/g of liver tissue). The same was observed in intact rabbits in which MNIC-MGD formation was induced by endogenous or exogenous NO binding to NO traps, viz., iron complexes with MGD. In mice, the content of MNIC-MGD in urine samples did not change after bacterial lipopolysaccharide-induced expression of iNOS. It was supposed that MNIC-MGD decomposition in intact animals was largely due to the release of NO from the complexes and its further transfer to other specific acceptors. In mice with iNOS expression, the main contribution to MNIC-MGD decomposition was made by superoxide ions whose destructive effect is mediated by an oxidative mechanism. This effect could fully compensate the augmented synthesis of MNIC-MGD involving endogenous NO whose production was supported by iNOS. Water-soluble dinitrosyl iron complexes (DNIC) with various thiol-containing ligands and thiosulfate injected to intact mice were also decomposed; however, in this case the effect was less pronounced than in the case of MNIC-MGD. It was concluded that DNIC decomposition was largely due to the oxidative effect of superoxide ions on these complexes. PMID:18222183

  12. Heterogeneous reaction probabilities, solubilities, and the physical state of cold volcanic aerosols

    NASA Technical Reports Server (NTRS)

    Toon, O.; Browell, E.; Gary, B.; Lait, L.; Livingston, J.; Newman, P.; Pueschel, R.; Russell, P.; Schoeberl, M.; Toon, G.

    1993-01-01

    On 19 January 1992, heterogeneous loss of HNO3, ClNO3, and HCl was observed in part of the Mount Pinatubo volcanic cloud that had cooled as a result of forced ascent. Portions of the volcanic cloud froze near 191 kelvin. The reaction probability of ClNO3 and the solubility of HNO3 were close to laboratory measurements on liquid sulfuric acid. The magnitude of the observed loss of HCl suggests that it underwent a heterogeneous reaction. Such reactions could lead to substantial loss of HCl on background sulfuric acid particles and so be important for polar ozone loss.

  13. Heterocyclic dithiocarbamato-iron(III) complexes: single-source precursors for aerosol-assisted chemical vapour deposition (AACVD) of iron sulfide thin films.

    PubMed

    Mlowe, Sixberth; Lewis, David J; Malik, Mohammad Azad; Raftery, James; Mubofu, Egid B; O'Brien, Paul; Revaprasadu, Neerish

    2016-02-14

    Tris-(piperidinedithiocarbamato)iron(III) (1) and tris-(tetrahydroquinolinedithiocarbamato)iron(iii) (2) complexes have been synthesized and their single-crystal X-ray structures were determined. Thermogravimetric analysis (TGA) of the complexes showed decomposition to iron sulfide. Both complexes were then used as single-source precursors for the deposition of iron sulfide thin films by aerosol-assisted chemical vapour deposition (AACVD). Energy-dispersive X-ray (EDX) spectroscopy confirmed the formation of iron sulfide films. The addition of tert-butyl thiol almost doubled the sulfur content in the deposited films. Scanning electron microscopy (SEM) images of the iron sulfide films from both complexes showed flakes/leaves/sheets, spherical granules and nanofibres. The sizes and shapes of these crystallites depended on the nature of the precursor, temperature, solvent and the amount of tert-butyl thiol used. The observed optical properties are dependent upon the variation of reaction parameters such as temperature and solvent. Powder X-ray diffraction (p-XRD) studies revealed that pyrrhotite, hexagonal (Fe0.975S), marcasite and smythite (Fe3S4) phases were differently deposited. PMID:26732865

  14. Carbonaceous and inorganic composition in long-range transported aerosols over northern Japan: Implication for aging of water-soluble organic fraction

    NASA Astrophysics Data System (ADS)

    Aggarwal, Shankar Gopala; Kawamura, Kimitaka

    To better understand the influence of sources and atmospheric processing on aerosol chemical composition, we collected atmospheric particles in Sapporo, northern Japan during spring and early summer 2005 under the air mass transport conditions from Siberia, China and surrounding seas. The aerosols were analyzed for inorganic ions, organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and the major water-soluble organic compound classes (i.e., dicarboxylic acids and sugars). SO 42- is the most abundant inorganic constituent (average 44% of the identified inorganic ion mass) followed by NH 4+ (21%) and NO 3- (13%). Concentrations of OC, EC, and WSOC ranged from 2.0-16, 0.24-2.9, and 0.80-7.9 μg m -3 with a mean of 7.4, 1.0, and 3.1 μg m -3, respectively. High OC/EC ratios (range: 3.6-19, mean: 8.7) were obtained, however WSOC/OC ratios (0.23-0.69, 0.44) do not show any significant diurnal changes. These results suggest that the Sapporo aerosols were already aged, but were not seriously affected by local photochemical processes. Identified water-soluble organic compounds (diacids + sugars) account for <10% of WSOC. Based on some marker species and air mass back trajectory analyses, and using stable carbon isotopic compositions of shorter-chain diacids (i.e., C 2-C 4) as photochemical aging factor of organic aerosols, the present study suggests that a fraction of WSOC in OC is most likely influenced by aerosol aging, although the OC loading in aerosols may be more influenced by their sources and source regions.

  15. Light absorption properties of water soluble organic aerosol from Residential Wood Burning in Fresno, CA: Results from 2013 NASA DISCOVER-AQ Campaign

    NASA Astrophysics Data System (ADS)

    Kim, H.; Zhang, Q.; Young, D. E.; Parworth, C.

    2015-12-01

    Light absorption properties of water soluble organic aerosol were investigated at Fresno, CA from 13 January to 11 February, 2013 as part of the NASA DISCOVER-AQ campaign. The light absorption spectra of water soluble organic aerosol in PM2.5 was measured using a UV/vis diode array detector (DAD) coupled with a particle into liquid sampler (PILS) that sampled downstream of a PM2.5 cyclone (URG). The PILS was also coupled with two ion chromatographs (IC) to measure inorganic and organic ionic species in PM2.5. In addition, an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed at the same site to measure size-resolved chemical composition of submicrometer aerosol (PM1) in real time during this study. Light absorption at 365 nm (Abs365), which is typically used as a proxy of water-soluble brown carbon (BrC), showed strong enhancement during night time and appeared to correlate well (r = 0.71) with biomass burning organic aerosol (BBOA) from residential wood burning for heating in the Fresno area. The tight correlations between Abs365 and biomass burning relevant tracers such as acetonitrile (r = 0.69), AMS-signature ions for phenolic compounds (r = 0.52-0.71), PAH (r = 0.74), and potassium (r = 0.67) further confirm that biomass burning contributed significantly to water soluble brown carbon during this study. The absorption angstrom exponent (Åa) values fitted between 300 and 700 nm wavelength were 3.3 ± 1.1, 2.0 ± 0.9 and 4.0 ± 0.8, respectively, in the morning, afternoon and nighttime, indicating that BrC is prevalent at night in Fresno during wintertime. However, there are also indications that small amount of BrC existed during the daytime as well, likely due to daytime wood burning and other sources such as the formation of light-absorbing secondary organic aerosol (SOA). Finally, light absorption at 300 nm, 330 nm, and 390 nm were found to correlate tightly with BBOA, which indicate that biomass burning also emits

  16. Use of levoglucosan, potassium, and water-soluble organic carbon to characterize the origins of biomass-burning aerosols

    NASA Astrophysics Data System (ADS)

    Urban, Roberta Cerasi; Lima-Souza, Michele; Caetano-Silva, Letícia; Queiroz, Maria Eugênia C.; Nogueira, Raquel F. P.; Allen, Andrew G.; Cardoso, Arnaldo A.; Held, Gerhard; Campos, Maria Lucia A. M.

    2012-12-01

    Three chemical species related to biomass burning, levoglucosan, potassium and water-soluble organic carbon (WSOC), were measured in aerosol samples collected in a rural area on the outskirts of the municipality of Ourinhos (São Paulo State, Brazil). This region is representative of the rural interior of the State, where the economy is based on agro-industrial production, and the most important crop is sugar cane. The manual harvesting process requires that the cane be first burned to remove excess foliage, leading to large emissions of particulate materials to the atmosphere. Most of the levoglucosan (68-89%) was present in small particles (<1.5 μm), and its concentration in total aerosol ranged from 25 to 1186 ng m-3. The highest values were found at night, when most of the biomass burning occurs. In contrast, WSOC showed no diurnal pattern, with an average concentration of 5.38 ± 2.97 μg m-3 (n = 27). A significant linear correlation between levoglucosan and WSOC (r = 0.54; n = 26; p < 0.0001) confirmed that biomass burning was in fact an important source of WSOC in the study region. A moderate (but significant) linear correlation between levoglucosan and potassium concentrations (r = 0.62; n = 40; p < 0.0001) was indicative of the influence of other sources of potassium in the study region, such as soil resuspension and fertilizers. When only the fine particles (<1.5 μm; typical of biomass burning) were considered, the linear coefficient increased to 0.91 (n = 9). In this case, the average levoglucosan/K+ ratio was 0.24, which may be typical of biomass burning in the study region. This ratio is about 5 times lower than that previously found for Amazon aerosol collected during the day, when flaming combustion prevails. This suggests that the levoglucosan/K+ ratio may be especially helpful for characterization of the type of vegetation burned (such as crops or forest), when biomass-burning is the dominant source of potassium. The relatively high

  17. [Size distributions of water-soluble inorganic ions in atmospheric aerosols in Fukang].

    PubMed

    Miao, Hong-Yan; Wen, Tian-Xue; Wang, Yue-Si; Liu, Zi-Rui; Wang, Li; Lan, Zhong-Dong

    2014-06-01

    To investigate the levels and size distributions of water soluble inorganic components, samples were collected with Andersen cascade sampler from Feb. 2011 to Feb. 2012, in Fukang, and were analyzed by IC. The variation trend, concentration level, composition, sources and size distribution of major ions during non-heating period were compared with heating period. Based on the specific samples, ionic compositions and size distributions were analyzed during heavy pollution, straw burning and spring planting periods. The results showed that inorganic components in Fukang were severely affected by heating. The total water soluble ions in fine and coarse particles during non-heating and heating periods were 11.17, 12.68 microg x m(-3) and 35.98, 22.22 microg x m(-3), respectively. SO4(2-) was mainly from saline-alkali soil, NO3(-) and NH4(+) were from resuspension of farmland soil during non-heating period, while SO4(2-), NO3(-) and NH4(+) were all from the fossil fuel consumption during the heating period. All ions were bimodal distribution during non-heating and heating periods. During the heating period, the particle size growth of SO4(2-), NO3(-) and NH4(+) in fine mode was found, SO4(2-) and NH4(+) peaked at 3.3-4.7 microm in coarse particles. Secondary pollutions were serious during heavy pollution days with high levels of secondary ions between 1.1 and 2.1 microm. Biomass burning obviously affected the size distribution of ions during the straw burning period and ions focused on smaller than 0.65 microm, while there were more soil dusts during spring planting periods and ions concentrated in larger than 3.3 microm.

  18. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

    SciTech Connect

    Wang, Bingbing; Laskin, Alexander

    2014-03-25

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  19. EPR investigation of iron in size segregated atmospheric aerosols collected at Dunkerque, Northern France

    NASA Astrophysics Data System (ADS)

    Ledoux, Frédéric; Zhilinskaya, Elena A.; Courcot, Dominique; Aboukaı̈s, Antoine; Puskaric, Emile

    Electron paramagnetic resonance (EPR) spectroscopy was used to study atmospheric aerosols at Dunkerque, a French sea-side city located on the southern coast of the North Sea. Particles were collected in June-July 2001 and January-February 2002 periods using global filtration and cascade impaction. EPR spectra obtained for these particles were attributed to Fe 3+ ions, mainly in the form of hematite ( α-Fe 2O 3) in interaction with other paramagnetic species (Fe 3+, Mn 2+, Cu 2+, etc.). From the EPR spectra intensities measured at 77 and 293 K, Fe 3+ ions were evidenced in the form of clusters and agglomerated species. Fe 3+ agglomerated species were observed mainly for winds blowing from the industrial park. Cascade impactor samples study evidenced that clusters are rather detected in the small size particles whereas agglomerated Fe 3+ ions species are rather present in the large ones. The small size particles are richer in iron than the large ones, thus such particles play an important role in the value of EPR parameters.

  20. The Exochelins of Pathogenic Mycobacteria: Unique, Highly Potent, Lipid- and Water-Soluble Hexadentate Iron Chelators with Multiple Potential Therapeutic Uses

    PubMed Central

    Horwitz, Lawrence D.

    2014-01-01

    Abstract Significance: Exochelins are lipid- and water-soluble siderophores of Mycobacterium tuberculosis with unique properties that endow them with exceptional pharmacologic utility. Exochelins can be utilized as probes to decipher the role of iron in normal and pathological states, and, since they rapidly cross cell membranes and chelate intracellular iron with little or no toxicity, exochelins are potentially useful for the treatment of a number of iron-dependent pathological phenomena. Recent Advances: In animal models, exochelins have been demonstrated to have promise for the treatment of transfusion-related iron overload, restenosis after coronary artery angioplasty, cancer, and oxidative injury associated with acute myocardial infarction and transplantation. Critical Issues: To be clinically effective, iron chelators should be able to rapidly enter cells and chelate iron at key intracellular sites. Desferri-exochelins, and other lipid-soluble chelators, can readily cross cell membranes and remove intracellular free iron; whereas deferoxamine, which is lipid insoluble, cannot do so. Clinical utility also requires that the chelators be nontoxic, which, we hypothesize, includes the capability to prevent iron from catalyzing free radical reactions which produce •OH or other reactive oxygen species. Lipid-soluble iron chelators currently available for clinical application are bidentate (deferiprone) or tridentate (desferasirox) molecules that do not block all six sites on the iron molecule capable of catalyzing free radical reactions. In contrast, desferri-exochelins are hexadentate molecules, and by forming a one-to-one binding relationship with iron, they prevent free radical reactions. Future Directions: Clinical studies are needed to assess the utility of desferri-exochelins in the treatment of iron-dependent pathological disorders. Antioxid. Redox Signal. 21, 2246–2261. PMID:24684595

  1. Soil abrasion and eolian dust production: Implications for iron partitioning and solubility

    NASA Astrophysics Data System (ADS)

    Mackie, D. S.; Peat, J. M.; McTainsh, G. H.; Boyd, P. W.; Hunter, K. A.

    2006-12-01

    Eolian dust is a source of iron for phytoplankton in many ocean areas, and there are complex pathways of atmospheric processing from soil to ocean. Overlooked parts of the pathways are the impact of large (>10 μm) grains (including a role as proxies for the behavior of smaller grains) and the effect of multiple cycles of uplift and abrasion in the dust source region. Partitioning (readily released, acid-leachable and refractory) and dissolution rates of iron were determined for an artificial dust (produced by abrading an Australian soil), untreated soil, abraded soil (after production of the artificial dust), and a natural Australian eolian dust sample taken during a dust storm. Readily released iron is not created during abrasion, and therefore the amount of readily released iron in a dust or dust-derived soil depends on processing events since the dust or soil last experienced an abrasion event. Our study develops a method for the partitioning of iron within airborne dusts and appears to be the first to consider the effect of multiple uplift events on iron partitioning.

  2. Seasonal variations in the light-absorbing properties of water-soluble and insoluble organic aerosols in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Hwajin; Kim, Jin Young; Jin, Hyoun Cher; Lee, Ji Yi; Lee, Se Pyo

    2016-03-01

    The spectral properties of light-absorbing organic aerosol extractions were investigated using 24-h average fine particulate matter (PM2.5) measurements from October 2012 to September 2013 in Seoul, Korea. The light-absorption spectra of water and methanol extracts exhibited strong evidence of brown carbon with Absorption Angstrom Exponent (AAE; fitted between 300 and 700 nm) ranges of 5.84-9.17 and 4.08-5.75, with averages of 7.23 ± 1.58 and 5.05 ± 0.67, respectively. The light absorption of both extracts at 365 nm (Abs365), which is typically used as a proxy for brown carbon (BrC), displayed strong seasonal variations and was well correlated with both water-soluble organic carbon (WSOC; r = 0.81) and organic carbon (OC; r = 0.85), indicating that both primary and secondary organics were sources of BrC in this region. Normalizing the Abs365 of water and methanol extracts to the mass of WSOC and OC yielded average solution mass absorption efficiency (MAE365) of 0.28-1.18 and 0.44-1.45 m2 g-1 C, respectively. MAE365 in Korea were in the same range or slightly lower than those in China, however, despite the same ranges, the seasonal variations were different, suggesting that the sources of light absorbers could be different. Combining the AAE, Abs365, and MAE365 of both extracts and a detailed chemical speciation of filter extracts identified the compounds responsible for the temporal variations of BrC in Korea. During summer, secondary organic aerosol (SOA), photochemically generated from anthropogenic emissions, was the major source; however, during winter, long range transported organics or transported BrC seem to be a source of BrC in Korea, a downwind site of China, where severe smog and BrC were observed during this season. Biomass burning was also an important source; however, unlike in previous studies, where it was identified as a major source during winter, here, it contributed during the whole year. Although many of its properties, sources, and potential

  3. Seasonal variation and secondary formation of size-segregated aerosol water-soluble inorganic ions during pollution episodes in Beijing

    NASA Astrophysics Data System (ADS)

    Huang, Xiaojuan; Liu, Zirui; Zhang, Junke; Wen, Tianxue; Ji, Dongsheng; Wang, Yuesi

    2016-02-01

    Particulate matter (PM) pollution is a serious issue that has aroused great public attention in Beijing. To examine the seasonal characteristics of aerosols in typical pollution episodes, water-soluble inorganic ions (SO42 -, NO3-, NH4+, Cl-, K+, Na+, Ca2 + and Mg2 +) in size-segregated PM collected by an Anderson sampler (equipped with 50% effective cut-off diameters of 9.0, 5.8, 4.7, 3.3, 2.1, 1.1, 0.65, 0.43 μm and an after filter) were investigated in four intensive campaigns from June 2013 to May 2014 in the Beijing urban area. Pronounced seasonal variation of TWSIs in fine particles (aerodynamic diameter less than 2.1 μm) was observed, with the highest concentration in summer (71.5 ± 36.3 μg/m3) and the lowest in spring (28.1 ± 15.2 μg/m3). Different ion species presented different seasonal characteristics of mass concentration and size distribution, reflecting their different dominant sources. As the dominant component, SO42 -, NO3- and NH4+ (SNA) in fine particles appeared to play an important role in the formation of high PM pollution since its contribution to the TWSIs and PM2.1 mass increased significantly during pollution episodes. Due to the hygroscopic growth and enhanced secondary formation in the droplet mode (0.65-2.1 μm) from clean days to polluted days, the size distribution peak of SNA in the fine mode tended to shift from 0.43-0.65 μm to 0.65-2.1 μm. Relative humidity (RH) and temperature contributed to influence the secondary formation and regulate the size distributions of sulfates and nitrates. Partial correlation analysis found that high RH would promote the sulfur and nitrogen oxidation rates in the fine mode, while high temperature favored the sulfur oxidation rate in the condensation mode (0.43-0.65 μm) and reduced the nitrogen oxidation rate in the droplet mode (0.65-2.1 μm). The NO3-/SO42 - mass ratio in PM2.1 (73% of the samples) exceeded 1.0, suggesting that vehicle exhaust currently makes a greater contribution to aerosol

  4. Validation of a continuous flow method for the determination of soluble iron in atmospheric dust and volcanic ash.

    PubMed

    Simonella, Lucio E; Gaiero, Diego M; Palomeque, Miriam E

    2014-10-01

    Iron is an essential micronutrient for phytoplankton growth and is supplied to the remote areas of the ocean mainly through atmospheric dust/ash. The amount of soluble Fe in dust/ash is a major source of uncertainty in modeling-Fe dissolution and deposition to the surface ocean. Currently in the literature, there exist almost as many different methods to estimate fractional solubility as researchers in the field, making it difficult to compare results between research groups. Also, an important constraint to evaluate Fe solubility in atmospheric dust is the limited mass of sample which is usually only available in micrograms to milligrams amounts. A continuous flow (CF) method that can be run with low mass of sediments (<10mg) was tested against a standard method which require about 1g of sediments (BCR of the European Union). For validation of the CF experiment, we run both methods using South American surface sediment and deposited volcanic ash. Both materials tested are easy eroded by wind and are representative of atmospheric dust/ash exported from this region. The uncertainty of the CF method was obtained from seven replicates of one surface sediment sample, and shows very good reproducibility. The replication was conducted on different days in a span of two years and ranged between 8 and 22% (i.e., the uncertainty for the standard method was 6-19%). Compared to other standardized methods, the CF method allows studies of dissolution kinetic of metals and consumes less reagents and time (<3h). The method validated here is suggested to be used as a standardized method for Fe solubility studies on dust/ash.

  5. Thermodynamic assessment of solubility and activity of iron, chromium, and nickel in lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Gossé, Stéphane

    2014-06-01

    Lead-Bismuth Eutectic (LBE) is a heavy liquid alloy used as a coolant for the Lead-Cooled Fast Reactors and spallation target for Accelerator Driven Systems. LBE is also considered in sodium fast reactor designs as coolant in secondary circuit to avoid any occurrence of the reaction between sodium and water in steam generators. Even if this coolant presents many advantages due to its thermophysical properties, corrosion towards structural materials remains one of the major issues of LBE. Because corrosion in LBE is partly driven by dissolution processes, the solubility and chemical activity of the main elements of the alloy are the key parameters to model the related corrosion processes. Using the Calphad method and the Thermo-Calc software, a thermodynamic database was developed to assess the interaction between Cr-Ni-Fe alloys and LBE. The current thermodynamic data on the Cr-Fe-Ni + Bi-Pb quinary system was reviewed and the Bi-Cr and Cr-Pb binary phase diagrams were assessed. Fe, Cr and Ni solubilities (in at. fraction, T in K) at LBE composition were calculated: Fe solubility at LBE composition: log10 (SFe)=0.5719-4398.6T (399-1173 K) Cr solubility at LBE composition: log10 (SCr)=-0.2757-3056.1T (399-1173 K) Ni solubility at LBE composition: log10 (SNi)=2.8717-2932.9T (528-742 K) log10 (SNi)=0.2871-1006.3T (742-1173 K) Then, the thermodynamic assessment performed in this study was used to predict more accurately the Fe, Cr and Ni activities and solubilities in the case of four austenitic model alloys also studied in the framework of corrosion tests [1]. The calculated activities and solubilities provide thermodynamic data to better understand dissolution or precipitation phenomena observed during LBE corrosion processes.

  6. A Green Analytical Method Using Ultrasound in Sample Preparation for the Flow Injection Determination of Iron, Manganese, and Zinc in Soluble Solid Samples by Flame Atomic Absorption Spectrometry

    PubMed Central

    Yebra, M. Carmen

    2012-01-01

    A simple and rapid analytical method was developed for the determination of iron, manganese, and zinc in soluble solid samples. The method is based on continuous ultrasonic water dissolution of the sample (5–30 mg) at room temperature followed by flow injection flame atomic absorption spectrometric determination. A good precision of the whole procedure (1.2–4.6%) and a sample throughput of ca. 25 samples h–1 were obtained. The proposed green analytical method has been successfully applied for the determination of iron, manganese, and zinc in soluble solid food samples (soluble cocoa and soluble coffee) and pharmaceutical preparations (multivitamin tablets). The ranges of concentrations found were 21.4–25.61 μg g−1 for iron, 5.74–18.30 μg g−1 for manganese, and 33.27–57.90 μg g−1 for zinc in soluble solid food samples and 3.75–9.90 μg g−1 for iron, 0.47–5.05 μg g−1 for manganese, and 1.55–15.12 μg g−1 for zinc in multivitamin tablets. The accuracy of the proposed method was established by a comparison with the conventional wet acid digestion method using a paired t-test, indicating the absence of systematic errors. PMID:22567553

  7. A green analytical method using ultrasound in sample preparation for the flow injection determination of iron, manganese, and zinc in soluble solid samples by flame atomic absorption spectrometry.

    PubMed

    Yebra, M Carmen

    2012-01-01

    A simple and rapid analytical method was developed for the determination of iron, manganese, and zinc in soluble solid samples. The method is based on continuous ultrasonic water dissolution of the sample (5-30 mg) at room temperature followed by flow injection flame atomic absorption spectrometric determination. A good precision of the whole procedure (1.2-4.6%) and a sample throughput of ca. 25 samples h(-1) were obtained. The proposed green analytical method has been successfully applied for the determination of iron, manganese, and zinc in soluble solid food samples (soluble cocoa and soluble coffee) and pharmaceutical preparations (multivitamin tablets). The ranges of concentrations found were 21.4-25.61 μg g(-1) for iron, 5.74-18.30 μg g(-1) for manganese, and 33.27-57.90 μg g(-1) for zinc in soluble solid food samples and 3.75-9.90 μg g(-1) for iron, 0.47-5.05 μg g(-1) for manganese, and 1.55-15.12 μg g(-1) for zinc in multivitamin tablets. The accuracy of the proposed method was established by a comparison with the conventional wet acid digestion method using a paired t-test, indicating the absence of systematic errors. PMID:22567553

  8. Water-soluble dicarboxylic acids and ω-oxocarboxylic acids in size-segregated aerosols over northern Japan during spring: sources and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, Dhananjay Kumar; Kawamura, Kimitaka; Kobayashi, Minoru; Gowda, Divyavani

    2016-04-01

    Seven sets (AF01-AF07) of size-segregated aerosol (12-sizes) samples were collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI) in Sapporo, Japan during the spring of 2001 to understand the sources and atmospheric processes of water-soluble organic aerosols in the outflow region of Asian dusts. The samples were analyzed for dicarboxylic acids (C2-C12) and ω-oxocarboxylic acids as well as inorganic ions. The molecular distribution of diacids showed the predominance of oxalic acid (C2) followed by malonic and succinic acids whereas ω-oxoacids showed the predominance of glyoxylic acid (ωC2) in size-segregated aerosols. SO42- and NH4+ are enriched in submicron mode whereas NO3- and Ca2+ are in supermicron mode. Most of diacids and ω-oxoacids are enriched in supermicron mode in the samples (AF01-AF03) influenced by the long-range transport of mineral dusts whereas enhanced presence in submicron mode was observed in other sample sets. The strong correlations of C2 with Ca2+ (r = 0.95-0.99) and NO3- (r = 0.96-0.98) in supermicron mode in the samples AF01-AF03 suggest the adsorption or production of C2 diacid via heterogeneous reaction on the surface of mineral dust during long-range atmospheric transport. The preferential enrichment of diacids and ω-oxoacids in mineral dust has important implications for the solubility and cloud nucleation properties of the dominant fraction of water-soluble organic aerosols. This study demonstrates that biofuel and biomass burning and mineral dust originated in East Asia are two major factors to control the size distribution of diacids and related compounds over northern Japan.

  9. Spatial and Temporal Distribution of Water-Soluble Anions and Organic Carbons in Bulk Aerosols Collected at the Ryukyu Islands, Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Somada, Y.; Azechi, S.; Ijyu, M.; Nakaema, F.; Handa, D.; Oshiro, Y.; Miyagi, Y.; Arakaki, T.; Tanahara, A.; Furukawa, M.

    2011-12-01

    Atmospheric aerosols pose health risks to humans and change global climate. Ryukyu Islands in Japan are mainly covered with maritime air mass in summer and continental air mass for the rest of the seasons. Thus, it is possible to estimate the origins of chemical components, in particular transboundary air pollutants from East Asia. Ryukyu Islands are one of the best locations for monitoring the changes in Asia's atmosphere. This study tried to elucidate the spatial and temporal distribution of water-soluble anions and organic carbons, and chemical changes during the transportation processes. Aerosol samples were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS, Sep. 2005 - Dec. 2010), Kume Island (KM, ca. 100 km from Naha), and Minami-Daitou Island (MD, ca. 350 km from Naha) from June 2008 to June 2010 on quartz filters by using identical high-volume air samplers. The sample filters were exchanged every week. The concentrations of water-soluble anions (Cl-,Br-,NO3-,NO2-,SO42-) and water-soluble organic carbon (WSOC) were determined by using ion chromatography and total organic carbon analyzer, respectively. And, concentrations of non-sea-salt SO(nss-SO42-) were calculated based on the concentrations of Na+. For the samples collected at CHAAMS, seawater component accounted for on average 56±5% of total aerosol mass. Monthly mean concentrations of nss-SO42- showed distinctive difference among the sampling sites (KM>CHAAMS>MD) during Jan. to May, suggesting that distance from Asian continent affected on its behavior. Yearly average concentrations of NO3- and nss-SO42- showed +42% and +16% increase, respectively between 2005 and 2011. Annual rate of NO3- increase was much faster than that of nss-SO42-, probably reflecting changes in lifestyles in Asian continent.

  10. Iron sulfide attenuates the methanogenic toxicity of elemental copper and zinc oxide nanoparticles and their soluble metal ion analogs.

    PubMed

    Gonzalez-Estrella, Jorge; Gallagher, Sara; Sierra-Alvarez, Reyes; Field, Jim A

    2016-04-01

    Elemental copper (Cu(0)) and zinc oxide (ZnO) nanoparticle (NP) toxicity to methanogens has been attributed to the release of soluble metal ions. Iron sulfide (FeS) partially controls the soluble concentration of heavy metals and their toxicity in aquatic environments. Heavy metals displace the Fe from FeS forming poorly soluble metal sulfides in the FeS matrix. Therefore, FeS may be expected to attenuate the NP toxicity. This work assessed FeS as an attenuator of the methanogenic toxicity of Cu(0) and ZnO NPs and their soluble salt analogs. The toxicity attenuation capacity of fine (25-75μm) and coarse (500 to 1200μm) preparations of FeS (FeS-f and FeS-c respectively) was tested in the presence of highly inhibitory concentrations of CuCl2, ZnCl2 Cu(0) and ZnO NPs. FeS-f attenuated methanogenic toxicity better than FeS-c. The results revealed that 2.5× less FeS-f than FeS-c was required to recover the methanogenic activity to 50% (activity normalized to uninhibited controls). The results also indicated that a molar FeS-f/Cu(0) NP, FeS-f/ZnO NP, FeS-f/ZnCl2, and FeS-f/CuCl2 ratio of 2.14, 2.14, 4.28, and 8.56 respectively, was necessary to recover the methanogenic activity to >75%. Displacement experiments demonstrated that CuCl2 and ZnCl2 partially displaced Fe from FeS. As a whole, the results indicate that not all the sulfide in FeS was readily available to react with the soluble Cu and Zn ions which may explain the need for a large stoichiometric excess of FeS to highly attenuate Cu and Zn toxicity. Overall, this study provides evidence that FeS attenuates the toxicity caused by Cu(0) and ZnO NPs and their soluble ion analogs to methanogens.

  11. Surface modification of iron oxide nanoparticles and their conjuntion with water soluble polymers for biomedical application

    NASA Astrophysics Data System (ADS)

    Thanh Huong, Nguyen; Thi Kieu Giang, Lam; Thanh Binh, Nguyen; Minh, Le Quoc

    2009-09-01

    Superparamagnetic iron oxide nanoparticles (SPION) coated with suitable bio-compatible substances have been used in biomedicine, particularly in magnetic resonance imaging (MRI), tissue engineering, and hyperthermia and drug delivery. In this study, we describe the synthesis of SPION and its surface modification for in-vitro experiments. The particle diameter and structure were estimated by FESEM, TEM, XRD analyses. The saturation magnetization was characterized. SPION with a mean size of 12 nm have been prepared under N2 atmosphere, with support of natural polymeric starch, by controlling chemical coprecipitation of magnetite phase from aqueous solutions containing suitable salts ratios of Fe2+ and Fe3+. The surface of SPION-nanoparticles was treated with a coordinatable agent for higher dispersion ability in water and remaining the superparamagnetic behavior. The prepared iron oxide nanoparticles were coated with starch, dextran, PEG or MPEG to extend the application potential in the quite different engineering field of nano biomedicine.

  12. Carbon Solubility in Silicon-Iron-Bearing Metals during Core Formation on Mercury

    NASA Technical Reports Server (NTRS)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Ross, D. Kent; Rapp, Jennifer F.; Danielson, Lisa R.; Keller, Lindsay P.; Righter, Kevin

    2016-01-01

    Recent results obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft showed the surface of Mercury has high S abundances (approximately 4 wt%) and low Iron(II) Oxide abundances (less than 2 wt%). Based on these extreme values, the oxygen fugacity of Mercury's surface materials was estimated to be approximately 3 to 7 log(sub 10) units below the IW buffer (Delta IW-3 to Delta IW-7). This highly reducing nature of the planet has resulted in a large core and relatively thin mantle, extending to only approximately 420 km depth (corresponding to a core-mantle boundary pressure of approximately 4-7 GPa) within the planet. Furthermore, MESSENGER results have suggested the presence of carbon on the surface of the planet. Previous experimental results from have also suggested the possibility of a primary floatation crust on Mercury composed of graphite, produced after a global magma ocean event. With these exotic conditions of this compositional end-member planet, it begs the question, what is the core composition of Mercury? Although no definitive conclusion has been reached, previous studies have made advances towards answering this question. Riner et al. and Chen et al. looked at iron sulfide systems and implemented various crystallization and layered core scenarios to try and determine the composition and structure of Mercury's core. Malavergne et al. examined core crystallization scenarios in the presence of sulfur and silicon. Hauck et al. used the most recent geophysical constraints from the MESSENGER spacecraft to model the internal structure of Mercury, including the core, in a iron-sulfur-silicon system. More recently, Chabot et al. conducted a series of metal-silicate partitioning experiments in a iron-sulfur-silicon system. These results showed the core of Mercury has the potential to contain more than 15 wt% silicon. However, with the newest results from MESSENGER's low altitude campaign, carbon is another

  13. Drug solubility in phospholipid carrier as a predictive parameter for drug recovery in microparticles produced by the aerosol solvent extraction system (ASES) process.

    PubMed

    Sarisuta, Narong; Kunastitchai, Sarinnate; Pichert, Lars; Müller, Bernd W

    2007-09-01

    The solubility of various drugs in a constant ratio of phosphatidylcholine-cholesterol carrier were studied to investigate their influence on drug recovery in drug-lipid microparticles produced by the aerosol solvent extraction system (ASES) process. Solubility of the drugs in such lipid carrier were determined by using differential scanning calorimetry and confirmed by X-ray powder diffraction study. The results showed that drug possessing relatively high solubility in the lipid carrier used could lead to a higher amount of drug recovered in the drug-lipid microparticles produced. However, too high amount of dissolved drug imposed an adverse effect on the solidification of the lipid carrier during ASES processing, which led to partial film formation in the production column and hence a lower yield of microparticles. Such adverse effect was not the case for the drugs with low solubility in the carrier but there was an incomplete recovery of drug in the produced microparticles due to the partial extraction by the supercritical gas instead. The maximum amount of drug recovered in the ASES-prepared microparticles was found to correlate to the solubility of drug in the lipid carrier so that it might be utilized as a predictive parameter for determining the amount of drug to be incorporated into the microparticles.

  14. Enhanced in vitro and in vivo cellular imaging with green tea coated water-soluble iron oxide nanocrystals.

    PubMed

    Xiao, Lisong; Mertens, Marianne; Wortmann, Laura; Kremer, Silke; Valldor, Martin; Lammers, Twan; Kiessling, Fabian; Mathur, Sanjay

    2015-04-01

    Fully green and facile redox chemistry involving reduction of colloidal iron hydroxide (Fe(OH)3) through green tea (GT) polyphenols produced water-soluble Fe3O4 nanocrystals coated with GT extracts namely epigallocatechin gallate (EGCG) and epicatechin (EC). Electron donating polyphenols stoichiometrically reduced Fe(3+) ions into Fe(2+) ions resulting in the formation of magnetite (Fe3O4) nanoparticles and corresponding oxidized products (semiquinones and quinones) that simultaneously served as efficient surface chelators for the Fe3O4 nanoparticles making them dispersible and stable in water, PBS, and cell culture medium for extended time periods. As-formed iron oxide nanoparticles (2.5-6 nm) displayed high crystallinity and saturation magnetization as well as high relaxivity ratios manifested in strong contrast enhancement observed in T2-weighted images. Potential of green tea-coated superparamagnetic iron oxide nanocrystals (SPIONs) as superior negative contrast agents was confirmed by in vitro and in vivo experiments. Primary human macrophages (J774A.1) and colon cancer cells (CT26) were chosen to assess cytotoxicity and cellular uptake of GT-, EGCGq-, and ECq-coated Fe3O4 nanoparticles, which showed high uptake efficiencies by J774A.1 and CT26 cells without any additional transfection agent. Furthermore, the in vivo accumulation characteristics of GT-coated Fe3O4 nanoparticles were similar to those observed in clinical studies of SPIONs with comparable accumulation in epidermoid cancer-xenograft bearing mice. Given their promising transport and uptake characteristics and new surface chemistry, GT-SPIONs conjugates can be applied for multimodal imaging and therapeutic applications by anchoring further functionalities. PMID:25729881

  15. Coal fly ash as a source of iron in atmospheric dust.

    PubMed

    Chen, Haihan; Laskin, Alexander; Baltrusaitis, Jonas; Gorski, Christopher A; Scherer, Michelle M; Grassian, Vicki H

    2012-02-21

    Anthropogenic coal fly ash (FA) aerosol may represent a significant source of bioavailable iron in the open ocean. Few measurements have been made that compare the solubility of atmospheric iron from anthropogenic aerosols and other sources. We report here an investigation of iron dissolution for three FA samples in acidic aqueous solutions and compare the solubilities with that of Arizona test dust (AZTD), a reference material for mineral dust. The effects of pH, simulated cloud processing, and solar radiation on iron solubility have been explored. Similar to previously reported results on mineral dust, iron in aluminosilicate phases provides the predominant component of dissolved iron. Iron solubility of FA is substantially higher than of the crystalline minerals comprising AZTD. Simulated atmospheric processing elevates iron solubility due to significant changes in the morphology of aluminosilicate glass, a dominant material in FA particles. Iron is continuously released into the aqueous solution as FA particles break up into smaller fragments. These results suggest that the assessment of dissolved atmospheric iron deposition fluxes and their effect on the biogeochemistry at the ocean surface should be constrained by the source, environmental pH, iron speciation, and solar radiation.

  16. Source identification of water-soluble organic aerosols at a roadway site using a positive matrix factorization analysis.

    PubMed

    Park, Seungshik; Cho, Sung Yong; Bae, Min-Suk

    2015-11-15

    Daily PM2.5 measurements were carried out at a local roadway every sixth day from May 2011 to August 2013 to obtain seasonal quantitative information on the primary and secondary sources of two water-soluble organic carbon (WSOC) fractions. Filter samples were analyzed for OC, elemental carbon (EC), WSOC, hydrophilic and hydrophobic WSOC fractions (WSOC(HPI) and WSOC(HPO)), and ionic species. An XAD solid phase extraction method and a total organic carbon analyzer were used to isolate the two WSOC fractions and determine their amounts, respectively. The WSOC/OC and WSOC(HPI)/WSOC ratios were 0.62±0.13 and 0.47±0.14, respectively. Similar seasonal profiles in EC, OC, and WSOC concentrations were observed, with higher concentrations occurring in the cold season and lower concentrations in the warm season. However, opposite results were obtained in WSOC/OC and WSOC(HPI)/WSOC ratios, with the higher in the warm season and the lower in the cold season. Correlation analyses indicated that two WSOC fractions in winter were likely attributed to secondary formation processes, biomass burning (BB), and traffic emissions, while WSOC(HPI) observed in other seasons were associated with secondary formation processes similar to those of oxalate and secondary inorganic species. A positive matrix factorization (PMF) model was employed to investigate the sources of two WSOC fractions. PMF indicated that concentrations of WSOC fractions were affected by five sources: secondary NO3(-) related, secondary SO4(2-) and oxalate related, traffic emissions, BB emissions, and sea-salt. Throughout the study period, secondary organic aerosols were estimated to be the most dominant contributor of WSOC fractions, with higher contributions occurring in the warm seasons. The contribution of secondary aerosol formation processes (NO3(-) related+SO4(2-) and oxalate related) to WSOC(HPI) and WSOC(HPO) was on an average 56.2% (45.0-73.8%) and 47.7% (39.6-52.1%), respectively. The seasonal average

  17. Contribution of dissolved organic matter to submicron water-soluble organic aerosols in the marine boundary layer over the eastern equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzo; Coburn, Sean; Ono, Kaori; Ho, David T.; Pierce, R. Bradley; Kawamura, Kimitaka; Volkamer, Rainer

    2016-06-01

    Stable carbon isotopic compositions of water-soluble organic carbon (WSOC) and organic molecular markers were measured to investigate the relative contributions of the sea surface sources to the water-soluble fraction of submicron organic aerosols collected over the eastern equatorial Pacific during the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO)/KA-12-01 cruise. On average, the water-soluble organic fraction of the total carbon (TC) mass in submicron aerosols was ˜ 30-35 % in the oceans with the low chlorophyll a (Chl a) concentrations, whereas it was ˜ 60 % in the high-Chl a regions. The average stable carbon isotope ratio of WSOC (δ13CWSOC) was -19.8 ± 2.0 ‰, which was systematically higher than that of TC (δ13CTC) (-21.8 ± 1.4 ‰). We found that in the oceans with both high and low Chl a concentrations the δ13CWSOC was close to the typical values of δ13C for dissolved organic carbon (DOC), ranging from -22 to -20 ‰ in surface seawater of the tropical Pacific Ocean. This suggests an enrichment of marine biological products in WSOC aerosols in the study region regardless of the oceanic area. In particular, enhanced levels of WSOC and biogenic organic marker compounds together with high values of WSOC / TC ( ˜ 60 %) and δ13CWSOC were observed over upwelling areas and phytoplankton blooms, which was attributed to planktonic tissues being more enriched in δ13C. The δ13C analysis estimated that, on average, marine sources contribute ˜ 90 ± 25 % of the aerosol carbon, indicating the predominance of marine-derived carbon in the submicron WSOC. This conclusion is supported by Lagrangian trajectory analysis, which suggests that the majority of the sampling points on the ship had been exposed to marine boundary layer (MBL) air for more than 80 % of the time during the previous 7 days. The combined analysis of the δ13C and monosaccharides, such as glucose and fructose, demonstrated that DOC concentration was

  18. The Influence of Siderophores Produced by Alkaliphilic Microorganisms on Iron and Metal Contaminant Speciation and Solubility

    NASA Astrophysics Data System (ADS)

    Aiken, A. M.; Peyton, B. M.; Petersen, J. N.; Apel, W. A.; Camper, A. K.

    2003-12-01

    Halomonas campisalis strain 4A has been identified as capable of producing siderophores under halo-alkaliphilic growth conditions. Because of the scarcity of iron under the alkaline conditions in which Halomonas campisalis thrives, we hypothesize that the siderophores secreted by Halomonas campisalis and other alkaliphilic bacteria will have a stronger affinity for binding and solubilizing ferrous iron than siderophores produced by mesophilic bacteria. Siderophore production by Halomonas campisalis was confirmed through the use of the chrome azural S (CAS) agar plate method which showed a red orange halo around the bacterial colonies indicative of siderophore production. The siderophores were found to be produced under conditions of both high salinity and pH with a salt concentrations ranging from 0.4 - 1.8 M NaCl and pH ranging from 8 - 11. The siderophores produced have been determined to be of the hydroxamate class via the Csaky method. A negative response to the Arnow assay indicated that the siderophore produced does not contain any catechol moieties in its chemical structure. It was found that maximum siderophore production was equivalent to approximately 400 mM desferrioxamine and occurred during mid stationary phase. Similar results were found at pH 8, 10 and 11. A purification scheme was developed that involved an initial extraction of the siderophore from the growth medium into benzyl alcohol followed by precipitation with diethyl ether. Additional purification was achieved via ion exchange chromatography and size exclusion chromatography. Final purification was achieved via HPLC. The structure of the purified siderophore was analyzed via LC/MS/MS equipped with an ESI source. To date, few studies have included the siderophores produced by microorganisms capable of tolerating highly saline and alkaline environments. In addition to unique structure and high affinity for iron, it is further hypothesized that siderophores from alkaliphilic bacteria will also

  19. Iron

    MedlinePlus

    ... cereals and breads. White beans, lentils, spinach, kidney beans, and peas. Nuts and some dried fruits, such as raisins. Iron in food comes in two forms: heme iron and nonheme iron. Nonheme iron is found in plant foods and iron-fortified food products. Meat, seafood, ...

  20. Coal Fly Ash as a Source of Iron in Atmospheric Dust

    SciTech Connect

    Chen, Haihan; Laskin, Alexander; Baltrusaitis, Jonas; Gorski, Christopher A.; Scherer, Michelle; Grassian, Vicki H.

    2012-01-18

    Anthropogenic coal fly ash aerosols may represent a significant source of bioavailable iron in the open ocean. Few measurements have been made to compare the solubility of atmospheric iron from anthropogenic aerosols and other sources. We report an investigation of the iron dissolution of three fly ash samples in acidic aqueous solutions and compare the solubilities with that of Arizona test dust, a reference material of mineral dust. The effects of pH, cloud processing, and solar irradiation on Fe solubility were explored. Similar to previously reported results on mineral dust, iron in aluminosilicate phases provide predominant dissolved iron compared with iron in oxides. Iron solubility of fly ash is higher than Arizona test dust, especially at the higher pH conditions investigated. Simulated atmospheric processing elevates iron solubility due to significant changes in the morphology aluminosilicate glass, a dominantly material in fly ash particle. Iron continuously releases into the aqueous solution as fly ash particles break up into smaller fragments. The assessment of dissolved atmospheric iron deposition fluxes, and their effect on the biogeochemistry at ocean surface should be constrained by taking into account the source, environment pH, Fe speciation, and solar radiation.

  1. Iron

    MedlinePlus

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  2. Study on size distribution of total aerosol and water-soluble ions during an Asian dust storm event at Jeju Island, Korea.

    PubMed

    Park, S H; Song, C B; Kim, M C; Kwon, S B; Lee, K W

    2004-01-01

    Soil dust particles transported from loess regions of the Asian continent, called Asian dust, highly influences the air quality of north-eastern Asia and the northern Pacific Ocean. In order to investigate the effects of these dust storms on the chemical composition of atmospheric aerosol particles with different size, measurements of size distributions of total aerosol and major ion species were carried out on Jeju Island, Korea during April 2001. Juju Island was chosen for the study because the levels of emissions of anthropogenic air pollutants are very low. A 5-stage cascade impactor was used to sample size-fractionated aerosol particles. Samples were analyzed for major water-soluble ions using Dionex DX-120 ion chromatograph. The average mass concentration of total aerosol was found to be 24.4 and 108.3 microg m(-3) for non-Asian dust and Asian dust periods, respectively. The total aerosol size distribution, measured during the non-Asian dust period, was bimodal, whereas the coarse particles dominated the size distribution of total aerosol during the Asian dust period. It was found that SO4(2-), NH4+ and K+ were mainly distributed in fine particles, while Cl-, NO3-, Na+, Mg2+ and Ca2+ were in coarse particles. Although SO4(2-) was mainly distributed in fine particles, during the Asian dust period, the concentrations in coarse particles were significantly increased. This indicates heterogeneous oxidation of SO2 on wet surfaces of basic soil dust particles. The NH4+ was found to exist as (NH4)2SO4 in fine particles, with a molar ratio of NH4+ to SO4(2-) of 2.37 and 1.52 for non-Asian dust and Asian dust periods, respectively. Taking into account the proximity of the sampling site to the sea, and the observed chloride depletion, coarse mode nitrate, during the non-Asian dust period, is assumed to originate from the reaction of nitric acid with sodium chloride on the surfaces of sea-salt particles although the chloride depletion was not shown to be large enough to

  3. Influence of iron solubility and charged surface-active compounds on lipid oxidation in fatty acid ethyl esters containing association colloids.

    PubMed

    Homma, Rika; Johnson, David R; McClements, D Julian; Decker, Eric A

    2016-05-15

    The impact of iron compounds with different solubilities on lipid oxidation was studied in the presence and absence of association colloids. Iron (III) sulfate only accelerated lipid oxidation in the presence of association colloids while iron (III) oleate accelerated oxidation in the presence and absence of association colloids. Further, iron (III) oxide retarded lipid oxidation both with and without association colloids. The impact of charged association colloids on lipid oxidation in ethyl oleate was also investigated. Association colloids consisting of the anionic surface-active compound dodecyl sulphosuccinate sodium salt (AOT), cationic surface-active compound hexadecyltrimethylammonium bromide (CTAB), and nonionic surface-active compound 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100) retarded, promoted, and had no effect on lipid oxidation rates, respectively. These results indicate that the polarity of metal compounds and the charge of association colloids play a big role in lipid oxidation.

  4. Influence of iron solubility and charged surface-active compounds on lipid oxidation in fatty acid ethyl esters containing association colloids.

    PubMed

    Homma, Rika; Johnson, David R; McClements, D Julian; Decker, Eric A

    2016-05-15

    The impact of iron compounds with different solubilities on lipid oxidation was studied in the presence and absence of association colloids. Iron (III) sulfate only accelerated lipid oxidation in the presence of association colloids while iron (III) oleate accelerated oxidation in the presence and absence of association colloids. Further, iron (III) oxide retarded lipid oxidation both with and without association colloids. The impact of charged association colloids on lipid oxidation in ethyl oleate was also investigated. Association colloids consisting of the anionic surface-active compound dodecyl sulphosuccinate sodium salt (AOT), cationic surface-active compound hexadecyltrimethylammonium bromide (CTAB), and nonionic surface-active compound 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100) retarded, promoted, and had no effect on lipid oxidation rates, respectively. These results indicate that the polarity of metal compounds and the charge of association colloids play a big role in lipid oxidation. PMID:26776045

  5. Water-soluble organic compounds in PM2.5 and size-segregated aerosols over Mount Tai in North China Plain

    NASA Astrophysics Data System (ADS)

    Wang, Gehui; Kawamura, Kimitaka; Umemoto, Nobuhiko; Xie, Mingjie; Hu, Shuyuan; Wang, Zifa

    2009-10-01

    Daytime and nighttime PM2.5 samples were collected at the summit of Mount Tai (1534 m) located in North China Plain during a week in 2006 summer. Size-segregated aerosol particles were also collected using an eight-stage impactor during the same period. Samples were analyzed for various water-soluble organic compounds using GC/FID and GC/MS techniques. Among the species identified in PM2.5 samples, dicarboxylic acids (C2-C11) were found as the most abundant compound class, followed by ketocarboxylic acids, saccharides, polyols and polyacids, and dicarbonyls. Daytime concentrations of most compounds were found to be 2-3 times higher than in nighttime. Such a diurnal variation was first interpreted by the depressed transport of pollutants in nighttime from the lowlands to the mountaintop owing to the decreased heights of planetary boundary layer, and second by the photochemical production in daytime. The diurnal variation trends of secondary organic aerosols (SOA) such as diacids at the mountain site are the same as those on lowlands, but the diurnal patterns of primary organic aerosols (POA) on the mountaintop are in contrast to those on lowlands, where POA such as saccharides and polyols are usually higher in nighttime owing to the accumulation within inversion layer developed. The eight-stage impactor samples showed bimodal distributions of diacids and related compounds peaking at size ranges of 0.70-1.1 μm and 5.8-9.0 μm. In the present study, water-soluble organics in the fine mode are largely originated from biomass burning and/or photooxidation of gaseous precursors and the subsequent adsorption on the preexisting particles, whereas those in the coarse mode are mainly derived from suspended soil particles and pollens and in part via the hygroscopic growth of fine particles and formation of cloud/fog droplets.

  6. The solubility of the aerosol, 137Cs and 60Co carrier, in the Ignalina Nuclear Power Plant region.

    PubMed

    Jasiulionis, Rimvydas; Rozkov, Andrej

    2008-12-01

    The dissolution of aerosol particles, carrier of (137)Cs and (60)Co, sampled on filters is studied by means of a leaching test with distilled water. Samples were collected from the ventilation stack of the operating Ignalina Nuclear Power Plant (NPP) reactor, the shut down reactor and in the ground-level air. The insolubility in water of radionuclides attached to aerosol particles sampled on filters, collected in the operating Unit 2 reactor effluents, is clearly lower than the insolubility in water of radionuclides attached to aerosol particles sampled on filters, collected in the ground-level air. The mean rate of the change in the insolubility in water of (60)Co and (137)Cs attached to aerosol particles, released from the Ignalina NPP and registered at a 3.5km distance from the NPP, is estimated. The radionuclide activity concentration distribution in the ground-level air is calculated in respect of the insolubility in water of (60)Co attached to aerosol particles and compared with experimental data.

  7. Iron chelating active packaging: Influence of competing ions and pH value on effectiveness of soluble and immobilized hydroxamate chelators.

    PubMed

    Ogiwara, Yoshiko; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2016-04-01

    Many packaged foods utilize synthetic chelators (e.g. ethylenediaminetetraacetic acid, EDTA) to inhibit iron-promoted oxidation or microbial growth which would result in quality loss. To address consumer demands for all natural products, we have previously developed a non-migratory iron chelating active packaging material by covalent immobilization of polyhydroxamate and demonstrated its efficacy in delaying lipid oxidation. Herein, we demonstrate the ability of this hydroxamate-functionalized iron chelating active packaging to retain iron chelating capacity; even in the presence of competing ions common in food. Both immobilized and soluble hydroxamate chelators retained iron chelating capacity in the presence of calcium, magnesium, and sodium competing ions, although at pH 5.0 the presence of calcium reduced immobilized hydroxamate iron chelation. A strong correlation was found between colorimetric and mass spectral analysis of iron chelation by the chelating packaging material. Such chelating active packaging may support reducing additive use in product formulations, while retaining quality and shelf life.

  8. Distributions of Beryllium 7 and Lead 210, and Soluble Aerosol-Associated Ionic Species Over the Western Pacific: PEM West B, February - March 1994

    NASA Technical Reports Server (NTRS)

    Dibb, J. E.; Talbot, R. W.; Lefer, B. L.; Scheuer, E.; Gregory, G. L.; Browell, E. V.; Bradshaw, J. D.; Sandholm, S. T.; Singh, H. B.

    1997-01-01

    Aerosol sampling for the determination of the concentrations of soluble ionic species and the natural radionuclides Be-7 and Pb-210 was conducted from the NASA DC-8 over the western Pacific as part of GTE/PEM-West B during February - March 1994. Concentrations of most soluble ionic species in the free troposphere were higher in samples collected on flights originating from Hong Kong and Japan than those collected further east over the open ocean. In both regions the measured concentrations were higher than those found during PEM-West A (fall 1991). Activities of Pb-210, a tracer of air masses influenced by sources on the Asian continent, showed the same patterns. These data indicate the effect of stronger continental outflow from Asia over the western Pacific during the spring compared to fall season. For readily scavenged aerosol-associated species and soluble acidic gases the strongest indications of Asian outflow were restricted to altitudes below 6 km. The distribution of the continental tracer Pb-210 was also compared to those of a large number of gas phase species measured on the DC-8. Relatively strong correlations were found with O3, and peroxyacetylnitrate (PAN), but only during the flights over the remote Pacific. During PEM-West A, similar correlations were seen, but they were stronger near Asia. We believe that correlations are a signature of continental air that has been processed by deep wet convection over land before being advected over the ocean. One flight over the Sea of Japan provided the opportunity to sample upper troposphere/lower stratosphere air in and around a tropopause fold. Concentrations of Be-7 reached 7 pCi/cu m STP, and peak O3, mixing ratios of 480 ppb were encountered at 10.7 km. The Be-7 data are used to estimate the fraction of stratospheric air mixed down into the troposphere by circulation in the fold.

  9. Distributions of Beryllium 7 and Lead 210, and Soluble Aerosol-Associated Ionic Species Over the Western Pacific: PEM West B

    NASA Technical Reports Server (NTRS)

    Didd, J. E.; Talbot, R. W.; Lefer, B. L.; Scheuer, E.; Gregory, G. L.; Browell, E. V.; Sandholm, S. T.; Singh, H. B.

    1997-01-01

    Aerosol sampling for the determination of the concentrations of soluble ionic species and the natural radionuclides Be-7 and Pb-210 was conducted from the NASA DC-8 over the western Pacific as part of GTE/PEM-West B during February - March 1994. Concentrations of most soluble ionic species in the free troposphere were higher in samples collected on flights originating from Hong Kong and Japan than those collected further east over the open ocean. In both regions the measured concentrations were higher than those found during PEM-West A (fall 1991). Activities of Pb-210 tracer of air masses influenced by sources on the Asian continent, showed the same patterns. These data indicate the effect of stronger continental outflow from Asia over the western Pacific during the spring compared to fall season. For readily scavenged aerosol-associated species and soluble acidic gases the strongest indications of Asian outflow were restricted to altitudes below 6 km. The distribution of the continental tracer Pb-210 was also compared to those of a large number of gas phase species measured on the DC-8. Relatively strong correlations were found with O3 and peroxyacetylnitrate (PAN), but only during the flights over the remote Pacific. During PEM-West A, similar correlations were seen, but they were stronger near Asia. We believe that these correlations are a signature of continental air that has been processed by deep wet convection over land before being advected over the ocean. One flight over the Sea of Japan provided the opportunity to sample upper troposphere/lower stratosphere air in and around a tropopause fold. Concentrations of Be-7 reached 7 pCi/cu m STP, and peak O3, mixing ratios of 480 ppb were encountered at 10.7 km. The Be-7 data are used to estimate the fraction of stratospheric air mixed down into the troposphere by circulation in the fold.

  10. Method of removing nitrogen monoxide from a nitrogen monoxide-containing gas using a water-soluble iron ion-dithiocarbamate, xanthate or thioxanthate

    DOEpatents

    Liu, D. Kwok-Keung; Chang, Shih-Ger

    1987-08-25

    The present invention relates to a method of removing of nitrogen monoxide from a nitrogen monoxide-containing gas which method comprises contacting a nitrogen oxide-containing gas with an aqueous solution of water soluble organic compound-iron ion chelate complex. The NO absorption efficiency of ferrous urea-dithiocarbamate and ferrous diethanolamine-xanthate as a function of time, oxygen content and solution ph is presented. 3 figs., 1 tab.

  11. Comparing soluble ferric pyrophosphate to common iron salts and chelates as sources of bioavailable iron in a caco-2 cell culture model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron bioavailability from supplements and fortificants varies depending upon the form of the iron and the presence or absence of iron absorption enhancers and inhibitors. Our objectives were to compare the effects of pH and selected enhancers and inhibitors and food matrices on the bioavailability o...

  12. Radiocarbon-Based Source Apportionment of the Water-Soluble Organic Carbon (wsoc) of Atmospheric Aerosols in South and East Asia

    NASA Astrophysics Data System (ADS)

    Kirillova, E. N.; Sheesley, R. J.; Andersson, A.; Gustafsson, O.; Safai, P. D.; Budhavant, K.; Rao, P. S.; Kang, E.; Han, J.; Lee, M.

    2011-12-01

    The air quality and regional climate in South and East Asia are considerably affected by atmospheric aerosols produced by anthropogenic activities. Recent studies have investigated the sources of the black carbon aerosol component in these regions. This study seeks to make progress in apportioning the sources of the water soluble organic carbon (WSOC) component, which makes up 20-65% of the carbonaceous aerosol mass in these areas. WSOC is important as it enhances the ability of particles to serve as cloud condensation nuclei (CCN) and, therefore, has an impact on regional climate and radiative forcing. Atmospheric particulate matter was collected during fifteen-month continuous sampling campaigns Jan 2008 - March 2009 at both the Maldives Climate Observatory at Hannimaadho (MCOH) and at the Sinhagad hilltop sampling site of the Indian Institute of Tropical Meteorology (SIN) in central-western India. The radiocarbon method is an ideal approach to identify fossil sources (14C "dead") compared to biogenic and biomass combustion products (with a contemporary 14C signal). WSOC is a large fraction of organic aerosols and its annual average contribution to TOC during 2008 is 26% at MCOH and 40% at SIN. There is a distinct seasonal variability in WSOC concentrations at both sites with high concentrations during the winter season (0.92±0.49μg m-3 at MCOH and 3.5±2.0μg m-3 at SIN) and very low concentrations during the summer monsoon season (0.08±0.04μg m-3 at MCOH and 0.27±0.20μg m-3 at SIN). The radiocarbon source apportionment of WSOC in winter dry season was similar at MCOH and SIN with 80-85% from biogenic/biomass combustion and the rest from fossil fuel precursors. For the rest of the year, the biogenic/biomass contribution to WSOC is higher at the Indian Ocean site (86-93%) compared to the Indian site (74-83%). In March 2011 the GoPoEx2011 intensive sampling campaign at the Gosan ABC Superstation, Jeju Island, South Korea was dedicated to study atmospheric

  13. Water-soluble species in the marine aerosol from the northern South China Sea: High chloride depletion related to air pollution

    NASA Astrophysics Data System (ADS)

    Hsu, Shih-Chieh; Liu, Shaw Chen; Kao, Shuh-Ji; Jeng, Woei-Lih; Huang, Yi-Tang; Tseng, Chun-Mao; Tsai, Fujung; Tu, Jien-Yi; Yang, Yih

    2007-10-01

    Dichotomous (PM2.5-10 and PM2.5 modes) and size-resolved marine aerosols collected during the northeastern monsoon on two wintertime cruises in the subtropical South China Sea (SCS) were analyzed for water-soluble ions. During the sampling periods the study region was under the influence of strong pollution originating primarily from the Asian continent. Elevated levels of non-sea-salt sulfate and ammonium ions of up to 4.5 and 1.2 μg/m3, respectively, were observed, indicating that the SCS is now substantially contaminated by massive amounts of air pollutants most likely from China and South/Southeast Asia. The non-sea-salt sulfate to nitrate mass ratios reaching 3.8 ± 1.9 are much larger than those (approximately 2) in and around East Asia and the western Pacific Ocean, suggesting that the Asian outflow aerosols measured in the SCS experienced different traveling history from those in the vicinity of source regions. High chloride depletion (Cl-depletion) measured in the SCS marine aerosols was, on average, 30% for coarse-mode particles and nearly 90% for fine-mode particles. Cl-depletion is size-dependent, and maximizes in submicrometer particles (i.e., Cl has almost been completely lost). Acid displacement is responsible for the observed high Cl-depletion: nitrate substitution accounts for the coarse-mode depletion, whereas sulfate substitution accounts for the fine-mode depletion. The acid displacement of sea salt aerosols may be related to a variety of factors, especially the substantial air pollution, which is discussed in detail in this paper. On cloudy/rainy days, fine-mode aerosol samples have moderate Cl-depletion (i.e., ˜40-50%), in contrast to nearly complete Cl loss on sunny days, presumably indicating that photochemical reactions would play a key role in the Cl-deficit; however, it merits further investigation as the available samples were limited.

  14. Evaporation kinetics of aqueous acetic acid droplets: effects of soluble organic aerosol components on the mechanism of water evaporation.

    PubMed

    Duffey, Kaitlin C; Shih, Orion; Wong, Nolan L; Drisdell, Walter S; Saykally, Richard J; Cohen, Ronald C

    2013-07-28

    The presence of organic surfactants in atmospheric aerosol may lead to a depression of cloud droplet growth and evaporation rates affecting the radiative properties and lifetime of clouds. Both the magnitude and mechanism of this effect, however, remain poorly constrained. We have used Raman thermometry measurements of freely evaporating micro-droplets to determine evaporation coefficients for several concentrations of acetic acid, which is ubiquitous in atmospheric aerosol and has been shown to adsorb strongly to the air-water interface. We find no suppression of the evaporation kinetics over the concentration range studied (1-5 M). The evaporation coefficient determined for 2 M acetic acid is 0.53 ± 0.12, indistinguishable from that of pure water (0.62 ± 0.09).

  15. Surface-Sensitive and Bulk Studies on the Complexation and Photosensitized Degradation of Catechol by Iron(III) as a Model for Multicomponent Aerosol Systems

    NASA Astrophysics Data System (ADS)

    Al-abadleh, H. A.; Tofan-Lazar, J.; Situm, A.; Ruffolo, J.; Slikboer, S.

    2013-12-01

    Surface water plays a crucial role in facilitating or inhibiting surface reactions in atmospheric aerosols. Little is known about the role of surface water in the complexation of organic molecules to transition metals in multicomponent aerosol systems. We will show results from real time diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments for the in situ complexation of catechol to Fe(III) and its photosensitized degradation under dry and humid conditions. Catechol was chosen as a simple model for humic-like substances (HULIS) in aerosols and aged polyaromatic hydrocarbons (PAH). It has also been detected in secondary organic aerosols (SOA) formed from the reaction of hydroxyl radicals with benzene. Given the importance of the iron content in aerosols and its biogeochemistry, our studies were conducted using FeCl3. For comparison, these surface-sensitive studies were complemented with bulk aqueous ATR-FTIR, UV-vis, and HPLC measurements for structural, quantitative and qualitative information about complexes in the bulk, and potential degradation products. The implications of our studies on understanding interfacial and condensed phase chemistry relevant to multicomponent aerosols, water thin islands on buildings, and ocean surfaces containing transition metals will be discussed.

  16. Mass size distributions of water-soluble inorganic and organic ions in size-segregated aerosols over metropolitan Newark in the US east coast

    NASA Astrophysics Data System (ADS)

    Zhao, Yunliang; Gao, Yuan

    2008-06-01

    To characterize the mass size distributions of water-soluble inorganic and organic ions associated with urban particulate matter, a total of 15 sets of size-segregated aerosol samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) in the urban area of Newark in New Jersey from July to December 2006. The mass concentrations of PM1.8 accounted for ∼68% of the mass concentrations of PM10. The mass concentrations of the total water-soluble ions in PM1.8 accounted for 31-81% of the mass concentrations of PM1.8. Sulfate was the dominant ion in fine particles, accounting for 31% of the PM1.8 mass with its dominant mode at 0.32-0.56 μm throughout all the samples. Nitrate size distributions were bi-modal, peaking at 0.32-0.56 and 3.2-5.6 μm, and the shift of the nitrate dominant fraction between fine and coarse modes was affected by temperature. The ratios of nitrate to PM1.8 varied significantly, 0.5-27%. The C2-C4 dicarboxylic acids accounted for 1.9±0.9% of PM1.8 mass, with oxalate being the dominant ion. The size distributions of oxalate exhibited two to four modes with the dominant one at 0.32-0.56 μm. Chloride existed in both coarse and fine modes, suggesting the influence of sea-salt aerosol and anthropogenic emissions. A crucial formation mechanism for the mass size distributions of these ions observed at this location is likely to be a combination of the gas-to-particle conversion and in-cloud/fog processing.

  17. Water-soluble organic compounds in biomass burning aerosols over Amazonia1. Characterization by NMR and GC-MS

    NASA Astrophysics Data System (ADS)

    Graham, Bim; Mayol-Bracero, Olga L.; Guyon, Pascal; Roberts, Gregory C.; Decesari, Stefano; Facchini, M. Cristina; Artaxo, Paulo; Maenhaut, Willy; Köll, Peter; Andreae, Meinrat O.

    2002-09-01

    As part of the European contribution to the Large-Scale Atmosphere-Biosphere Experiment in Amazonia (LBA-EUSTACH), aerosols were sampled at representative pasture and primary rainforest sites in Rondônia, Brazil, during the 1999 ``burning season'' and dry-to-wet season transition (September-October). Water-soluble organic compounds (WSOCs) within the samples were characterized using a combination of 1H Nuclear Magnetic Resonance (NMR) spectroscopy for chemical functional group analysis, and Gas Chromatography-Mass Spectrometry (GC-MS) for identification and quantification of individual low-molecular-weight compounds. The 1H NMR analysis indicates that WSOCs are predominantly aliphatic or oxygenated aliphatic compounds (alcohols, carboxylic acids, etc.), with a minor content of aromatic rings carrying carboxylic and phenolic groups. Levoglucosan (1,6-anhydro-β-D-glucose), a well-known cellulose combustion product, was the most abundant individual compound identified by GC-MS (0.04-6.90 μg m-3), accounting for 1-6% of the total carbon (TC) and 2-8% of the water-soluble organic carbon (WSOC). Other anhydrosugars, produced by hemicellulose breakdown, were detected in much smaller amounts, in addition to series of acids, hydroxyacids, oxoacids, and polyalcohols (altogether 2-5% of TC, 3-6% of WSOC). Most correlated well with organic carbon, black carbon, and potassium, indicating biomass burning to be the major source. A series of sugar alcohols (mannitol, arabitol, erythritol) and sugars (glucose, fructose, mannose, galactose, sucrose, trehalose) were identified as part of the natural background aerosol and are probably derived from airborne microbes and other biogenic material. The bulk of the WSOCs (86-91% WSOC) eluded analysis by GC-MS and may be predominantly high-molecular weight in nature.

  18. Determination of water-soluble vitamins in infant milk and dietary supplement using a liquid chromatography on-line coupled to a corona-charged aerosol detector.

    PubMed

    Márquez-Sillero, Isabel; Cárdenas, Soledad; Valcárcel, Miguel

    2013-10-25

    A simple and rapid method for the simultaneous determination of seven water-soluble vitamins (thiamine, folic acid, nicotinic acid, ascorbic acid, pantothenic acid, pyridoxine and biotin) was developed by high performance liquid chromatographic separation and corona-charged aerosol detection. The water-soluble vitamins were separated on a Lichrosorb RP-C18 column under isocratic conditions with a mobile phase consisting of 0.05 M ammonium acetate:methanol 90:10 (v/v) at the flow rate 0.5 mL min(-1). The vitamins were extracted from the infant milk (liquid and powder format) using a precipitation step with 2.5 M acetic acid remaining the analyte in the supernatant. As far as dietary supplements are concerned, only a dilution with distilled water was required. The detection limits ranged from 0.17 to 0.62 mg L(-1) for dietary supplements and 1.7 to 6.5 mg L(-1) for milk samples. The precision of the method was evaluated in terms of relative standard deviation (%, RSD) under repeatability and reproducibility conditions, being the average values for each parameter 2.6 and 2.7 for dietary supplements and 4.3 and 4.6 for milk samples. The optimized method was applied to different infant milk samples and dietary supplements. The results of the analysis were in good agreement with the declared values.

  19. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K.; Kelly, T.; Hanft, E.; Mishoe, K.; Rogers, C.; Proost, R.; Lear, G.; Frelink, T.; Walker, J. T.

    2011-12-01

    Ambient air monitoring as part of the U.S. EPA's Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The U.S. EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to examine ecosystem exposure to nitrogen and sulfur compounds at higher time resolution and with greater accuracy than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at hourly temporal resolution. The performance of the MARGA was assessed under the U.S. EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, NC from September 8th-October 8th, 2010. Precision of the MARGA was evaluated by comparing duplicate units and accuracy was evaluated by comparing duplicate MARGAs to duplicate reference denuder/filter packs. The MARGA utilizes a Wet Rotating Denuder (WRD) to collect gases, while aerosols are collected by a Steam Jet Aerosol Collector (SJAC). Both the WRD and the SJAC produce aqueous sample streams, which are analyzed by online ion chromatography for anions and cations. The reference denuder/filter pack consisted of sodium carbonate (Na2CO3) and phosphorous acid (H3PO3) coated denuders followed by a Teflon filter, a nylon filter, and a citric acid coated cellulose filter. The assessment of the MARGA units focused on gaseous SO2, HNO3 and NH3 and aerosol SO4-, NO3- and NH4+. To evaluate accuracy, hourly MARGA concentrations were averaged over 12 hours to match with 12-hour integrated concentrations from the reference system. The concentrations were compared using linear regression with performance goals of slope between 0.8-1.2 and y-intercept between -10 ppb and 10 ppb. Accuracy was further quantified as the median absolute relative percent difference (MARPD) between 12-hour MARGA and reference concentrations, with a performance goal of ≤ 40%. The precision of

  20. Milk peptides increase iron solubility in water but do not affect DMT-1 expression in Caco-2 cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In vitro digestion of milk produces peptide fractions that enhance iron uptake by Caco-2 cells. Our objectives were to investigate whether these fractions a) exert their effect by increasing relative gene expression of DMT-1 in Caco-2 cells b) enhance iron dialyzability when added in meals. Peptid...

  1. Method of removing nitrogen monoxide from a nitrogen monoxide-containing gas using a water-soluble iron ion-dithiocarbamate, xanthate or thioxanthate

    DOEpatents

    Liu, David K.; Chang, Shih-Ger

    1989-01-01

    A method of removing nitrogen monoxide from a nitrogen monoxide-containing gas, which method comprises: (a) contacting a nitrogen oxide-containing gas with an aqueous solution of water soluble organic compound-iron ion chelate of the formula: ##STR1## wherein the water-soluble organic compound is selected from compounds of the formula: ##STR2## wherein: R is selected from hydrogen or an organic moiety having at least one polar functional group; Z is selected from oxygen, sulfur, or --N--A wherein N is nitrogen and A is hydrogen or lower alkyl having from one to four carbon atoms; and M is selected from hydrogen, sodium or potassium; and n is 1 or 2, in a contacting zone for a time and at a temperature effective to reduce the nitrogen monoxide. These mixtures are useful to provide an unexpensive method of removing NO from gases, thus reducing atmospheric pollution from flue gases.

  2. Phosphate inhibits in vitro Fe3+ loading into transferrin by forming a soluble Fe(III)-phosphate complex: a potential non-transferrin bound iron species.

    PubMed

    Hilton, Robert J; Seare, Matthew C; Andros, N David; Kenealey, Zachary; Orozco, Catalina Matias; Webb, Michael; Watt, Richard K

    2012-05-01

    In chronic kidney diseases, NTBI can occur even when total iron levels in serum are low and transferrin is not saturated. We postulated that elevated serum phosphate concentrations, present in CKD patients, might disrupt Fe(3+) loading into apo-transferrin by forming Fe(III)-phosphate species. We report that phosphate competes with apo-transferrin for Fe(3+) by forming a soluble Fe(III)-phosphate complex. Once formed, the Fe(III)-phosphate complex is not a substrate for donating Fe(3+) to apo-transferrin. Phosphate (1-10mM) does not chelate Fe(III) from diferric transferrin under the conditions examined. Complexed forms of Fe(3+), such as iron nitrilotriacetic acid (Fe(3+)-NTA), and Fe(III)-citrate are not susceptible to this phosphate complexation reaction and efficiently deliver Fe(3+) to apo-transferrin in the presence of phosphate. This reaction suggests that citrate might play an important role in protecting against Fe(III), phosphate interactions in vivo. In contrast to the reactions of Fe(3+) and phosphate, the addition of Fe(2+) to a solution of apo-transferrin and phosphate lead to rapid oxidation and deposition of Fe(3+) into apo-transferrin. These in vitro data suggest that, in principle, elevated phosphate concentrations can influence the ability of apo-transferrin to bind iron, depending on the oxidation state of the iron.

  3. Characterization of water-soluble species of PM10 and PM2.5 aerosols in urban area in Nanjing, China

    NASA Astrophysics Data System (ADS)

    Wang, Gehui; Huang, Liming; Gao, Shixiang; Gao, Songting; Wang, Liansheng

    The characterization for water-soluble species of PM10 (particle matter with aerodynamical diameter <10 μm) and PM2.5 (particle matter with aerodynamical diameter <2.5 μm) in five sites of Nanjing, China was carried out during February-May 2001.The pH and conductivity K of water-soluble matters of PM10 and PM2.5 were determined, and the water-soluble fraction of the sample was followed to identify the total carbon (TC), total organic carbon (TOC), inorganic carbon (IC), elements, NO 3-, SO 42- and NH 3-N.The experimental results show that water-soluble matters of PM10 and PM2.5 in Nanjing are acidic, and the pH of PM2.5 is lower than PM10. Conductivity of water-soluble species of PM10 and PM2.5 aerosols varied over a wide range from 1087 to 225 μs/cm. Conductivity between PM10 and PM2.5 has a linear correlationship, and the equation is Y=0.8459 X+44.74, r2=0.9376 ( Y: conductivity of PM2.5, X: conductivity of PM10). TOC make up the majority of TC and accounts for 3.17-14.13% of PM10 and/or PM2.5 loadings, while IC only accounts for 0.12-0.47% of PM10 and/or PM2.5 mass. Al, As, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Ti, V and Zn, 17 elements were detected in water-soluble matters of PM10 and/or PM2.5. Ca, K and Na are the most abundant chemical components, which account for more than 95% of total water-soluble elements (TWSE). Of all the five sites, TWSE accounts for 1.80-6.13% of the particle mass and 61.28-72.73% of TWSE of PM10 is enriched in fine particles (<2.5 μm in diameter). Nitrate (NO 3-), sulfate (SO 42-), ammonia and ammonium (NH 3-N) were determined. The highest level of nitrate was 15.49 μg/m 3 for PM10 and 12.66 μg/m 3 for PM2.5 at site FZ. As was the case for nitrate, the highest level of sulfate was also presented at the same site, which was 28.22 μg/m 3 for PM10 and 21.48 μg/m 3 for PM2.5. However, a higher level of ammonia and ammonium was presented at site ZS, which was 36.05 μg/m 3 for PM10 and 22.06 μg/m 3 for PM2.5.

  4. Water-soluble ions in atmospheric aerosols measured in five sites in the Yangtze River Delta, China: Size-fractionated, seasonal variations and sources

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; Xu, Honghui; An, Junlin; Xue, Guoqiang; Cao, Jinfei

    2015-12-01

    In order to investigate the regional variations of water-soluble ions (WSIs), size-resolved measurement of aerosol particles and WSIs was conducted by using Anderson Sampler and Ion Chromatography at five sites (Nanjing, Suzhou, Lin'an, Hangzhou and Ningbo) in the Yangtze River Delta (YRD) region, China in the Autumn of 2012 and Winter, Spring and Summer of 2013. WSIs exhibited obvious seasonal variations due to the monsoon conversion, with the highest level in winter and lowest level in summer. The aerosol mass concentrations and WSIs in different size segments varied with four seasons. The dominant ions concentrations in PM2.1 ranked in the order of SO42- > NO3- > NH4+ > Cl- > K+ > Ca2+, and the dominant ions concentrations in PM2.1-10 ranked in the order of Ca2+ > NO3- > SO42- > Cl- > NH4+ > Na+. The size spectra of mass and WSIs concentration peaked mostly at 0.43-0.65 μm in four seasons. The concentration discrepancies of WSIs in different cities were caused by the geographic locations and emission source. It's belonged to ammonium-rich distribution in PM2.1 and ammonium-poor distribution in PM2.1-10 in the YRD region. The impact of temperature on mass concentrations of NO3- and NH4+ in PM2.1 were stronger than those in PM2.1-10. PCA analysis shows that the sources of WSIs dominant by anthropogenic sources, soil particles or falling dust, sea salt and burning process.

  5. The composition and flux of water-soluble organic nitrogen and carbon in the marine aerosol of a remote island over the southern East China Sea

    NASA Astrophysics Data System (ADS)

    Chen, H.; Wang, B.; Wang, W.

    2012-12-01

    We analyzed 194 aerosol samples, collected coarse and fine particles by using a dichotomous sampler from September 2009 to September 2010 at a remote island (Pengchiayu) on the southern East China Sea, for water-soluble major ions, inorganic nitrogen, and high/low organic nitrogen and carbon. To investigate the possible sources of WSON and WSOC, an Ultrafiltration method was used to separate WSON and WSOC into high (HMW; >1kDa) and low (LMW; <1kDa) molecular weight categories. In addition, 4-d back trajectories of air masses arriving daily at the sampling site were calculated to determine the potential aerosol source regions. In this study, the sources of WSON and WSOC were identified by indicator ions (Na+, nss-SO42-, nss-K+ and nss-Ca2+), and the fluxes of nitrogen and carbon were calculated by a dual mode model. The obtained concentrations of major ions indicate that a continental source was dominant from January to May and from November to December, a local source derived from Taiwan Island from June and July, and an oceanic source during August. The measured atmospheric concentrations of nitrogen and carbon species show clear seasonal variations and correspond to the different sources and weather conditions. The results indicate that HMW/ LMW of organic nitrogen and carbon contributed 63%/37% and 29%/71%, respectively, to the total dissolved organic species concentration. The results of a factor analysis of combined major ions and organic nitrogen and carbon indicate that biomass burning, crustal sources, and marine sources are the three major controlling factors. The annual fluxes of HMW/ LMW organic nitrogen and carbon were estimated to be 7.61/12.0 and 29.6/12.7 mmol m-2 yr-1, respectively.

  6. Kinetics of soluble chromium removal from contaminated water by zerovalent iron media: corrosion inhibition and passive oxide effects.

    PubMed

    Melitas, N; Chuffe-Moscoso, O; Farrell, J

    2001-10-01

    Permeable reactive barriers containing zerovalent iron are being increasingly employed for in situ remediation of groundwater contaminated with redox active metals and chlorinated organic compounds. This research investigated the effect of chromate concentration on its removal from solution by zerovalent iron. Removal rates of aqueous Cr(VI) by iron wires were measured in batch experiments for initial chromium concentrations ranging from 100 to 10 000 microg/L. Chromate removal was also measured in columns packed with zerovalent iron filings over this same concentration range. Electrochemical measurements were made to determine the free corrosion potential and corrosion rate of the iron reactants. In both the batch and column reactors, absolute rates of chromium removal declined with increasing chromate concentration. Corrosion current measurements indicated that the rate of iron corrosion decreased with increasing Cr(VI) concentrations between 0 and 5000 microg/L. At a Cr(VI) concentration of 10 000 microg/L, Tafel polarization diagrams showed that chromium removal was affected by its diffusion rate through a passivating oxide film and by the ability of iron to release Fe2+ at anodic sites. In contrast, water reduction was not mass transfer limited, but chromium did decrease the exchange current for the hydrogen evolution reaction. Even at the most passivating concentration of 10 000 microng/L, effluent Cr(VI) concentrations in the column reactors reached a steady state, indicating that passivation had also reached a steady state. Although chromate contributes to iron surface passivation, the removal rates are still sufficiently fast for in situ iron barriers to be effective for Cr(VI) removal at most environmentally relevant concentrations.

  7. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K. A.; Walker, J. T.; Kelly, T. J.; Hanft, E. A.; Mishoe, K.; Rogers, C.; Proost, R.; Beachley, G. M.; Lear, G.; Frelink, T.; Otjes, R. P.

    2013-09-01

    Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina from 8 September-8 October 2010 and focused on gaseous SO2, HNO3 and NH3 and aerosol SO4-, NO3- and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of <25%. The accuracy of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42- and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for

  8. An assessment of the performance of the Monitor for AeRosols and GAses in ambient air (MARGA): a semi-continuous method for soluble compounds

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Cowen, K. A.; Walker, J. T.; Kelly, T. J.; Hanft, E. A.; Mishoe, K.; Rogers, C.; Proost, R.; Beachley, G. M.; Lear, G.; Frelink, T.; Otjes, R. P.

    2014-06-01

    Ambient air monitoring as part of the US Environmental Protection Agency's (US EPA's) Clean Air Status and Trends Network (CASTNet) currently uses filter packs to measure weekly integrated concentrations. The US EPA is interested in supplementing CASTNet with semi-continuous monitoring systems at select sites to characterize atmospheric chemistry and deposition of nitrogen and sulfur compounds at higher time resolution than the filter pack. The Monitor for AeRosols and GAses in ambient air (MARGA) measures water-soluble gases and aerosols at an hourly temporal resolution. The performance of the MARGA was assessed under the US EPA Environmental Technology Verification (ETV) program. The assessment was conducted in Research Triangle Park, North Carolina, from 8 September to 8 October 2010 and focused on gaseous SO2, HNO3, and NH3 and aerosol SO42-, NO3-, and NH4+. Precision of the MARGA was evaluated by calculating the median absolute relative percent difference (MARPD) between paired hourly results from duplicate MARGA units (MUs), with a performance goal of ≤ 25%. The accuracy of the MARGA was evaluated by calculating the MARPD for each MU relative to the average of the duplicate denuder/filter pack concentrations, with a performance goal of ≤ 40%. Accuracy was also evaluated by using linear regression, where MU concentrations were plotted against the average of the duplicate denuder/filter pack concentrations. From this, a linear least squares line of best fit was applied. The goal was for the slope of the line of best fit to be between 0.8 and 1.2. The MARGA performed well in comparison to the denuder/filter pack for SO2, SO42-, and NH4+, with all three compounds passing the accuracy and precision goals by a significant margin. The performance of the MARGA in measuring NO3- could not be evaluated due to the different sampling efficiency of coarse NO3- by the MUs and the filter pack. Estimates of "fine" NO3- were calculated for the MUs and the filter pack

  9. Cellular Dose of Partly Soluble Cu Particle Aerosols at the Air–Liquid Interface Using an In Vitro Lung Cell Exposure System

    PubMed Central

    Cronholm, Pontus; Karlsson, Hanna L.; Midander, Klara; Odnevall Wallinder, Inger; Möller, Lennart

    2013-01-01

    Abstract Background There is currently a need to develop and test in vitro systems for predicting the toxicity of nanoparticles. One challenge is to determine the actual cellular dose of nanoparticles after exposure. Methods In this study, human epithelial lung cells (A549) were exposed to airborne Cu particles at the air–liquid interface (ALI). The cellular dose was determined for two different particle sizes at different deposition conditions, including constant and pulsed Cu aerosol flow. Results Airborne polydisperse particles with a geometric mean diameter (GMD) of 180 nm [geometric standard deviation (GSD) 1.5, concentration 105 particles/mL] deposited at the ALI yielded a cellular dose of 0.4–2.6 μg/cm2 at pulsed flow and 1.6–7.6 μg/cm2 at constant flow. Smaller polydisperse particles in the nanoregime (GMD 80 nm, GSD 1.5, concentration 107 particles/mL) resulted in a lower cellular dose of 0.01–0.05 μg/cm2 at pulsed flow, whereas no deposition was observed at constant flow. Exposure experiments with and without cells showed that the Cu particles were partly dissolved upon deposition on cells and in contact with medium. Conclusions Different cellular doses were obtained for the different Cu particle sizes (generated with different methods). Furthermore, the cellular doses were affected by the flow conditions in the cell exposure system and the solubility of Cu. The cellular doses of Cu presented here are the amount of Cu that remained on the cells after completion of an experiment. As Cu particles were partly dissolved, Cu (a nonnegligible contribution) was, in addition, present and analyzed in the nourishing medium present beneath the cells. This study presents cellular doses induced by Cu particles and demonstrates difficulties with deposition of nanoparticles at the ALI and of partially soluble particles. PMID:22889118

  10. One-pot synthesis of water-soluble superparamagnetic iron oxide nanoparticles and their MRI contrast effects in the mouse brains.

    PubMed

    Wang, Jun; Zhang, Baolin; Wang, Lei; Wang, Ming; Gao, Fabao

    2015-03-01

    Water-soluble superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by the thermal decomposition of iron (III) acetylacetonate (Fe(acac)3) in the mixture of poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI). The average sizes of the SPIONs are in the range of 6-12nm, which could be tuned by adjusting the synthesis temperature and molecular weight of PEI. Benefiting from the coating of hydrophilic PEG and PEI, the resulted SPIONs showed excellent colloidal stability in deionized water and other physiological buffers. The XRD patterns indicate that the obtained SPIONs are magnetite. The PEG/PEI-SPIONs exhibited high r2/r1 ratio. In vivo magnetic resonance imaging (MRI) of the mouse brains after intravenous injection of the SPIONs showed their good contrast effect. Considering the facile fabrication process and excellent imaging performance of the water soluble PEG-SPIONs and PEG/PEI-SPIONs, it is believed that the SPIONs will find great potential in advanced MRI.

  11. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    NASA Astrophysics Data System (ADS)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  12. Major 20th century changes of water-soluble humic-like substances (HULISWS) aerosol over Europe inferred from Alpine ice cores

    NASA Astrophysics Data System (ADS)

    Guilhermet, J.; Preunkert, S.; Voisin, D.; Baduel, C.; Legrand, M.

    2013-05-01

    Using a newly developed method dedicated to measurements of water-soluble humic-like substances (HULISWS) in atmospheric aerosol samples, the carbon mass quantification of HULISWS in an Alpine ice core is achieved for the first time. The method is based on the extraction of HULISWS with a weak anion-exchanger resin and the subsequent quantification of the extracted carbon fraction with a total organic carbon (TOC) analyzer. Measurements were performed along a Col du Dôme (4250 m above sea level, French Alps) ice core covering the 1920-2004 time period. The HULISWS concentrations exhibit a well-marked seasonal cycle with winter minima close to 7 ppbC and summer maxima ranging between 10 and 50 ppbC. Whereas the winter HULISWS concentrations remained unchanged over the twentieth century, the summer concentrations increased from 20 ppbC prior to the Second World War to 35 ppbC in the 1970-1990s. These different trends reflect the different types of HULISWS sources in winter and summer. HULISWS are mainly primarily emitted by domestic wood burning in winter and secondary in summer being produced from biogenic precursors. For unknown reason, the HULISWS signal is found to be unusual in ice samples corresponding to World War II.

  13. KINETICS OF SOLUBLE CHROMIUM REMOVAL FROM CONTAMINATED WATER BY ZEROVALENT IRON MEDIA: CORROSION INHIBITION AND PASSIVE OXIDE EFFECTS. (R825223)

    EPA Science Inventory

    Permeable reactive barriers containing zerovalent iron are being increasingly
    employed for in situ remediation of groundwater contaminated with redox active
    metals and chlorinated organic compounds. This research investigated the effect
    of chromate concentration on...

  14. High abundances of water-soluble dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the mountaintop aerosols over the North China Plain during wheat burning season

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Okuzawa, K.; Aggarwal, S. G.; Kanaya, Y.; Wang, Z. F.

    2013-08-01

    Aerosol (TSP) samples were collected at the summit of Mount Tai (elevation: 1534 m a.s.l., 36.25° N, 117.10° E) located in the North China Plain using a high-volume air sampler and pre-combusted quartz filters. Sampling was conducted on day/night or 3 h basis in the period from 29 May to 28 June 2006 during the field burning of wheat straw residue and the post-burning season. The filter samples were analyzed for low-molecular-weight dicarboxylic acids, ketoacids and α-dicarbonyls using capillary gas chromatography (GC) and GC-MS employing water extraction and butyl ester derivatization. Molecular distributions of dicarboxylic acids (C2-C11, 220-6070 ng m-3) were characterized by a predominance of oxalic (C2) acid (105-3920 ng m-3) followed by succinic (C4) or malonic (C3) acid. Unsaturated aliphatic diacids, including maleic (M), isomaleic (iM) and fumaric (F) acids, were also detected together with aromatic diacids (phthalic, isophthalic and terephthalic acids). ω-oxocarboxylic acids (C2-C9, 24-610 ng m-3) were detected as the second most abundant compound class with the predominance of glyoxylic acid (11-360 ng m-3), followed by α-ketoacid (pyruvic acid, 3-140 ng m-3) and α-dicarbonyls (glyoxal, 1-230 ng m-3 and methylglyoxal, 2-120 ng m-3). We found that these levels (>6000 ng m-3 for diacids) are several times higher than those reported in Chinese megacities at ground levels. The concentrations of diacids increased from late May to early June, showing a maximum on 7 June, and then significantly decreased during the period 8-11 June, when the wind direction shifted from southerly to northerly. Similar temporal trends were found for ketocarboxylic acids and α-dicarbonyls as well as total carbon (TC) and water-soluble organic carbon (WSOC). The temporal variations of water-soluble organics were interpreted by the direct emission from the field burning of agricultural wastes (wheat straw) in the North China Plain and the subsequent photochemical oxidation of

  15. High abundances of water-soluble dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the mountain aerosols over the North China Plain during wheat burning season

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Okuzawa, K.; Aggarwal, S. G.; Kanaya, Y.; Wang, Z. F.

    2013-02-01

    Aerosol (TSP) samples were collected at the summit of Mount Tai (elevation: 1534 m a.s.l., 36.25° N; 117.10° E) located in the North China Plain using a high-volume air sampler and pre-combusted quartz filters. Sampling was conducted on day/night or 3 h basis in the period from 29 May to 28 June 2006 during the field burning of wheat straw residue and the post-burning season. The filter samples were analyzed for low molecular weight dicarboxylic acids, ketoacids and α-dicarbonyls using capillary gas chromatography (GC) and GC-MS employing water extraction and butyl ester derivatization. Dicarboxylic acids (C2-C11, 220-6070 ng m-3) were characterized by a predominance of oxalic (C2) acid (105-3920 ng m-3) followed by succinic (C4) or malonic (C3) acid. Unsaturated aliphatic diacids, including maleic (M), isomaleic (iM) and fumaric (F) acid, were also detected together with aromatic diacids (phthalic, iso-phthalic and tere-phthalic acids). ω-Oxocarboxylic acids (C2-C9, 24-610 ng m-3) were detected as the second most abundant compound class with the predominance of glyoxylic acid (11-360 ng m-3), followed by α-ketoacid (pyruvic acid, 3-140 ng m-3) and α-dicarbonyls (glyoxal, 1-230 ng m-3 and methylglyoxal, 2-120 ng m-3). We found that these levels (> 6000 ng m-3 for diacids) are several times higher than those reported in Chinese megacities at ground levels. The concentrations of diacids increased from late May to early June showing a maximum on 7 June and then significantly decreased during 8-11 June when the wind direction shifted from northeasterly to northerly. Similar temporal trends were found for ketocarboxylic acids and α-dicarbonyls as well as total carbon (TC) and water-soluble organic carbon (WSOC). The temporal variations of water-soluble organics were interpreted by the direct emission from the field burning products of agricultural wastes (wheat straw) in the North China Plain and the subsequent photochemical oxidation of volatile and semi

  16. Controls on iron distributions in the deep water column of the North Pacific Ocean: Iron(III) hydroxide solubility and marine humic-type dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Kitayama, Saori; Kuma, Kenshi; Manabe, Eri; Sugie, Koji; Takata, Hyoe; Isoda, Yutaka; Toya, Kenji; Saitoh, Sei-Ichi; Takagi, Shohgo; Kamei, Yoshihiko; Sakaoka, Keiichiro

    2009-08-01

    Dissolved Fe in the western and central North Pacific Ocean was characterized by surface depletion, middepth maxima and, below that, a slight decrease with depth similar to the vertical distributions of nutrients, apparent oxygen utilization, Fe(III) hydroxide solubility, and humic-type fluorescence (H-flu) intensity. Dissolved Fe concentrations ([D-Fe], <0.22-μm fraction) in the deep water column were one-half lower in the central region (0.3-0.6 nM) than the western region (0.5-1.2 nM) although the Fe(III) solubility ([Fe(III)sol], <0.025-μm fraction) levels and distributions in deep waters were almost the same between both regions with middepth maxima (˜0.6 nM) at 500-1500-m depth range and then a gradual decrease to ˜0.3 nM at 5000-m depth. Higher [D-Fe] than [Fe(III)sol] in the deep water column of the western region results from the higher production of dissolved Fe from the decomposition of sinking particulate organic matter in the western region than the central region because of the high atmospheric and/or lateral Fe inputs in the western region. Similarity between [D-Fe] level and [Fe(III)sol] value at each deep water depth in the central region may be attributed to [D-Fe] being nearly in the solubility equilibrium with Fe(III) hydroxide in seawater. Strong linear correlation between [D-Fe] and H-flu intensity in the central region and relatively similar linear relationships between [Fe(III)sol] and H-flu intensity in the western and central regions are the first confirmation that humic-type fluorescent dissolved organic matter may be responsible for [D-Fe] in the deep water column as natural organic ligands complexing with Fe(III).

  17. Using Soluble Transferrin Receptor and Taking Inflammation into Account When Defining Serum Ferritin Cutoffs Improved the Diagnosis of Iron Deficiency in a Group of Canadian Preschool Inuit Children from Nunavik

    PubMed Central

    Turgeon O'Brien, Huguette; Blanchet, Rosanne; Gagné, Doris; Vézina, Carole

    2016-01-01

    The prevalence of iron depletion, iron deficient erythropoiesis (IDE), and iron deficiency anemia (IDA) was assessed in preschool Inuit children using soluble transferrin receptor (sTfR) and traditional indicators of iron status while disregarding or taking inflammation into account when defining SF cutoffs. Iron depletion was defined as follows: (1) SF < 15 μg/L regardless of the C-reactive protein (CRP) level and (2) SF < 15 or <50 μg/L with CRP ≤ 5 or >5 mg/L, respectively. IDE corresponded to iron depletion combined with total iron binding capacity > 72 μmol/L and/or transferrin saturation < 16%. Iron depletion and IDE affected almost half of the children when accounting for inflammation, compared to one-third when the SF cutoff was defined regardless of CRP level (P < 0.0001). The prevalence of IDE adjusted for inflammation (45.1%) was very similar to the prevalence observed when sTfR was used as a sole marker of IDE (47.4%). The prevalence of anemia was 15%. The prevalence of IDA (IDE + hemoglobin < 110 g/L) was higher when accounting for than when disregarding inflammation (8.0% versus 6.2%, P = 0.083). Using sTfR and different SF cutoffs for children with versus without inflammation improved the diagnosis of iron depletion and IDE. Our results confirm that Inuit children are at particularly high risk for iron deficiency. PMID:27382488

  18. Using Soluble Transferrin Receptor and Taking Inflammation into Account When Defining Serum Ferritin Cutoffs Improved the Diagnosis of Iron Deficiency in a Group of Canadian Preschool Inuit Children from Nunavik.

    PubMed

    Turgeon O'Brien, Huguette; Blanchet, Rosanne; Gagné, Doris; Lauzière, Julie; Vézina, Carole

    2016-01-01

    The prevalence of iron depletion, iron deficient erythropoiesis (IDE), and iron deficiency anemia (IDA) was assessed in preschool Inuit children using soluble transferrin receptor (sTfR) and traditional indicators of iron status while disregarding or taking inflammation into account when defining SF cutoffs. Iron depletion was defined as follows: (1) SF < 15 μg/L regardless of the C-reactive protein (CRP) level and (2) SF < 15 or <50 μg/L with CRP ≤ 5 or >5 mg/L, respectively. IDE corresponded to iron depletion combined with total iron binding capacity > 72 μmol/L and/or transferrin saturation < 16%. Iron depletion and IDE affected almost half of the children when accounting for inflammation, compared to one-third when the SF cutoff was defined regardless of CRP level (P < 0.0001). The prevalence of IDE adjusted for inflammation (45.1%) was very similar to the prevalence observed when sTfR was used as a sole marker of IDE (47.4%). The prevalence of anemia was 15%. The prevalence of IDA (IDE + hemoglobin < 110 g/L) was higher when accounting for than when disregarding inflammation (8.0% versus 6.2%, P = 0.083). Using sTfR and different SF cutoffs for children with versus without inflammation improved the diagnosis of iron depletion and IDE. Our results confirm that Inuit children are at particularly high risk for iron deficiency. PMID:27382488

  19. Determination of Water Soluble Organic Carbon Collected ~1 km above the Earth's Surface during a Mid-Atlantic Air Quality Episode and Comparison to Aerosol Optical Properties

    NASA Astrophysics Data System (ADS)

    Brent, L. C.; He, H.; Arkinson, H. L.; Stehr, J. W.; Ring, A.; Marufu, L.; Reiner, J.; Sander, L. C.; Dickerson, R. R.

    2014-12-01

    Routine, light aircraft air-monitoring conducted in MD provides insight into atmospheric photochemical processing as a function of altitude in the boundary layer and lower free troposphere. We present correlations between the optical properties and chemical composition of aerosols at ~1 km altitude over Maryland. Data were collected during the peak smog day and a dissipation day during an air quality episode studied in DISCOVER-AQ, July 2011. Post flight filter sample analysis shows a positive trend between measurable carboxylate concentrations and particle size with a recirculating, aged, urban air mass influenced with southeasterly marine winds (peak day). A westerly influx of air from the Ohio River Valley on the dissipation day was depleted in carboxylates compared with samples collected over the same location two days prior. These samples contained quantifiable concentrations of cis-pinonic acid, a reaction product of pinene after ozonation and photochemical oxidation. New techniques were developed to improve airborne data collection and analysis of water soluble organic acids (WSOA), a frequently dominant fraction of particulate matter (PM). An ion chromatographic mass spectrometric method was developed using NIST Standard Referencing Material 1649b, Urban Dust, as a surrogate material to achieve separation and resolution of at least 34 organic acids. Analysis of aircraft filter samples resulted in detection of 16 organic acids of which 12 were quantified. Eight inorganic species were also quantified. Aged, re-circulated metropolitan air showed a greater number of dicarboxylic acids than new transport air from the west and may provide a useful test of SOA formation theory.

  20. Chemical characterization of the ambient organic aerosol soluble in water: 1. Isolation of hydrophobic and hydrophilic fractions with a XAD-8 resin

    NASA Astrophysics Data System (ADS)

    Sullivan, Amy P.; Weber, Rodney J.

    2006-03-01

    Group separation of the aqueous extract of fine particles bearing water-soluble organic carbon (WSOC) provides unique insights into the sources of organic carbon (OC). XAD-8 resin coupled with a Total Organic Carbon analyzer allows for direct quantification. We term the fraction of WSOC not retained by a XAD-8 resin column at pH 2 as hydrophilic WSOC (WSOCxp); this includes saccharides, amines, and carbonyls and aliphatic monocarboxylic/dicarboxylic/oxocarboxylic acids with less than 4 or 5 carbons. The fraction of WSOC retained by XAD-8, termed the hydrophobic fraction (WSOCxr), include aromatic acids, phenols, organic nitrates, cyclic acids, and carbonyls and monocarboxylic/dicarboxylic acids with greater than 3 or 4 carbons. However, only aromatic compounds (or aromatic-like compounds with similar properties) can subsequently be extracted from XAD-8 with high efficiency. By coupling a Particle-into-Liquid Sampler with this technique, online measurements of WSOC, WSOCxp, and WSOCxr are possible. Urban measurements from St. Louis and Atlanta, on a carbon mass basis, show an increase in the mean WSOC fraction from winter (51%) to summer (61%), due to increases in the WSOCxp/OC from 0.25 to 0.35. During a summer Atlanta PM event, WSOC to OC was 0.75, driven largely by increases in the WSOCxp. The results are consistent with the view that in the summer, there are increased amounts of oxygenated polar compounds, possibly from secondary organic aerosol production, and that these compounds account for an even larger fraction of OC during stagnation events. A companion paper describes a method to further group speciate these XAD-8 isolated fractions.

  1. Chemical characterization of water-soluble organic carbon aerosols at a rural site in the Pearl River Delta, China, in the summer of 2006

    NASA Astrophysics Data System (ADS)

    Miyazaki, Y.; Kondo, Y.; Shiraiwa, M.; Takegawa, N.; Miyakawa, T.; Han, S.; Kita, K.; Hu, M.; Deng, Z. Q.; Zhao, Y.; Sugimoto, N.; Blake, D. R.; Weber, R. J.

    2009-07-01

    Online measurements of water-soluble organic carbon (WSOC) aerosols were made using a particle-into-liquid sampler (PILS) combined with a total organic carbon (TOC) analyzer at a rural site in the Pearl River Delta region, China, in July 2006. A macroporous nonionic (DAX-8) resin was used to quantify hydrophilic and hydrophobic WSOC, which are defined as the fractions of WSOC that penetrated through and retained on the DAX-8 column, respectively. Laboratory calibrations showed that hydrophilic WSOC (WSOCHPI) included low-molecular aliphatic dicarboxylic acids and carbonyls, saccharides, and amines, while hydrophobic WSOC (WSOCHPO) included longer-chain aliphatic dicarboxylic acids and carbonyls, aromatic acids, phenols, organic nitrates, cyclic acids, and fulvic acids. On average, total WSOC (TWSOC) accounted for 60% of OC, and WSOCHPO accounted for 60% of TWSOC. Both WSOCHPI and WSOCHPO increased with photochemical aging determined from the NOx/NOy ratio. In particular, the average WSOCHPO mass was found to increase by a factor of five within a timescale of ˜10 hours, which was substantially larger than that of WSOCHPI (by a factor of 2-3). The total increase in OC mass with photochemical aging was associated with the large increase in WSOCHPO mass. These results, combined with the laboratory calibrations, suggest that significant amounts of hydrophobic organic compounds (likely containing large carbon numbers) were produced by photochemical processing. By contrast, water-insoluble OC (WIOC) mass did not exhibit significant changes with photochemical aging, suggesting that chemical transformation of WIOC to WSOC was not a dominant process for the production of WSOC during the study period.

  2. Biopharmaceutical characterisation of ciprofloxacin-metallic ion interactions: comparative study into the effect of aluminium, calcium, zinc and iron on drug solubility and dissolution.

    PubMed

    Stojković, Aleksandra; Tajber, Lidia; Paluch, Krzysztof J; Djurić, Zorica; Parojčić, Jelena; Corrigan, Owen I

    2014-03-01

    Ciprofloxacin bioavailability may be reduced when ciprofloxacin is co-administered with metallic ion containing preparations. In our previous study, physicochemical interaction between ciprofloxacin and ferrous sulphate was successfully simulated in vitro. In the present work, comparative in vitro ciprofloxacin solubility and dissolution studies were performed in the reactive media containing aluminium hydroxide, calcium carbonate or zinc sulphate. Solid phases collected from the dissolution vessel with aluminium hydroxide, calcium carbonate and zinc sulphate were investigated for their properties. The results obtained indicate that different types of adducts may form and retard ciprofloxacin solubility and dissolution. In the case of aluminium, no phase changes were observed. The solid phase generated in the presence of calcium carbonate was identified as hydrated ciprofloxacin base. Similarly to iron, a new complex consistent with Zn(SO4)2(Cl)2(ciprofloxacin)2 × nH2O stoichiometry was generated in the presence of relatively high concentrations of ciprofloxacin hydrochloride and zinc sulphate, indicating that small volume dissolution experiments can be useful for biorelevant dissolution tests.

  3. Binding Studies of a New Water-Soluble Iron(III) Schiff Base Complex to DNA Using Multispectroscopic Methods

    PubMed Central

    Shahabadi, Nahid; Ghasemian, Zeinab; Hadidi, Saba

    2012-01-01

    A novel iron(III) complex [Fe(SF)](ClO4)3.2H2O; in which SF = N,N0-bis{5-[(triphenylphosphonium chloride)-methyl] salicylidene}-o-phenylenediamine) has been synthesized and characterized using different physicochemical methods. The binding of this complex with calf thymus (CT) DNA was investigated by circular dichroism, absorption studies, emission spectroscopy, voltammetric studies, and viscosity measurements. The results showed that this complex can bind to DNA via external and groove binding modes. PMID:22899896

  4. Water-Soluble Dinitrosyl Iron Complex (DNIC): a Nitric Oxide Vehicle Triggering Cancer Cell Death via Apoptosis.

    PubMed

    Wu, Shou-Cheng; Lu, Chung-Yen; Chen, Yi-Lin; Lo, Feng-Chun; Wang, Ting-Yin; Chen, Yu-Jen; Yuan, Shyng-Shiou; Liaw, Wen-Feng; Wang, Yun-Ming

    2016-09-19

    Nitric oxide (NO) is an important cellular signaling molecule that modulates various physiological activities. Angiogenesis-promoting activities of NO-donor drugs have been explored in both experimental and clinical studies. In this study, a structurally well characterized and water-soluble neutral {Fe(NO)2}(9) DNIC [(S(CH2)2OH)(S(CH2)2NH3)Fe(NO)2] (DNIC 2) was synthesized to serve as a NO-donor species. The antitumor activity of DNIC 2 was determined by MTT assay, confocal imaging, and Annexin-V/PI staining. The IC50 values of DNIC 2 were 18.8, 42.9, and 38.6 μM for PC-3, SKBR-3, and CRL5866 tumor cells, respectively. Moreover, DNIC 2 promoted apoptotic cell death via activation of apoptosis-associated proteins and inhibition of survival associated proteins. In particular, DNIC 2 treatment suppressed PC-3 tumor growth by 2.34- and 19.3-fold at 7 and 21 days, in comparison with the control group. These results indicate that water-soluble DNIC 2 may serve as a promising drug for cancer therapy.

  5. Concentration characteristics of bromine and iodine in aerosols in Shanghai, China

    NASA Astrophysics Data System (ADS)

    Gao, Yunchuan; Sun, Mingxing; Wu, Xiaowei; Liu, Yongdi; Guo, Yaqi; Wu, Ji

    2010-11-01

    Aerosol samples (TSP and PM 10) during each season were collected at a national monitoring point in Shanghai in 2008. Halogens (Br, I) were determined in samples along with sodium (Na) by ICP-MS and ICP-OES after microwave digestion. In this report we focused on the concentration characteristics of halogen elements Br and I and their seasonal distributions. The mean annual concentrations of total Br and I were 24 ng m -3 and 12 ng m -3 for TSP, 21 ng m -3 and 9 ng m -3 for PM 10, respectively. Concentrations of Br and I in TSP and PM 10 were lowest in summer but an increase occurred in autumn and winter. Water-soluble Br and I accounted for about 32% of the total Br and I in aerosols, and about 68% of Br and I was non soluble which may be non-soluble organic species. These non-soluble organic species are present in aerosols in the possible binding forms as mineral dust, natural organic matter, and adsorption to black carbon or mineral material such as iron oxides. Soluble Br and I in PM 10 extracted by a dilute acid solution (HNO 3 + H 2SO 4) increased by 22% and 18%, respectively, compared with water-soluble Br and I. A positive correlation with Na and sea water enrichment factors for Br and I indicated that bromine and iodine in aerosols originated mostly from marine sources in Shanghai.

  6. Rapid and gradual modes of aerosol trace metal dissolution in seawater

    PubMed Central

    Mackey, Katherine R. M.; Chien, Chia-Te; Post, Anton F.; Saito, Mak A.; Paytan, Adina

    2015-01-01

    Atmospheric deposition is a major source of trace metals in marine surface waters and supplies vital micronutrients to phytoplankton, yet measured aerosol trace metal solubility values are operationally defined, and there are relatively few multi-element studies on aerosol-metal solubility in seawater. Here we measure the solubility of aluminum (Al), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) from natural aerosol samples in seawater over a 7 days period to (1) evaluate the role of extraction time in trace metal dissolution behavior and (2) explore how the individual dissolution patterns could influence biota. Dissolution behavior occurs over a continuum ranging from rapid dissolution, in which the majority of soluble metal dissolved immediately upon seawater exposure (Cd and Co in our samples), to gradual dissolution, where metals dissolved slowly over time (Zn, Mn, Cu, and Al in our samples). Additionally, dissolution affected by interactions with particles was observed in which a decline in soluble metal concentration over time occurred (Fe and Pb in our samples). Natural variability in aerosol chemistry between samples can cause metals to display different dissolution kinetics in different samples, and this was particularly evident for Ni, for which samples showed a broad range of dissolution rates. The elemental molar ratio of metals in the bulk aerosols was 23,189Fe: 22,651Al: 445Mn: 348Zn: 71Cu: 48Ni: 23Pb: 9Co: 1Cd, whereas the seawater soluble molar ratio after 7 days of leaching was 11Fe: 620Al: 205Mn: 240Zn: 20Cu: 14Ni: 9Pb: 2Co: 1Cd. The different kinetics and ratios of aerosol metal dissolution have implications for phytoplankton nutrition, and highlight the need for unified extraction protocols that simulate aerosol metal dissolution in the surface ocean. PMID:25653645

  7. Molecular Characteristics of Aerosol Water Soluble Organic Matter from the 2010 and 2011 US GEOTRACES Cruises in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Wozniak, A. S.; Sleighter, R. L.; Gurganus, S.; McElhenie, S. D.; Hatcher, P. G.

    2013-12-01

    Aerosol particulate samples (n=39) were collected on a transatlantic transect in the North Atlantic Ocean during the 2010 and 2011 US GEOTRACES cruises. Air mass trajectory analyses were used to operationally-define the samples as European-, North African-, North American-, or marine-influenced. Aerosol water soluble organic matter (WSOM) was isolated and analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), and a total of 13,739 unique molecular formulas containing C, H, O, N, S, and P as potential constituents were identified. Principal component analysis (PCA) was performed to facilitate comparisons within this extensive dataset using the assigned molecular formulas (weighted by peak intensity) as input variables. The samples were assigned to five groups based on their principal component scores. Using the the air mass trajectory analyses, the sample groups were classified as 1) marine, 2) marine/N. American, 3) N. American, 4) 2011 N. African, and 5) the 2010 samples. Each PCA-defined sample group showed PCA loadings (molecular formulas) with distinguishing characteristics that are supported by average molecular formula characteristics calculated for the samples in each group. The marine, marine/N. American, and N. American-influenced groups were all characterized as being relatively more aliphatic (higher H/C ratio) and having higher heteroatom (N, S, P) content than the 2011 N. African and 2010 samples. The ';marine' and N. American-influenced samples both showed S containing compounds to be important for their PCA scores with the N. American-influenced samples having CHO and CHOS formulas with a higher O/C content. The high relative O content suggests that these N. American-influenced samples are characterized by a high degree of oxidation and may be linked to high contributions from combustion-derived sulfate and carboxylic acid functional groups. The marine/N. American sample group had the highest contributions from N

  8. Thermodynamic data for modeling acid mine drainage problems: compilation and estimation of data for selected soluble iron-sulfate minerals

    USGS Publications Warehouse

    Hemingway, Bruch S.; Seal, Robert R., II; Chou, I-Ming

    2002-01-01

    Enthalpy of formation, Gibbs energy of formation, and entropy values have been compiled from the literature for the hydrated ferrous sulfate minerals melanterite, rozenite, and szomolnokite, and a variety of other hydrated sulfate compounds. On the basis of this compilation, it appears that there is no evidence for an excess enthalpy of mixing for sulfate-H2O systems, except for the first H2O molecule of crystallization. The enthalpy and Gibbs energy of formation of each H2O molecule of crystallization, except the first, in the iron(II) sulfate - H2O system is -295.15 and -238.0 kJ?mol-1, respectively. The absence of an excess enthalpy of mixing is used as the basis for estimating thermodynamic values for a variety of ferrous, ferric, and mixed-valence sulfate salts of relevance to acid-mine drainage systems.

  9. Enhanced removal of soluble Cr(VI) by using zero-valent iron composite supported by surfactant-modified zeolites.

    PubMed

    Dang, Hongyu; Zhang, Yongxiang; Du, Peiwen

    2014-01-01

    Zero-valent iron (ZVI) was immobilized onto surfactant-modified zeolites (SMZ) using calcium alginate. Scanning electron microscopy showed that ZVI powder was uniformly immobilized on the surface of the SMZ. The added ZVI powder resulted in enhanced dichromate removal efficiency and the heterogeneous surface of the composite. The adsorption of dichromate onto the ZVI-SMZ composites fitted well to a pseudo-second-order model and the Langmuir adsorption isotherm. The maximum dichromate adsorption capacity of the composite was 2.49 mg/g at the temperature of 293 K. Higher removal efficiency was obtained at pH lower than 7. X-ray photoelectron spectrometry revealed that the composites combined the strong reductive quality of ZVI and superior adsorption of SMZ. PMID:25353946

  10. At the frontier between heterogeneous and homogeneous catalysis: hydrogenation of olefins and alkynes with soluble iron nanoparticles.

    PubMed

    Rangheard, Claudine; de Julián Fernández, César; Phua, Pim-Huat; Hoorn, Johan; Lefort, Laurent; de Vries, Johannes G

    2010-09-28

    The use of non-supported Fe nanoparticles in the hydrogenation of unsaturated C-C bonds is a green catalytic concept at the frontier between homogeneous and heterogeneous catalysis. Iron nanoparticles can be obtained by reducing Fe salts with strong reductants in various solvents. FeCl(3) reduced by 3 equivalents of EtMgCl forms an active catalyst for the hydrogenation of a range of olefins and alkynes. Olefin hydrogenation is relatively fast at 5 bar using 5 mol% of catalyst. The catalyst is also active for terminal olefins and 1,1' and 1,2-cis disubstituted olefins while trans-olefins react much slower. 1-Octyne is hydrogenated to mixtures of 1-octene and octane. Kinetic studies led us to propose a mechanism for this latter transformation where octane is obtained by two different pathways. Characterization of the nanoparticles via TEM, magnetic measurements and poisoning experiments were undertaken to understand the true nature of our catalyst.

  11. Polynuclear water-soluble dinitrosyl iron complexes with cysteine or glutathione ligands: electron paramagnetic resonance and optical studies.

    PubMed

    Vanin, Anatoly F; Poltorakov, Alexander P; Mikoyan, Vasak D; Kubrina, Lyudmila N; Burbaev, Dosymzhan S

    2010-09-15

    Electron paramagnetic resonance and optical spectrophotometric studies have demonstrated that low-molecular dinitrosyl iron complexes (DNICs) with cysteine or glutathione exist in aqueous solutions in the form of paramagnetic mononuclear (capital EM, Cyrillic-DNICs) and diamagnetic binuclear complexes (B-DNICs). The latter represent Roussin's red salt esters and can be prepared by treatment of aqueous solutions of Fe(2+) and thiols (small er, Cyrilliccapital EN, Cyrillic 7.4) with gaseous nitric oxide (NO) at the thiol:Fe(2+) ratio 1:1. capital EM, Cyrillic-DNICs are synthesized under identical conditions at the thiol:Fe(2+) ratios above 20 and produce an EPR signal with an electronic configuration {Fe(NO)(2)}(7) at g(aver.)=2.03. At neutral pH, aqueous solutions contain both M-DNICs and B-DNICs (the content of the latter makes up to 50% of the total DNIC pool). The concentration of B-DNICs decreases with a rise in pH; at small er, Cyrilliccapital EN, Cyrillic 9-10, the solutions contain predominantly M-DNICs. The addition of thiol excess to aqueous solutions of B-DNICs synthesized at the thiol:Fe(2+) ratio 1:2 results in their conversion into capital EM, Cyrillic-DNICs, the total amount of iron incorporated into M-DNICs not exceeding 50% of the total iron pool in B-DNICs. Air bubbling of cys-capital EM, Cyrillic-DNIC solutions results in cysteine oxidation-controlled conversion of capital EM, Cyrillic-DNICs first into cys-B-DNICs and then into the EPR-silent compound capital HA, Cyrillic able to generate a strong absorption band at 278 nm. In the presence of glutathione or cysteine excess, compound capital HA, Cyrillic is converted into B-DNIC/M-DNIC and is completely decomposed under effect of the Fe(2+) chelator small o, Cyrillic-phenanthroline or N-methyl-d-glucamine dithiocarbamate (MGD). Moreover, MGD initiates the synthesis of paramagnetic mononitrosyl iron complexes with MGD. It is hypothesized that compound capital HA, Cyrillic represents a polynuclear

  12. Spatial and seasonal variations of fine particle water-soluble organic carbon (WSOC) over the southeastern United States: implications for secondary organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Liu, Z.; Hecobian, A.; Zheng, M.; Frank, N. H.; Edgerton, E. S.; Weber, R. J.

    2012-07-01

    Secondary organic aerosol (SOA) in the southeastern US is investigated by analyzing the spatial-temporal distribution of water-soluble organic carbon (WSOC) and other PM2.5 components from 900 archived 24-h Teflon filters collected at 15 urban or rural EPA Federal Reference Method (FRM) network sites throughout 2007. Online measurements of WSOC at an urban/rural-paired site in Georgia in the summer of 2008 are contrasted to the filter data. Based on FRM filters, excluding biomass-burning events (levoglucosan < 50 ng m-3), WSOC and sulfate were highly correlated with PM2.5 mass (r2~0.7). Both components comprised a large mass fraction of PM2.5 (13% and 31%, respectively, or ~25% and 50% for WSOM and ammonium sulfate). Sulfate and WSOC both tracked ambient temperature throughout the year, suggesting the temperature effects were mainly linked to faster photochemistry and/or synoptic meteorology and less due to enhanced biogenic hydrocarbon emissions. FRM WSOC, and to a lesser extent sulfate, were spatially homogeneous throughout the region, yet WSOC was moderately enhanced (27%) in locations of greater predicted isoprene emissions in summer. A Positive Matrix Factorization (PMF) analysis identified two major source types for the summer WSOC; 22% of the WSOC were associated with ammonium sulfate, and 56% of the WSOC were associated with brown carbon and oxalate. A small urban excess of FRM WSOC (10%) was observed in the summer of 2007, however, comparisons of online WSOC measurements at one urban/rural pair (Atlanta/Yorkville) in August 2008 showed substantially greater difference in WSOC (31%) relative to the FRM data, suggesting a low bias for urban filters. The measured Atlanta urban excess, combined with the estimated boundary layer heights, gave an estimated Atlanta daily WSOC production rate in August of 0.55 mgC m-2 h-1 between mid-morning and mid-afternoon. This study characterizes the regional nature of fine particles in the southeastern US, confirming the

  13. Effects of soluble flavin on heterogeneous electron transfer between surface-exposed bacterial cytochromes and iron oxides

    NASA Astrophysics Data System (ADS)

    Wang, Zheming; Shi, Zhi; Shi, Liang; White, Gaye F.; Richardson, David J.; Clarke, Thomas A.; Fredrickson, Jim K.; Zachara, John M.

    2015-08-01

    Dissimilatory iron-reducing bacteria can utilize insoluble Fe(Mn)-oxides as a terminal electron acceptor under anaerobic conditions. For Shewanella species specifically, evidence suggests that iron reduction is associated with the secretion of flavin mononucleotide (FMN) and riboflavin. However, the exact mechanism of flavin involvement is unclear; while some indicate that flavins mediate electron transfer (Marsili et al., 2008), others point to flavin serving as co-factors to outer membrane proteins (Okamoto et al., 2013). In this work, we used methyl viologen (MVrad +)-encapsulated, porin-cytochrome complex (MtrCAB) embedded liposomes (MELs) as a synthetic model of the Shewanella outer membrane to investigate the proposed mediating behavior of microbially produced flavins. The reduction kinetics of goethite, hematite and lepidocrocite (200 μM) by MELs ([MVrad +] ∼ 40 μM and MtrABC ⩽ 1 nM) were determined in the presence FMN at pH 7.0 in N2 atmosphere by monitoring the concentrations of MVrad + and FMN through their characteristic UV-visible absorption spectra. Experiments were performed where (i) FMN and Fe(III)-oxide were mixed and then reacted with the reduced MELs and (ii) FMN was reacted with the reduced MELs followed by addition of Fe(III)-oxide. The redox reactions proceeded in two steps: a fast step that was completed in a few seconds, and a slower one lasting over 400 s. For all three Fe(III)-oxides, the initial reaction rate in the presence of a low concentration of FMN (⩽1 μM) was at least a factor of five faster than those with MELs alone, and orders of magnitude faster than those by FMNH2, suggesting that FMN may serve as a co-factor that enhances electron transfer from outer-membrane c-cytochromes to Fe(III)-oxides. The rate and extent of the initial reaction followed the order of lepidocrocite > hematite > goethite, the same as their reduction potentials, implying thermodynamic control on reaction rate. For LEP, with the highest reduction

  14. Effects of soluble flavin on heterogeneous electron transfer between surface-exposed bacterial cytochromes and iron oxides

    SciTech Connect

    Wang, Zheming; Shi, Zhi; Shi, Liang; White, Gaye F.; Richardson, David J.; Clarke, Thomas A.; Fredrickson, Jim K.; Zachara, John M.

    2015-08-25

    Dissimilatory iron-reducing bacteria can utilize insoluble Fe(Mn)-oxides as a terminal electron acceptor under anaerobic conditions. For Shewanella species specifically, some evidence suggests that iron reduction is associated with the secretion of flavin mononucleotide (FMN) and riboflavin that are proposed to mediate electron transfer (Marsili et al., 2008). In this work, we used methyl viologen (MV•+)-encapsulated, porin-cytochrome complex (MtrCAB) embedded liposomes (MELs) as a synthetic model of the Shewanella outer membrane to investigate the proposed mediating behavior of secreted flavins. The reduction kinetics of goethite, hematite and lepidocrocite (200 µM) by MELs ([MV•+] ~ 42 µM and MtrABC ≤ 1 nM) were determined in the presence FMN at pH 7.0 in N2 atmosphere by monitoring the concentrations of MV•+ and FMN through their characteristic UV-visible absorption spectra. Experiments were performed where i) FMN and Fe(III)-oxide were mixed and then reacted with the reduced MELs and ii) FMN was reacted with the reduced MELs followed by addition of Fe(III)-oxide. The redox reactions proceeded in two steps: a fast step that was completed in a few seconds, and a slower one lasting over 400 seconds. For all three Fe(III)-oxides, the initial reaction rate in the presence of a low concentration of FMN (≤ 1 µM) was at least a factor of five faster than those with MELs alone, and orders of magnitude faster than those by FMNH2, suggesting that FMN may serve as a co-factor that enhances electron transfer from outer-membrane c-cytochromes to Fe(III)-oxides. The rate and extent of the initial reaction followed the order of lepidocrocite > hematite > goethite, the same as their reduction potentials, implying thermodynamic control on reaction rate. However, at higher FMN concentrations (> 1 µM), the reaction rates for both steps decreased and varied inversely with FMN concentration, indicating that FMN inhibited the MEL to Fe(III)-oxide electron transfer

  15. Concerted dismutation of chlorite ion: water-soluble iron-porphyrins as first generation model complexes for chlorite dismutase.

    PubMed

    Zdilla, Michael J; Lee, Amanda Q; Abu-Omar, Mahdi M

    2009-03-01

    Three iron-5,10,15,20-tetraarylporphyrins (Fe(Por-Ar4), Ar = 2,3,5,6-tetrafluro-N,N,N-trimethylanilinium (1), N,N,N-trimethylanilinium (2), and p-sulfonatophenyl (3)) have been investigated as catalysts for the dismutation of chlorite (ClO2-). Degradation of ClO2- by these catalysts occurs by two concurrent pathways. One leads to formation of chlorate (ClO3-) and chloride (Cl-), which is determined to be catalyzed by O=FeIV(Por) (Compound II) based on stopped-flow absorption spectroscopy, competition with 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonicacid), 18O-labeling studies, and kinetics. The second pathway is a concerted dismutation of chlorite to dioxygen (O2) and chloride. On the basis of isotope labeling studies using a residual gas analyzer, the mechanism is determined to be formation of O=FeIV(Por)*+ (Compound I) from oxygen atom transfer, and subsequent rebound with the resulting hypochlorite ion (ClO-) to give dioxygen and chloride. While the chlorate production pathway is dominant for catalysts 2 and 3, the O2-producing pathway is significant for catalyst 1. In addition to chlorite dismutation, complex 1 catalyzes hypochlorite disproportionation to chloride and dioxygen quantitatively.

  16. Enhanced sandwich immunoassay using antibody-functionalized magnetic iron-oxide nanoparticles for extraction and detection of soluble transferrin receptor on a photonic crystal biosensor.

    PubMed

    Peterson, Ross D; Chen, Weili; Cunningham, Brian T; Andrade, Juan E

    2015-12-15

    Iron deficiency anemia (IDA) has detrimental effects on individuals and societies worldwide. A standard sandwich assay (SA) for the detection of soluble transferrin receptor (sTfR), a biomarker of IDA, on a photonic crystal (PC) biosensor was established, but it was susceptible to non-specific signals from complex matrixes. In this study, iron-oxide nanoparticles (fAb-IONs) were used as magnetic immuno-probes to bind sTfR and minimize non-specific signals, while enhancing detection on the PC biosensor. This inverse sandwich assay (IA) method completely bound sTfR with low variability (<4% RSD) in buffer and allowed for its accurate and precise detection in sera (Liquichek™ control sera) on the PC biosensor using two certified ELISAs as reference methods. A linear dose-response curve was elicited at the fAb-IONs concentration in which the theoretical binding ratio (sTfR:fAb-IONs) was calculated to be <1 on the IA. The LoDs for sTfR in the SA and IA were similar (P>0.05) at 14 and 21 μg/mL, respectively. The inherent imprecision of the IA and reference ELISAs was σ(δ)=0.45 µg/mL and the mean biases for Liquichek™ 1, 2 and 3 were 0.18, 0.19 and -0.04 µg/mL, respectively. Whereas the inherent imprecision of the SA and reference ELISAs was σ(δ)=0.52 µg/mL and the biases for Liquichek™ 1, 2 and 3 were 0.66, 0.14 and -0.67 µg/mL, respectively. Thus, unlike the SA, the IA method measures sTfR with the same bias as the reference ELISAs. Combined magnetic separation and detection of nutrition biomarkers on PC biosensors represents a facile method for their accurate and reliable quantification in complex matrixes.

  17. Subchronic inhalation toxicity of iron oxide (magnetite, Fe(3) O(4) ) in rats: pulmonary toxicity is determined by the particle kinetics typical of poorly soluble particles.

    PubMed

    Pauluhn, Jürgen

    2012-07-01

    Wistar rats were nose-only exposed to pigment-sized iron oxide dust (Fe(3) O(4) , magnetite) in a subchronic 13-week inhalation study according to the OECD testing guidelines TG#413 and GD#39. A 4 week pilot study with a 6 month post exposure period served as basis for validating the kinetic modeling approaches utilized to design the subchronic study. Kinetic analyses made during this post exposure period demonstrated that a diminution in particle clearance and lung inflammation occurred at cumulative exposure levels exceeding the lung overload threshold. Animals were exposed 6 h per day, five days per week for 13 consecutive weeks at actual concentrations of 0, 4.7, 16.6 and 52.1 mg m(-3) (mass median aerodynamic diameter ≈1.3 μm, geometric standard deviation = 2). The exposure to iron oxide dust was tolerated without mortality, consistent changes in body weights, food and water consumption or systemic toxicity. While general clinical pathology and urinalysis were unobtrusive, hematology revealed changes of unclear toxicological significance (minimally increased differential neutrophil counts in peripheral blood). Elevations of neutrophils in bronchoalveolar lavage (BAL) appeared to be the most sensitive endpoint of study. Histopathology demonstrated responses to particle deposition in the upper respiratory tract (goblet cell hyper- and/or metaplasia, intraepithelial eosinophilic globules in the nasal passages) and the lower respiratory tract (inflammatory changes in the bronchiolo-alveolar region). Consistent changes suggestive of pulmonary inflammation were evidenced by BAL, histopathology, increased lung and lung-associated-lymph node (LALN) weights at 16.6 and 52.1 mg m(-3) . Increased septal collagenous fibers were observed at 52.1 mg m(-3) . Particle translocation into LALN occurred at exposure levels causing pulmonary inflammation. In summary, the retention kinetics iron oxide reflected that of poorly soluble particles. The empirical

  18. Evaluation of the simultaneous effects of processing parameters on the iron and zinc solubility of infant sorghum porridge by response surface methodology.

    PubMed

    Kayodé, A P Polycarpe; Nout, Martinus J R; Bakker, Evert J; Van Boekel, Martinus A J S

    2006-06-14

    The purpose of this study was to improve the micronutrient quality of indigenous African infant flour using traditional techniques available in the region. Response surface methodology was used to study the effect of duration of soaking, germination, and fermentation on phytate and phenolic compounds (PC), pH, viscosity, and the in vitro solubility (IVS) of iron and zinc in infant sorghum flour. The phytate and the PC concentrations of the flour were significantly modified as a result of the duration of germination and fermentation and their mutual interaction. These modifications were accompanied by a significant increase in % IVS Zn after 24 h of sprouting. Except for the interaction of soaking and fermentation, none of the processing parameters exerted a significant effect on the % IVS Fe. The viscosity of the porridge prepared with the flour decreased significantly with the duration of germination, making it possible to produce a porridge with high energy and nutrient density. The use of germination in combination with fermentation is recommended in the processing of cereals for infant feeding in developing countries.

  19. Atmospheric delivery of anthropogenic bioavailable iron from mineral dust to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, A.; Shi, Z.

    2015-12-01

    Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. Here, we interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. We firstly examined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). We then constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water, by using acidity as a master variable. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean. However, our modeled Fe solubility was significantly lower than that deduced from observations over the South Atlantic east downwind from the Patagonian dust source regions. Our modeled Fe solubility for dry deposition over the Atlantic is in good agreement the measurement, while that for wet deposition is significantly lower than the measurement. Our model results suggest that human activities contribute to about half of the soluble Fe supply to a significant portion of the oceans in the Northern Hemisphere, while their contribution to oceans in the high latitude remains highly uncertain

  20. Quantitative LC–MS for water-soluble heterocyclic amines in fine aerosols (PM2.5) at Duke Forest, USA

    EPA Science Inventory

    In this study, a quantitative liquid chromatography-mass spectrometry (LC-MS) technique capable of measuring the concentrations of heterocyclic nitrogen compounds in ambient fine aerosols (PM2.5) has been developed. Quadrupole time-of-flight (Q-TOF) MS technology is used to provi...

  1. Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: new metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes

    PubMed Central

    Cappelletti, Martina; Presentato, Alessandro; Milazzo, Giorgio; Turner, Raymond J.; Fedi, Stefano; Frascari, Dario; Zannoni, Davide

    2015-01-01

    Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD—coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation—were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria–Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step. PMID:26029173

  2. Determination of water-soluble and insoluble (dilute-HCl-extractable) fractions of Cd, Pb and Cu in Antarctic aerosol by square wave anodic stripping voltammetry: distribution and summer seasonal evolution at Terra Nova Bay (Victoria Land).

    PubMed

    Annibaldi, A; Truzzi, C; Illuminati, S; Bassotti, E; Scarponi, G

    2007-02-01

    Eight PM10 aerosol samples were collected in the vicinity of the "Mario Zucchelli" Italian Antarctic Station (formerly Terra Nova Bay Station) during the 2000-2001 austral summer using a high-volume sampler and precleaned cellulose filters. The aerosol mass was determined by differential weighing of filters carried out in a clean chemistry laboratory under controlled temperature and humidity. A two-step sequential extraction procedure was used to separate the water-soluble and the insoluble (dilute-HCl-extractable) fractions. Cd, Pb and Cu were determined in the two fractions using an ultrasensitive square wave anodic stripping voltammetric (SWASV) procedure set up for and applied to aerosol samples for the first time. Total extractable metals showed maxima at midsummer for Cd and Pb and a less clear trend for Cu. In particular, particulate metal concentrations ranged as follows: Cd 0.84-9.2 microg g(-1) (average 4.7 microg g(-1)), Pb 13.2-81 microg g(-1) (average 33 microg g(-1)), Cu 126-628 microg g(-1) (average 378 microg g(-1)). In terms of atmospheric concentration, the values were: Cd 0.55-6.3 pg m(-3) (average 3.4 pg m(-3)), Pb 8.7-48 pg m(-3) (average 24 pg m(-3)), Cu 75-365 pg m(-3) (average 266 pg m(-3)). At the beginning of the season the three metals appear widely distributed in the insoluble (HCl-extractable) fraction (higher proportions for Cd and Pb, 90-100%, and lower for Cu, 70-90%) with maxima in the second half of December. The soluble fraction then increases, and at the end of the season Cd and Pb are approximately equidistributed between the two fractions, while for Cu the soluble fraction reaches its maximum level of 36%. Practically negligible contributions are estimated for crustal and sea-spray sources. Low but significant volcanic contributions are estimated for Cd and Pb (approximately 10% and approximately 5%, respectively), while there is an evident although not quantified marine biogenic source, at least for Cd. The estimated natural

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

    NASA Astrophysics Data System (ADS)

    Boreddy, S. K. R.; Kawamura, K.

    2015-03-01

    In order to characterize the long term trend of remote marine aerosols, a 12 year observation was conducted for water-soluble inorganic ions in TSP aerosols collected from 2001-2012 in the Asian outflow region at a 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 nss-SO42-, NO3-, NH4+, nss-K+ and nss-Ca2+ are high in winter and spring and low in summer. On the other hand, MSA- 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 2007-2012, probably due to the decreased SO2 emissions in East Asia especially in China. In contrast, nss-K+ and MSA- concentrations continuously increased from 2001-2012 during winter and spring seasons, demonstrating that biomass burning and/or terrestrial biological emissions in East Asia are increasingly more transported from the Asian continent to the western North Pacific.

  4. Secondary Inorganic Soluble Aerosol in Hong Kong: Continuous Measurements, Formation Mechanism Discussion and Improvement of an Observation-Based Model to Study Control Strategies

    NASA Astrophysics Data System (ADS)

    Xue, Jian

    Work in this thesis focuses on half-hourly or hourly measurements of PM2.5 secondary inorganic aerosols (SIA) in two locations in Hong Kong (HK) using a continuous system, PILS (Particle-into-Liquid System) coupled to two ion chromatographs. The high-resolution data sets allow the examination of SIA temporal dynamics in the scale of hours that the filter-based approach is incapable of providing. (1) Impacts of local emissions, regional transports and their interactions on chemical composition and concentrations of PM2.5 SIA and other ionic species were investigated at the Hong Kong University of Science and Technology (HKUST), a receptor site, under three synoptic conditions. (2) Chemical compositions and size characteristics of ionic species were investigated at Tung Chung, a new town area located in the Southwest part of HK. The sampling period was from 17 to 26 December 2009, covering both normal conditions and an aerosol episode. The three major secondary inorganic ions, SO42, NH4+ and NO 3-, accounted for 47 +/- 6% of PM2.5 mass. Further examination of size characteristics of NO3 - shows that fine mode NO3- is more likely to occur in environments when the fine particles are less acidic and the sea-salt aerosol contributions are low. (3) The ionic chemical composition of PM2.5 and meteorological parameters (e.g., temperature, RH) obtained at the HKUST site under all three different synoptic conditions are input into Aerosol Inorganic Model (AIM-III) for estimation of in situ pH through calculation of H+ amount and aerosol liquid water content (LWC). The second part of this thesis work is to improve an observation-based model (OBAMAP) for SIA, which was first developed by Dr. Zibing Yuan (2006) to evaluate the sensitivity of formation of nitrate ad sulfate to changes in the emissions of their precursors (i.e., NOx, SO2, and VOCs). The improvement work includes incorporating updated chemical mechanisms, thermodynamic equilibrium for gas-aerosol phase

  5. Soluble Iron as an In Situ Indicator of the Redox State of Humic Substances in Arctic Soil: Implications for Seasonal Regeneration of Oxidized Terminal Electron Acceptors

    NASA Astrophysics Data System (ADS)

    Lipson, D.; Zlamal, J. E.; Srinivas, A. J.; Raab, T. K.

    2014-12-01

    Ferric iron (Fe(III)) and humic substances (HS) are important terminal electron acceptors for anaerobic respiration in wet tundra soils of the Arctic Coastal Plain near Barrow, Alaska. These soils are rich in both solid phase Fe minerals (including oxides such as ferrihydrite and goethite and other minerals with reduced or mixed valence such as siderite and magnetite) and soluble Fe, chelated by siderophores and other small organic molecules. This latter pool may also include nanocolloidal Fe: extremely fine-grained minerals that pass through a 0.2 micron filter. Both the solid phase and aqueous Fe pools undergo seasonal changes in redox state as a result of biological reduction by Fe-reducing microorganisms and oxidation by a variety of potential mechanisms, both abiotic and biotic. These redox cycles of solid and aqueous pools are not in phase: solid phase Fe became progressively more reduced from mid- to late summer, while aqueous phase Fe became reduced over the first half of the summer. It is well-known that HS interact with Fe, and that HS can act as electron shuttles in the reduction of Fe oxides. In other ecosystems chelated Fe(III) has been incubated with soil samples and the resulting Fe(II) produced is used as an indicator of the reducing power of HS. In these Fe-rich Arctic soils, HS are continuously in contact with chelated Fe, and therefore we interpret the redox state of this pool as an indicator of HS redox status. To verify this we conducted redox titrations of extracted HS with both reduced and oxidized Fe chelates and showed that chelated Fe could interact with HS both as electron acceptor and donator. In a field experiment, the addition of oxidized humic acids to soils resulted in an immediate oxidation of the aqueous Fe pool within 24 hours, which we attribute to abiotic oxidation of Fe by HS, followed by a slow reduction of this pool over the next week, presumably due to biological Fe reduction of the HS/aqueous Fe pool. At the end of summer

  6. Water-soluble ions species of size-resolved aerosols: Implications for the atmospheric acidity in São Paulo megacity, Brazil

    NASA Astrophysics Data System (ADS)

    Vieira-Filho, Marcelo; Pedrotti, Jairo J.; Fornaro, Adalgiza

    2016-11-01

    Over the last decade, an increase of ammonium salts in atmospheric deposition has been reported worldwide, especially in megacities. The present study aims to give a better comprehension analysis about particulate matter acidity in São Paulo megacity (MASP), Brazil. Size-resolved aerosols were sampled in MASP, during 2012 winter, showing a bimodal mass concentration distribution, with sulfate concentration exceeding 3.40 μg m- 3, which accounted for over 25% of PM0.56 mass. Regarding the relative distribution of ionic species, 90% of NH4+ levels, were restricted to smaller than 1 μm diameter range. The average neutralization index for PM < 1 μm was 0.62, which indicated an ammonia-limiting atmosphere due to partial neutralization of atmospheric acids. Particles of the accumulation mode presented more acid behavior than other aerosol fractions, with pH value as low as 4.15 in PM0.56. The total neutralization index registered the lowest value for PM0.56, but it did not respond promptly to aerosol variations as the E-AIM model predictions. The highest discrepancies between the acidity proxies occurred in the smaller fractions of particulate matter, especially in the after-filter (AF) stage (diameter < 0.020 μm). In addition, AF stage had the highest contribution to PM total mass, about 14% for all the stages analyzed. Such contribution indicates that acidity in ultrafine particles are still mixed for the MASP and need further investigation.

  7. Diel Variability of Total and Speciated Water-Soluble Inorganic Iodine in PM2.5 Aerosol at a Southern California Coastal Site

    NASA Astrophysics Data System (ADS)

    Pszenny, A.; Cotter, K.; Deegan, B.; Fischer, E.; Johnson, D.

    2007-12-01

    PM2.5 aerosol was sampled over nominal 3-hour intervals at the head of Zuma Beach in Malibu, California (USA) from 6 to 24 October 2006 by filtration at 1.13 m3 min-1 (STP) through 20 x 25 cm cellulose fiber (Whatman 41) filters that had been rinsed with deionized water (DIW). Exposed filters were removed from support cartridges as soon as possible after retrieval (usually within 2 hours), immediately sealed in clean polyethylene bags, and stored frozen until further processing. Following the field campaign one quarter of each filter was pressed into a pellet (2.0 cm diameter x 0.5 cm thick) and analyzed by neutron activation for total concentrations of I and several other trace elements. Our preliminary analyses indicate that sodium and iodine show a clear diel variation characterized by higher concentrations from late morning to early evening. We hypothesize that this diel variability is related to a persistent land/sea breeze circulation associated with the nearby coastal region. Other elements are indicative of variability in other aerosol sources such as soil dust (Al, Mn) and fossil fuel combustion (V). Second quarters are currently being extracted in DIW and analyzed in two ways: 1) for iodide by ion chromatography, and 2) for inorganic iodine in higher oxidation states (i.e., V to 0) by chemical reduction with ascorbic acid followed by determination of iodide by ion chromatography. Results of the trace element and speciated iodine analyses will be presented.

  8. Iron supply and demand in the upper ocean

    SciTech Connect

    Fung, I.Y.; Meyn, S.K.; Tegen, I.; Doney, S.C.; John, J.; Bishop, J.

    1999-09-29

    Iron is hypothesized to be a limiting micronutrient for ocean primary production. This paper presents an analysis of the iron budget in the upper ocean. The global distribution of annual iron assimilation by phytoplankton was estimated from distributions of satellite-derived oceanic primary production and measured (Fe:C)(cellular) ratios. The distributions of iron supply by upwelling/mixing and aeolian deposition were obtained by applying (Fe:NO3)(dissolved) ratios to the nitrate supply and by assuming the soluble fraction of mineral aerosols. A lower bound on the rate of iron recycling in the photic zone was estimated as the difference between iron assimilation and supply. Global iron assimilation by phytoplankton for the open ocean was estimated to be 12 x 10(9) mol Fe yr(-1). Atmospheric deposition of total Fe is estimated to be 96 x 10(9) mol Fe yr(-1) in the open ocean, with the soluble Fe fraction ranging between 1 and 10 percent (or 1-10 x 10(9) mol Fe yr(-1)). By comparison, the upwelling/entrainment supply of dissolved Fe to the upper ocean is small, similar to 0.7 x 10(9) mol Fe yr(-1). Uncertainties in the aeolian flux and assimilation may be as large as a factor of 5-10 but remain difficult to quantify, as information is limited about the form and transformation of iron from the soil to phytoplankton incorporation. An iron stress index, relating the (Fe:N) demand to the (Fe:N) supply, confirms the production in the high-nitrate low-chlorophyll regions is indeed limited by iron availability.

  9. Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: I. Iron-copper-zinc-lead sulfide solubility relations

    USGS Publications Warehouse

    Hemley, J.J.; Cygan, G.L.; Fein, J.B.; Robinson, G.R.; d'Angelo, W. M.

    1992-01-01

    Experimental studies, using cold-seal and extraction vessel techniques, were conducted on Fe, Pb, Zn, and Cu sulfide solubilities in chloride soultions at temperatures from 300?? to 700??C and pressures from 0.5 to 2 kbars. The solutions were buffered in pH by quartz monzonite and the pure potassium feldspar-muscovite-quartz assemblage and in fS2-fO2 largely by the assemblage pyrite-pyrrhotite-magnetite. Solubilities increase with increasing temperature and total chloride, and decrease with increasing pressure. The effect of increasing chloride concentration on solubility reflects primarily a shift to lower pH via the silicate buffer reactions. Similarity in behaviour with respect to the temperature and pressure of Fe, Zn, and Pb sulfide solubilities points to similarity in chloride speciation, and the neutral species appear to be dominant in the high-temperature region. -from Authors

  10. 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

    NASA Astrophysics Data System (ADS)

    Boreddy, S. K. R.; Kawamura, K.

    2015-06-01

    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.

  11. Electronic and Spatial Structures of Water-Soluble Dinitrosyl Iron Complexes with Thiol-Containing Ligands Underlying Their Ability to Act as Nitric Oxide and Nitrosonium Ion Donors

    PubMed Central

    Vanin, Anatoly F.; Burbaev, Dosymzhan Sh.

    2011-01-01

    The ability of mononuclear dinitrosyl iron commplexes (M-DNICs) with thiolate ligands to act as NO donors and to trigger S-nitrosation of thiols can be explain only in the paradigm of the model of the [Fe+(NO+)2] core ({Fe(NO)2}7 according to the Enemark-Feltham classification). Similarly, the {(RS−)2Fe+(NO+)2}+ structure describing the distribution of unpaired electron density in M-DNIC corresponds to the low-spin (S = 1/2) state with a d7 electron configuration of the iron atom and predominant localization of the unpaired electron on MO(dz2) and the square planar structure of M-DNIC. On the other side, the formation of molecular orbitals of M-DNIC including orbitals of the iron atom, thiolate and nitrosyl ligands results in a transfer of electron density from sulfur atoms to the iron atom and nitrosyl ligands. Under these conditions, the positive charge on the nitrosyl ligands diminishes appreciably, the interaction of the ligands with hydroxyl ions or with thiols slows down and the hydrolysis of nitrosyl ligands and the S-nitrosating effect of the latter are not manifested. Most probably, the S-nitrosating effect of nitrosyl ligands is a result of weak binding of thiolate ligands to the iron atom under conditions favoring destabilization of M-DNIC. PMID:22505886

  12. [Composition and Regional Characteristics of Atmosphere Aerosol and Its Water Soluble Ions over the Yangtze River Delta Region in a Winter Haze Period].

    PubMed

    Wang, Man-ting; Zhu, Bin; Wang, Hong-lei; Xue, Guo-qiang; He, Jun; Xu, Hong-hui; Cao, Jin-fei

    2015-07-01

    To investigate the pollution characteristics of water soluble ions in fine atmospheric particles in Yangtze River Delta during the haze period from 18th to 24th Jan 2013, a joint sampling campaign using Andersen sampler was conducted at five cities (including Nanjing, Suzhou, Hangzhou, Lin'an and Ningbo). The analysis of size distribution of these ionic species coupled with the local meteorological conditions may shed some insightful light on the haze formation mechanism in this region. The result has shown: firstly, during the observation period, when Yangtze River Delta located at high pressure or in the front of high pressure, and has a large pressure gradient, the lower atmosphere has a significant airflow divergence in favor of pollutant dispersion; while located in weak low pressure and weak high pressure, the equalizing pressure field is not favorable for pollutant dispersion, especially accompanied with lower atmosphere convergence airflow. Secondly, during the hazy period, the concentration of fine particles and total water-soluble inorganic ions (TWSS) has increased dramatically; the increasing proportions of TWSS in fine particles are: Hangzhou 0. 9%, Lin'an 4. 2%, Nanjing 8. 1%. The particle size of secondary ions of SO(4)2-, NO3-, NH4+ complies fine mode(particle size <2. 1 µm), whose peaks migrates from 0. 43-0. 65 µm to 0. 65-1. 1 µm during the observation period, the peak of particle size of Ca2+ , Mg2+ appears at 4.7-5. 8 µm, while the ions of Na+, Cl-, K+ show a bimodal distribution. Moreover, secondary inorganic ions play a significant role in the formation of haze pollution, where the concentrations of secondary inorganic ions of NH4+, SO2- and NO3 have higher increasing rates; their relative proportions of increasing from each monitoring points are: Hangzhou 3%, Lin'an 55% and Nanjing 64.9%. Finally, SO(4)2- has the highest mass contribution to SNA, up to 45% ; also, the NO-/SO- ratios in each monitoring points are always higher than a fair

  13. Spatial trends in surface-based carbonaceous aerosol, including organic, water-soluble and elemental carbon, during DISCOVER-AQ in Houston, TX

    NASA Astrophysics Data System (ADS)

    Sheesley, R. J.; Barrett, T. E.; Yoon, S.; Clark, A. E.; Hildebrandt Ruiz, L.; Griffin, R. J.; Karakurt Cevik, B.; Long, R.; Duvall, R.; Usenko, S.

    2014-12-01

    DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) is a NASA funded air quality research program that focused on Houston, TX in September 2013. NASA's P-3B and B200 were deployed to sample vertical profiles over specific focus areas using a spiraling vertical profile flight plan on select days during the 30 day sampling campaign. In this project, we measured organic carbon (OC), elemental carbon (EC), inorganic carbon and water-soluble organic carbon (WSOC) from filter-based sampling efforts at four ground-based sites across the Houston metropolitan area. Ground-based sites were chosen to represent the downtown area, upwind and downwind as well as the Houston Ship Channel (industrial area). Ratios of EC:OC and WSOC:OC will be used to track contributions of primary and secondary organic carbon (POC and SOC), respectively. Spatial and temporal trends in POC and SOC for the Houston metropolitan area will be discussed.

  14. Solubility Database

    National Institute of Standards and Technology Data Gateway

    SRD 106 IUPAC-NIST Solubility Database (Web, free access)   These solubilities are compiled from 18 volumes (Click here for List) of the International Union for Pure and Applied Chemistry(IUPAC)-NIST Solubility Data Series. The database includes liquid-liquid, solid-liquid, and gas-liquid systems. Typical solvents and solutes include water, seawater, heavy water, inorganic compounds, and a variety of organic compounds such as hydrocarbons, halogenated hydrocarbons, alcohols, acids, esters and nitrogen compounds. There are over 67,500 solubility measurements and over 1800 references.

  15. The anthropogenic influence on Iron deposition over the oceans: a 3-D global modeling

    NASA Astrophysics Data System (ADS)

    Myriokefalitakis, Stelios; Mihalopoulos, Nikos; Baker, Alex; Kanakidou, Maria

    2014-05-01

    Iron (Fe) deposition over oceans is directly linked to the marine biological productivity and consequently to atmospheric CO2 concentrations. Experimental and modeling results support that both inorganic (sulphate, ammonium and nitrate) and organic (e.g. oxalate) ligands can increase the Fe mobilization. Mineral dust deposition is considered as the most important supply of bioavailable Fe in the oceans. Although, due to the low soil soluble iron fractions, atmospheric processes which are also related to anthropogenic emissions, can convert iron to more soluble forms in the atmosphere. Recent studies also support that anthropogenic emissions of Fe from combustion sources also significantly contribute to the dissolved Fe atmospheric pool. The evaluation of the impact of humans on atmospheric soluble or bioavailable Fe deposition remains challenging, since Fe mobilization due to changes in anthropogenic emissions is largely uncertain. In the present study, the global atmospheric Fe cycle is parameterized in the 3-D chemical transport global model TM4-ECPL and the model is used to calculate the Fe deposition over the oceans. The model considers explicitly organic, sulfur and nitrogen gas-phase chemistry, aqueous-phase organic chemistry, including oxalate and all major aerosol constituents. TM4-ECPL simulates the organic and inorganic ligand-promoted mineral Fe dissolution and also aqueous-phase photochemical reactions between different forms of Fe (III/II). Primary emissions of Fe associated with dust and soluble Fe from combustion processes as well as atmospheric processing of the emitted Fe is taken into account in the model Sensitivity simulations are performed to study the impact of anthropogenic emissions on Fe deposition. For this preindustrial, present and future emission scenarios are used in the model in order to examine the response of chemical composition of iron-containing aerosols to environmental changes. The release of soluble iron associated with

  16. Trans-hemispheric contribution of C2-C10 α, ω-dicarboxylic acids, and related polar compounds to water-soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions

    NASA Astrophysics Data System (ADS)

    SempéRé, Richard; Kawamura, Kimitaka

    2003-06-01

    Marine aerosol samples were collected during a western Pacific cruise covering the latitude range between 35°N and 40°S (140°E-180°E). They were analyzed for total carbon (TC), total nitrogen (TN), water-soluble organic carbon (WSOC) along with the molecular distributions of C2-C10 α, ω-dicarboxylic acids, and related polar compounds, mainly, ω-oxocarboxylic acids (C2-C9) and α-dicarbonyls (C2-C3). Oxalic acid (C2) was the most abundant followed by malonic (C3) and succinic (C4) acids. The total diacid concentration range was 7-605 ng m-3 (av. 85 ng m-3) and the diacid-carbon accounted for 2-15% (average 8%) of WSOC which comprised 29-55% (average 40%) of TC. Dry depositions of total diacids over the northern and southern Pacific Ocean were estimated to be 256-1907 μg m-2 yr-1 (average 735; n = 4) and 22-396 μg m-2 yr-1 (average 134; n = 14), respectively, whereas the air-to-sea flux of oxalic acid was 18-1351 μg m-2 yr-1 (average 466 μg m-2 yr-1) and 7.5-275 μg m-2 yr-1 (average 75 μg m-2 yr-1) in the Northern and Southern Hemispheres. We observed that the concentration ratios of diacid-C/WSOC, azelaic acid (C9)/ω-oxononanoic acid, maleic acid (iC4cis)/fumaric (iC4trans) acid and succinic acid (C4)/total diacids were correlated with air temperature. These findings showed that the intensity of photochemical oxidation reactions and thus the variation in sunlight intensity characterized here by air temperature, significantly control the molecular distribution of water-soluble organic compounds during the long-range transport of anthropogenic and/or biogenic higher molecular weight organic compounds.

  17. Atmospheric iron deposition in the northwestern Pacific Ocean and its adjacent marginal seas: The importance of coal burning

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Chiu; Chen, Jen-Ping; Ho, Tung-Yuan; Tsai, I.-Chun

    2015-02-01

    This study applied a regional air quality model, incorporated with an emission module, to quantitatively differentiate the atmospheric iron sources originating from lithogenic dusts or coal-burning fly ashes deposited in the Northwestern Pacific Ocean and its marginal seas. Particular attention was paid to the high iron content of fly ashes emitted from steel and iron plants burning coals. Using the year 2007 as an example, the modeling results exhibit large seasonal variations in iron deposition, with highest deposition fluxes occurred during spring and autumn, which are comparable to the seasonal fluctuation of chlorophyll a concentrations estimated by satellite images in the oceanic regions. Fly ash from coal burning accounted for 7.2% of the total iron deposited over the northwestern Pacific Ocean and 15% of that over the northern South China Sea. After considering the difference of iron solubility in the aerosols, anthropogenic aerosol associated with coal burning would be the major bioavailable iron source in the surface water of the oceanic regions.

  18. Modeling of atmospheric iron processing carried by mineral dust and its deposition to ocean

    NASA Astrophysics Data System (ADS)

    Nickovic, Slobodan; Vukovic, Ana; Vujadinovic, Mirjam

    2014-05-01

    Relatively insoluble iron in dust originating from desert soils increases its solubility after Fe carried by mineral dust is chemically processed by the atmosphere. After dust is deposited deposition to the ocean, soluble Fe as a nutrient could enhance the marine primary production. The atmospheric dust cycle is driven by the atmospheric processes often of smaller, meso-scales. The soil mineralogy of dust emitted from sources determines also how much Fe in the aerosol will be finding. Once Fe is exposed to the atmospheric processes, the atmospheric radiation, clouds and polluted air will chemically affect the iron in dust. Global dust-iron models, having typical horizontal resolutions of 100-300 km which are mostly used to numerically simulate the fate of iron in the atmosphere can provide rather global picture of the dust and iron transport, but not details. Such models often introduce simplistic approximation on the Fe content in dust-productive soils. To simulate the Fe processing we instead implemented a high resolution regional atmospheric dust-iron model with detailed 1km global map for the geographic distribution of Fe content in soil. We also introduced a parameterization of the Fe processing caused by dust mineralogy, cloud processes and solar radiation. We will present results from simulation experiments in order to explore the model capability to reproduce major observed patterns of deposited Fe into the Atlantic cruises.

  19. Influence of biochars, compost and iron grit, alone and in combination, on copper solubility and phytotoxicity in a Cu-contaminated soil from a wood preservation site.

    PubMed

    Oustriere, Nadège; Marchand, Lilian; Galland, William; Gabbon, Lunel; Lottier, Nathalie; Motelica, Mikael; Mench, Michel

    2016-10-01

    Two biochars, a green waste compost and iron grit were used, alone and in combination, as amendment to improve soil properties and in situ stabilize Cu in a contaminated soil (964mgCukg(-1)) from a wood preservation site. The pot experiment consisted in 9 soil treatments (% w/w): untreated Cu-contaminated soil (Unt); Unt soil amended respectively with compost (5%, C), iron grit (1%, Z), pine bark-derived biochar (1%, PB), poultry-manure-derived biochar (1%, AB), PB or AB+C (5%, PBC and ABC), and PB or AB+Z (1%, PBZ and ABZ). After a 3-month reaction period, the soil pore water (SPW) was sampled in potted soils and dwarf beans were grown for a 2-week period. In the SPW, all amendments decreased the Cu(2+) concentration, but total Cu concentration increased in all AB-amended soils due to high dissolved organic matter (DOM) concentration. No treatment improved root and shoot DW yields, which even decreased in the ABC and ABZ treatments. The PBZ treatment decreased total Cu concentration in the SPW while reducing the gap with common values for root and shoot yields of dwarf bean plants. A field trial is underway before any recommendation for the PB-based treatments. PMID:27259036

  20. Infrared refractive index of atmospheric aerosol substances.

    PubMed

    Volz, F E

    1972-04-01

    The optical constants in the ir from lambda2.5 microm to 40 microm (4000-250 cm(-1)) of dry natural aerosol substances and of sea salt are presented. The aerosol substances were obtained from rain and snow water: dust and soot by sedimentation, and water soluble salts by evaporation. The spectra of the absorption index n' were derived from our published transmittance measurements of potassium bromide disks. The real part n of the refractive index was calculated from the specular reflectance at near normal incidence of disks of pure aerosol substance. The observed spectral features are being related to chemical constituents, notably sulfates and alcohol soluble organics. Optical constants of composite and wet aerosol are discussed. A simple model confirms the measured transmission of a coarse dry powder of water solubles and shows that the extinction by natural aerosol should have a minimum near 8 microm and a strong maximum near 9 microm.

  1. Ash iron mobilization in volcanic eruption plumes

    NASA Astrophysics Data System (ADS)

    Hoshyaripour, G.; Hort, M.; Langmann, B.

    2014-12-01

    It has been shown that volcanic ash fertilizes the Fe-limited areas of the surface ocean through releasing soluble iron. As ash iron is mostly insoluble upon the eruption, it is hypothesized that heterogeneous in-plume and in-cloud processing of the ash promote the iron solubilization. Direct evidences concerning such processes are, however, lacking. In this study, a 1-D numerical model is developed to simulate the physicochemical interactions of gas-ash-aerosol in volcanic eruption plumes focusing on the iron mobilization processes at temperatures between 600 and 0 °C. Results show that sulfuric acid and water vapor condense at ~150 and ~50 °C on the ash surface, respectively. This liquid phase then efficiently scavenges the surrounding gases (>95% of HCl, 3-20% of SO2 and 12-62% of HF) forming an extremely acidic coating at the ash surface. The low pH conditions of the aqueous film promote acid-mediated dissolution of the Fe-bearing phases present in the ash material. We estimate that 0.1 to 33% of the total iron available at the ash surface is dissolved in the aqueous phase before the freezing point is reached. The efficiency of dissolution is controlled by the halogen content of the erupted gas as well as the mineralogy of the iron at ash surface: elevated halogen concentrations and presence of Fe2+-carrying phases lead to the highest dissolution efficiency. Findings of this study are in agreement with the data obtained through leaching experiments.

  2. Application of methyl silane coated iron oxide magnetic nanoparticles for solid-phase extraction and determination of fat-soluble vitamins by high performance liquid chromatography.

    PubMed

    Momenbeik, Fariborz; Yazdani, Elham

    2015-01-01

    Methyl silane coated Fe3O4 magnetic nanoparticles were used for simultaneous extraction of the fat-soluble vitamins (FSVs). The amounts of extracted vitamins were determined by HPLC. The synthesized Fe3O4 nanoparticles were coated with silica and then modified with trimethoxymethylsilane (TMMS). The prepared particles were characterized by different methods. The best amounts of silica and TMMS in sorbent synthesis were 1.2 and 0.5 mL, respectively. The optimum pH values for the sample solution and washing buffer were 5 and 3, respectively. Application of 100 mg sorbent, 700 μL tetrahydrofuran, 5-fold dilution of the sample solution, and 1 min for sorption and desorption times were among the best conditions. At the optimum conditions, the calibration plots for each vitamin were obtained with good linearity (R(2) >0.9992) and suitable linear ranges. This method has a low LOD (<76.1 μg/mL), acceptable repeatability (RSD <5.63%) and reproducibility (RSD <4.71%), and good accuracy (recovery >90.3%). Preconcentration of low concentrations of vitamin D3 was performed, and results showed 3.7 times greater sensitivity after preconcentration. Finally, the amounts of the FSVs in pharmaceutical formulations were determined using the proposed method, and results showed good agreement with those reported by manufacturers.

  3. Iron deficiency anaemia.

    PubMed

    Lopez, Anthony; Cacoub, Patrice; Macdougall, Iain C; Peyrin-Biroulet, Laurent

    2016-02-27

    Anaemia affects roughly a third of the world's population; half the cases are due to iron deficiency. It is a major and global public health problem that affects maternal and child mortality, physical performance, and referral to health-care professionals. Children aged 0-5 years, women of childbearing age, and pregnant women are particularly at risk. Several chronic diseases are frequently associated with iron deficiency anaemia--notably chronic kidney disease, chronic heart failure, cancer, and inflammatory bowel disease. Measurement of serum ferritin, transferrin saturation, serum soluble transferrin receptors, and the serum soluble transferrin receptors-ferritin index are more accurate than classic red cell indices in the diagnosis of iron deficiency anaemia. In addition to the search for and treatment of the cause of iron deficiency, treatment strategies encompass prevention, including food fortification and iron supplementation. Oral iron is usually recommended as first-line therapy, but the most recent intravenous iron formulations, which have been available for nearly a decade, seem to replenish iron stores safely and effectively. Hepcidin has a key role in iron homoeostasis and could be a future diagnostic and therapeutic target. In this Seminar, we discuss the clinical presentation, epidemiology, pathophysiology, diagnosis, and acute management of iron deficiency anaemia, and outstanding research questions for treatment.

  4. Iron deficiency anaemia.

    PubMed

    Lopez, Anthony; Cacoub, Patrice; Macdougall, Iain C; Peyrin-Biroulet, Laurent

    2016-02-27

    Anaemia affects roughly a third of the world's population; half the cases are due to iron deficiency. It is a major and global public health problem that affects maternal and child mortality, physical performance, and referral to health-care professionals. Children aged 0-5 years, women of childbearing age, and pregnant women are particularly at risk. Several chronic diseases are frequently associated with iron deficiency anaemia--notably chronic kidney disease, chronic heart failure, cancer, and inflammatory bowel disease. Measurement of serum ferritin, transferrin saturation, serum soluble transferrin receptors, and the serum soluble transferrin receptors-ferritin index are more accurate than classic red cell indices in the diagnosis of iron deficiency anaemia. In addition to the search for and treatment of the cause of iron deficiency, treatment strategies encompass prevention, including food fortification and iron supplementation. Oral iron is usually recommended as first-line therapy, but the most recent intravenous iron formulations, which have been available for nearly a decade, seem to replenish iron stores safely and effectively. Hepcidin has a key role in iron homoeostasis and could be a future diagnostic and therapeutic target. In this Seminar, we discuss the clinical presentation, epidemiology, pathophysiology, diagnosis, and acute management of iron deficiency anaemia, and outstanding research questions for treatment. PMID:26314490

  5. [Soluble of Metals within TSP in Shanghai].

    PubMed

    Chang, Yan; Feng, Chong; Qu, Jian-guo; Zhang, Jing

    2015-04-01

    The dissolution of metals within aerosol particles is meaningful to evaluate the bioavailability and mobility of metals. Total suspended particles (TSP) samples were collected in Shanghai. We extracted the water soluble and acid soluble (pH = 2) metals by the mini-recirculation-leach-system and measured their concentrations by the high resolution inductively coupled plasma mass spectrometry. The dissolution kinetics were rapid, the maximum solubility of metals could be reached in a few minutes. Overall, the average water-soluble concentrations were low for Co, Cr, Cd, V and Ni, median for Cu, Pb and Mn and high for Fe, Al, Zn and Mg. Combine the soluble metal concentrations with the back trajectory, the original air mass had significant impacts on water soluble metal concentrations. The water solubility and acid solubility were different for various metals, the water solubility of Fe was the lowest (2.0%), others followed an order: Al, Cr, V, Pb, Co, Ni, Cu, Cd, Mn, Mg, Zn. The metals' solubility was increased with the decrease of the solvent pH value. While the chemical speciation of metals was the internal cause of metals' solubility, the metals' ionic potential and the water solubility was negatively correlated.

  6. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  7. Water and acid soluble trace metals in atmospheric particles

    NASA Technical Reports Server (NTRS)

    Lindberg, S. E.; Harriss, R. C.

    1983-01-01

    Continental aerosols are collected above a deciduous forest in eastern Tennessee and subjected to selective extractions to determine the water-soluble and acid-leachable concentrations of Cd, Mn, Pb, and Zn. The combined contributions of these metals to the total aerosol mass is 0.5 percent, with approximately 70 percent of this attributable to Pb alone. A substantial fraction (approximately 50 percent or more) of the acid-leachable metals is soluble in distilled water. In general, this water-soluble fraction increases with decreasing particle size and with increasing frequency of atmospheric water vapor saturation during the sampling period. The pattern of relative solubilities (Zn being greater than Mn, which is approximately equal to Cd, which is greater than Pb) is found to be similar to the general order of the thermodynamic solubilities of the most probable salts of these elements in continental aerosols with mixed fossil fuel and soil sources.

  8. Characterization and Acid-Mobilization Study of Iron-Containing Mineral Dust Source Materials

    SciTech Connect

    Cwiertny, David M.; Baltrusaitis, Jonas; Hunter, Gordon J.; Laskin, Alexander; Scherer, Michelle; Grassian, Vicki H.

    2008-03-04

    Processes that solubilize the iron in mineral dust aerosols may increase the amount of iron supplied to ocean surface waters, and thereby stimulate phytoplankton productivity. It was recently proposed that mixing of mineral dusts with SO2 and HNO3 produces extremely acidic environments that favor the formation of bioavailable Fe(II). Here, four authentic mineral dust source materials (Saudi Beach sand (SB), Inland Saudi sand (IS), Saharan Sand (SS) and China Loess (CL)) and one commercial reference material (Arizona Test Dust (AZTD)) were spectroscopically characterized, and their dissolution at pH 1 was examined in aqueous batch systems. Spectroscopic analyses indicated that the bulk and near-surface region of all samples possessed similar elemental compositions and that iron was unevenly distributed among dust 10 particles. Mössbauer spectroscopy revealed Fe(III) in all samples, although SB, CL and AZTD also contained appreciable Fe(II). Both Fe(II) and Fe(III) were primarily substituted into aluminosilicates, although CL, AZTD and IS also contained Fe(III) oxides. Total iron solubility (defined as the summed concentration of dissolved Fe(II) and Fe(III) measured after 24 h) ranged 14 between 4-12% of the source materials’ iron content, but did not scale with either the surface area or the iron content of the samples. This suggests that other factors such as iron speciation and mineralogy may play a key role in iron solubility. Also, the elevated nitrate concentrations encountered from nitric acid at pH 1 suppressed dissolution of Fe(II) from AZTD, CL and SB particles, which we propose results from the surface-mediated, non-photochemical reduction of nitrate by Fe(II).

  9. Properties and sources of individual particles and some chemical species in the aerosol of a metropolitan underground railway station

    NASA Astrophysics Data System (ADS)

    Salma, Imre; Pósfai, Mihály; Kovács, Kristóf; Kuzmann, Ernő; Homonnay, Zoltán; Posta, József

    Aerosol samples in PM 10-2.0 and PM 2.0 size fractions were collected on the platform of a metropolitan underground railway station in central Budapest. Individual aerosol particles were studied using atomic force microscopy, scanning electron microscopy and transmission electron microscopy with energy-dispersive X-ray spectrometry and electron diffraction. The bulk aerosol samples were investigated by 57Fe Mössbauer spectroscopy, and they were subjected to chemical speciation analysis for Cr. The particles were classified into groups of iron oxides and iron, carbonates, silicates, quartz and carbonaceous debris. Electron micrographs showed that the Fe-rich particles in the PM 2.0 size fraction typically consisted of aggregates of nano-sized hematite crystals that were randomly oriented, had round shapes and diameters of 5-15 nm. In addition to hematite, a minor fraction of the iron oxide particles also contained magnetite. In addition, the PM 2.0-fraction particles typically had a rugged surface with layered or granular morphologies. Mössbauer spectroscopy suggested that hematite was a major Fe-bearing species in the PM 10-2.0 size fraction; its mass contribution to the Fe was 36%. Further constituents (ferrite, carbides and FeOOH) were also identified. The water soluble amounts of Cr for the underground railway station and city center were similar. In the PM 10-2.0 size fraction, practically all dissolved Cr had an oxidation state of three, which corresponds to ambient conditions. In the PM 2.0 size fraction, however, approximately 7% of the dissolved Cr was present as Cr(VI), which was different from that for the urban aerosol. It is suggested that the increased adverse health effects of aerosol particles in metros with respect to ambient outdoor particles is linked to the differences in the oxidation states, surface properties or morphologies.

  10. Predicting the Mineral Composition of Dust Aerosols

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Perez, C.; Miller, R. L.; Rodriguez, S.

    2012-12-01

    Models of the soil (''mineral'') dust aerosol cycle, embedded in climate and Earth system models, are essential tools for understanding the causal relationships and feedbacks between dust and climate. Many soil dust schemes in Earth system models use a simplified representation of soil dust aerosols, where the soil dust is distinguished by size bins or size distribution modes, with a globally uniform representation of the mineralogical composition of the particles. Although models with such a simplified assumption about the properties of soil dust particles have already significantly contributed to the understanding of the role of soil dust aerosols in climate, this is a limitation for a number of reasons: 1. The response of clouds and the large-scale circulation depends on the radiative properties like the single scattering albedo, which should vary with the mineral composition of the source region; 2. Chemical processes at the surface of the soil dust particles that form sulfate and nitrate coatings depend on the dust mineral composition; 3. The availability of soil dust minerals as cloud condensation nuclei depends on their hygroscopicity, which in turn depends on the mineral composition; 4. Fertilization of phytoplankton with soluble iron, a process that influences ocean carbon uptake, depends upon mineral types. We present a new version of the soil dust scheme in the NASA GISS Earth System ModelE, which takes into account the mineral composition of the soil dust particles. Soil dust aerosols are represented as a mixture of externally and internally mixed minerals, such as Illite, Kaolinite, Smectite, Calcite, Iron(hydr)oxide, Quartz, Feldspar, and Gypsum, as well as aggregates between Iron(hydr)oxide and each of the minerals. We test two approaches to constrain the mineral composition of the soil dust particles against data from measurements published in literature as well as measurements from Izaña (Tenerife). The comparison between modeled and measured data

  11. Does a theoretical estimation of the dust size distribution at emission suggest more bioavailable iron deposition.

    SciTech Connect

    Ito, A; Kok, J; Feng, Y; Penner, J

    2012-01-01

    Global models have been used to deduce atmospheric iron supply to the ocean, but the uncertainty remains large. We used a global chemical transport model to investigate the effect of the estimated size distribution of dust on the bioavailable iron deposition. Simulations are performed with six different size distributions for dust aerosols at emission using similar aerosol optical depths (AODs) to constrain the total emission flux of dust. The global dust emission rate using a recent theoretical estimate for the dust size distribution at emission (2116 Tg yr{sup -1}) is about two times larger than the average of estimates using the other four empirical size distributions (1089 {+-} 469 Tg yr{sup -1}). In contrast to the large differences in total emissions, the emission of fine dust (diameter < 2.5 {mu}m) is relatively robust (176 {+-} 34 Tg yr{sup -1}), due to the strong constraint of AOD on fine dust emission. Our model results indicate that soluble iron (SFe) deposition is relatively invariant to the dust size distribution at emission in regions where most soluble iron is provided by acid mobilization of fine dust. In contrast, the use of the theoretical size distribution suggests a larger deposition of SFe (by a factor of 1.2 to 5) in regions where the concentration of acidic gases is insufficient to promote iron dissolution in dust particles, such as the South Atlantic. These results could have important implications for the projection of marine ecosystem feedbacks to climate change and highlight the necessity to improve the dust size distribution.

  12. Iron Test

    MedlinePlus

    ... detect and help diagnose iron deficiency or iron overload. In people with anemia , these tests can help ... also be ordered when iron deficiency or iron overload is suspected. Early iron deficiency often goes unnoticed. ...

  13. Cellular iron metabolism.

    PubMed

    Ponka, P

    1999-03-01

    Iron is essential for oxidation-reduction catalysis and bioenergetics, but unless appropriately shielded, iron plays a key role in the formation of toxic oxygen radicals that can attack all biological molecules. Hence, specialized molecules for the acquisition, transport (transferrin), and storage (ferritin) of iron in a soluble nontoxic form have evolved. Delivery of iron to most cells, probably including those of the kidney, occurs following the binding of transferrin to transferrin receptors on the cell membrane. The transferrin-receptor complexes are then internalized by endocytosis, and iron is released from transferrin by a process involving endosomal acidification. Cellular iron storage and uptake are coordinately regulated post-transcriptionally by cytoplasmic factors, iron-regulatory proteins 1 and 2 (IRP-1 and IRP-2). Under conditions of limited iron supply, IRP binding to iron-responsive elements (present in 5' untranslated region of ferritin mRNA and 3' untranslated region of transferrin receptor mRNA) blocks ferritin mRNA translation and stabilizes transferrin receptor mRNA. The opposite scenario develops when iron in the transit pool is plentiful. Moreover, IRP activities/levels can be affected by various forms of "oxidative stress" and nitric oxide. The kidney also requires iron for metabolic processes, and it is likely that iron deficiency or excess can cause disturbed function of kidney cells. Transferrin receptors are not evenly distributed throughout the kidney, and there is a cortical-to-medullary gradient in heme biosynthesis, with greatest activity in the cortex and least in the medulla. This suggests that there are unique iron/heme metabolism features in some kidney cells, but the specific aspects of iron and heme metabolism in the kidney are yet to be explained.

  14. Aerosol Chemical and Physical Properties Observed over Puerto Rico in the Tropical North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Jusino-Atresino, R.; Xia, L.; Song, F.; Gao, Y.

    2008-12-01

    Tropospheric aerosols that originate in Africa and are transported over the Atlantic Ocean have potential impacts over the Caribbean region. To investigate aerosol properties over this region, air sampling was conducted at San Juan Cape (18.46°N, 66.12°W), Puerto Rico during the summer months in 2006. Aerosol samples were collected by both commercial PM2.5 sampler and in-house fabricated TSP sampler. Analyses of aerosols were made through the use of the following instrumental methods: (1)Ion Chromatography for the determinations of water-soluble cations (sodium, ammonium, potassium, magnesium and calcium) and anions (fluoride, acetate, propionate, methanesulfonate, chloride, nitrate, succinate, malonate, sulfate and oxalate); (2)Inductively Coupled Plasma Mass Spectrometry for the concentrations of selected trace elements (Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V); (3)Scanning Electron Microscopy for individual aerosol particle characterization. Crustal enrichment factors were calculated to determine the strength of crustal source. Preliminary results indicate that sodium (22 - 99 μg m- 3) and ammonium (1.1 - 50 μg m-3) were the major cations and chloride (1.5 - 99 μg m-3) and sulfate (35 μg m-3) were the dominant anions. Malonate (3.8 - 6.9 μg m- 3) was the most abundant organic anion. Atmospheric concentrations of iron ranged 0.30 - 3.3 ng m- 3. The elements, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V, were enriched by factors of 600 to 40,000 relative to their natural abundance in crustal soil. Principal components analysis indicates six assemblages of fifteen types of aerosol particles, dominated by Si - rich particles.

  15. Incorporation of Mg and Ca into nanostructured Fe2O3 improves Fe solubility in dilute acid and sensory characteristics in foods.

    PubMed

    Hilty, Florentine M; Knijnenburg, Jesper T N; Teleki, Alexandra; Krumeich, Frank; Hurrell, Richard F; Pratsinis, Sotiris E; Zimmermann, Michael B

    2011-01-01

    Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe

  16. Proteolytic digestion of meat is not necessary for iron solubilization.

    PubMed

    Carpenter, C E; Mahoney, A W

    1989-10-01

    The effects of digested cooked or raw meat and nondigested cooked or raw meat on iron solubility were investigated in vitro. Experiment 1 involved adding iron to meat slurries followed by in vitro digestion using pepsin and then pancreatin. Pepsin and pancreatin were excluded from incubation mixtures used as the nondigested treatment. Ferric iron in aqueous solution was used as an iron-only control. Dialyzable iron for each treatment was determined by measuring iron able to cross a dialysis membrane having a molecular weight cut-off of 6,000-8,000. Soluble iron was determined as that iron remaining in solution after centrifugation at 2,500 x g for 15 min. No differences (P greater than 0.05) in dialyzable iron were observed between treatments. However, soluble iron in the digested meat treatments was greater than soluble iron in the nondigested treatments (P = 0.05) or iron-only controls (P = 0.01). There was no difference (P greater than 0.05) between nondigested and iron-only treatments. In experiment 2, meat components were first separated by dialysis from digested or nondigested meat. The pH of the isolated components was adjusted to 2.0, iron added, and the pH adjusted to 7.0. Dialyzable and soluble iron were then determined. As in experiment 1, no differences (P greater than 0.05) in dialyzable iron among treatments were observed. Dialyzable components from digested or nondigested meat increased soluble iron as compared to the iron-only control (P = 0.01), with soluble iron values for the nondigested treatment being greater (P = 0.01) than for the digested treatment. Thus, meat contains a factor(s) that solubilizes iron independent of proteolytic digestion.

  17. Controls on dissolved cobalt in surface waters of the Sargasso Sea: Comparisons with iron and aluminum

    NASA Astrophysics Data System (ADS)

    Shelley, R. U.; Sedwick, P. N.; Bibby, T. S.; Cabedo-Sanz, P.; Church, T. M.; Johnson, R. J.; Macey, A. I.; Marsay, C. M.; Sholkovitz, E. R.; Ussher, S. J.; Worsfold, P. J.; Lohan, M. C.

    2012-06-01

    Dissolved cobalt (dCo), iron (dFe) and aluminum (dAl) were determined in water column samples along a meridional transect (˜31°N to 24°N) south of Bermuda in June 2008. A general north-to-south increase in surface concentrations of dFe (0.3-1.6 nM) and dAl (14-42 nM) was observed, suggesting that aerosol deposition is a significant source of dFe and dAl, whereas no clear trend was observed for near-surface dCo concentrations. Shipboard aerosol samples indicate fractional solubility values of 8-100% for aerosol Co, which are significantly higher than corresponding estimates of the solubility of aerosol Fe (0.44-45%). Hydrographic observations and analysis of time series rain samples from Bermuda indicate that wet deposition accounts for most (>80%) of the total aeolian flux of Co, and hence a significant proportion of the atmospheric input of dCo to our study region. Our aerosol data imply that the atmospheric input of dCo to the Sargasso Sea is modest, although this flux may be more significant in late summer. The water column dCo profiles reveal a vertical distribution that predominantly reflects `nutrient-type' behavior, versus scavenged-type behavior for dAl, and a hybrid of nutrient- and scavenged-type behavior for dFe. Mesoscale eddies also appear to impact on the vertical distribution of dCo. The effects of biological removal of dCo from the upper water column were apparent as pronounced sub-surface minima (21 ± 4 pM dCo), coincident with maxima in Prochlorococcus abundance. These observations imply that Prochlorococcus plays a major role in removing dCo from the euphotic zone, and that the availability of dCo may regulate Prochlorococcus growth in the Sargasso Sea.

  18. Atmospheric iron deposition: global distribution, variability, and human perturbations.

    PubMed

    Mahowald, Natalie M; Engelstaedter, Sebastian; Luo, Chao; Sealy, Andrea; Artaxo, Paulo; Benitez-Nelson, Claudia; Bonnet, Sophie; Chen, Ying; Chuang, Patrick Y; Cohen, David D; Dulac, Francois; Herut, Barak; Johansen, Anne M; Kubilay, Nilgun; Losno, Remi; Maenhaut, Willy; Paytan, Adina; Prospero, Joseph M; Shank, Lindsey M; Siefert, Ronald L

    2009-01-01

    Atmospheric inputs of iron to the open ocean are hypothesized to modulate ocean biogeochemistry. This review presents an integration of available observations of atmospheric iron and iron deposition, and also covers bioavailable iron distributions. Methods for estimating temporal variability in ocean deposition over the recent past are reviewed. Desert dust iron is estimated to represent 95% of the global atmospheric iron cycle, and combustion sources of iron are responsible for the remaining 5%. Humans may be significantly perturbing desert dust (up to 50%). The sources of bioavailable iron are less well understood than those of iron, partly because we do not know what speciation of the iron is bioavailable. Bioavailable iron can derive from atmospheric processing of relatively insoluble desert dust iron or from direct emissions of soluble iron from combustion sources. These results imply that humans could be substantially impacting iron and bioavailable iron deposition to ocean regions, but there are large uncertainties in our understanding.

  19. Direct Biohydrometallurgical Extraction of Iron from Ore

    SciTech Connect

    T.C. Eisele

    2005-10-01

    A completely novel approach to iron extraction was investigated, based on reductive leaching of iron by anaerobic bacteria. Microorganisms were collected from an anaerobic bog where natural seepage of dissolved iron was observed. This mixed culture was used to reduce insoluble iron in a magnetite ore to the soluble ferrous (Fe{sup +2}) state. While dissolution rates were slow, concentrations of dissolved iron as high as 3487 mg/l could be reached if sufficient time was allowed. A factorial study of the effects of trace nutrients and different forms of organic matter indicated that the best dissolution rates and highest dissolved iron concentrations were achieved using soluble carbohydrate (sucrose) as the bacterial food source, and that nutrients other than nitrogen, phosphorus, potassium, sodium, and acetate were not necessary. A key factor in reaching high levels of dissolved iron was maintaining a high level of carbon dioxide in solution, since the solubility of iron carbonates increases markedly as the quantity of dissolved carbon dioxide increases. Once the iron is dissolved, it has been demonstrated that the ferrous iron can then be electroplated from solution, provided that the concentration of iron is sufficiently high and the hydrogen ion concentration is sufficiently low. However, if the leaching solution is electrolyzed directly, organic matter precipitates at the cathode along with the metallic iron. To prevent this problem, the ferrous iron should be separated from the bulk solution in a more concentrated, purified form. One route to accomplishing this is to take advantage of the change in solubility of ferrous iron as a function of carbon dioxide concentration. By cycling the concentration of carbon dioxide in solution, it is possible to produce an iron-rich concentrate that should be suitable for electrolysis. This represents the first viable hydrometallurgical method for leaching iron directly from ore and producing metallic iron.

  20. Iron Chelation

    MedlinePlus

    ... iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you have ... may want to perform: How quickly does iron overload happen? This is different for each person. It ...

  1. In vitro bioavailability of iron from the heme analogue sodium iron chlorophyllin.

    PubMed

    Miret, Silvia; Tascioglu, Serpil; van der Burg, Monique; Frenken, Leon; Klaffke, Werner

    2010-01-27

    The use of heme analogues from vegetable origin could provide an alternative iron source of potentially high bioavailability. Sodium iron chlorophyllin is a water-soluble semisynthetic chlorophyll derivative where the magnesium in the porphyrin ring has been substituted by iron. We have used an in vitro model that combines gastric and intestinal digestion followed by intestinal iron uptake in Caco-2 cells to determine the bioavailability of iron from sodium iron chlorophyllin. Our results demonstrate that sodium iron chlorophyllin is stable under simulated gastrointestinal conditions and is able to deliver bioavailable iron to Caco-2 cells. Similar to the heme, the bioavailability of iron from sodium iron chlorophyllin is dependent on the food matrix, and it was inhibited by calcium. Potentially, sodium iron chlorophyllin could be used as an iron fortificant from vegetable origin with high bioavailability.

  2. Aerosolized Antibiotics.

    PubMed

    Restrepo, Marcos I; Keyt, Holly; Reyes, Luis F

    2015-06-01

    Administration of medications via aerosolization is potentially an ideal strategy to treat airway diseases. This delivery method ensures high concentrations of the medication in the targeted tissues, the airways, with generally lower systemic absorption and systemic adverse effects. Aerosolized antibiotics have been tested as treatment for bacterial infections in patients with cystic fibrosis (CF), non-CF bronchiectasis (NCFB), and ventilator-associated pneumonia (VAP). The most successful application of this to date is treatment of infections in patients with CF. It has been hypothesized that similar success would be seen in NCFB and in difficult-to-treat hospital-acquired infections such as VAP. This review summarizes the available evidence supporting the use of aerosolized antibiotics and addresses the specific considerations that clinicians should recognize when prescribing an aerosolized antibiotic for patients with CF, NCFB, and VAP.

  3. Global Aerosols

    Atmospheric Science Data Center

    2013-04-19

    ... sizes and from multiple sources, including biomass burning, mineral dust, sea salt and regional industrial pollution. A color scale is ... desert source region. Deserts are the main sources of mineral dust, and MISR obtains aerosol optical depth at visible wavelengths ...

  4. Soluble dust as source of nutrients to the oceans and the role of humans

    NASA Astrophysics Data System (ADS)

    Tsigaridis, K.; Kanakidou, M.; Myriokefalitakis, S.; Nikolaou, P.; Daskalakis, N.; Theodosi, C.; Nenes, A.; Mihalopoulos, N.

    2014-12-01

    Atmospheric deposition of trace constituents, both of natural and anthropogenic origin, can act as a nutrient source into the open ocean and affect marine ecosystem functioning and subsequently the exchange of CO2 between the atmosphere and the global ocean. Dust is known as a major source of nutrients (Fe and P) into the atmosphere, but only a fraction of these nutrients is released in soluble form that can be assimilated by the ecosystems. Dust is also known to enhance N deposition by interacting with anthropogenic pollutants and neutralisation of part of the acidity of the atmosphere by crustal alkaline species. The link between the soluble iron (Fe) and phosphorus (P) atmospheric deposition and atmospheric acidity, as well as anthropogenic sources, is investigated. The global atmospheric Fe, P and N cycle are parameterized in the global 3-D chemical transport model TM4-ECPL. Both primary emissions of total and soluble Fe and P associated with dust and combustion processes are taken into account, as well as inorganic and organic N emissions. The impact of atmospheric acidity on nutrient solubility is parameterised based on experimental findings. The model results are evaluated by comparison with available observations. The impact of air-quality changes on soluble nutrient deposition is studied by performing sensitivity simulations using preindustrial, present and future emission scenarios. The response of the chemical composition of nutrient-containing aerosols to environmental changes is demonstrated and quantified. This work has been supported by ARISTEIA - PANOPLY grant co-financed by European Union (ESF) and Greek national funds NSRF.

  5. Soluble dust as source of nutrients to the global ocean and the role of humans.

    NASA Astrophysics Data System (ADS)

    Kanakidou, Maria; Myriokefalitakis, Stelios; Nikolaou, Panagiota; Daskalakis, Nikos; Theodosi, Christina; Nenes, Athanassios; Tsigaridis, Kostas; Mihalopoulos, Nikos

    2015-04-01

    Atmospheric deposition of trace constituents, both of natural and anthropogenic origin, can act as a nutrient source into the open ocean and affect marine ecosystem functioning and subsequently the exchange of CO2 between the atmosphere and the global ocean. Dust is known as a major source of nutrients (Fe and P) into the atmosphere, but only a fraction of these nutrients is released in soluble form that can be assimilated by the ecosystems. Dust is also known to enhance N deposition by interacting with anthropogenic pollutants and neutralisation of part of the acidity of the atmosphere by crustal alkaline species. The link between the soluble iron (Fe) and phosphorus (P) atmospheric deposition and atmospheric acidity, as well as anthropogenic sources, is investigated. The global atmospheric Fe, P and N cycle are parameterized in the global 3-D chemical transport model TM4-ECPL. Both primary emissions of total and soluble Fe and P associated with dust and combustion processes are taken into account, as well as inorganic and organic N emissions. The impact of atmospheric acidity on nutrient solubility is parameterised based on experimental findings. The model results are evaluated by comparison with available observations. The impact of air-quality changes on soluble nutrient deposition is studied by performing sensitivity simulations using preindustrial, present and future emission scenarios. The response of the chemical composition of nutrient-containing aerosols to environmental changes is demonstrated and quantified. This work has been supported by ARISTEIA - PANOPLY grant co-financed by European Union (ESF) and Greek national funds NSRF.

  6. Properties of aerosol processed by ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Y.; Adler, G.; Moise, T.; Erlick-Haspel, C.

    2012-12-01

    We suggest that highly porous aerosol (HPA) can form in the upper troposphere/lower stratosphere when ice particles encounter sub-saturation leading to ice sublimation similar to freeze drying. This process can occur at the lower layers of cirrus clouds (few km), at anvils of high convective clouds and thunderstorms, in clouds forming in atmospheric gravitational waves, in contrails and in high convective clouds injecting to the stratosphere. A new experimental system that simulates freeze drying of proxies for atmospheric aerosol at atmospheric pressure was constructed and various proxies for atmospheric soluble aerosol were studied. The properties of resulting HPA were characterized by various methods. It was found that the resulting aerosol have larger sizes (extent depends on substance and mixing), lower density (largevoid fraction), lower optical extinction and higher CCN activity and IN activity. Implication of HPA's unique properties and their atmospheric consequences to aerosol processing in ice clouds and to cloud cycles will be discussed.

  7. Soluble vs. insoluble fiber

    MedlinePlus

    ... soluble and insoluble. Both are important for health, digestion, and preventing diseases. Soluble fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  8. THERMODYNAMIC MODELING OF LIQUID AEROSOLS CONTAINING DISSOLVED ORGANICS AND ELECTROLYTES

    EPA Science Inventory

    Many tropospheric aerosols contain large fractions of soluble organic material, believed to derive from the oxidation of precursors such alpha-pinene. The chemical composition of aerosol organic matter is complex and not yet fully understood.

    The key properties of solu...

  9. Regulation of iron transport systems in Enterobacteriaceae in response to oxygen and iron availability.

    PubMed

    Carpenter, Chandra; Payne, Shelley M

    2014-04-01

    Iron is an essential nutrient for most bacteria. Depending on the oxygen available in the surrounding environment, iron is found in two distinct forms: ferrous (Fe(II)) or ferric (Fe(III)). Bacteria utilize different transport systems for the uptake of the two different forms of iron. In oxic growth conditions, iron is found in its insoluble, ferric form, and in anoxic growth conditions iron is found in its soluble, ferrous form. Enterobacteriaceae have adapted to transporting the two forms of iron by utilizing the global, oxygen-sensing regulators, ArcA and Fnr to regulate iron transport genes in response to oxygen.

  10. Tropospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    It is widely believed that "On a clear day you can see forever," as proclaimed in the 1965 Broadway musical of the same name. While an admittedly beautiful thought, we all know that this concept is only figurative. Aside from Earth's curvature and Rayleigh scattering by air molecules, aerosols - colloidal suspensions of solid or liquid particles in a gas - limit our vision. Even on the clearest day, there are billions of aerosol particles per cubic meter of air.Atmospheric aerosols are commonly referred to as smoke, dust, haze, and smog, terms that are loosely reflective of their origin and composition. Aerosol particles have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period, the natural background aerosol has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. One manifestation of this impact is reduced visibility (Figure 1). Thus, perhaps more than in other realms of geochemistry, when considering the composition of the troposphere one must consider the effects of these activities. The atmosphere has become a reservoir for vast quantities of anthropogenic emissions that exert important perturbations on it and on the planetary ecosystem in general. Consequently, much recent research focuses on the effects of human activities on the atmosphere and, through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric aerosols in particular, must include the effects of human activities. (201K)Figure 1. Impairment of visibility by aerosols. Photographs at Yosemite National Park, California, USA. (a) Low aerosol concentration (particulate matter of aerodynamic diameter less than 2.5 μm, PM2.5=0.3 μg m-3; particulate matter of aerodynamic diameter less than 10

  11. Characterization of aerosol over the Northern South China Sea during two cruises in 2003

    NASA Astrophysics Data System (ADS)

    Zhang, Xingying; Zhuang, Guoshun; Guo, Jinghua; Yin, Kedong; Zhang, Peng

    Atmospheric transport of trace elements has been found to be an important pathway for their input to the ocean. TSP, PM10, and PM2.5 aerosol samples were collected over the Northern South China Sea in two cruises in 2003 to estimate the input of aerosol from continent to the ocean. About 23 elements and 14 soluble ions in aerosol samples were measured. The average mass concentration of TSP in Cruise I in January (78 μg m -3) was ˜twice of that in Cruise II in April (37 μg m -3). Together with the crustal component, heavy metals from pollution sources over the land (especially from the industry and automobiles in Guangzhou) were transported to and deposited into the ocean. The atmospheric MSA concentrations in PM2.5 (0.048 μg m -3 in Cruise I and 0.043 μg m -3 in Cruise II) over Northern South China Sea were comparable to those over other coastal regions. The ratio of non-sea-salt (NSS)-sulfate to MSA is 103-655 for Cruise I and 15-440 for Cruise II in PM2.5 samples, which were much higher than those over remote oceans. The estimated anthropogenic sulfate accounts for 83-98% in Cruise I and 63-95% in Cruise II of the total NSS-sulfate. Fe (II) concentration in the aerosols collected over the ocean ranged from 0.1 to 0.9 μg m -3, accounting for 16-82% of the total iron in the aerosol, which could affect the marine biogeochemical cycle greatly.

  12. CCN activity of aliphatic amine secondary aerosol

    NASA Astrophysics Data System (ADS)

    Tang, X.; Price, D.; Praske, E.; Vu, D.; Purvis-Roberts, K.; Silva, P. J.; Cocker, D. R., III; Asa-Awuku, A.

    2014-01-01

    Aliphatic amines can form secondary aerosol via oxidation with atmospheric radicals (e.g. hydroxyl radical and nitrate radical). The particle composition can contain both secondary organic aerosol (SOA) and inorganic salts. The fraction of organic to inorganic materials in the particulate phase influences aerosol hygroscopicity and cloud condensation nuclei (CCN) activity. SOA formed from trimethylamine (TMA) and butylamine (BA) reactions with hydroxyl radical (OH) is composed of organic material of low hygroscopicity (single hygroscopicity parameter, κ ≤ 0.25). Secondary aerosol formed from the tertiary aliphatic amine (TMA) with N2O5 (source of nitrate radical, NO3), contains less volatile compounds than the primary aliphatic amine (BA) aerosol. TMA + N2O5 form semi-volatile organics in low RH conditions that have κ ~ 0.20, indicative of slightly soluble organic material. As RH increases, several inorganic amine salts are formed as a result of acid-base reactions. The CCN activity of the humid TMA-N2O5 aerosol obeys Zdanovskii, Stokes, and Robinson (ZSR) ideal mixing rules. Higher CCN activity (κ > 0.3) was also observed for humid BA+N2O5 aerosols compared with dry aerosol (κ ~ 0.2), as a result of the formation of inorganic salts such as NH4NO3 and butylamine nitrate (C4H11N · HNO3). Compared with TMA, BA+N2O5 reactions produce more volatile aerosols. The BA+N2O5 aerosol products under humid experiments were found to be very sensitive to the temperature within the stream-wise continuous flow thermal gradient CCN counter. The CCN counter, when set above a 21 °C temperature difference, evaporates BA+N2O5 aerosol formed at RH ≥ 30%; κ ranges from 0.4 to 0.7 and is dependent on the instrument supersaturation (ss) settings. The aerosol behaves non-ideally, hence simple ZSR rules cannot be applied to the CCN results from the primary aliphatic amine system. Overall, aliphatic amine aerosol systems κ ranges from 0.2 < κ < 0.7. This work indicates that

  13. Colorimetric determination of zirconium in antiperspirant aerosols.

    PubMed

    Beavin, P

    1976-07-01

    A rapid direct dilution procedure for the estimation of soluble zirconium and a fusion procedure for the determination of total zirconium (soluble and insoluble forms) in cream base concentrates prepared from antiperspirant aerosols are described. The direct dilution procedure involves extraction of soluble zirconium with HCl (55 + 45). The filtered extract is reacted with alizarin red S to form a stable colored complex which is measured spectrophotometrically. The fusion procedure involves ashing the aerosol concentrate followed by fusion of the ash with potassium pyrosulfate to form an acid-soluble melt. Zirconium is precipitated from solution as the hydroxide and washed to eliminate interfering ions, particularly sulfate. After redissolving in HCl (55 + 45) and reacting with alizarin red S, total zirconium is measured. Zirconyl chloride octahydrate, assayed gravimetrically by hydroxide precipitation and conversion to the oxide, is used as the zirconium reference standard. Concentration range of zirconium measured was 200-500 mug/100 ml. Recoveries of standard zirconium added to commercial aerosols labeled to contain aluminum and zirconyl hydroxychlorides ranged from 97 to 101% by the fusion procedure. Analysis of these aerosols by direct dilution gave generally slightly lower results than by fusion. It is recommended that the procedures be collaboratively studied after further testing of their general applicability to a variety of drugs and cosmetics. PMID:939750

  14. Influences of external vs. core-shell mixing on aerosol optical properties at various relative humidities.

    PubMed

    Ramachandran, S; Srivastava, Rohit

    2013-05-01

    Aerosol optical properties of external and core-shell mixtures of aerosol species present in the atmosphere are calculated in this study for different relative humidities. Core-shell Mie calculations are performed using the values of radii, refractive indices and densities of aerosol species that act as core and shell, and the core-shell radius ratio. The single scattering albedo (SSA) is higher when the absorbing species (black carbon, BC) is the core, while for a sulfate core SSA does not vary significantly as the BC in the shell dominates the absorption. Absorption gets enhanced in core-shell mixing of absorbing and scattering aerosols when compared to their external mixture. Thus, SSA is significantly lower for a core-shell mixture than their external mixture. SSA is more sensitive to core-shell ratio than mode radius when BC is the core. The extinction coefficient, SSA and asymmetry parameter are higher for external mixing when compared to BC (core)-water soluble aerosol (shell), and water soluble aerosol (core)-BC (shell) mixtures in the relative humidity range of 0 to 90%. Spectral SSA exhibits the behaviour of the species which acts as a shell in core-shell mixing. The asymmetry parameter for an external mixture of water soluble aerosol and BC is higher than BC (core)-water soluble aerosol (shell) mixing and increases as function of relative humidity. The asymmetry parameter for the water soluble aerosol (core)-BC (shell) is independent of relative humidity as BC is hydrophobic. The asymmetry parameter of the core-shell mixture decreases when BC aerosols are involved in mixing, as the asymmetry parameter of BC is lower. Aerosol optical depth (AOD) of core-shell mixtures increases at a higher rate when the relative humidity exceeds 70% in continental clean and urban aerosol models, whereas AOD remains the same when the relative humidity exceeds 50% in maritime aerosol models. The SSA for continental aerosols varies for core-shell mixing of water soluble

  15. Microbial reduction of iron ore

    DOEpatents

    Hoffmann, M.R.; Arnold, R.G.; Stephanopoulos, G.

    1989-11-14

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry. 11 figs.

  16. Microbial reduction of iron ore

    DOEpatents

    Hoffmann, Michael R.; Arnold, Robert G.; Stephanopoulos, Gregory

    1989-01-01

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry.

  17. [Aerosol therapy].

    PubMed

    Wildhaber, J H

    1998-08-15

    Aerosol therapy plays a major role in the diagnosis and treatment of various lung diseases. The aim of inhalation therapy is to deposit a reproducible and adequate dose of a specific drug to the airways, in order to achieve a high, local, clinical effect while avoiding serious systemic side effects. To achieve this goal, it is therefore important to have an efficient inhalation device to deliver different medications. However, the currently available therapeutic inhalation devices (nebuliser, pressurised metered-dose inhaler and dry powder inhaler) are not very efficient in aerosol delivery and have several disadvantages. Inhalation devices can be assessed by in vitro studies, filter studies and radiolabelled deposition studies. Several radiolabelled deposition studies have shown that nebulisers and pressurised metered-dose inhalers are not very efficient in aerosol delivery. In children, before 1997, only 0.5% to 15% of the total nebulised or actuated dose from a nebuliser or pressurised metered-dose inhaler actually reached the lungs. These numbers were somewhat improved in adults, 30% of the total nebulised or actuated dose reaching the airways. Aerosol therapy with dry powder inhalers was the most efficient before 1997, 30% of the total dose being deposited in the lungs of adults and children. In 1997, new developments in pressurised metered-dose inhalers much improved their efficiency in aerosol delivery. Lung deposition can be increased by up to 60% with use of a non-electrostatic holding chamber and/or a pressurised metered-dose inhaler with a hydrofluoroalkane propellant possessing superior aerosol characteristics. Several studies comparing the clinical efficiency of different inhalation devices have shown that the choice of an optimal inhalation device is crucial. In addition to the aerosol characteristics, ventilation parameters and airway morphology have an important bearing on deposition patterns. These parameters may be greatly influenced by the

  18. Effect of nitrate and sulfate relative abundance in PM2.5 on liquid water content explored through half-hourly observations of inorganic soluble aerosols at a polluted receptor site

    NASA Astrophysics Data System (ADS)

    Xue, Jian; Griffith, Stephen M.; Yu, Xin; Lau, Alexis K. H.; Yu, Jian Zhen

    2014-12-01

    Liquid water content (LWC) is the amount of liquid water on aerosols. It contributes to visibility degradation, provides a surface for gas condensation, and acts as a medium for heterogeneous gas/particle reactions. In this study, 520 half-hourly measurements of ionic chemical composition in PM2.5 at a receptor site in Hong Kong are used to investigate the dependence of LWC on ionic chemical composition, particularly on the relative abundance of sulfate and nitrate. LWC was estimated using a thermodynamic model (AIM-III). Within this data set of PM2.5 ionic compositions, LWC was highly correlated with the multivariate combination of sulfate and nitrate concentrations and RH (R2 = 0.90). The empirical linear regression result indicates that LWC is more sensitive to nitrate mass than sulfate. During a nitrate episode, the highest LWC (80.6 ± 17.9 μg m-3) was observed and the level was 70% higher than that during a sulfate episode despite a similar ionic PM2.5 mass concentration. A series of sensitivity tests were conducted to study LWC change as a function of the relative nitrate and sulfate abundance, the trend of which is expected to shift to more nitrate in China as a result of SO2 reduction and increase in NOx emission. Starting from a base case that uses the average of measured PM2.5 ionic chemical composition (63% SO42-, 11% NO3-, 19% NH4+, and 7% other ions) and an ionic equivalence ratio, [NH4+]/(2[SO42-] + [NO3-]), set constant to 0.72, the results show LWC would increase by 204% at RH = 40% when 50% of the SO42- is replaced by NO3- mass concentration. This is largely due to inhibition of (NH4)3H(SO4)2 crystallization while PM2.5 ionic species persist in the aqueous phase. At RH = 90%, LWC would increase by 12% when 50% of the SO42- is replaced by NO3- mass concentration. The results of this study highlight the important implications to aerosol chemistry and visibility degradation associated with LWC as a result of a shift in PM2.5 ionic chemical

  19. Changes in soluble transferrin receptor and hemoglobin concentrations in Malawian mothers are associated with those values in their exclusively breastfed, HIV-exposed infants.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infant iron status at birth is influenced bymaternal iron status during pregnancy; however, there are limited data on the extent to which maternal iron status is associated with infant iron status during exclusive breastfeeding. We evaluated how maternal and infant hemoglobin and iron status [solubl...

  20. Acceleration of oxygen decline in the tropical Pacific over the past decades by aerosol pollutants

    NASA Astrophysics Data System (ADS)

    Ito, T.; Nenes, A.; Johnson, M. S.; Meskhidze, N.; Deutsch, C.

    2016-06-01

    Dissolved oxygen in the mid-depth tropical Pacific Ocean has declined in the past several decades. The resulting expansion of the oxygen minimum zone has consequences for the region's ecosystem and biogeochemical cycles, but the causes of the oxygen decline are not yet fully understood. Here we combine models of atmospheric chemistry, ocean circulation and biogeochemical cycling to test the hypothesis that atmospheric pollution over the Pacific Ocean contributed to the redistribution of oxygen in deeper waters. We simulate the pollution-induced enhancement of atmospheric soluble iron and fixed nitrogen deposition, as well as its impacts on ocean productivity and biogeochemical cycling for the late twentieth century. The model reproduces the magnitude and large-scale pattern of the observed oxygen changes from the 1970s to the 1990s, and the sensitivity experiments reveal the reinforcing effects of pollution-enhanced iron deposition and natural climate variability. Despite the aerosol deposition being the largest in mid-latitudes, its effect on oceanic oxygen is most pronounced in the tropics, where ocean circulation transports added iron to the tropics, leading to an increased regional productivity, respiration and subsurface oxygen depletion. These results suggest that anthropogenic pollution can interact and amplify climate-driven impacts on ocean biogeochemistry, even in remote ocean biomes.

  1. Overexpression of Arabidopsis VIT1 increases accumulation of iron in cassava roots and stems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iron is extremely abundant in the soil, but its uptake in plants is limited due to low solubility in neutral or alkaline soils. Plants can rely on rhizosphere acidification to increase iron solubility. AtVIT1 was previously found to be involved in mediating vacuolar sequestration of iron, which indi...

  2. Micromilling enhances iron bioaccessibility from wholegrain wheat.

    PubMed

    Latunde-Dada, G O; Li, X; Parodi, A; Edwards, C H; Ellis, P R; Sharp, P A

    2014-11-19

    Cereals constitute important sources of iron in human diet; however, much of the iron in wheat is lost during processing for the production of white flour. This study employed novel food processing techniques to increase the bioaccessibility of naturally occurring iron in wheat. Iron was localized in wheat by Perl's Prussian blue staining. Soluble iron from digested wheat flour was measured by a ferrozine spectrophotometric assay. Iron bioaccessibility was determined using an in vitro simulated peptic-pancreatic digestion, followed by measurement of ferritin (a surrogate marker for iron absorption) in Caco-2 cells. Light microscopy revealed that iron in wheat was encapsulated in cells of the aleurone layer and remained intact after in vivo digestion and passage through the gastrointestinal tract. The solubility of iron in wholegrain wheat and in purified wheat aleurone increased significantly after enzymatic digestion with Driselase, and following mechanical disruption using micromilling. Furthermore, following in vitro simulated peptic-pancreatic digestion, iron bioaccessibility, measured as ferritin formation in Caco-2 cells, from micromilled aleurone flour was significantly higher (52%) than from whole aleurone flour. Taken together our data show that disruption of aleurone cell walls could increase iron bioaccessibility. Micromilled aleurone could provide an alternative strategy for iron fortification of cereal products.

  3. Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation

    NASA Astrophysics Data System (ADS)

    Beaver, M. R.; Elrod, M. J.; Garland, R. M.; Tolbert, M. A.

    2006-03-01

    Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C3 and C9) on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s) at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

  4. Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation

    NASA Astrophysics Data System (ADS)

    Beaver, M. R.; Elrod, M. J.; Garland, R. M.; Tolbert, M. A.

    2006-08-01

    Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C3 and C9) on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s) at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the inferred mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

  5. Characterization and source apportionment of aerosol light extinction in Chengdu, southwest China

    NASA Astrophysics Data System (ADS)

    Tao, Jun; Zhang, Leiming; Cao, Junji; Hsu, Shih-Chieh; Xia, Xiangao; Zhang, Zhisheng; Lin, Zejian; Cheng, Tiantao; Zhang, Renjian

    2014-10-01

    To investigate aerosol properties in the Sichuan Basin of China, field aerosol sampling was carried out in Chengdu, China during four one-month periods, each in a different season in 2011. Aerosol scattering coefficient (bsp) at dry (RH<40%) and wet (40% < RH<90%) conditions and aerosol absorption coefficient (bap) were measured. Additionally, daily PM2.5 and PM10 samples were also collected. PM2.5 samples were subject to chemical analysis for various chemical components including major water-soluble ions, organic and elemental carbon (OC and EC), trace elements, as well as anhydrosugar Levoglucosan (LG) and Mannosan (MN). A multiple linear regression analysis was applied to the measured dry bsp against (NH4)2SO4, NH4NO3, organic mass (OM), fine soil (FS), and coarse mass (CM, PM2.5-10), and to the measured bap against EC in all the four seasons to evaluate the impact of individual chemical components of PM2.5 and CM on aerosol light extinction (bext = bsp + bap). Mass scattering efficiency (MSE) and mass absorption efficiency (MAE) of the individual chemical components of PM2.5 were estimated based on seasonal regression equations and were then used for estimating bext. The annual bsp, bap and single scattering albedo (SSA) at dry conditions were 456 ± 237 Mm-1, 96 ± 48 Mm-1 and 0.82 ± 0.05, respectively. The annual average bsp at ambient conditions estimated through hygroscopic curve of aerosol (f(RH)) was 763 ± 415 Mm-1, which was 1.7 times of the dry bsp. The annual average SSA at ambient conditions also increased to 0.88 ± 0.04. The estimated dry bext was only 2 ± 9% higher than the measurements and the estimated ambient bext from individual chemical components was only 1 ± 10% lower, on an annual basis, than that estimated from using f(RH). Secondary inorganic aerosols, coal combustion, biomass burning, iron and steel industry, Mo-related industry, soil dust, and CM to bext were estimated to account for 41 ± 19%, 18 ± 12%, 14 ± 13%, 13 ± 11%, 5

  6. Aerosol Transport Over Equatorial Africa

    NASA Technical Reports Server (NTRS)

    Gatebe, C. K.; Tyson, P. D.; Annegarn, H. J.; Kinyua, A. M.; Piketh, S.; King, M.; Helas, G.

    1999-01-01

    Long-range and inter-hemispheric transport of atmospheric aerosols over equatorial Africa has received little attention so far. Most aerosol studies in the region have focussed on emissions from rain forest and savanna (both natural and biomass burning) and were carried out in the framework of programs such as DECAFE (Dynamique et Chimie Atmospherique en Foret Equatoriale) and FOS (Fires of Savanna). Considering the importance of this topic, aerosols samples were measured in different seasons at 4420 meters on Mt Kenya and on the equator. The study is based on continuous aerosol sampling on a two stage (fine and coarse) streaker sampler and elemental analysis by Particle Induced X-ray Emission. Continuous samples were collected for two seasons coinciding with late austral winter and early austral spring of 1997 and austral summer of 1998. Source area identification is by trajectory analysis and sources types by statistical techniques. Major meridional transports of material are observed with fine-fraction silicon (31 to 68 %) in aeolian dust and anthropogenic sulfur (9 to 18 %) being the major constituents of the total aerosol loading for the two seasons. Marine aerosol chlorine (4 to 6 %), potassium (3 to 5 %) and iron (1 to 2 %) make up the important components of the total material transport over Kenya. Minimum sulfur fluxes are associated with recirculation of sulfur-free air over equatorial Africa, while maximum sulfur concentrations are observed following passage over the industrial heartland of South Africa or transport over the Zambian/Congo Copperbelt. Chlorine is advected from the ocean and is accompanied by aeolian dust recirculating back to land from mid-oceanic regions. Biomass burning products are transported from the horn of Africa. Mineral dust from the Sahara is transported towards the Far East and then transported back within equatorial easterlies to Mt Kenya. This was observed during austral summer and coincided with the dying phase of 1997/98 El

  7. Formation and Reactivity of Biogenic Iron Microminerals

    SciTech Connect

    Beveridge, Terrance J.; Ferris, F. Grant

    2001-08-15

    The overall purpose of the project was to explore and quantify the processes that control the formation and reactivity of biogenic iron microminerals and their impact on the solubility of metal contaminants. The research addressed how surface components of bacterial cells, extracellular organic material, and the aqueous geochemistry of the DIRB microenvironment impacts the mineralogy, chemical state and micromorphology of reduced iron phases.

  8. Formation and Reactivity of Biogenic Iron Microminerals

    SciTech Connect

    Beveridge, Terrance J.; Glasauer, Susan; Korenevsky, Anton; Ferris, F. Grant

    2000-08-08

    The overall purpose of the project is to explore and quantify the processes that control the formation and reactivity of biogenic iron microminerals and their impact on the solubility of metal contaminants. The research addresses how surface components of bacterial cells, extracellular organic material, and the aqueous geochemistry of the DIRB microenvironment impacts the mineralogy, chemical state and micromorphology of reduced iron phases.

  9. Solubility of HCL in sulfuric acid at stratospheric temperatures

    NASA Technical Reports Server (NTRS)

    Williams, Leah R.; Golden, David M.

    1993-01-01

    The solubility of HCl in sulfuric acid was measured using a Knudsen cell technique. Effective Henry's law constants are reported for sulfuric acid concentrations between 50 and 60 weight percent and for temperatures between 220 and 230 K. The measured values indicate that very little HCl will be dissolved in the stratospheric sulfate aerosol particles.

  10. Salting Constants of Small Organic Molecules in Aerosol-Relevant Salts and Application to Aerosol Formation in the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Waxman, E.; Carlton, A. M. G.; Ziemann, P. J.; Volkamer, R. M.

    2014-12-01

    Secondary organic aerosol (SOA) formation from small water-soluble molecules such as glyoxal and methyl glyoxal is a topic of emerging interest. Results from recent field campaigns, e.g. Waxman et al. (2013, GRL) and Knote et al. (2014, ACP), show that these molecules can form significant SOA mass as a result of 'salting-in'. Salting-in happens when a molecule's solubility increases with salt concentration and salting-out is the reverse. Salting effects modify the solubility exponentially with increasing salt concentration, and thus the effective Henry's law constant can strongly modify partitioning, and multiphase chemical reaction rates in aerosol water. Moreover, the solubility in aerosol water cannot easily inferred based on the solubility in cloud water, as the salting effects could change the solubility by a factor of 104 or more. In this work, we have devised and applied a novel experimental setup to measure salting constants using an ion trap mass spectrometer. We focus on small, water soluble molecules like methyl glyoxal and similar compounds and measure salting constants for aerosol-relevant salts including ammonium sulfate, ammonium nitrate, and sodium chloride. The Setschenow salting-constant values are then used to parameterize the effects of salting in CMAQ. We present a series of sensitivity studies of the effects that inorganic aerosols have on the SOA formation from small soluble molecules in the southeastern United States.

  11. Toxicity of chelated iron (Fe-DTPA) in American cranberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    American cranberry (Vaccinium macrocarpon) is naturally adapted to environments with high concentrations of soluble iron. Yet, there is a need to further explore iron nutrition in cranberry given concerns of toxicity problems from irrigation with iron-rich water. This study investigated the threat o...

  12. Iron deficiency.

    PubMed

    Scrimshaw, N S

    1991-10-01

    The world's leading nutritional problem is iron deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. Iron deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune system which reduces the body's ability to fight infection. Iron deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's iron. This iron is always being recycled as more red blood cells are made. The rest of the needed iron does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This iron comes from our diet, especially meat. Even though some plants, such as spinach, are high in iron, the body can only absorb 1.4-7% of the iron in plants whereas it can absorb 20% of the iron in red meat. In many developing countries, the common vegetarian diets contribute to high rates of iron deficiency. Parasitic diseases and abnormal uterine bleeding also promote iron deficiency. Iron therapy in anemic children can often, but not always, improve behavior and cognitive performance. Iron deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess iron can be damaging. Too much supplemental iron in a malnourished child promotes fatal infections since the excess iron is available for the pathogens use. Many countries do not have an effective system for diagnosing, treating, and preventing iron deficiency. Therefore a concerted international effort is needed to eliminate iron deficiency in the world.

  13. Amyloid Fibril Solubility.

    PubMed

    Rizzi, L G; Auer, S

    2015-11-19

    It is well established that amyloid fibril solubility is protein specific, but how solubility depends on the interactions between the fibril building blocks is not clear. Here we use a simple protein model and perform Monte Carlo simulations to directly measure the solubility of amyloid fibrils as a function of the interaction between the fibril building blocks. Our simulations confirms that the fibril solubility depends on the fibril thickness and that the relationship between the interactions and the solubility can be described by a simple analytical formula. The results presented in this study reveal general rules how side-chain-side-chain interactions, backbone hydrogen bonding, and temperature affect amyloid fibril solubility, which might prove to be a powerful tool to design protein fibrils with desired solubility and aggregation properties in general. PMID:26496385

  14. Amyloid Fibril Solubility.

    PubMed

    Rizzi, L G; Auer, S

    2015-11-19

    It is well established that amyloid fibril solubility is protein specific, but how solubility depends on the interactions between the fibril building blocks is not clear. Here we use a simple protein model and perform Monte Carlo simulations to directly measure the solubility of amyloid fibrils as a function of the interaction between the fibril building blocks. Our simulations confirms that the fibril solubility depends on the fibril thickness and that the relationship between the interactions and the solubility can be described by a simple analytical formula. The results presented in this study reveal general rules how side-chain-side-chain interactions, backbone hydrogen bonding, and temperature affect amyloid fibril solubility, which might prove to be a powerful tool to design protein fibrils with desired solubility and aggregation properties in general.

  15. Identifying Aerosol Type/Mixture from Aerosol Absorption Properties Using AERONET

    NASA Technical Reports Server (NTRS)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Dickerson, R. R.; Thompson, A. M.; Slutsker, I.; Li, Z.; Tripathi, S. N.; Singh, R. P.; Zibordi, G.

    2010-01-01

    Aerosols are generated in the atmosphere through anthropogenic and natural mechanisms. These sources have signatures in the aerosol optical and microphysical properties that can be used to identify the aerosol type/mixture. Spectral aerosol absorption information (absorption Angstrom exponent; AAE) used in conjunction with the particle size parameterization (extinction Angstrom exponent; EAE) can only identify the dominant absorbing aerosol type in the sample volume (e.g., black carbon vs. iron oxides in dust). This AAE/EAE relationship can be expanded to also identify non-absorbing aerosol types/mixtures by applying an absorption weighting. This new relationship provides improved aerosol type distinction when the magnitude of absorption is not equal (e.g, black carbon vs. sulfates). The Aerosol Robotic Network (AERONET) data provide spectral aerosol optical depth and single scattering albedo - key parameters used to determine EAE and AAE. The proposed aerosol type/mixture relationship is demonstrated using the long-term data archive acquired at AERONET sites within various source regions. The preliminary analysis has found that dust, sulfate, organic carbon, and black carbon aerosol types/mixtures can be determined from this AAE/EAE relationship when applying the absorption weighting for each available wavelength (Le., 440, 675, 870nm). Large, non-spherical dust particles absorb in the shorter wavelengths and the application of 440nm wavelength absorption weighting produced the best particle type definition. Sulfate particles scatter light efficiently and organic carbon particles are small near the source and aggregate over time to form larger less absorbing particles. Both sulfates and organic carbon showed generally better definition using the 870nm wavelength absorption weighting. Black carbon generation results from varying combustion rates from a number of sources including industrial processes and biomass burning. Cases with primarily black carbon showed

  16. Ash iron mobilization through physicochemical processing in volcanic eruption plumes: a numerical modeling approach

    NASA Astrophysics Data System (ADS)

    Hoshyaripour, G. A.; Hort, M.; Langmann, B.

    2015-08-01

    It has been shown that volcanic ash fertilizes the Fe-limited areas of the surface ocean through releasing soluble iron. As ash iron is mostly insoluble upon the eruption, it is hypothesized that heterogeneous in-plume and in-cloud processing of the ash promote the iron solubilization. Direct evidences concerning such processes are, however, lacking. In this study, a 1-D numerical model is developed to simulate the physicochemical interactions of the gas-ash-aerosol in volcanic eruption plumes focusing on the iron mobilization processes at temperatures between 600 and 0 °C. Results show that sulfuric acid and water vapor condense at ~ 150 and ~ 50 °C on the ash surface, respectively. This liquid phase then efficiently scavenges the surrounding gases (> 95 % of HCl, 3-20 % of SO2 and 12-62 % of HF) forming an extremely acidic coating at the ash surface. The low pH conditions of the aqueous film promote acid-mediated dissolution of the Fe-bearing phases present in the ash material. We estimate that 0.1-33 % of the total iron available at the ash surface is dissolved in the aqueous phase before the freezing point is reached. The efficiency of dissolution is controlled by the halogen content of the erupted gas as well as the mineralogy of the iron at ash surface: elevated halogen concentrations and presence of Fe2+-carrying phases lead to the highest dissolution efficiency. Findings of this study are in agreement with the data obtained through leaching experiments.

  17. Preparation and characterization of magnetizable aerosols.

    PubMed

    Baumann, Romy; Glöckl, Gunnar; Nagel, Stefan; Weitschies, Werner

    2012-04-11

    Magnetizable aerosols can be used for inhalative magnetic drug targeting in order to enhance the drug concentration at a certain target site within the lung. The aim of the present study was to clarify how a typical ferrofluid can be atomized in a reproducible way. The influence of the atomization principle, the concentration of magnetic nanoparticles within the carrier liquid and the addition of commonly used pharmaceutical excipients on the aerosol droplet size were investigated. Iron oxide (magnetite) nanoparticles were synthesized by alkaline precipitation of mixtures of iron(II)- and iron(III)-chloride and coated with citric acid. The resulting ferrofluid was characterized by photon correlation spectroscopy and vibrating sample magnetometry. Two different nebulizers (Pari Boy and eFlow) with different atomization principles were used to generate ferrofluid aerosols. A range of substances that influence the surface tension, viscosity, density or vapor pressure of the ferrofluid were added to investigate their impact on the generated aerosol droplets. The particle size was determined by laser diffraction. A stable ferrofluid with a magnetic core diameter of 10.7 ± 0.45 nm and a hydrodynamic diameter of 124 nm was nebulized by Pari Boy and eFlow. The aerosol droplet size of Pari Boy was approximately 2.5 μm and remained unaffected by the addition of substances that changed the physical properties of the solvent. The droplet size of aerosols generated by eFlow was approximately 5 μm. It was significantly reduced by the addition of Cremophor RH 40, glycerol, polyvinyl pyrrolidone and ethanol. PMID:22306649

  18. Atmospheric Deposition of Soluble Organic Nitrogen due to Biomass Burning

    NASA Astrophysics Data System (ADS)

    Ito, A.; Lin, G.; Penner, J. E.

    2014-12-01

    Atmospheric deposition of reactive nitrogen (N) species from large fires may contribute to enrichment of nutrients in aquatic ecosystems. Here we use an atmospheric chemistry transport model to investigate the supply of soluble organic nitrogen (ON) from open biomass burning to the ocean. The model results show that the annual deposition rate of soluble ON to the oceans is increased globally by 13% with the increase being particularly notable over the coastal water downwind from the source regions. The estimated deposition of soluble ON due to haze events from the secondary formation is more than half of that from the primary sources. We examine the secondary formation of particulate C-N compounds (e.g., imidazole) from the reactions of glyoxal and methylglyoxal with atmospheric ammonium in wet aerosols and upon cloud evaporation. These ON sources result in a significant contribution to the open ocean, suggesting that atmospheric processing in aqueous phase may have a large effect. We compare the soluble ON concentration in aerosols with and without open biomass burning as a case study in Singapore. The model results demonstrate that the soluble ON concentration in aerosols is episodically enriched during the fire events, compared to the without smoke simulations. However, the model results show that the daily soluble ON concentration can be also enhanced in the without smoke simulations during the same period, compared to the monthly averages. This indicates that care should be taken when using in-situ observations to constrain the soluble ON source strength from biomass burning. More accurate quantification of the soluble ON burdens with no smoke sources is therefore needed to assess the effect of biomass burning on bioavailable ON input to the oceans.

  19. Chemical distribution in high-solids paint overspray aerosols.

    PubMed

    D'Arcy, J B; Chan, T L

    1990-03-01

    The chemical composition of high-solids basecoat paint overspray aerosols was determined as a function of particle size. Detailed information on the chemical composition of the overspray aerosols is important in health hazard evaluation since the composition and distribution within the airborne particles may differ significantly from the bulk paint material. This study was conducted in a typical down-draft paint booth equipped with air-atomized spray painting equipment. A fixed paint target was used to simulate typical overspray generation conditions and the aerosols were collected isokinetically with a seven-stage cascade impactor for size-fractionated analysis. The overspray aerosol from six paints consisted of organic paint binders with varying amounts of inorganic species as pigments or luster enhancers. These overspray aerosols had mass median aerodynamic diameters (MMAD) ranging from 2.9 to 9.7 microns. The size-fractionated paint samples collected on the impaction stages were analyzed by energy dispersive X-ray spectrometry on a scanning electron microscope (SEM-EDXRS) to identify the metallic elements. Atomic absorption spectrometry was used to determine the mass distribution of aluminum and iron as indicators of nonuniform distribution. Three of the aerosols containing aluminum were found to have bimodal distributions with most aluminum distributions having cumulative MMADs larger than the total aerosol. Iron in the aerosols was bimodal for three of the paints with all samples having an overall iron MMAD less than or equal to the overspray aerosol MMAD. Analysis using ultraviolet spectrometry revealed that the organic compounds present in the size-fractionated particulate samples consisted of a single, polydispersed mode with an MMAD similar to that of the total overspray aerosol.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2327324

  20. Chemical distribution in high-solids paint overspray aerosols

    SciTech Connect

    D'Arcy, J.B.; Chan, T.L. )

    1990-03-01

    The chemical composition of high-solids basecoat paint overspray aerosols was determined as a function of particle size. Detailed information on the chemical composition of the overspray aerosols is important in health hazard evaluation since the composition and distribution within the airborne particles may differ significantly from the bulk paint material. This study was conducted in a typical down-draft paint booth equipped with air-atomized spray painting equipment. A fixed paint target was used to simulate typical overspray generation conditions and the aerosols were collected isokinetically with a seven-stage cascade impactor for size-fractionated analysis. The overspray aerosol from six paints consisted of organic paint binders with varying amounts of inorganic species as pigments or luster enhancers. These overspray aerosols had mass median aerodynamic diameters (MMAD) ranging from 2.9 to 9.7 microns. The size-fractionated paint samples collected on the impaction stages were analyzed by energy dispersive X-ray spectrometry on a scanning electron microscope (SEM-EDXRS) to identify the metallic elements. Atomic absorption spectrometry was used to determine the mass distribution of aluminum and iron as indicators of nonuniform distribution. Three of the aerosols containing aluminum were found to have bimodal distributions with most aluminum distributions having cumulative MMADs larger than the total aerosol. Iron in the aerosols was bimodal for three of the paints with all samples having an overall iron MMAD less than or equal to the overspray aerosol MMAD. Analysis using ultraviolet spectrometry revealed that the organic compounds present in the size-fractionated particulate samples consisted of a single, polydispersed mode with an MMAD similar to that of the total overspray aerosol.

  1. Comment on "The Southern Ocean biological response to aeolian iron deposition".

    PubMed

    Boyd, Philip W; Mackie, Douglas

    2008-01-11

    Cassar et al. (Reports, 24 August 2007, p. 1067) proposed that aerosol-iron input enhances Southern Ocean export production. Their conclusion critically depends upon aerosol-iron modeling simulations not validated with iron-deposition data and dust dissolution rates based on Northern Hemisphere atmospheric chemical conditions (low pH). This diminishes the relevance of their findings and demonstrates that applying such models to this region is premature.

  2. GADOLINIUM SOLUBILITY AND VOLATILITY DURING DWPF PROCESSING

    SciTech Connect

    Reboul, S

    2008-01-30

    Understanding of gadolinium behavior, as it relates to potential neutron poisoning applications at the DWPF, has increased over the past several years as process specific data have been generated. Of primary importance are phenomena related to gadolinium solubility and volatility, which introduce the potential for gadolinium to be separated from fissile materials during Chemical Process Cell (CPC) and Melter operations. Existing data indicate that gadolinium solubilities under moderately low pH conditions can vary over several orders of magnitude, depending on the quantities of other constituents that are present. With respect to sludge batching processes, the gadolinium solubility appears to be highly affected by iron. In cases where the mass ratio of Fe:Gd is 300 or more, the gadolinium solubility has been observed to be low, one milligram per liter or less. In contrast, when the ratio of Fe:Gd is 20 or less, the gadolinium solubility has been found to be relatively high, several thousands of milligrams per liter. For gadolinium to serve as an effective neutron poison in CPC operations, the solubility needs to be limited to approximately 100 mg/L. Unfortunately, the Fe:Gd ratio that corresponds to this solubility limit has not been identified. Existing data suggest gadolinium and plutonium are not volatile during melter operations. However, the data are subject to inherent uncertainties preventing definitive conclusions on this matter. In order to determine if gadolinium offers a practical means of poisoning waste in DWPF operations, generation of additional data is recommended. This includes: Gd solubility testing under conditions where the Fe:Gd ratio varies from 50 to 150; and Gd and Pu volatility studies tailored to quantifying high temperature partitioning. Additional tests focusing on crystal aging of Gd/Pu precipitates should be pursued if receipt of gadolinium-poisoned waste into the Tank Farm becomes routine.

  3. Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    A meteorite composed mainly of nickel-iron, with traces of other metals; also referred to simply as an iron, and formerly known as a siderite. Irons account for over 6% of all known meteorite specimens. They are the easiest type to identify, being heavy, magnetic and rust-colored; their metallic sheen tarnishes quickly on the Earth's surface, but otherwise irons show better resistance to weatheri...

  4. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

  5. Reconciling modeled and observed atmospheric deposition of soluble organic nitrogen at coastal locations

    NASA Astrophysics Data System (ADS)

    Ito, Akinori; Lin, Guangxing; Penner, Joyce E.

    2014-06-01

    Atmospheric deposition of reactive nitrogen (N) species from air pollutants is a significant source of exogenous nitrogen in marine ecosystems. Here we use an atmospheric chemical transport model to investigate the supply of soluble organic nitrogen (ON) from anthropogenic sources to the ocean. Comparisons of modeled deposition with observations at coastal and marine locations show good overall agreement for inorganic nitrogen and total soluble nitrogen. However, previous modeling approaches result in significant underestimates of the soluble ON deposition if the model only includes the primary soluble ON and the secondary oxidized ON in gases and aerosols. Our model results suggest that including the secondary reduced ON in aerosols as a source of soluble ON contributes to an improved prediction of the deposition rates (g N m-2 yr-1). The model results show a clear distinction in the vertical distribution of soluble ON in aerosols between different processes from the primary sources and the secondary formation. The model results (excluding the biomass burning and natural emission changes) suggest an increase in soluble ON outflow from atmospheric pollution, in particular from East Asia, to the oceans in the twentieth century. These results highlight the necessity of improving the process-based quantitative understanding of the chemical reactions of inorganic nitrogen species with organics in aerosol and cloud water.

  6. Aerosol gels

    NASA Technical Reports Server (NTRS)

    Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

    2010-01-01

    An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

  7. Ice-condenser aerosol tests

    SciTech Connect

    Ligotke, M.W.; Eschbach, E.J.; Winegardner, W.K. )

    1991-09-01

    This report presents the results of an experimental investigation of aerosol particle transport and capture using a full-scale height and reduced-scale cross section test facility based on the design of the ice compartment of a pressurized water reactor (PWR) ice-condenser containment system. Results of 38 tests included thermal-hydraulic as well as aerosol particle data. Particle retention in the test section was greatly influenced by thermal-hydraulic and aerosol test parameters. Test-average decontamination factor (DF) ranged between 1.0 and 36 (retentions between {approximately}0 and 97.2%). The measured test-average particle retentions for tests without and with ice and steam ranged between DF = 1.0 and 2.2 and DF = 2.4 and 36, respectively. In order to apparent importance, parameters that caused particle retention in the test section in the presence of ice were steam mole fraction (SMF), noncondensible gas flow rate (residence time), particle solubility, and inlet particle size. Ice-basket section noncondensible flows greater than 0.1 m{sup 3}/s resulted in stable thermal stratification whereas flows less than 0.1 m{sup 3}/s resulted in thermal behavior termed meandering with frequent temperature crossovers between flow channels. 10 refs., 66 figs., 16 tabs.

  8. What Variables Affect Solubility?

    ERIC Educational Resources Information Center

    Baker, William P.; Leyva, Kathryn

    2003-01-01

    Helps middle school students understand the concept of solubility through hands-on experience with a variety of liquids and solids. As they explore factors that affect solubility and saturation, students gain content mastery and an understanding of the inquiry process. Also enables teachers to authentically assess student performance on several…

  9. Applications of Solubility Data

    ERIC Educational Resources Information Center

    Tomkins, Reginald P. T.

    2008-01-01

    This article describes several applications of the use of solubility data. It is not meant to be exhaustive but rather to show that knowledge of solubility data is required in a variety of technical applications that assist in the design of chemical processes. (Contains 3 figures and 1 table.)

  10. Preparation of iron bound succinylated milk protein concentrate and evaluation of its stability.

    PubMed

    Shilpashree, B G; Arora, Sumit; Sharma, Vivek; Bajaj, Rajesh Kumar; Tomar, S K

    2016-04-01

    Major problems associated with the fortification of soluble iron salts include chemical reactivity and incompatibility with other components. Milk protein concentrate (MPC) are able to bind significant amount of iron due to the presence of both casein and whey protein. MPC in its native state possess very poor solubility, therefore, succinylated derivatives of MPC (succ. MPC) were also used for the preparation of protein-iron complex. Preparation of the complex involved centrifugation (to remove insoluble iron), ultrafiltration (to remove unbound iron) and lyophilisation (to attain in dry form). Iron binding ability of MPC enhanced significantly (P<0.05) upon succinylation. Stability of bound iron from both varieties of complexes was monitored under different conditions encountered during processing. Higher stability (P<0.05) of bound iron was observed in succ. MPC-iron complex than native protein complex. This method could be adopted for the production of stable iron enriched protein, an organic iron source. PMID:26593557

  11. Preparation of iron bound succinylated milk protein concentrate and evaluation of its stability.

    PubMed

    Shilpashree, B G; Arora, Sumit; Sharma, Vivek; Bajaj, Rajesh Kumar; Tomar, S K

    2016-04-01

    Major problems associated with the fortification of soluble iron salts include chemical reactivity and incompatibility with other components. Milk protein concentrate (MPC) are able to bind significant amount of iron due to the presence of both casein and whey protein. MPC in its native state possess very poor solubility, therefore, succinylated derivatives of MPC (succ. MPC) were also used for the preparation of protein-iron complex. Preparation of the complex involved centrifugation (to remove insoluble iron), ultrafiltration (to remove unbound iron) and lyophilisation (to attain in dry form). Iron binding ability of MPC enhanced significantly (P<0.05) upon succinylation. Stability of bound iron from both varieties of complexes was monitored under different conditions encountered during processing. Higher stability (P<0.05) of bound iron was observed in succ. MPC-iron complex than native protein complex. This method could be adopted for the production of stable iron enriched protein, an organic iron source.

  12. Aerosol typing - key information from aerosol studies

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

    2016-04-01

    Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the

  13. Steady generation of aerosols with an improved constant output atomizer

    NASA Technical Reports Server (NTRS)

    Dea, J. Y.; Katz, U.

    1981-01-01

    It is common practice to generate laboratory aerosols of soluble materials with pneumatic atomizers. In a typical device, a solution of the substance to be aerosolized is injected into a jet of air and the liquid is broken up into very small droplets. After forced evaporation, a dry aerosol of the solute is produced. A number of commercially available devices were tested, and despite differences in design, all the atomizers tested suffered from short- and/or long-term fluctuations of their output particle number concentrations. The mechanisms responsible for atomizer instabilities are discussed and methods for alleviating these problems are considered.

  14. Aerosols in clean and smoky air at Bozeman, Montana

    NASA Astrophysics Data System (ADS)

    Shaw, J. A.; Thomas, M.; Lathem, T. L.; Shaw, G. E.; Nenes, A.; Pust, N.; Repasky, K. S.

    2010-12-01

    The northern Rocky Mountain region of the United States is a natural laboratory for studying aerosols in a relatively uncontaminated environment punctuated by episodes of wildfire smoke. In autumn 2009, we conducted a field experiment at Montana State University in Bozeman, Montana to characterize the boundary layer aerosols as they transition from smoky periods to relatively clean background air. Physical and chemical properties of the aerosols were conducted, including high time resolution of Cloud Condensation Nuclei and inter comparison with AERONET data during times of deep atmospheric mixing. The key results of this experiment are: 1) the air in this northern Rocky Mountain location is surprisingly pristine with frequent aerosol size distributions devoid of a an accumulation mode; 2) periods of night-time growth of Aitken-mode aerosols were observed; 3) a persistent diurnal variation occurred, with upslope daytime winds bringing aerosols exhibiting moderate anthropogenic influence , and down slope nighttime winds bringing aerosols with weak accumulation mode; 4) the smoke aerosol was weakly soluble; and 5) satisfactory agreement was found between the inverted estimate of the fine mode aerosol from AERONET solar radiometry with that measured in situ.

  15. Nanostructured Polyphase Catalysts Based on the Solid Component of Welding Aerosol for Ozone Decomposition

    NASA Astrophysics Data System (ADS)

    Rakitskaya, Tatyana; Truba, Alla; Ennan, Alim; Volkova, Vitaliya

    2015-12-01

    Samples of the solid component of welding aerosols (SCWAs) were obtained as a result of steel welding by ANO-4, TsL-11, and UONI13/55 electrodes of Ukrainian manufacture. The phase compositions of the samples, both freshly prepared (FP) and modified (M) by water treatment at 60 °C, were studied by X-ray phase analysis and IR spectroscopy. All samples contain magnetite demonstrating its reflex at 2 θ ~ 35° characteristic of cubic spinel as well as manganochromite and iron oxides. FP SCWA-TsL and FP SCWA-UONI contain such phases as CaF2, water-soluble fluorides, chromates, and carbonates of alkali metals. After modification of the SCWA samples, water-soluble phases in their composition are undetectable. The size of magnetite nanoparticles varies from 15 to 68 nm depending on the chemical composition of electrodes under study. IR spectral investigations confirm the polyphase composition of the SCWAs. As to IR spectra, the biggest differences are apparent in the regions of deformation vibrations of M-O-H bonds and stretching vibrations of M-O bonds (M-Fe, Cr). The catalytic activity of the SCWAs in the reaction of ozone decomposition decreases in the order SCWA-ANO > SCWA-UONI > SCWA-TsL corresponding to the decrease in the content of catalytically active phases in their compositions.

  16. Nanostructured Polyphase Catalysts Based on the Solid Component of Welding Aerosol for Ozone Decomposition.

    PubMed

    Rakitskaya, Tatyana; Truba, Alla; Ennan, Alim; Volkova, Vitaliya

    2015-12-01

    Samples of the solid component of welding aerosols (SCWAs) were obtained as a result of steel welding by ANO-4, TsL‑11, and UONI13/55 electrodes of Ukrainian manufacture. The phase compositions of the samples, both freshly prepared (FP) and modified (M) by water treatment at 60 °C, were studied by X-ray phase analysis and IR spectroscopy. All samples contain magnetite demonstrating its reflex at 2θ ~ 35° characteristic of cubic spinel as well as manganochromite and iron oxides. FP SCWA-TsL and FP SCWA-UONI contain such phases as СaF2, water-soluble fluorides, chromates, and carbonates of alkali metals. After modification of the SCWA samples, water-soluble phases in their composition are undetectable. The size of magnetite nanoparticles varies from 15 to 68 nm depending on the chemical composition of electrodes under study. IR spectral investigations confirm the polyphase composition of the SCWAs. As to IR spectra, the biggest differences are apparent in the regions of deformation vibrations of M-O-H bonds and stretching vibrations of M-O bonds (M-Fe, Cr). The catalytic activity of the SCWAs in the reaction of ozone decomposition decreases in the order SCWA-ANO > SCWA-UONI > SCWA-TsL corresponding to the decrease in the content of catalytically active phases in their compositions.

  17. Luminescent iron clusters in solution

    NASA Astrophysics Data System (ADS)

    Goswami, Nirmal; Baksi, Ananya; Giri, Anupam; Xavier, Paulrajpillai Lourdu; Basu, Gautam; Pradeep, Thalappil; Pal, Samir Kumar

    2014-01-01

    Metal clusters, composed of a few atoms at the core, exhibit unique properties and have potential applications. Although atomically precise clusters of noble metals have been synthesized, analogous systems of reactive metals, such as iron, have not been realized in solution due to high reactivity. Here we report the synthesis and characterization of novel iron clusters in the hemoglobin matrix that are highly luminescent (quantum yield 10% at 565 nm). The super-paramagnetic iron clusters, after successful ligand exchange from protein and phase transfer from water to chloroform using tri-octylphosphineoxide (TOPO), were detected as [Fe10(TOPO)3(H2O)3]+, [Fe13(TOPO)2(H2O)]+ and [Fe8(TOPO)(H2O)2]+ by mass spectrometry. This study lays the groundwork for exploiting unique properties of soluble iron clusters.Metal clusters, composed of a few atoms at the core, exhibit unique properties and have potential applications. Although atomically precise clusters of noble metals have been synthesized, analogous systems of reactive metals, such as iron, have not been realized in solution due to high reactivity. Here we report the synthesis and characterization of novel iron clusters in the hemoglobin matrix that are highly luminescent (quantum yield 10% at 565 nm). The super-paramagnetic iron clusters, after successful ligand exchange from protein and phase transfer from water to chloroform using tri-octylphosphineoxide (TOPO), were detected as [Fe10(TOPO)3(H2O)3]+, [Fe13(TOPO)2(H2O)]+ and [Fe8(TOPO)(H2O)2]+ by mass spectrometry. This study lays the groundwork for exploiting unique properties of soluble iron clusters. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05784d

  18. Organic Aerosols as Cloud Condensation Nuclei

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.

    2002-05-01

    The large organic component of the atmospheric aerosol contributes to both natural and anthropogenic cloud condensation nuclei (CCN). Moreover, some organic substances may reduce droplet surface tension (Facchini et al. 1999), while others may be partially soluble (Laaksonen et al. 1998), and others may inhibit water condensation. The interaction of organics with water need to be understood in order to better understand the indirect aerosol effect. Therefore, laboratory CCN spectral measurements of organic aerosols are presented. These are measurements of the critical supersaturation (Sc), the supersaturation needed to produce an activated cloud droplet, as a function of the size of the organic particles. Substances include sodium lauryl (dodecyl) sulfate, oxalic, adipic, pinonic, hexadecanedioic, glutaric, stearic, succinic, phthalic, and benzoic acids. These size-Sc relationships are compared with theoretical and measured size-Sc relationships of common inorganic compounds (e.g., NaCl, KI, ammonium and calcium sulfate). Unlike most inorganics some organics display variations in solubility per unit mass as a function of particle size. Those showing relatively greater solubility at smaller sizes may be attributable to surface tension reduction, which is greater for less water dilution, as is the case for smaller particles, which are less diluted at the critical sizes. This was the case for sodium dodecyl sulfate, which does reduce surface tension. Relatively greater solubility for larger particles may be caused by greater dissolution at the higher dilutions that occur with larger particles; this is partial solubility. Measurements are also presented of internal mixtures of various organic and inorganic substances. These measurements were done with two CCN spectrometers (Hudson 1989) operating simultaneously. These two instruments usually displayed similar results in spite of the fact that they have different flow rates and supersaturation profiles. The degree of

  19. Aerosol mobility size spectrometer

    DOEpatents

    Wang, Jian; Kulkarni, Pramod

    2007-11-20

    A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

  20. What Should We Teach Beginners about Solubility and Solubility Products?

    ERIC Educational Resources Information Center

    Hawkes, Stephen J.

    1998-01-01

    Argues that consideration should be given to whether teaching solubility product calculations is at all useful. Claims that experienced teachers seriously misunderstand and misuse solubility product calculations. (DDR)

  1. Iron-binding properties of sugar cane yeast peptides.

    PubMed

    de la Hoz, Lucia; Ponezi, Alexandre N; Milani, Raquel F; Nunes da Silva, Vera S; Sonia de Souza, A; Bertoldo-Pacheco, Maria Teresa

    2014-01-01

    The extract of sugar-cane yeast (Saccharomyces cerevisiae) was enzymatically hydrolysed by Alcalase, Protex or Viscozyme. Hydrolysates were fractionated using a membrane ultrafiltration system and peptides smaller than 5kDa were evaluated for iron chelating ability through measurements of iron solubility, binding capacity and dialyzability. Iron-chelating peptides were isolated using immobilized metal affinity chromatography (IMAC). They showed higher content of His, Lys, and Arg than the original hydrolysates. In spite of poor iron solubility, hydrolysates of Viscozyme provided higher iron dialyzability than those of other enzymes. This means that more chelates of iron or complexes were formed and these kept the iron stable during simulated gastro-intestinal digestion in vitro, improving its dialyzability.

  2. Soluble and insoluble fiber (image)

    MedlinePlus

    ... stool. There are two types of dietary fiber, soluble and insoluble. Soluble fiber retains water and turns to gel during ... and nutrient absorption from the stomach and intestine. Soluble fiber is found in foods such as oat ...

  3. AEROSOL AND GAS MEASUREMENT

    EPA Science Inventory

    Measurements provide fundamental information for evaluating and managing the impact of aerosols on air quality. Specific measurements of aerosol concentration and their physical and chemical properties are required by different users to meet different user-community needs. Befo...

  4. Aerosols and environmental pollution

    NASA Astrophysics Data System (ADS)

    Colbeck, Ian; Lazaridis, Mihalis

    2010-02-01

    The number of publications on atmospheric aerosols has dramatically increased in recent years. This review, predominantly from a European perspective, summarizes the current state of knowledge of the role played by aerosols in environmental pollution and, in addition, highlights gaps in our current knowledge. Aerosol particles are ubiquitous in the Earth’s atmosphere and are central to many environmental issues; ranging from the Earth’s radiative budget to human health. Aerosol size distribution and chemical composition are crucial parameters that determine their dynamics in the atmosphere. Sources of aerosols are both anthropogenic and natural ranging from vehicular emissions to dust resuspension. Ambient concentrations of aerosols are elevated in urban areas with lower values at rural sites. A comprehensive understanding of aerosol ambient characteristics requires a combination of measurements and modeling tools. Legislation for ambient aerosols has been introduced at national and international levels aiming to protect human health and the environment.

  5. Aerosols and environmental pollution.

    PubMed

    Colbeck, Ian; Lazaridis, Mihalis

    2010-02-01

    The number of publications on atmospheric aerosols has dramatically increased in recent years. This review, predominantly from a European perspective, summarizes the current state of knowledge of the role played by aerosols in environmental pollution and, in addition, highlights gaps in our current knowledge. Aerosol particles are ubiquitous in the Earth's atmosphere and are central to many environmental issues; ranging from the Earth's radiative budget to human health. Aerosol size distribution and chemical composition are crucial parameters that determine their dynamics in the atmosphere. Sources of aerosols are both anthropogenic and natural ranging from vehicular emissions to dust resuspension. Ambient concentrations of aerosols are elevated in urban areas with lower values at rural sites. A comprehensive understanding of aerosol ambient characteristics requires a combination of measurements and modeling tools. Legislation for ambient aerosols has been introduced at national and international levels aiming to protect human health and the environment.

  6. Protein solubility modeling

    NASA Technical Reports Server (NTRS)

    Agena, S. M.; Pusey, M. L.; Bogle, I. D.

    1999-01-01

    A thermodynamic framework (UNIQUAC model with temperature dependent parameters) is applied to model the salt-induced protein crystallization equilibrium, i.e., protein solubility. The framework introduces a term for the solubility product describing protein transfer between the liquid and solid phase and a term for the solution behavior describing deviation from ideal solution. Protein solubility is modeled as a function of salt concentration and temperature for a four-component system consisting of a protein, pseudo solvent (water and buffer), cation, and anion (salt). Two different systems, lysozyme with sodium chloride and concanavalin A with ammonium sulfate, are investigated. Comparison of the modeled and experimental protein solubility data results in an average root mean square deviation of 5.8%, demonstrating that the model closely follows the experimental behavior. Model calculations and model parameters are reviewed to examine the model and protein crystallization process. Copyright 1999 John Wiley & Sons, Inc.

  7. Solubility of Organic Compounds

    ERIC Educational Resources Information Center

    James, K. C.

    1972-01-01

    Outlines factors to be considered in choosing suitable solvents for non-electrolytes and salts of weak acids and bases. Describes how, in some simple situation, the degree of solubility can be estimated. (Author/DF)

  8. Learning about Solubility

    ERIC Educational Resources Information Center

    Salinas, Dino G.; Reyes, Juan G.

    2015-01-01

    Qualitative questions are proposed to assess the understanding of solubility and some of its applications. To improve those results, a simple quantitative problem on the precipitation of proteins is proposed.

  9. Quantification of Iron Oxides and Hydroxides in Desert Aeolian Particles

    NASA Astrophysics Data System (ADS)

    Lafon, S.; Rajot, J.; Alfaro, S.; Gaudichet, A.

    2002-12-01

    Long range transport of desert dust over oceans constitute a source of iron for the surface water. Assessing the iron cycle and its biogeochemical implications in oceanic areas requires determination and quantification of the iron status in aeolian particles. Indeed, in such aerosols, the iron is either trapped in the silicate structure or present under the form of oxides and hydroxides (free iron). We propose a method to apportion iron between free and entrapped forms in mineral aerosols. It consists in the adaptation of a well known method used for soil characterization to the treatment of aerosol samples, which represent less than 1 mg of material collected by air filtration on polycarbonate filters. The iron oxides and hydroxides are extracted selectively using the combined action of reductive and complexant agents in a buffered solution. The iron content is measured before and after this chemical extraction using X ray fluorescence spectrometry. We attempt to give some values for three main desert source areas using aerosol samples collected near Niamey (Niger) either during Harmattan events or during local erosion events, and samples collected downwind of the Gobi desert in China. Results emphasize firstly that iron trapped in the structure of silicate minerals represents an important part of total iron content. This suggests that, regarding dissolution processes in sea water, total elemental iron content of aeolian dust can not be used directly to calculate the flux of iron available. Secondly, our results show that the free iron content vary according to the origin of dusts. Niger samples have contents in free iron of 4.4 % (SD = 0.8) for local erosion and 2.8 % (SD = 1.0) for Harmattan. Chinese samples contain 3.7 % (SD = 0.5) of free iron. These differences could be linked to the parent soil mineralogical composition that varies with geographical location, but for some of our samples it also could be linked to a size fractionation process occurring first

  10. Aerosol distribution apparatus

    DOEpatents

    Hanson, W.D.

    An apparatus for uniformly distributing an aerosol to a plurality of filters mounted in a plenum, wherein the aerosol and air are forced through a manifold system by means of a jet pump and released into the plenum through orifices in the manifold. The apparatus allows for the simultaneous aerosol-testing of all the filters in the plenum.

  11. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  12. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  13. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  14. Iron refractory iron deficiency anemia

    PubMed Central

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

  15. Iron fertilisation of the ocean through major volcanic eruptions. A case study of the Kasatochi eruption 2008

    NASA Astrophysics Data System (ADS)

    Lindenthal, A.; Langmann, B.; Hort, M.; Hoshyaripour, G.; Paetsch, J.; Lorkowski, I.

    2012-04-01

    Until recently it was more or less common sense that once volcanic ash enters the ocean it simply deposits into the sediments without any further impact on ocean biochemistry. This view has been notably revised after the eruption of Kasatochi volcano in 2008. During the eruption significant amounts of ash were deposited into oceanic NE Pacific. The NE Pacific is known as a high-nutrient-low-chlorophyll (HNLC) region where algae growth is limited by the bio-available, i.e. soluble iron. These bio-available iron salts residing on the volcanic ash are most likely formed by gas-ash/aerosol interactions inside the volcanic plume. The physico-chemical mechanisms behind the processes contributing to bio-available iron production in volcanic plumes, however, are still poorly constrained. As the eruption occurred in early August, the atmospheric and oceanic conditions were favourable to generate a massive phytoplankton bloom as was observed by satellite instruments and in-situ measurements. Here we investigate this event with the marine biogeochemical model ECOHAM, which is a regional scale three-dimensional ocean biogeochemistry model, coupled to the hydrodynamic model HAMSON. It has been successfully applied mainly over the NW European continental shelf area where iron limitation does not play a role. For applications of this model to the eruption of Kasatochi volcano, an iron cycle model has been implemented, which considers the influence of iron addition to the euphotic zone on diatoms, flagellates, and carbon dioxide concentrations. This model-approach assumes that all dissolved iron in the first meters of seawater is bio-available for phytoplankton uptake. It describes the limitation of phytoplankton growth rates by iron in addition to the limitation by the macro-nutrients nitrogen, phosphate and silicate as well as by light. The surface ocean iron input associated with the eruption of Kasatochi volcano has been determined by an atmospheric-aerosol model to be on the

  16. Formation and Reactivity of Biogenic Iron Microminerals

    SciTech Connect

    Beveridge, Terrance J.; Ferris, F. Grant

    1999-06-01

    The overall purpose of the project is to explore and quantify the processes that control the formation and reactivity of biogenic iron microminerals, and the impact of these processes on the solubility of metal contaminants, e.g., uranium, chromium and nickel. The research addresses how surface components of bacterial cells, extracellular organic material, and the aqueous geochemistry of the DIRB microenvironment impacts the mineralogy, chemical state and micromorphology of reduced iron phases.

  17. Fog and Cloud Induced Aerosol Modification Observed by AERONET

    NASA Technical Reports Server (NTRS)

    Eck, T. F.; Holben, B. N.; Reid, J. S.; Giles, D. M.; Rivas, M. A.; Singh, R. P.; Tripathi, S. N.; Bruegge, C. J.; Platnick, S. E.; Arnold, G. T.; Krotkov, N. A.; Carn, S. A.; Sinyuk, A.; Dubovik, O.; Arola, A.; Schafer, J. S.; Artaxo, P.; Smirnov, A.; Chen, H.; Goloub, P.

    2011-01-01

    Large fine mode (sub-micron radius) dominated aerosols in size distributions retrieved from AERONET have been observed after fog or low-altitude cloud dissipation events. These column-integrated size distributions have been obtained at several sites in many regions of the world, typically after evaporation of low altitude cloud such as stratocumulus or fog. Retrievals with cloud processed aerosol are sometimes bimodal in the accumulation mode with the larger size mode often approx.0.4 - 0.5 microns radius (volume distribution); the smaller mode typically approx.0.12 to aprrox.0.20 microns may be interstitial aerosol that were not modified by incorporation in droplets and/or aerosol that are less hygroscopic in nature. Bimodal accumulation mode size distributions have often been observed from in situ measurements of aerosols that have interacted with clouds, and AERONET size distribution retrievals made after dissipation of cloud or fog are in good agreement with particle sizes measured by in situ techniques for cloud-processed aerosols. Aerosols of this type and large size range (in lower concentrations) may also be formed by cloud processing in partly cloudy conditions and may contribute to the shoulder of larger size particles in the accumulation mode retrievals, especially in regions where sulfate and other soluble aerosol are a significant component of the total aerosol composition. Observed trends of increasing aerosol optical depth (AOD) as fine mode radius increased suggests higher AOD in the near cloud environment and therefore greater aerosol direct radiative forcing than typically obtained from remote sensing, due to bias towards sampling at low cloud fraction.

  18. Solubility and secretability.

    PubMed

    Schein, C H

    1993-08-01

    The solubility and secretability of proteins can often be affected by extremely small changes in their primary structure. Attempts to determine empirical rules for the alteration of protein structure to improve either of these characteristics have met with only partial success. Those (mostly serendipitous) improvements in solubility that have been obtained via mutagenesis cannot be considered to be 'protein engineering'. The most successful examples where directed mutagenesis has been used to alter protein solubility, hemoglobin and insulin, have relied on established crystal structures and a wealth of data about the relationship between sequence and structure of the targeted protein. Currently, optimizing culture growth conditions by trial and error remains the fastest way to improve expression.

  19. Field and Laboratory Studies of Atmospheric Organic Aerosol

    NASA Astrophysics Data System (ADS)

    Coggon, Matthew Mitchell

    these conditions to all measurements conducted during E-PEACE demonstrated that a large fraction of cloud droplet (72%) and dry aerosol mass (12%) sampled in the California coastal study region was heavily or moderately influenced by ship emissions. Another study investigated the chemical and physical evolution of a controlled organic plume emitted from the R/V Point Sur. Under sunny conditions, nucleated particles composed of oxidized organic compounds contributed nearly an order of magnitude more cloud condensation nuclei (CCN) than less oxidized particles formed under cloudy conditions. The processing time necessary for particles to become CCN active was short ( 4 hr). Laboratory chamber experiments were also conducted to evaluate particle-phase processes influencing aerosol phase and composition. In one study, ammonium sulfate seed was coated with a layer of secondary organic aerosol (SOA) from toluene oxidation followed by a layer of SOA from α-pinene oxidation. The system exhibited different evaporative properties than ammonium sulfate seed initially coated with α-pinene SOA followed by a layer of toluene SOA. This behavior is consistent with a shell-and-core model and suggests limited mixing among different SOA types. Another study investigated the reactive uptake of isoprene epoxy diols (IEPOX) onto non-acidified aerosol. It was demonstrated that particle acidity has limited influence on organic aerosol formation onto ammonium sulfate seed, and that the chemical system is limited by the availability of nucleophiles such as sulfate. Flow tube experiments were conducted to examine the role of iron in the reactive uptake and chemical oxidation of glycolaldehyde. Aerosol particles doped with iron and hydrogen peroxide were mixed with gas-phase glycolaldehyde and photochemically aged in a custom-built flow reactor. Compared to particles free of iron, iron-doped aerosols significantly enhanced the oxygen to carbon (O/C) ratio of accumulated organic mass. The primary

  20. The Remote Sensing of Mineral Aerosols and their Impact on Phytoplankton Productivity

    NASA Technical Reports Server (NTRS)

    Tindale, Neil W.

    1997-01-01

    The overall objective of this experiment was to test the iron hypothesis does the addition of iron to nutrient rich surface waters enhance productivity? Our specific objectives in this experiment included sampling and studying the marine aerosol size and type (which are related to chemical reactivity) during the PlumEx cruise to determine the importance of local (Galapagos Islands) versus long-range sources of atmospheric material. Detailed results of single particle analysis of our samples are being prepared for publication in two papers. We collect aerosol samples and they have been analyzed for trace metals and other elements. We are mapped aerosol distribution and the desert source areas around the Arabian Sea region. We did record a clear relationship between the aerosol radiance and synoptic weather patterns with distinct signals over the ocean northwest and southwest of Australia. While the interpretation was limited an aerosol climatology pattern was presented.

  1. Marine submicron aerosol gradients, sources and sinks

    NASA Astrophysics Data System (ADS)

    Ceburnis, Darius; Rinaldi, Matteo; Ovadnevaite, Jurgita; Martucci, Giovanni; Giulianelli, Lara; O'Dowd, Colin D.

    2016-10-01

    Aerosol principal sources and sinks over eastern North Atlantic waters were studied through the deployment of an aerosol chemistry gradient sampling system. The chemical gradients of primary and secondary aerosol components - specifically, sea salt (SS), water-insoluble organic matter (WIOM), water-soluble organic matter (WSOM), nitrate, ammonium, oxalate, amines, methanesulfonic acid (MSA) and water-soluble organic nitrogen (WSON) - were examined in great detail. Sea salt fluxes were estimated by the boundary layer box model and ranged from 0.3 to 3.5 ng m-2 s-1 over the wind speed range of 5-12 m s-1 and compared well with the derived fluxes from existing sea salt source parameterisations. The observed seasonal pattern of sea salt gradients was mainly driven by wind stress in addition to the yet unquantified effect of marine OM modifying fractional contributions of SS and OM in sea spray. WIOM gradients were a complex combination of rising and waning biological activity, especially in the flux footprint area, and wind-driven primary sea spray production supporting the coupling of recently developed sea spray and marine OM parameterisations.

  2. The inhibitory effect of bran on iron absorption in man.

    PubMed

    Simpson, K M; Morris, E R; Cook, J D

    1981-08-01

    The effects of whole wheat bran and its components on the absorption of nonheme dietary iron were measured using a double isotope technique in human volunteers. When 12 g bran was added to a light meal, absorption decreased by 51 to 74%; this inhibitory effect of bran was shown for meals of both high and low iron availability. Inhibition was not explained by monoferric phytate, the major form of iron in bran, because labeled iron from monoferric phytate was absorbed at least as well as the common pool of nonheme dietary iron. Furthermore, removal of phytate from bran by endogenous phytase did not in itself alter the inhibitory effect of the bran on iron absorption. Studies in which dephytinized bran was separated into a soluble, phosphate-rich fraction and an insoluble, high-fiber fraction indicated that the soluble fraction was more inhibitory than the insoluble fraction. PMID:6267927

  3. Aerosol dynamics in ship tracks

    NASA Astrophysics Data System (ADS)

    Russell, Lynn M.; Seinfeld, John H.; Flagan, Richard C.; Ferek, Ronald J.; Hegg, Dean A.; Hobbs, Peter V.; Wobrock, Wolfram; Flossmann, Andrea I.; O'Dowd, Colin D.; Nielsen, Kurt E.; Durkee, Phillip A.

    1999-01-01

    Ship tracks are a natural laboratory to isolate the effect of anthropogenic aerosol emissions on cloud properties. The Monterey Area Ship Tracks (MAST) experiment in the Pacific Ocean west of Monterey, California, in June 1994, provides an unprecedented data set for evaluating our understanding of the formation and persistence of the anomalous cloud features that characterize ship tracks. The data set includes conditions in which the marine boundary layer is both clean and continentally influenced. Two case studies during the MAST experiment are examined with a detailed aerosol microphysical model that considers an external mixture of independent particle populations. The model allows tracking individual particles through condensational and coagulational growth to identify the source of cloud condensation nuclei (CCN). In addition, a cloud microphysics model was employed to study specific effects of precipitation. Predictions and observations reveal important differences between clean (particle concentrations below 150 cm-3) and continentally influenced (particle concentrations above 400 cm-3) background conditions: in the continentally influenced conditions there is a smaller change in the cloud effective radius, drop number and liquid water content in the ship track relative to the background than in the clean marine case. Predictions of changes in cloud droplet number concentrations and effective radii are consistent with observations although there is significant uncertainty in the absolute concentrations due to a lack of measurements of the plume dilution. Gas-to-particle conversion of sulfur species produced by the combustion of ship fuel is predicted to be important in supplying soluble aerosol mass to combustion-generated particles, so as to render them available as CCN. Studies of the impact of these changes on the cloud's potential to precipitate concluded that more complex dynamical processes must be represented to allow sufficiently long drop

  4. Aromatic Structure in Simulates Titan Aerosol

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    demonstrated in the aerosol mass spectra shown in Figure 2. The aromatic aerosol also demonstrates strong chemical reactivity when exposed to laboratory air, indicating substantial stored chemical potential. Oxidatoin and solubility studies wil be presented and implicatoins for prebiotic chemistry o nTitan will be discussed.

  5. A pathway analysis of global aerosol processes

    NASA Astrophysics Data System (ADS)

    Schutgens, N. A. J.; Stier, P.

    2014-11-01

    We present a detailed budget of the changes in atmospheric aerosol mass and numbers due to various processes: emission (including instant condensation of soluble biogenic emissions), nucleation, coagulation, H2SO4 condensation and in-cloud production, aging and deposition. The budget is created from monthly averaged tracer tendencies calculated by the global aerosol model ECHAM5.5-HAM2 and allows us to investigate process contributions at various length-scales and timescales. As a result, we show in unprecedented detail what processes drive the evolution of aerosol. In particular, we show that the processes that affect aerosol masses are quite different from those that affect aerosol numbers. Condensation of H2SO4 gas onto pre-existing particles is an important process, dominating the growth of small particles in the nucleation mode to the Aitken mode and the aging of hydrophobic matter. Together with in-cloud production of H2SO4, it significantly contributes to (and often dominates) the mass burden (and hence composition) of the hydrophilic Aitken and accumulation mode particles. Particle growth itself is the leading source of number densities in the hydrophilic Aitken and accumulation modes, with their hydrophobic counterparts contributing (even locally) relatively little. As expected, the coarse mode is dominated by primary emissions and mostly decoupled from the smaller modes. Our analysis also suggests that coagulation serves mainly as a loss process for number densities and that, relative to other processes, it is a rather unimportant contributor to composition changes of aerosol. The analysis is extended with sensitivity studies where the impact of a lower model resolution or pre-industrial emissions is shown to be small. We discuss the use of the current budget for model simplification, prioritization of model improvements, identification of potential structural model errors and model evaluation against observations.

  6. Uranium, soluble salts

    Integrated Risk Information System (IRIS)

    Uranium , soluble salts ; no CASRN Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Eff

  7. Thallium (I), soluble salts

    Integrated Risk Information System (IRIS)

    Thallium ( I ) , soluble salts ; CASRN Various Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarc

  8. Nickel, soluble salts

    Integrated Risk Information System (IRIS)

    Nickel , soluble salts ; CASRN Various Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  9. Fluorine (soluble fluoride)

    Integrated Risk Information System (IRIS)

    Fluorine ( soluble fluoride ) ; CASRN 7782 - 41 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for No

  10. Volcanic ash as an iron-fertilizer in ocean surface water

    NASA Astrophysics Data System (ADS)

    Olgun, N.; Duggen, S.; Croot, P.; Dietze, H.; Schacht, U.; Oskarsson, N.; Siebe, C.; Auer, A.

    2007-12-01

    Surface ocean fertilisation with iron may affect the marine primary productivity, C-cycles and eventually climate development. Volcanic ash has the potential to release iron on contact with seawater and to stimulate phytoplankton growth (1,2) but the relative importance of volcanism at destructive plate margins (subduction zones, SZ) and intraplate volcanic settings (ocean islands at hot spots) remains unknown. Here we present new results from geochemical experiments with natural seawater and numerous volcanic ash samples from SZ volcanoes in the Pacific Ring of Fire (Alaska, Japan, Kamchatka, Northern and Central America and Papua New Guinea) and hot spot volcanoes (on Iceland and Hawaii). The release of iron as a function of time was determined in situ in seawater by means of Cathodic Stripping Voltammetry. Our experiments show that: A) volcanic ash from both SZ and hot spot volcanic areas mobilise significant amounts of iron, B) with the highest mobilisation rates within the first 10-20 minutes and C) indicate that volcanic ash from hot spot volcanoes mobilise less iron than volcanic ash from SZ. We propose that the higher iron-mobilisation potential of SZ volcanic ash results from higher HCl/HF ratios in SZ volcanic gases that seem to be involved in the formation of Fe-bearing soluble salt coatings (condensed gases and adsorbed aerosols) on ash particles (1,2,3). Higher HCl/HF ratios in SZ volcanic gases thus appear to be linked to the recycling of seawater through subduction of oceanic lithosphere at destructive plate margins. Together, taking into account differences in ash-fluxes from SZ and hot spot volcanoes into the oceans, our study suggests that SZ volcanic ash plays a more important role for the global surface ocean iron budget than ash from volcanoes in hot spot areas. 1 Frogner, Gislason, Oskarsson (2001). Geology, 29, 487-490. 2 Duggen, Croot, Schacht, Hofmann (2007) Geoph. Res. Letters 34, 5. 3 Oskarsson (1980), J. Volc. and Geoth. Res. 8, 251-266.

  11. METABOLISM OF IRON STORES

    PubMed Central

    SAITO, HIROSHI

    2014-01-01

    ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since the pioneering research by Shoden in 1953. However, we recently developed a new method for determining ferritin iron and hemosiderin iron by computer-assisted serum ferritin kinetics. Serum ferritin increase or decrease curves were measured in patients with normal storage iron levels (chronic hepatitis C and iron deficiency anemia treated by intravenous iron injection), and iron overload (hereditary hemochromatosis and transfusion dependent anemia). We thereby confirmed the existence of two iron pathways where iron flows followed the numbered order (1) labile iron, (2) ferritin and (3) hemosiderin in iron deposition and mobilization among many previously proposed but mostly unproven routes. We also demonstrated the increasing and decreasing phases of ferritin iron and hemosiderin iron in iron deposition and mobilization. The author first demonstrated here the change in proportion between pre-existing ferritin iron and new ferritin iron synthesized by removing iron from hemosiderin in the course of iron removal. In addition, the author disclosed the cause of underestimation of storage iron turnover rate which had been reported by previous investigators in estimating storage iron turnover rate of normal subjects. PMID:25741033

  12. Aerosol MTF revisited

    NASA Astrophysics Data System (ADS)

    Kopeika, Norman S.; Zilberman, Arkadi; Yitzhaky, Yitzhak

    2014-05-01

    Different views of the significance of aerosol MTF have been reported. For example, one recent paper [OE, 52(4)/2013, pp. 046201] claims that the aerosol MTF "contrast reduction is approximately independent of spatial frequency, and image blur is practically negligible". On the other hand, another recent paper [JOSA A, 11/2013, pp. 2244-2252] claims that aerosols "can have a non-negligible effect on the atmospheric point spread function". We present clear experimental evidence of common significant aerosol blur and evidence that aerosol contrast reduction can be extremely significant. In the IR, it is more appropriate to refer to such phenomena as aerosol-absorption MTF. The role of imaging system instrumentation on such MTF is addressed too.

  13. Atmospheric aerosol composition and source apportionments to aerosol in southern Taiwan

    NASA Astrophysics Data System (ADS)

    Tsai, Ying I.; Chen, Chien-Lung

    In this study, the chemical characteristics of winter aerosol at four sites in southern Taiwan were determined and the Gaussian Trajectory transfer coefficient model (GTx) was then used to identify the major air pollutant sources affecting the study sites. Aerosols were found to be acidic at all four sites. The most important constituents of the particulate matter (PM) by mass were SO 42-, organic carbon (OC), NO 3-, elemental carbon (EC) and NH 4+, with SO 42-, NO 3-, and NH 4+ together constituting 86.0-87.9% of the total PM 2.5 soluble inorganic salts and 68.9-78.3% of the total PM 2.5-10 soluble inorganic salts, showing that secondary photochemical solution components such as these were the major contributors to the aerosol water-soluble ions. The coastal site, Linyuan (LY), had the highest PM mass percentage of sea salts, higher in the coarse fraction, and higher sea salts during daytime than during nighttime, indicating that the prevailing daytime sea breeze brought with it more sea-salt aerosol. Other than sea salts, crustal matter, and EC in PM 2.5 at Jenwu (JW) and in PM 2.5-10 at LY, all aerosol components were higher during nighttime, due to relatively low nighttime mixing heights limiting vertical and horizontal dispersion. At JW, a site with heavy traffic loadings, the OC/EC ratio in the nighttime fine and coarse fractions of approximately 2.2 was higher than during daytime, indicating that in addition to primary organic aerosol (POA), secondary organic aerosol (SOA) also contributed to the nighttime PM 2.5. This was also true of the nighttime coarse fraction at LY. The GTx produced correlation coefficients ( r) for simulated and observed daily concentrations of PM 10 at the four sites (receptors) in the range 0.45-0.59 and biases from -6% to -20%. Source apportionment indicated that point sources were the largest PM 10 source at JW, LY and Daliao (DL), while at Meinung (MN), a suburban site with less local PM 10, SO x and NO x emissions, upwind

  14. Sampling Submicron T1 Bacteriophage Aerosols

    PubMed Central

    Harstad, J. Bruce

    1965-01-01

    Liquid impingers, filter papers, and fritted bubblers were partial viable collectors of radioactive submicron T1 bacteriophage aerosols at 30, 55, and 85% relative humidity. Sampler differences for viable collection were due to incomplete physical collection (slippage) and killing of phage by the samplers. Dynamic aerosols of a mass median diameter of 0.2 μ were produced with a Dautrebande generator from concentrated aqueous purified phage suspensions containing extracellular soluble radioactive phosphate as a physical tracer. There was considerable destruction of phage by the Dautrebande generator; phage titers of the Dautrebande suspension decreased exponentially, but there was a progressive (linear) increase in tracer titers. Liquid impingers recovered the most viable phage but allowed considerable (30 to 48%) slippage, which varies inversely with the aerosol relative humidity. Filter papers were virtually complete physical collectors of submicron particles but were the most destructive. Fritted bubbler slippage was more than 80%. With all samplers, phage kill was highest at 85% relative humidity and lowest at 55% relative humidity. An electrostatic precipitator was used to collect aerosol samples for particle sizing with an electron microscope. The particle size was slightly larger at 85% relative humidity than at 30 or 55% relative humidity. Images Fig. 1 Fig. 4 PMID:5866038

  15. Synergistic intracellular iron chelation combinations: mechanisms and conditions for optimizing iron mobilization.

    PubMed

    Vlachodimitropoulou Koumoutsea, Evangelia; Garbowski, Maciej; Porter, John

    2015-09-01

    Iron chelators are increasingly combined clinically but the optimal conditions for cellular iron mobilization and mechanisms of interaction are unclear. Speciation plots for iron(III) binding of paired combinations of the licensed iron chelators desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) suggest conditions under which chelators can combine as 'shuttle' and 'sink' molecules but this approach does not consider their relative access and interaction with cellular iron pools. To address this issue, a sensitive ferrozine-based detection system for intracellular iron removal from the human hepatocyte cell line (HuH-7) was developed. Antagonism, synergism or additivity with paired chelator combinations was distinguished using mathematical isobologram analysis over clinically relevant chelator concentrations. All combinations showed synergistic iron mobilization at 8 h with clinically achievable concentrations of sink and shuttle chelators. Greatest synergism was achieved by combining DFP with DFX, where about 60% of mobilized iron was attributable to synergistic interaction. These findings predict that the DFX dose required for a half-maximum effect can be reduced by 3·8-fold when only 1 μmol/l DFP is added. Mechanisms for the synergy are suggested by consideration of the iron-chelate speciation plots together with the size, charge and lipid solubilities for each chelator. Hydroxypyridinones with low lipid solubilities but otherwise similar properties to DFP were used to interrogate the mechanistic interactions of chelator pairs. These studies confirm that synergistic cellular iron mobilization requires one chelator to have the physicochemical properties to enter cells, chelate intracellular iron and subsequently donate iron to a second 'sink' chelator.

  16. Synergistic intracellular iron chelation combinations: mechanisms and conditions for optimizing iron mobilization.

    PubMed

    Vlachodimitropoulou Koumoutsea, Evangelia; Garbowski, Maciej; Porter, John

    2015-09-01

    Iron chelators are increasingly combined clinically but the optimal conditions for cellular iron mobilization and mechanisms of interaction are unclear. Speciation plots for iron(III) binding of paired combinations of the licensed iron chelators desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) suggest conditions under which chelators can combine as 'shuttle' and 'sink' molecules but this approach does not consider their relative access and interaction with cellular iron pools. To address this issue, a sensitive ferrozine-based detection system for intracellular iron removal from the human hepatocyte cell line (HuH-7) was developed. Antagonism, synergism or additivity with paired chelator combinations was distinguished using mathematical isobologram analysis over clinically relevant chelator concentrations. All combinations showed synergistic iron mobilization at 8 h with clinically achievable concentrations of sink and shuttle chelators. Greatest synergism was achieved by combining DFP with DFX, where about 60% of mobilized iron was attributable to synergistic interaction. These findings predict that the DFX dose required for a half-maximum effect can be reduced by 3·8-fold when only 1 μmol/l DFP is added. Mechanisms for the synergy are suggested by consideration of the iron-chelate speciation plots together with the size, charge and lipid solubilities for each chelator. Hydroxypyridinones with low lipid solubilities but otherwise similar properties to DFP were used to interrogate the mechanistic interactions of chelator pairs. These studies confirm that synergistic cellular iron mobilization requires one chelator to have the physicochemical properties to enter cells, chelate intracellular iron and subsequently donate iron to a second 'sink' chelator. PMID:26033030

  17. Iron-Tolerant Cyanobacteria: Ecophysiology and Fingerprinting

    NASA Technical Reports Server (NTRS)

    Brown, I. I.; Mummey, D.; Lindsey, J.; McKay, D. S.

    2006-01-01

    Although the iron-dependent physiology of marine and freshwater cyanobacterial strains has been the focus of extensive study, very few studies dedicated to the physiology and diversity of cyanobacteria inhabiting iron-depositing hot springs have been conducted. One of the few studies that have been conducted [B. Pierson, 1999] found that cyanobacterial members of iron depositing bacterial mat communities might increase the rate of iron oxidation in situ and that ferrous iron concentrations up to 1 mM significantly stimulated light dependent consumption of bicarbonate, suggesting a specific role for elevated iron in photosynthesis of cyanobacteria inhabiting iron-depositing hot springs. Our recent studies pertaining to the diversity and physiology of cyanobacteria populating iron-depositing hot springs in Great Yellowstone area (Western USA) indicated a number of different isolates exhibiting elevated tolerance to Fe(3+) (up to 1 mM). Moreover, stimulation of growth was observed with increased Fe(3+) (0.02-0.4 mM). Molecular fingerprinting of unialgal isolates revealed a new cyanobacterial genus and species Chroogloeocystis siderophila, an unicellular cyanobacterium with significant EPS sheath harboring colloidal Fe(3+) from iron enriched media. Our preliminary data suggest that some filamentous species of iron-tolerant cyanobacteria are capable of exocytosis of iron precipitated in cytoplasm. Prior to 2.4 Ga global oceans were likely significantly enriched in soluble iron [Lindsay et al, 2003], conditions which are not conducive to growth of most contemporary oxygenic cyanobacteria. Thus, iron-tolerant CB may have played important physiological and evolutionary roles in Earths history.

  18. Iron, phytoplankton growth, and the carbon cycle.

    PubMed

    Street, Joseph H; Paytan, Adina

    2005-01-01

    Iron is an essential nutrient for all living organisms. Iron is required for the synthesis of chlorophyll and of several photosynthetic electron transport proteins and for the reduction of CO2, SO4(2-), and NO3(-) during the photosynthetic production of organic compounds. Iron concentrations in vast areas of the ocean are very low (<1 nM) due to the low solubility of iron in oxic seawater. Low iron concentrations have been shown to limit primary production rates, biomass accumulation, and ecosystem structure in a variety of open-ocean environments, including the equatorial Pacific, the subarctic Pacific and the Southern Ocean and even in some coastal areas. Oceanic primary production, the transfer of carbon dioxide into organic carbon by photosynthetic plankton (phytoplankton), is one process by which atmospheric CO2 can be transferred to the deep ocean and sequestered for long periods of time. Accordingly, iron limitation of primary producers likely plays a major role in the global carbon cycle. It has been suggested that variations in oceanic primary productivity, spurred by changes in the deposition of iron in atmospheric dust, control atmospheric CO2 concentrations, and hence global climate, over glacial-interglacial timescales. A contemporary application of this "iron hypothesis" promotes the large-scale iron fertilization of ocean regions as a means of enhancing the ability of the ocean to store anthropogenic CO2 and mitigate 21st century climate change. Recent in situ iron enrichment experiments in the HNLC regions, however, cast doubt on the efficacy and advisability of iron fertilization schemes. The experiments have confirmed the role of iron in regulating primary productivity, but resulted in only small carbon export fluxes to the depths necessary for long-term sequestration. Above all, these experiments and other studies of iron biogeochemistry over the last two decades have begun to illustrate the great complexity of the ocean system. Attempts to

  19. Free amino acids in Antarctic aerosol: potential markers for the evolution and fate of marine aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, E.; Zangrando, R.; Vecchiato, M.; Piazza, R.; Cairns, W. R. L.; Capodaglio, G.; Barbante, C.; Gambaro, A.

    2015-05-01

    To investigate the impact of marine aerosols on global climate change it is important to study their chemical composition and size distribution. Amino acids are a component of the organic nitrogen in aerosols and particles containing amino acids have been found to be efficient ice nuclei. The main aim of this study was to investigate the L- and D-free amino acid composition as possible tracers of primary biological production in Antarctic aerosols from three different areas: two continental bases, Mario Zucchelli Station (MZS) on the coast of the Ross Sea, Concordia Station at Dome C on the Antarctic Plateau, and the Southern Ocean near the Antarctic continent. Studying the size distribution of amino acids in aerosols allowed us to characterize this component of the water-soluble organic carbon (WSOC) in marine aerosols near their source and after long-range transport. The presence of only free L-amino acids in our samples is indicative of the prevalence of phytoplanktonic material. Sampling at these three points allowed us to study the reactivity of these compounds during long-range transport. The mean total amino acid concentration detected at MZS was 11 pmol m-3, a higher percentage of amino acids were found in the fine fraction. The aerosol samples collected at Dome C had the lowest amino acid values (0.7 and 0.8 pmol m-3), and the coarse particles were found to have higher concentrations of amino acids compared to the coastal site. The amino acid composition in the aerosol collected at Dome C had also changed compared to the coastal site, suggesting that physical and chemical transformations had occurred during long range transport. During the sampling cruise on the R/V Italica on the Southern Ocean, high concentrations of amino acids were found in the total suspended particles, this we attribute to the presence of intact biological material (as microorganisms or plant material) in the sample.

  20. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

  1. Thermoluminescent aerosol analysis

    NASA Technical Reports Server (NTRS)

    Rogowski, R. S.; Long, E. R., Jr. (Inventor)

    1977-01-01

    A method for detecting and measuring trace amounts of aerosols when reacted with ozone in a gaseous environment was examined. A sample aerosol was exposed to a fixed ozone concentration for a fixed period of time, and a fluorescer was added to the exposed sample. The sample was heated in a 30 C/minute linear temperature profile to 200 C. The trace peak was measured and recorded as a function of the test aerosol and the recorded thermoluminescence trace peak of the fluorescer is specific to the aerosol being tested.

  2. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    NASA Astrophysics Data System (ADS)

    Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

    2016-11-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

  3. Aerosol processing in stratiform clouds in ECHAM6-HAM

    NASA Astrophysics Data System (ADS)

    Neubauer, David; Lohmann, Ulrike; Hoose, Corinna

    2013-04-01

    Aerosol processing in stratiform clouds by uptake into cloud particles, collision-coalescence, chemical processing inside the cloud particles and release back into the atmosphere has important effects on aerosol concentration, size distribution, chemical composition and mixing state. Aerosol particles can act as cloud condensation nuclei. Cloud droplets can take up further aerosol particles by collisions. Atmospheric gases may also be transferred into the cloud droplets and undergo chemical reactions, e.g. the production of atmospheric sulphate. Aerosol particles are also processed in ice crystals. They may be taken up by homogeneous freezing of cloud droplets below -38° C or by heterogeneous freezing above -38° C. This includes immersion freezing of already immersed aerosol particles in the droplets and contact freezing of particles colliding with a droplet. Many clouds do not form precipitation and also much of the precipitation evaporates before it reaches the ground. The water soluble part of the aerosol particles concentrates in the hydrometeors and together with the insoluble part forms a single, mixed, larger particle, which is released. We have implemented aerosol processing into the current version of the general circulation model ECHAM6 (Stevens et al., 2013) coupled to the aerosol module HAM (Stier et al., 2005). ECHAM6-HAM solves prognostic equations for the cloud droplet number and ice crystal number concentrations. In the standard version of HAM, seven modes are used to describe the total aerosol. The modes are divided into soluble/mixed and insoluble modes and the number concentrations and masses of different chemical components (sulphate, black carbon, organic carbon, sea salt and mineral dust) are prognostic variables. We extended this by an explicit representation of aerosol particles in cloud droplets and ice crystals in stratiform clouds similar to Hoose et al. (2008a,b). Aerosol particles in cloud droplets are represented by 5 tracers for the

  4. The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal

    SciTech Connect

    Richmond, Scott; Bridgewater, Jon S; Ward, John W; Allen, Thomas A

    2009-01-01

    Pressure-Composition-Temperature (PCT) data are presented for the plutonium-hydrogen (Pu-H) and plutonium-deuterium (Pu-D) systems in the solubility region up to terminal solubility (precipitation of PuH{sub 2}). The heats of solution for PuH{sub s} and PuD{sub s} are determined from PCT data in the ranges 350-625 C for gallium alloyed Pu and 400-575 C for unalloyed Pu. The solubility of high purity plutonium alloyed with 2 at.% gallium is compared to high purity unalloyed plutonium. Significant differences are found in hydrogen solubility for unalloyed Pu versus gallium alloyed Pu. Differences in hydrogen solubility due to an apparent phase change are observable in the alloyed and unalloyed solubilities. The effect of iron impurities on Pu-Ga alloyed Pu is shown via hydrogen solubility data as preventing complete homogenization.

  5. Characteristics of water-soluble ions before, during and after fog events

    NASA Astrophysics Data System (ADS)

    Li, P.; Du, H.; Yang, C.; Yao, J.; Du, J.; Chen, J.

    2010-07-01

    Two atmospheric processes of rain-fog-haze and haze-fog-rain were observed on Feb.8th and Mar. 14th, 2010 in urban Shanghai. On-line characterization of water-soluble ions of aerosol was performed before, during and after two fog episodes by an instrument of Monitoring AeRosoles and GAses (MARGA). Fog water samples were also collected to study the chemical ion characteristics for identifying the property of fogs. After rain, total water-soluble ion concentration in PM2.5 increased by 71.9%. Afterwards, a fog formation was observed as a frontal fog. Six fog water samples were collected to measure concentration of water-soluble ions, whose total concentrations decreased from beginning to end of fog. At the end of fog, the total water-soluble ion concentration of aerosol was continually increased. Meanwhile with a sharp decline of RH down to 70% in two hours, and a haze episode was observed. The reverse process, haze-fog-rain process, was also investigated. After the haze episode, total water-soluble ions concentration of aerosol rarely increased, but fog appeared with sharp increase of RH. Concentration of water-soluble ions in the fog water sample was higher than mean concentration of samples in 2009. When the fog started to disperse, the ion concentration hardly changed. As water vapor continued to increase, rain was observed. The inorganic compositions of aerosol in both fog events were dominated by sulfate and ammonium. The in situ investigation clearly illustrated that fog water mainly influenced by continental sources was dirtier and contained more sediment comparing with fog water influenced by marine sources.

  6. Fluorite solubility equilibria in selected geothermal waters

    USGS Publications Warehouse

    Nordstrom, D.K.; Jenne, E.A.

    1977-01-01

    Calculation of chemical equilibria in 351 hot springs and surface waters from selected geothermal areas in the western United States indicate that the solubility of the mineral fluorite, CaF2, provides an equilibrium control on dissolved fluoride activity. Waters that are undersaturated have undergone dilution by non-thermal waters as shown by decreased conductivity and temperature values, and only 2% of the samples are supersaturated by more than the expected error. Calculations also demonstrate that simultaneous chemical equilibria between the thermal waters and calcite as well as fluorite minerals exist under a variety of conditions. Testing for fluorite solubility required a critical review of the thermodynamic data for fluorite. By applying multiple regression of a mathematical model to selected published data we have obtained revised estimates of the pK (10,96), ??Gof (-280.08 kcal/mole), ??Hof (-292.59 kcal/mole), S?? (16.39 cal/deg/mole) and CoP (16.16 cal/deg/mole) for CaF2 at 25??C and 1 atm. Association constants and reaction enthalpies for fluoride complexes with boron, calcium and iron are included in this review. The excellent agreement between the computer-based activity products and the revised pK suggests that the chemistry of geothermal waters may also be a guide to evaluating mineral solubility data where major discrepancies are evident. ?? 1977.

  7. Development of ATLID-MSI synergy for retrieving the vertical profiles of aerosol components

    NASA Astrophysics Data System (ADS)

    Kudo, R.; Nishizawa, T.; Higurashi, A.; Sugimoto, N.; Oikawa, E.

    2014-12-01

    EarthCARE is an earth observation satellite and will be launched in 2016. Using its two sensors, ATLID (High spectral resolution lidar) and MSI (Multi-spectral imager), we are developing the synergy algorithm to retrieve the vertical profiles of extinction coefficients at 355 nm of four aerosol components (Water-soluble, black carbon, dust, and sea-salt particles), and the column mean of mode radii of water-soluble and dust particles. The ATLID data are extinction coefficient, backscatter coefficient, and depolarization ratio for total aerosols at 355 nm. The MSI data are radiances at 670 and 865 nm. The dry volume concentrations of four aerosol components at each altitude and the mode radii of water-soluble and dust particles in the column are simultaneously optimized to ATLID and MSI data by the gauss newton method. After the optimization, the vertical profiles of the extinction coefficient at 355 nm of four aerosol components are obtained. The size distributions of four aerosol components are assumed to be a lognormal distribution. The refractive indices of four aerosol components are given from previously observational studies. The humidity growth is considered for water-soluble and sea-salt particles. The volume concentration and the mode radius of the sea-salt particle are parameterized using the surface wind speed on the ocean. We assumed that the shape of the water-soluble, black carbon, and sea-salt particles are spherical, and the shape of the dust particle is spheroidal. We tested the algorithm using the ATLID and MSI data simulated using clean, dust-transported, and smoke-transported aerosols. The extinction coefficients of each component at 355 nm are retrieved well. The mode radius of water-soluble and dust particles were somehow overestimated.

  8. Modeling aqueous solubility.

    PubMed

    Butina, Darko; Gola, Joelle M R

    2003-01-01

    This paper describes the development of an aqueous solubility model based on solubility data from the Syracuse database, calculated octanol-water partition coefficient, and 51 2D molecular descriptors. Two different statistical packages, SIMCA and Cubist, were used and the results were compared. The Cubist model, which comprises a collection of rules, each of which has an associated Multiple Linear Regression model (MLR), gave better overall results on a test set of 640 compounds with an overall squared correlation coefficient of 0.74 and an absolute average error of 0.68 log units. Both training and independent test sets had similar distributions of structures in terms of the different functionalities present-60% neutral, 14% acidic, 8% phenolic, 11% monobasic, 4% polybasic, and 3% zwitterionic molecules. Sets were designed by random selection, with 2688 (81%) and 640 (19%) molecules, respectively, forming the training and the test sets.

  9. A Perspective on Solubility Rules.

    ERIC Educational Resources Information Center

    Monroe, Manus; Abrams, Karl

    1984-01-01

    Presents four generalizations about solubilities. These generalizations (rules), are useful in introducing the dynamic topics of solubility and in helping high school and introductory college chemistry students make some order out of the tremendous number of facts available. (JN)

  10. Comprehensive characterization of PM2.5 aerosols in Singapore

    NASA Astrophysics Data System (ADS)

    Balasubramanian, R.; Qian, W.-B.; Decesari, S.; Facchini, M. C.; Fuzzi, S.

    2003-08-01

    A comprehensive characterization of PM2.5 aerosols collected in Singapore from January through December 2000 is presented. The annual average mass concentration of PM2.5 was 27.2 μg/m3. The atmospheric loading of PM2.5 was elevated sporadically from March through May, mainly due to advection of biomass burning (deliberate fires to clear plantation areas) impacted air masses from Sumatra, Indonesia. Satellite images of the area, trajectory calculations, and surface wind direction data are in support of the transport of pyrogenic products from Sumatra toward Singapore. Aerosol samples collected during the dry season were analyzed for water-soluble ions, water-soluble organic compounds (WSOC), elemental carbon (EC), organic carbon, and trace elements using a number of analytical techniques. The major components were sulfate, EC, water-soluble carbonaceous materials, and water-insoluble carbonaceous materials. Aerosol WSOC were characterized based on a combination of chromatographic separations by ion exchange chromatography, functional group investigation by proton nuclear magnetic resonance, and total organic carbon determination. The comprehensive chemical characterization of PM2.5 particles revealed that both non-sea-salt sufate (nss-SO42-) and carbonaceous aerosols mainly contributed to the increase in the mass concentration of aerosols during the smoke haze period. Using a mass closure test (a mass balance), we determined whether the physical measurement of gravimetric fine PM concentration of a sample is equal to the summed concentrations of the individually identified chemical constituents (measured or inferred) in the sample. The sum of the determined groups of aerosol components and the gravimetrically determined mass agreed reasonably well. Principal component analysis was performed from the combined data set, and five factors were observed: a soil dust component, a metallurgical industry factor, a factor representing emissions from biomass burning and

  11. FeCycle: Attempting an iron biogeochemical budget from a mesoscale SF6 tracer experiment in unperturbed low iron waters

    NASA Astrophysics Data System (ADS)

    Boyd, P. W.; Law, C. S.; Hutchins, D. A.; Abraham, E. R.; Croot, P. L.; Ellwood, M.; Frew, R. D.; Hadfield, M.; Hall, J.; Handy, S.; Hare, C.; Higgins, J.; Hill, P.; Hunter, K. A.; Leblanc, K.; Maldonado, M. T.; McKay, R. M.; Mioni, C.; Oliver, M.; Pickmere, S.; Pinkerton, M.; Safi, K.; Sander, S.; Sanudo-Wilhelmy, S. A.; Smith, M.; Strzepek, R.; Tovar-Sanchez, A.; Wilhelm, S. W.

    2005-12-01

    An improved knowledge of iron biogeochemistry is needed to better understand key controls on the functioning of high-nitrate low-chlorophyll (HNLC) oceanic regions. Iron budgets for HNLC waters have been constructed using data from disparate sources ranging from laboratory algal cultures to ocean physics. In summer 2003 we conducted FeCycle, a 10-day mesoscale tracer release in HNLC waters SE of New Zealand, and measured concurrently all sources (with the exception of aerosol deposition) to, sinks of iron from, and rates of iron recycling within, the surface mixed layer. A pelagic iron budget (timescale of days) indicated that oceanic supply terms (lateral advection and vertical diffusion) were relatively small compared to the main sink (downward particulate export). Remote sensing and terrestrial monitoring reveal 13 dust or wildfire events in Australia, prior to and during FeCycle, one of which may have deposited iron at the study location. However, iron deposition rates cannot be derived from such observations, illustrating the difficulties in closing iron budgets without quantification of episodic atmospheric supply. Despite the threefold uncertainties reported for rates of aerosol deposition (Duce et al., 1991), published atmospheric iron supply for the New Zealand region is ˜50-fold (i.e., 7- to 150-fold) greater than the oceanic iron supply measured in our budget, and thus was comparable (i.e., a third to threefold) to our estimates of downward export of particulate iron. During FeCycle, the fluxes due to short term (hours) biological iron uptake and regeneration were indicative of rapid recycling and were tenfold greater than for new iron (i.e. estimated atmospheric and measured oceanic supply), giving an "fe" ratio (uptake of new iron/uptake of new + regenerated iron) of 0.17 (i.e., a range of 0.06 to 0.51 due to uncertainties on aerosol iron supply), and an "Fe" ratio (biogenic Fe export/uptake of new + regenerated iron) of 0.09 (i.e., 0.03 to 0.24).

  12. Enhanced solubility and ecological impact of atmospheric phosphorus deposition upon extended seawater exposure.

    PubMed

    Mackey, Katherine R M; Roberts, Kathryn; Lomas, Michael W; Saito, Mak A; Post, Anton F; Paytan, Adina

    2012-10-01

    Atmospheric P solubility affects the amount of P available for phytoplankton in the surface ocean, yet our understanding of the timing and extent of atmospheric P solubility is based on short-term leaching experiments where conditions may differ substantially from the surface ocean. We conducted longer- term dissolution experiments of atmospheric aerosols in filtered seawater, and found up to 9-fold greater dissolution of P after 72 h compared to instantaneous leaching. Samples rich in anthropogenic materials released dissolved inorganic P (DIP) faster than mineral dust. To gauge the effect of biota on the fate of atmospheric P, we conducted field incubations with aerosol samples collected in the Sargasso Sea and Red Sea. In the Sargasso Sea phytoplankton were not P limited, and biological activity enhanced DIP release from aerosols, and aerosols induced biological mineralization of dissolved organic P in seawater, leading to DIP accumulation. However, in the Red Sea where phytoplankton were colimited by P and N, soluble P was rapidly consumed by phytoplankton following aerosol enrichment. Our results suggest that atmospheric P dissolution could continue over multiple days once reaching the surface ocean, and that previous estimates of atmospheric P deposition may underestimate the contribution from this source. PMID:22574853

  13. Enhanced solubility and ecological impact of atmospheric phosphorus deposition upon extended seawater exposure.

    PubMed

    Mackey, Katherine R M; Roberts, Kathryn; Lomas, Michael W; Saito, Mak A; Post, Anton F; Paytan, Adina

    2012-10-01

    Atmospheric P solubility affects the amount of P available for phytoplankton in the surface ocean, yet our understanding of the timing and extent of atmospheric P solubility is based on short-term leaching experiments where conditions may differ substantially from the surface ocean. We conducted longer- term dissolution experiments of atmospheric aerosols in filtered seawater, and found up to 9-fold greater dissolution of P after 72 h compared to instantaneous leaching. Samples rich in anthropogenic materials released dissolved inorganic P (DIP) faster than mineral dust. To gauge the effect of biota on the fate of atmospheric P, we conducted field incubations with aerosol samples collected in the Sargasso Sea and Red Sea. In the Sargasso Sea phytoplankton were not P limited, and biological activity enhanced DIP release from aerosols, and aerosols induced biological mineralization of dissolved organic P in seawater, leading to DIP accumulation. However, in the Red Sea where phytoplankton were colimited by P and N, soluble P was rapidly consumed by phytoplankton following aerosol enrichment. Our results suggest that atmospheric P dissolution could continue over multiple days once reaching the surface ocean, and that previous estimates of atmospheric P deposition may underestimate the contribution from this source.

  14. Portable Aerosol Contaminant Extractor

    DOEpatents

    Carlson, Duane C.; DeGange, John J.; Cable-Dunlap, Paula

    2005-11-15

    A compact, portable, aerosol contaminant extractor having ionization and collection sections through which ambient air may be drawn at a nominal rate so that aerosol particles ionized in the ionization section may be collected on charged plate in the collection section, the charged plate being readily removed for analyses of the particles collected thereon.

  15. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  16. Direct Aerosol Forcing Uncertainty

    DOE Data Explorer

    Mccomiskey, Allison

    2008-01-15

    Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

  17. Ganges valley aerosol experiment.

    SciTech Connect

    Kotamarthi, V.R.; Satheesh, S.K.

    2011-08-01

    In June 2011, the Ganges Valley Aerosol Experiment (GVAX) began in the Ganges Valley region of India. The objective of this field campaign is to obtain measurements of clouds, precipitation, and complex aerosols to study their impact on cloud formation and monsoon activity in the region.

  18. Analysis of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Prather, Kimberly A.; Hatch, Courtney D.; Grassian, Vicki H.

    2008-07-01

    Aerosols represent an important component of the Earth's atmosphere. Because aerosols are composed of solid and liquid particles of varying chemical complexity, size, and phase, large challenges exist in understanding how they impact climate, health, and the chemistry of the atmosphere. Only through the integration of field, laboratory, and modeling analysis can we begin to unravel the roles atmospheric aerosols play in these global processes. In this article, we provide a brief review of the current state of the science in the analysis of atmospheric aerosols and some important challenges that need to be overcome before they can become fully integrated. It is clear that only when these areas are effectively bridged can we fully understand the impact that atmospheric aerosols have on our environment and the Earth's system at the level of scientific certainty necessary to design and implement sound environmental policies.

  19. Iron and alloys of iron. [lunar resources

    NASA Technical Reports Server (NTRS)

    Sastri, Sankar

    1992-01-01

    All lunar soil contains iron in the metallic form, mostly as an iron-nickel alloy in concentrations of a few tenths of 1 percent. Some of this free iron can be easily separated by magnetic means. It is estimated that the magnetic separation of 100,000 tons of lunar soil would yield 150-200 tons of iron. Agglutinates contain metallic iron which could be extracted by melting and made into powder metallurgy products. The characteristics and potential uses of the pure-iron and iron-alloy lunar products are discussed. Processes for working iron that might be used in a nonterrestrial facility are also addressed.

  20. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  1. Investigating the Internal Structure of Individual Aerosol Particles Using Atomic Force and Raman Microscopies

    NASA Astrophysics Data System (ADS)

    Freedman, M. A.; Baustian, K. J.; Wise, M. E.; Tolbert, M. A.

    2009-12-01

    We have used Atomic Force Microscopy (AFM) and Raman Microscopy to probe aerosol internal structures in order to understand the optical properties of aerosols composed of mixtures of organic and inorganic components. While AFM gives only topographical information about the particles, indirect chemical information can be obtained by using substrates with different surface properties. With Raman microscopy, chemical signatures of the components of the aerosol are obtained, but we have limited spatial resolution. We have explored the use of these two techniques to look at aerosol internal structure using a range of different model aerosols composed of mixtures of ammonium sulfate with organic compounds of various solubilities such as sucrose, succinic acid, and palmitic acid. At the extremes of solubility, AFM provides suitable information for interpreting aerosol microstructure. For example, AFM clearly shows the presence of core-shell structures for aerosol particles composed of palmitic acid and ammonium sulfate, while the results for aerosol particles composed of succinic acid and ammonium sulfate are more difficult to interpret. Information about size and shape can be obtained when hydrophilic particles are impacted on hydrophobic substrates and vise versa. With Raman microscopy, core-shell structures were readily identified for ammonium sulfate with palmitic acid or succinic acid coatings. For the case of succinic acid and ammonium sulfate mixtures, we are using microscopy results to aid in interpreting the refractive indices we retrieved from cavity ring-down studies.

  2. Predicted modification of the O/C ratio of SOA due to cloud and aerosol processing

    NASA Astrophysics Data System (ADS)

    Carlton, A. G.; Ervens, B.

    2011-12-01

    The formation of secondary organic aerosol formation in cloud and aerosol water (aqSOA) has attracted great attention over the past years and many laboratory data are available to describe such processes in detail. While it has been recognized that aqSOA formation might significantly contribute to the total SOA budget in humid and cloudy regions, the modification of individual aerosol properties, such as oxygenation state (O/C ratio), size (distribution), and light-absorbing properties has not been explored by means of model studies. Precursors of aqSOA are more highly oxidized and water-soluble than those for traditional (gas)SOA and thus aqSOA products have also distinctly higher O/C ratio. Since aqSOA occurs in clouds and in aerosol water at elevated RH, aerosols modified by such processes exhibit a unique vertical profile as compared to gasSOA and add to the organic carbon budget aloft. In this process model study, we will show the extent to which the O/C ratio of aerosols is modified due to aqSOA formation in cloud and aerosol water. The O/C ratio can be considered as a proxy for other aerosol properties such as hygroscopicity (particle growth and CCN activity) and interactions with light (scattering/absorption) which affect the direct and indirect aerosol effects on radiation. Implications of aqSOA formation on these aerosol properties as a function of vertical profile will be discussed.

  3. The relationship between the iron isotopic composition of human whole blood and iron status parameters.

    PubMed

    Van Heghe, Lana; Delanghe, Joris; Van Vlierberghe, Hans; Vanhaecke, Frank

    2013-11-01

    As the iron status of an individual cannot be adequately assessed on the basis of the (total) Fe concentration in whole blood or serum, in medicine a number of parameters, such as the serum concentrations of ferritin, transferrin and soluble transferrin receptor and the transferrin saturation, are routinely determined instead. As previous research has shown that also the isotopic composition of Fe in blood and tissues is dependent on the metabolism, the present study assessed whether Fe isotopic composition in whole blood provides information as to an individual's iron status. Fe isotopic analysis of whole blood samples from a reference population (healthy volunteers) was carried out using multi-collector ICP-mass spectrometry (after chromatographic target element isolation) and the results obtained were investigated by statistical means as to their potential relation with the iron status parameters conventionally used in medicine. A low δ(56)Fe value was demonstrated to coincide with high iron status and a high δ(56)Fe value with low iron status, thus reflecting the response of the body to this iron status in terms of iron uptake, distribution between blood and stores and mobilization of storage iron. In a second phase, the iron isotopic composition in blood from patients treated for hemochromatosis type I and from patients with anemia of chronic disease (ACD) was determined. The results for hemochromatosis patients plotted with the values of low iron status, while those for ACD patients plotted with the values of high iron status. By taking a closer look at the aberrant iron metabolism that comes with these diseases, it can be seen that the patient samples confirm the conclusions drawn for the reference population. Patients with hemochromatosis type I have a strongly upregulated iron uptake, like healthy individuals with low iron status. The metabolism of patients suffering from ACD tries to remove iron from the circulation by downregulating the iron uptake

  4. Solubility and Solubility Product Determination of a Sparingly Soluble Salt: A First-Level Laboratory Experiment

    ERIC Educational Resources Information Center

    Bonomo, Raffaele P.; Tabbi, Giovanni; Vagliasindi, Laura I.

    2012-01-01

    A simple experiment was devised to let students determine the solubility and solubility product, "K"[subscript sp], of calcium sulfate dihydrate in a first-level laboratory. The students experimentally work on an intriguing equilibrium law: the constancy of the product of the ion concentrations of a sparingly soluble salt. The determination of…

  5. Iron and iron derived radicals

    SciTech Connect

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

  6. Soluble porphyrin polymers

    SciTech Connect

    Gust, Jr., John Devens; Liddell, Paul Anthony

    2015-07-07

    Porphyrin polymers of Structure 1, where n is an integer (e.g., 1, 2, 3, 4, 5, or greater) ##STR00001## are synthesized by the method shown in FIGS. 2A and 2B. The porphyrin polymers of Structure 1 are soluble in organic solvents such as 2-MeTHF and the like, and can be synthesized in bulk (i.e., in processes other than electropolymerization). These porphyrin polymers have long excited state lifetimes, making the material suitable as an organic semiconductor for organic electronic devices including transistors and memories, as well as solar cells, sensors, light-emitting devices, and other opto-electronic devices.

  7. Aqueous aerosol SOA formation: impact on aerosol physical properties.

    PubMed

    Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

    2013-01-01

    Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions. PMID:24601011

  8. The impact of atmospheric aerosols on trace metal chemistry in open ocean surface seawater. 2. Copper

    SciTech Connect

    Maring, H.B.; Duce, R.A. )

    1989-01-15

    Atmospheric deposition contributes copper to the surface ocean. The biogeochemical importance and fate of this copper is poorly understood for open ocean regions. Atmospheric aerosols collected at Enewetak Atoll, in the tropical North Pacific, were exposed to seawater and artificial rainwater in laboratory experiments. Aerosol copper during the high-dust season at Enewetak Atoll is made up of aluminosilicate, oceanic, and possibly soil organic matter components. During the low-dust season, marine aerosols collected at Enewetak is soluble in seawater. Dissolved organic matter and possibly cations in seawater increase the dissolution of aerosol copper. The net atmospheric flux of soluble copper to the tropical North Pacific surface waters as does upwelling to eastern North Pacific surface waters. Atmospheric copper deposition, which appears to be primarily of natural origin, may be the most important input of copper to the surface waters of the central gyre of the North Pacific.

  9. Aerosol transport from Chiang Mai, Thailand to Mt. Lulin, Taiwan - Implication of aerosol aging during long-range transport

    NASA Astrophysics Data System (ADS)

    Chuang, Ming-Tung; Lee, Chung-Te; Chou, Charles C.-K.; Engling, Guenter; Chang, Shih-Yu; Chang, Shuenn-Chin; Sheu, Guey-Rong; Lin, Neng-Huei; Sopajaree, Khajornsak; Chang, You-Jia; Hong, Guo-Jun

    2016-07-01

    The transport of biomass burning (BB) aerosol from Indochina may cause a potential effect on climate change in Southeast Asia, East Asia, and the Western Pacific. Up to now, the understanding of BB aerosol composition modification during long-range transport (LRT) is still very limited due to the lack of observational data. In this study, atmospheric aerosols were collected at the Suthep/Doi Ang Khang (DAK) mountain sites in Chiang Mai, Thailand and the Lulin Atmospheric Background Station (Mt. Lulin) in central Taiwan from March to April 2010 and from February to April 2013, respectively. During the study period, an upwind and downwind relationship between the Suthep/DAK and Lulin sites (2400 km apart) was validated by backward trajectories. Comprehensive aerosol properties were resolved for PM2.5 water-soluble inorganic ions, carbonaceous content, water-soluble/insoluble organic carbon (WSOC/WIOC), dicarboxylic acids and their salts (DCAS), and anhydrosugars. A Modification Factor (MF) is proposed by employing non-sea-salt potassium ion (nss-K+) or fractionalized elemental carbon evolved at 580 °C after pyrolized OC correction (EC1-OP) as a BB aerosol tracer to evaluate the mass fraction changes of aerosol components from source to receptor regions during LRT. The MF values of nss-SO42-, NH4+, NO3-, OC1 (fractionalized organic carbon evolved from room temperature to 140 °C), OP (pyrolized OC fraction), DCAS, and WSOC were above unity, which indicated that these aerosol components were enhanced during LRT as compared with those in the near-source region. In contrast, the MF values of anhydrosugars ranged from 0.1 to 0.3, indicating anhydrosugars have degraded during LRT.

  10. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  11. Formaldehyde content of atmospheric aerosol.

    PubMed

    Toda, Kei; Yunoki, Satoru; Yanaga, Akira; Takeuchi, Masaki; Ohira, Shin-Ichi; Dasgupta, Purnendu K

    2014-06-17

    Formaldehyde (HCHO) is a highly soluble polar molecule with a large sticking coefficient and thus likely exists in both gaseous and particulate forms. Few studies, however, address particulate HCHO (HCHO(p)). Some report that HCHO(p) concentrations (obtained only with long duration sampling) are very low. The lack of data partly reflects the difficulty of specifically measuring HCHO(p). Long duration filter sampling may not produce meaningful results for a variety of reasons. In this work, gaseous HCHO (HCHO(g)) and (HCHO(p)) were, respectively, collected with a parallel plate wet denuder (PPWD) followed by a mist chamber/hydrophilic filter particle collector (PC). The PPWD quantitatively removed HCHO(g) and the PC then collected the transmitted aerosol. The collected HCHO from either device was alternately analyzed by Hantzsch reaction-based continuous flow fluorometry. Each gas and particle phase measurement took 5 min each, with a 10 min cycle. The limits of detection were 0.048 and 0.0033 μg m(-3), respectively, for HCHO(g) and HCHO(p). The instrument was deployed in three separate campaigns in a forest station in western Japan in March, May, and July of 2013. Based on 1296 data pairs, HCHO(p), was on the average, 5% of the total HCHO. Strong diurnal patterns were observed, with the HCHO(p) fraction peaking in the morning. The relative humidity dependence of the partition strongly suggests that it is driven by the liquid water content of the aerosol phase. However, HCHO(p) was 100× greater than that expected from Henry's law. We propose that the low water activity in the highly saline droplets lead to HCHO oligomerization.

  12. Validation of the assimilation of satellite-based aerosol measurements into a chemical transport model using aerosol component information

    NASA Astrophysics Data System (ADS)

    Martynenko, Dmytro; Holzer-Popp, Thomas; Schroedter-Homscheidt, Marion

    Aerosol monitoring is of growing interest due to the impact of aerosol particle concentration on human health and the global climate. The key question of this paper is to understand how the assimilation of satellite atmospheric aerosol observations with enhanced observation and background covariance matrices improves the capability of a chemical transport model in reproducing the distribution of tropospheric particles. The task of this study is a validation of assimilation results by using ground-based AERONET measurements for 2006-2008 at stations from Europe and Africa regions. The study is carried out using the Model for Atmospheric Transport and Chemistry (MATCH operated at DLR). As measurement input vector for as-similation satellite data from SCIAMACHY and AATSR instruments onboard ENVISAT was used. Synergetic Aerosol Retrieval (SYNAER) observational and model data have been cou-pled by means of data the two-dimensional variational assimilation. SYNAER measurements are able to distinguish between different aerosol components such as water-soluble, soot, sea salt and long-range transported mineral aerosols. The final analysis is highly dependent on the specification of the error covariance matrices. Since observation and background error covari-ance matrices are not perfectly known, a large potential for improvements of the analyses is offered by methods allowing their constructing and tuning. In this study, a method proposed by Desroziers and Ivanov (2001) is used to tune background and observational error statistics of the 2D-Var assimilation procedure by using information content analysis of the retrieval algorithm.

  13. Comparison of aerosol code predictions with experimental observations on the behavior of aerosols in steam

    SciTech Connect

    Tobias, M.L.

    1983-01-01

    Several computer codes have been developed to predict the behavior of aerosols in steam, a situation which is expected to occur in a light-water reactor accident. Among the codes with capabilities in this respect are MAEROS (Sandia) AEROMECH (University of Missouri) and NAUA-Mod4 (Karlsruhe). NAUA was specifically developed to model steam-aerosol behavior in hypothetical accidents in pressurized water reactors. It is based upon a series of experiments, in which aerosols of uranium oxide, platinum oxide, and sodium nitrate were generated in a steam atmosphere. Several series of experiments have been conducted in the NSPP vessel using aerosols generated by plasma torch in a steam-air atmosphere. From these experiments we have selected those performed with iron oxide or uranium oxide for comparison with various computer codes, principally NAUA-Mod4. Comparisons of particle size are displayed also. Results of parameter studies to determine the sensitivity of the calculated results to the steam input level, initial particle size, deposition parameters, and assumed particle density are presented.

  14. Analysis of atmospheric aerosols by PIXE: the importance of real time and complementary measurements

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Castanho, Andrea D.; Yamasoe, Marcia A.; Martins, José Vanderlei; Longo, Karla M.

    1999-04-01

    aerosol bulk PIXE measurements can be complemented with soluble concentrations provided by Ion Chromatography (IC) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Recent developments in remote sensing techniques and products also enhance significantly regional aerosol studies. Three-dimensional air mass trajectories should be integrated in aerosol studies for urban and remote areas. The applications of these techniques to study urban aerosols from São Paulo and Santiago de Chile have broadened extensively the scientific scope of these studies.

  15. The type of fortificant and the leaf matrix both influence iron and zinc bioaccessibility in iron-fortified green leafy vegetable sauces from Burkina Faso.

    PubMed

    Icard-Vernière, C; Picq, C; Courbis, L; Mouquet-Rivier, C

    2016-02-01

    Leafy vegetable sauces from Burkina Faso were assessed as a potential vehicle for food fortification. First, iron and zinc bioaccessibility were measured by dialysability method in amaranth and Jew's mallow sauces and in traditional whole dishes consisting of maize paste plus leafy vegetable sauces. Iron dialysability and solubility were higher in amaranth than in Jew's mallow sauce, pointing to a marked effect of the matrix. Iron dialysability was hardly affected by the maize paste contrary to zinc dialysability, which was reduced. Second, iron and zinc bioaccessibility was assessed in the same sauces fortified with NaFeEDTA or iron sulfate. Added iron, i.e. iron supplied by fortification, represented 60% of total iron at the low fortification level and 80% at high level. In amaranth sauces with the high level of fortification using NaFeEDTA and iron sulfate, fractional dialysable iron reached respectively 66% and 26% compared to only 8.1% in the unfortified sauce. Similarly, in Jew's mallow sauces, fractional dialysable iron was 57% and 5% respectively with NaFeEDTA and iron sulfate and less than 1% in the unfortified sauce. Concomitantly, fractional dialysable zinc increased by respectively 20% and 40% in amaranth and Jew's mallow sauces fortified with NaFeEDTA whereas it remained unchanged with iron sulfate. Iron fortification could be an efficient way to greatly increase the available iron content of green leafy vegetable sauces and for this purpose NaFeEDTA is more effective than iron sulfate whatever the food matrix.

  16. CCN activity of multi-component organic particles: The role of the water solubility distribution

    NASA Astrophysics Data System (ADS)

    Rastak, Narges; Riipinen, Ilona; Pandis, Spyros

    2014-05-01

    Introduction Interactions of atmospheric aerosol particles with the ambient water vapour determine to a large extent the influence that aerosols have on climate. To pin down the climate effects of aerosol particles on clouds and climate it is thus necessary to know how much they absorb water at sub-saturated conditions and at which conditions they can activate as CCN and form cloud droplets. The solubility in water is one of the key properties governing the water-absorption and CCN activation behaviour of aerosol particles. Organic constituents contribute a large fraction (20-90%, depending on the environment) of atmospheric submicron particulate mass which is the part of the aerosol size distribution that typically dominates the CCN numbers. Atmospheric organic compounds have a wide range of solubilities, spanning from practically insoluble material to highly water soluble compounds (e.g. Raymond and Pandis 2003). To accurately predict the water content and CCN activation of atmospheric OA information on the dissolution behaviour and aqueous phase interactions of these complex mixtures is needed. We investigate the dissolution behaviour of complex organic mixtures and their CCN activity using a theoretical framework (Solubility Basis Set, SBS) representing the mixture components with a continuous distribution of solubilities, similar to the VBS (Donahue et al., 2006). Method In this study we consider a monodisperse population of spherical aerosol particles consisting of an internal mixture of organic compounds. When exposed to water vapour, these particles grow reaching a thermodynamic equilibrium between the water vapour and the particle phase. The wet particle is allowed to consist of maximum two phases: the insoluble organic phase and the aqueous phase. The compositions of the organic and aqueous phases are determined on one hand by the equilibrium between the aqueous phase and the water vapour, and on the other hand by the equilibrium of the aqueous phase with

  17. Transgenic petunia with the iron(III)-phytosiderophore transporter gene acquires tolerance to iron deficiency in alkaline environments.

    PubMed

    Murata, Yoshiko; Itoh, Yoshiyuki; Iwashita, Takashi; Namba, Kosuke

    2015-01-01

    Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as mugineic acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic acids and the specific iron(III)-mugineic acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2'-deoxymugineic acid complex, free 2'-deoxymugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2'-deoxymugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to diverse

  18. Solubilisation of aerosol trace metals by cloud processing: A laboratory study

    SciTech Connect

    Spokes, L.J.; Jickells, T.D.; Lim, B. )

    1994-08-01

    The atmosphere has now been recognized as a major source of both trace metals and nutrients to the oceans, with wet deposition being a major contributor to the flux. Solution pH has been suggested to be the major control on metal solubility in rainwater, but for many trace metals this relationship is not a simple one. Aerosols are typically exposed to [approximately]10 condensation/evaporation cloud cycles before removal in rain and, as a result of H[sub 2]SO[sub 4] and HNO[sub 3] uptake and SO[sub 2] oxidation, cloudwater pH can be very low. Laboratory studies have been conducted, using Saharan and Urban aerosols, to assess the effect of pH on trace metal solubility. The results for the crustal elements Al and Fe in the Saharan aerosol show that metal solubility is a strong function of pH with highest solubilities seen under low pH conditions, comparable to those found in clouds. Increasing the pH to simulate neutralization of acidity by ammonia and crustal material results in almost complete removal of these elements from the solution phase, suggesting that a simple relationship between pH and solubility should exist in rainwater. For Al and Fe in the Urban aerosol there is evidence that some of the material solubilized at low pH is kept in solution at high pH, perhaps as the result of complexation by organic matter. Manganese shows high solubility after the initial acidification from both the Saharan and Urban materials with only slight removal from solution at increased pH. For this element it appears, therefore, that the pH-dependent dissolution process is not reversible. It is tentatively suggested that Fe in the Urban aerosol, under these experimental conditions, is under solubility control.

  19. Volcanic Aerosol Radiative Properties

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew

    2015-01-01

    Large sporadic volcanic eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.

  20. Palaeoclimate: Aerosols and rainfall

    NASA Astrophysics Data System (ADS)

    Partin, Jud

    2015-03-01

    Instrumental records have hinted that aerosol emissions may be shifting rainfall over Central America southwards. A 450-year-long precipitation reconstruction indicates that this shift began shortly after the Industrial Revolution.

  1. The hygroscopicity of indoor aerosol particles

    SciTech Connect

    Wei, L.

    1993-07-01

    A system to study the hygroscopic growth of particle was developed by combining a Tandem Differential Mobility Analyzer (TDMA) with a wetted wall reactor. This system is capable of mimicking the conditions in human respiratory tract, and measuring the particle size change due to the hygroscopic growth. The performance of the system was tested with three kinds of particles of known composition, NaCl, (NH{sub 4}){sub 2}SO{sub 4}, and (NH{sub 4})HS0{sub 4} particles. The hygroscopicity of a variety of common indoor aerosol particles was studied including combustion aerosols (cigarette smoking, cooking, incenses and candles) and consumer spray products such as glass cleaner, general purpose cleaner, hair spray, furniture polish spray, disinfectant, and insect killer. Experiments indicate that most of the indoor aerosols show some hygroscopic growth and only a few materials do not. The magnitude of hygroscopic growth ranges from 20% to 300% depending on the particle size and fraction of water soluble components.

  2. Water soluble laser dyes

    DOEpatents

    Hammond, Peter R.; Feeman, James F.; Field, George F.

    1998-01-01

    Novel water soluble dyes of the formula I are provided ##STR1## wherein R.sup.1 and R.sup.4 are alkyl of 1 to 4 carbon atoms or hydrogen; or R.sup.1 -R.sup.2 or R.sup.2 -R.sup.4 form part of aliphatic heterocyclic rings; R.sup.2 is hydrogen or joined with R.sup.1 or R.sup.4 as described above; R.sup.3 is --(CH.sub.2).sub.m --SO.sub.3.sup.-, where m is 1 to 6; X is N, CH or ##STR2## where Y is 2 --SO.sub.3.sup.- ; Z is 3, 4, 5 or 6 --SO.sub.3.sup.-. The novel dyes are particularly useful as the active media in water solution dye lasers.

  3. Water soluble laser dyes

    DOEpatents

    Hammond, P.R.; Feeman, J.F.; Field, G.F.

    1998-08-11

    Novel water soluble dyes of the formula 1 are provided by the formula described in the paper wherein R{sup 1} and R{sup 4} are alkyl of 1 to 4 carbon atoms or hydrogen; or R{sup 1}--R{sup 2} or R{sup 2}--R{sup 4} form part of aliphatic heterocyclic rings; R{sup 2} is hydrogen or joined with R{sup 1} or R{sup 4} as described above; R{sup 3} is --(CH{sub 2}){sub m}--SO{sub 3}{sup {minus}}, where m is 1 to 6; X is N, CH or formula 2 given in paper where Y is 2 --SO{sub 3}{sup {minus}} ; Z is 3, 4, 5 or 6 --SO{sub 3}{sup {minus}}. The novel dyes are particularly useful as the active media in water solution dye lasers.

  4. Aerosol coating of silica fibers with nanoparticles

    SciTech Connect

    Fotou, G.P.; Scott, S.J.; Pratsinis, S.E.

    1994-12-31

    Dendritic silica fibers are in demand for applications such as hot-gas filtration, chromatography, and fabrication of ceramic composites. Because of their high interception area, these fibers are particularly suitable for use as filter elements for high-efficiency, low-pressure drop filtration of particles from gas streams. An aerosol process was developed recently for coating ultrafine silica fibers with nonsize silica particles. Fibers were suspended in air and introduced in a particle-laden flame. Coagulation between the silica particles and the fibers resulted in dendritic structures that increased the specific surface area of the fibers by up to 16 times. Sol-gel processing has also been used for coating fibers. In this study, the catalytic effect of ferrocene on the flame synthesis of high-surface area particle-coated fibers is investigated. Ferrocene (dicylopentadienyl iron) is an organometallic compound of iron. It has been used in the past as catalyst in whisker growth on carbon fibers in a laser reactor. It has also been used as additive for the control of soot growth in hydrocarbon flames. These studies showed that the effect of ferrocene on soot particle growth is related to residence time and mixing of the reactants in the flame. The efficiency of the aerosol coating process is evaluated in terms of the specific surface area enhancement of the fibers.

  5. River-derived humic substances as iron chelators in seawater

    PubMed Central

    Krachler, Regina; Krachler, Rudolf F.; Wallner, Gabriele; Hann, Stephan; Laux, Monika; Cervantes Recalde, Maria F.; Jirsa, Franz; Neubauer, Elisabeth; von der Kammer, Frank; Hofmann, Thilo; Keppler, Bernhard K.

    2015-01-01

    The speciation of iron(III) in oxic seawater is dominated by its hydrolysis and sedimentation of insoluble iron(III)-oxyhydroxide. As a consequence, many oceanic areas have very low iron levels in surface seawater which leads to iron deficiency since phytoplankton require iron as a micronutrient in order to grow. Fortunately, iron solubility is not truly as low as Fe(III) solubility measurements in inorganic seawater would suggest, since oceanic waters contain organic molecules which tend to bind the iron and keep it in solution. Various iron-binding organic ligands which combine to stabilize dissolved iron have been detected and thoroughly investigated in recent years. However, the role of iron-binding ligands from terrestrial sources remains poorly constrained. Blackwater rivers supply large amounts of natural organic material (NOM) to the ocean. This NOM (which consists mainly of vascular plant-derived humic substances) is able to greatly enhance iron bioavailability in estuaries and coastal regions, however, breakdown processes lead to a rapid decrease of river-derived NOM concentrations with increasing distance from land. It has therefore been argued that the influence of river-derived NOM on iron biogeochemistry in offshore seawater does not seem to be significant. Here we used a standard method based on 59Fe as a radiotracer to study the solubility of Fe(III)-oxyhydroxide in seawater in the presence of riverine NOM. We aimed to address the question how effective is freshwater NOM as an iron chelator under open ocean conditions where the concentration of land-derived organic material is about 3 orders of magnitude smaller than in coastal regions, and does this iron chelating ability vary between NOM from different sources and between different size fractions of the river-borne NOM. Our results show that the investigated NOM fractions were able to substantially enhance Fe(III)-oxyhydroxide solubility in seawater at concentrations of the NOM ≥ 5

  6. [Effects of iron on azoreduction by Shewanella decolorationis S12].

    PubMed

    Chen, Xing-Juan; Xu, Mei-Ying; Sun, Guo-Ping

    2010-01-01

    The effects of soluble and insoluble Fe(III) on anaerobic azoreduction by Shewanella decolorationis S12 were examined in a series of experiments. Results showed that the effects of iron on anaerobic azoreduction depended on the solubility and concentration of the compounds. Azoreduction was inhibited by insoluble Fe(III) and 0.05-2 mmol/L Fe2 O3 all decelerated the azoreduction activity of 0.2 mmol/L amaranth, but the increase in the concentrations of Fe2O3 did not cause an increasing inhibition. Soluble Fe(III) of which concentration less than 0.4 mmol/L enhanced azoreduction activity of 0.2 mmol/L amaranth but there was no linear relationship between the concentration of soluble Fe(III) and azoreduction activity. Soluble Fe(III) of which concentration more than 1 mmol/L inhibited azoreduction activity of 0.2 mmol/L amaranth and an increasing concentration resulted in an increased inhibition. The inhibition was strengthened under the conditions of limited electron donor. On the other hand, soluble Fe(III) and Fe(II) could relieve the inhibition of azoreduction by dicumarol which blocked quinone cycle. It suggests that in addition to quinone cycle, there is a Fe(III) <--> Fe(II) cycle shuttling electrons in cytoplasmic and periplasmic environment. That is the reason why low concentration of soluble Fe(III) or Fe (II) can enhance azoreduction of S. decolorationis S12. It also indicates that insoluble Fe(III) and high concentration of soluble Fe(III) do compete with azo dye for electrons once it acts as electron acceptor. Thus, when iron and azo dye coexisted, iron could serve as an electron transfer agent or electron competitive inhibitor for anaerobic azoreduction under different conditions. High efficiency of azoreduction can be achieved through controlling the solubility and concentration of irons.

  7. Emergency Protection from Aerosols

    SciTech Connect

    Cristy, G.A.

    2001-11-13

    Expedient methods were developed that could be used by an average person, using only materials readily available, to protect himself and his family from injury by toxic (e.g., radioactive) aerosols. The most effective means of protection was the use of a household vacuum cleaner to maintain a small positive pressure on a closed house during passage of the aerosol cloud. Protection factors of 800 and above were achieved.

  8. Emergency protection from aerosols

    SciTech Connect

    Cristy, G.A.; Chester, C.V.

    1981-07-01

    Expedient methods were developed that could be used by an average person, using only materials readily available, to protect himself and his family from injury by toxic (e.g., radioactive) aerosols. The most effective means of protection was the use of a household vacuum cleaner to maintain a small positive pressure on a closed house during passage of the aerosol cloud. Protection factors of 800 and above were achieved.

  9. Monodisperse aerosol generator

    DOEpatents

    Ortiz, Lawrence W.; Soderholm, Sidney C.

    1990-01-01

    An aerosol generator is described which is capable of producing a monodisperse aerosol within narrow limits utilizing an aqueous solution capable of providing a high population of seed nuclei and an organic solution having a low vapor pressure. The two solutions are cold nebulized, mixed, vaporized, and cooled. During cooling, particles of the organic vapor condense onto the excess seed nuclei, and grow to a uniform particle size.

  10. MISR Aerosol Typing

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2014-01-01

    AeroCom is an open international initiative of scientists interested in the advancement of the understanding of global aerosol properties and aerosol impacts on climate. A central goal is to more strongly tie and constrain modeling efforts to observational data. A major element for exchanges between data and modeling groups are annual meetings. The meeting was held September 20 through October 2, 1014 and the organizers would like to post the presentations.

  11. Soluble Moringa oleifera leaf extract reduces intracellular cadmium accumulation and oxidative stress in Saccharomyces cerevisiae.

    PubMed

    Kerdsomboon, Kittikhun; Tatip, Supinda; Kosasih, Sattawat; Auesukaree, Choowong

    2016-05-01

    Moringa oleifera leaves are a well-known source of antioxidants and traditionally used for medicinal applications. In the present study, the protective action of soluble M. oleifera leaf extract (MOLE) against cadmium toxicity was investigated in the model eukaryote Saccharomyces cerevisiae. The results showed that this extract exhibited a protective effect against oxidative stress induced by cadmium and H2O2 through the reduction of intracellular reactive oxygen species. Interestingly, not only the co-exposure of soluble MOLE with cadmium but also pretreatment of this extract prior to cadmium exposure significantly reduced the cadmium uptake through an inhibition of Fet4p, a low-affinity iron(II) transporter. In addition, the supplementation of soluble MOLE significantly reduced intracellular iron accumulation in a Fet4p-independent manner. Our findings suggest the potential use of soluble extract from M. oleifera leaves as a dietary supplement for protection against cadmium accumulation and oxidative stress. PMID:26675819

  12. Soluble Moringa oleifera leaf extract reduces intracellular cadmium accumulation and oxidative stress in Saccharomyces cerevisiae.

    PubMed

    Kerdsomboon, Kittikhun; Tatip, Supinda; Kosasih, Sattawat; Auesukaree, Choowong

    2016-05-01

    Moringa oleifera leaves are a well-known source of antioxidants and traditionally used for medicinal applications. In the present study, the protective action of soluble M. oleifera leaf extract (MOLE) against cadmium toxicity was investigated in the model eukaryote Saccharomyces cerevisiae. The results showed that this extract exhibited a protective effect against oxidative stress induced by cadmium and H2O2 through the reduction of intracellular reactive oxygen species. Interestingly, not only the co-exposure of soluble MOLE with cadmium but also pretreatment of this extract prior to cadmium exposure significantly reduced the cadmium uptake through an inhibition of Fet4p, a low-affinity iron(II) transporter. In addition, the supplementation of soluble MOLE significantly reduced intracellular iron accumulation in a Fet4p-independent manner. Our findings suggest the potential use of soluble extract from M. oleifera leaves as a dietary supplement for protection against cadmium accumulation and oxidative stress.

  13. Stable isotopes as a tool to apportion atmospheric iron.

    PubMed

    Majestic, Brian J; Anbar, Ariel D; Herckes, Pierre

    2009-06-15

    Identification of atmospheric iron is a key parameter to understanding the source of iron in urban and remote areas. Atmospheric deposition of desert dust, which also can include an anthropogenic component, is a primary nutrient source for most of the open ocean. To better assess particulate matter (PM) sources specific to iron, we measured the iron isotopic composition of aerosols in two size fractions: PM with aerodynamic diameters less than 2.5 microm and less than 10 microm (PM2.5 and PM10, respectively). Using colocated samplers, atmospheric aerosol samples were collected in the U.S. desert Southwest at a mixed suburban/agricultural site near Phoenix, AZ. The measurements are presented as delta56Fe relative to the IRMM-014 (Institute for Reference Materials and Measurements) standard. Using multiple collector inductively coupled plasma mass spectrometry, we found differences in iron isotopic composition within the PM10 aerosol. Half of the PM10 samples had an iron isotopic signature similar to crustal material (+0.03 per thousand), which implicates wind-blown soil-dust as the primary source. The other PM10 samples showed a lighter iron isotopic composition, centered at -0.18 per thousand. Further analysis showed thatthe lighter iron was associated with winds originating from the southwest. This strongly suggests that there is a different PM10 source in this direction, with a distinct iron isotopic composition. The iron in the PM2.5 samples was usually substantially lighter than the corresponding PM10 samples, which is consistent with coarse and fine particles having different sources, again with distinctively different isotopic compositions. The magnitude of the iron isotopic difference between the PM10 and the PM2.5 size fractions (delta56Fe(PM10) - delta56Fe(PM2.5)) correlated with the PM2.5 concentrations of elements known to be emitted from industrial sources (Pb, Cd, As, V, and Cr). This observation implies that the isotopically light iron is created or

  14. RACORO aerosol data processing

    SciTech Connect

    Elisabeth Andrews

    2011-10-31

    The RACORO aerosol data (cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol size distributions) need further processing to be useful for model evaluation (e.g., GCM droplet nucleation parameterizations) and other investigations. These tasks include: (1) Identification and flagging of 'splash' contaminated Twin Otter aerosol data. (2) Calculation of actual supersaturation (SS) values in the two CCN columns flown on the Twin Otter. (3) Interpolation of CCN spectra from SGP and Twin Otter to 0.2% SS. (4) Process data for spatial variability studies. (5) Provide calculated light scattering from measured aerosol size distributions. Below we first briefly describe the measurements and then describe the results of several data processing tasks that which have been completed, paving the way for the scientific analyses for which the campaign was designed. The end result of this research will be several aerosol data sets which can be used to achieve some of the goals of the RACORO mission including the enhanced understanding of cloud-aerosol interactions and improved cloud simulations in climate models.

  15. Pharmacology of Iron Transport

    PubMed Central

    Byrne, Shaina L.; Krishnamurthy, Divya; Wessling-Resnick, Marianne

    2013-01-01

    Elucidating the molecular basis for the regulation of iron uptake, storage, and distribution is necessary to understand iron homeostasis. Pharmacological tools are emerging to identify and distinguish among different iron transport pathways. Stimulatory or inhibitory small molecules with effects on iron uptake can help characterize the mechanistic elements of iron transport and the roles of the transporters involved in these processes. In particular, iron chelators can serve as potential pharmacological tools to alleviate diseases of iron overload. This review focuses on the pharmacology of iron transport, introducing iron transport membrane proteins and known inhibitors. PMID:23020294

  16. Quantification of dissolved iron sources to the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Conway, Tim M.; John, Seth G.

    2014-07-01

    Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the oceans. The relative importance of different sources of iron to the oceans is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and oceanic sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (δ56Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique δ56Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-Atlantic Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North Atlantic are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate.

  17. Iron/soot interaction in a laminar ethylene nonpremixed flame

    SciTech Connect

    Zhang, J.; Megaridis, C.M.

    1994-12-31

    A laminar, coannular, ethylene/air nonpremixed flame doped with ferrocene additive is employed to address the fundamental question of how iron becomes incorporated into the carbonaceous soot phase, thus interfering with the soot formation processes. The structure and chemical composition of individual aggregates are characterized with respect to flame coordinates via a combination of thermophoretic sampling, transmission electron microscopy, and energy dispersive spectrometry. Soot aggregate microstructure clearly reveals iron occlusion, as well as stratification of soot layers over the occluded phase. The study provides physical evidence that the soot and iron compounds combine in the flame to form a hybrid (inhomogeneous) particulate phase. The reported observations are consistent with the hypothesis that ferrocene decomposes early in the combustion process and before the onset of soot particle inception, thus forming a fine aerosol for the subsequent deposition of carbonaceous substances. Examination of a series of inhomogeneous soot aggregates shows that the flame aerosol composition varies with flame coordinates. In particular, aggregates transported in the soot annulus near the luminous flame front are primarily composed of carbon and oxygen, with traces of iron finely dispersed through the aggregate matrix. On the other hand, carbonaceous soot transported at low heights and near the flame axis contains iron in its elemental form. Finally, soot aggregates in all other areas of the flame contain both iron and oxygen, thus implying the possible presence of iron oxides within the carbonaceous matrix.

  18. Speciation of Fe in ambient aerosol and cloudwater

    SciTech Connect

    Siefert, L.

    1996-08-15

    Atmospheric iron (Fe) is thought to play an important role in cloudwater chemistry (e.g., S(IV) oxidation, oxidant production, etc.), and is also an important source of Fe to certain regions of the worlds oceans where Fe is believed to be a rate-limiting nutrient for primary productivity. This thesis focuses on understanding the chemistry, speciation and abundance of Fe in cloudwater and aerosol in the troposphere, through observations of Fe speciation in the cloudwater and aerosol samples collected over the continental United States and the Arabian Sea. Different chemical species of atmospheric Fe were measured in aerosol and cloudwater samples to help assess the role of Fe in cloudwater chemistry.

  19. Disputable issues in interpreting the results of chemical extraction of iron compounds from soils

    NASA Astrophysics Data System (ADS)

    Vodyanitskii, Yu. N.; Shoba, S. A.

    2014-06-01

    In Russia, iron is chemically fractionated according to a parallel scheme. Pyrophosphate-soluble iron (Fepyr) is considered to participate in organomineral complexes, oxalate-soluble iron (Feox) is believed to enter amorphous + poorly crystallized compounds, and dithionite-soluble iron (Fedit) is meant to represent the free (nonsilicate) compounds. However, the investigations prove that the commonly used subtraction operations (Feox - Fepyr) and (Fedit - Feox) are invalid because of the nonadditive action of the reagents in the parallel scheme of extraction. The low selectivity of reagents requires a new interpretation of chemically extracted iron compounds. In automorphic soils, the content of oxalate-soluble iron should be interpreted as the amount of Fe(III) capable of complexing with organic ligands; in hydromorphic soils with a stagnant moisture regime, it should be interpreted as the amount of iron (III) capable of being reduced in a short time. The content of dithionite-soluble compounds should be regarded as the amount of iron (III) within both (hydr)oxides and silicates potentially prone to reduction.

  20. Computational modeling and analysis of iron release from macrophages.

    PubMed

    Potdar, Alka A; Sarkar, Joydeep; Das, Nupur K; Ghosh, Paroma; Gratzl, Miklos; Fox, Paul L; Saidel, Gerald M

    2014-07-01

    A major process of iron homeostasis in whole-body iron metabolism is the release of iron from the macrophages of the reticuloendothelial system. Macrophages recognize and phagocytose senescent or damaged erythrocytes. Then, they process the heme iron, which is returned to the circulation for reutilization by red blood cell precursors during erythropoiesis. The amount of iron released, compared to the amount shunted for storage as ferritin, is greater during iron deficiency. A currently accepted model of iron release assumes a passive-gradient with free diffusion of intracellular labile iron (Fe2+) through ferroportin (FPN), the transporter on the plasma membrane. Outside the cell, a multi-copper ferroxidase, ceruloplasmin (Cp), oxidizes ferrous to ferric ion. Apo-transferrin (Tf), the primary carrier of soluble iron in the plasma, binds ferric ion to form mono-ferric and di-ferric transferrin. According to the passive-gradient model, the removal of ferrous ion from the site of release sustains the gradient that maintains the iron release. Subcellular localization of FPN, however, indicates that the role of FPN may be more complex. By experiments and mathematical modeling, we have investigated the detailed mechanism of iron release from macrophages focusing on the roles of the Cp, FPN and apo-Tf. The passive-gradient model is quantitatively analyzed using a mathematical model for the first time. A comparison of experimental data with model simulations shows that the passive-gradient model cannot explain macrophage iron release. However, a facilitated-transport model associated with FPN can explain the iron release mechanism. According to the facilitated-transport model, intracellular FPN carries labile iron to the macrophage membrane. Extracellular Cp accelerates the oxidation of ferrous ion bound to FPN. Apo-Tf in the extracellular environment binds to the oxidized ferrous ion, completing the release process. Facilitated-transport model can correctly predict

  1. Impact of springtime biomass-burning aerosols on radiative forcing over northern Thailand during the 7SEAS campaign

    NASA Astrophysics Data System (ADS)

    Pani, Shantanu Kumar; Wang, Sheng-Hsiang; Lin, Neng-Huei; Lee, Chung-Te; Tsay, Si-Chee; Holben, Brent; Janjai, Serm; Hsiao, Ta-Chih; Chuang, Ming-Tung; Chantara, Somporn

    2016-04-01

    Biomass-burning (BB) aerosols are the significant contributor to the regional/global aerosol loading and radiation budgets. BB aerosols affect the radiation budget of the earth and atmosphere by scattering and absorbing directly the incoming solar and outgoing terrestrial radiation. These aerosols can exert either cooling or warming effect on climate, depending on the balance between scattering and absorption. BB activities in the form of wildland forest fires and agricultural crop burning are very pronounced in the Indochina peninsular regions in Southeast Asia mainly in spring (late February to April) season. The region of interest includes Doi Ang Khang (19.93° N, 99.05° E, 1536 msl) in northern Thailand, as part of the Seven South East Asian Studies (7-SEAS)/BASELInE (Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles & Interactions Experiment) campaign in 2013. In this study, for the first time, the direct aerosol radiative effects of BB aerosols over near-source BB emissions, during the peak loading spring season, in northern Indochina were investigated by using ground-based physical, chemical, and optical properties of aerosols as well as the aerosol optical and radiative transfer models. Information on aerosol parameters in the field campaign was used in the OPAC (Optical Properties of Aerosols and Clouds) model to estimate various optical properties corresponding to aerosol compositions. Clear-sky shortwave direct aerosol radiative effects were further estimated with a raditive transfer model SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer). The columnar aerosol optical depth (AOD500) was found to be ranged from 0.26 to 1.13 (with the mean value 0.71 ± 0.24). Fine-mode (fine mode fraction ≈0.98, angstrom exponent ≈1.8) and significantly absorbing aerosols (columnar single-scattering albedo ≈0.89, asymmetry-parameter ≈0.67 at 441 nm wavelength) dominated in this region. Water soluble and black carbon (BC) aerosols mainly

  2. Aerosol Acidity in the New England Coastal Atmosphere During Summer 2002

    NASA Astrophysics Data System (ADS)

    Pszenny, A. A.; Keene, W. C.; Maben, J. R.; Stevenson, E.; Wall, A.

    2003-12-01

    Aerosol pH controls important multiphase chemical pathways in the atmosphere but absolute values are poorly constrained. As part of the New England Air Quality Study, aerosol pH was quantified based on multiple independent approaches and results were intercompared for consistency. Soluble, reactive trace gases with pH-dependent solubilities (HNO3, NH3, HCl, HCOOH, and CH3COOH) were sampled with mist chambers. Size-segregated aerosols were sampled in parallel with cascade impactors and analyzed for major ionic constituents. H+ was measured directly in minimally diluted, 5-μ L spots on surfaces of impaction substrates with a flat-surface, field-effect transistor. Aerosol liquid water contents (LWCs) were calculated with hygrospocity models. Aerosol pHs required to sustain the measured phase partitioning of each analyte were inferred based on corresponding thermodynamic properties and direct pH measurements were extrapolated to ambient LWCs. The ensemble of approaches yielded coherent results. Sea-salt pHs ranged from about 2 to the mid 4s and sub-μ m aerosol pHs ranged from <1 to the mid 3s. The H+ + SO42-<-> HSO4- equilibrium strongly buffered aerosol pH in all size fractions.

  3. Transferrin Saturation: A Body Iron Biomarker.

    PubMed

    Elsayed, M E; Sharif, M U; Stack, A G

    2016-01-01

    Iron is an essential element for several metabolic pathways and physiological processes. The maintenance of iron homeostasis within the human body requires a dynamic and highly sophisticated interplay of several proteins, as states of iron deficiency or excess are both potentially deleterious to health. Among these is plasma transferrin, which is central to iron metabolism not only through iron transport between body tissues in a soluble nontoxic form but also through its protective scavenger role in sequestering free toxic iron. The transferrin saturation (TSAT), an index that takes into account both plasma iron and its main transport protein, is considered an important biochemical marker of body iron status. Its increasing use in many health systems is due to the increased availability of measurement methods, such as calorimetry, turbidimetry, nephelometry, and immunochemistry to estimate its value. However, despite its frequent use in clinical practice to detect states of iron deficiency or iron overload, careful attention should be paid to the inherent limitations of the test especially in certain settings such as inflammation in order to avoid misinterpretation and erroneous conclusions. Beyond its usual clinical use, an emerging body of evidence has linked TSAT levels to major clinical outcomes such as cardiovascular mortality. This has the potential to extend the utility of TSAT index to risk stratification and prognostication. However, most of the current evidence is mainly driven by observational studies where the risk of residual confounding cannot be fully eliminated. Indeed, future efforts are required to fully explore this capability in well-designed clinical trials or prospective large-scale cohorts.

  4. A Monodisperse Aerosol Dynamics Model Mono32

    NASA Astrophysics Data System (ADS)

    Pirjola, L.

    A recently developed aerosol dynamics model MONO32 (and MULTIMONO) (Pir- jola and Kulmala, 2000) is a Lagrangian type box model which uses mondisperse representation for particle size distribution. The model takes into account gas-phase chemistry and aerosol dynamics including emissions and dry deposition of gases and particles, chemical reactions in the gas phase, homogeneous binary H2SO4-H2O or ternary H2SO4-H2O-NH3 nucleation, multicomponent condensation of H2SO4, H2O, HNO3, NH3 and some organic vapour onto particles as well as inter- and in- tramode coagulation of particles. Particles can consist of soluble material such as sul- phate, nitrate, ammonium, sodium cloride, as well as insoluble material such as or- ganic carbon, elemental carbon and mineral dust. Hygroscopic properties and growth of particles were studied by the model. Simulations predicted that nucleation mode particles grew with a growth rate of 2.5-3 nm/h if the source rate of a condensable nonvolatile organic vapour exceeded 10^5 cm^-3 s^-1 and the condensation sink of the pre-existing particles was 0.9x10^-3 s^-1. These results are in good agreemnet with the measurements in Southern Finland. Further, these particles are able to grow to CCN sizes, thus affecting climate. The model was compared very well with the sectional model AEROFOR2 (Pirjola and Kulmala, 2001). It is physically sound and computa- tionally efficient model also for using as a module for regional transport models. Pirjola, L. and Kulmala, M. (2000) Aerosol dynamical model MULTIMONO, Boreal research 5, 361-372. Pirjola, L. and Kulmala, M. (2001) Development of particle size and composition distribution with aerosol dynamics model AEROFOR2. Tellus 53B, 491-509. Pirjola, L., Korhonen, H. and Kulmala, M. (2002) Condensation/ evaporation of insoluble organic vapour as functions of source rate and saturation vapour pressure. J. Geophys. Res. (in press).

  5. Mapping and characterization of iron compounds in Alzheimer's tissue

    SciTech Connect

    Collingwood, Joanna; Dobson, Jon

    2008-06-16

    Understanding the management of iron in the brain is of great importance in the study of neurodegeneration, where regional iron overload is frequently evident. A variety of approaches have been employed, from quantifying iron in various anatomical structures, to identifying genetic risk factors related to iron metabolism, and exploring chelation approaches to tackle iron overload in neurodegenerative disease. However, the ease with which iron can change valence state ensures that it is present in vivo in a wide variety of forms, both soluble and insoluble. Here, we review recent developments in approaches to locate and identify iron compounds in neurodegenerative tissue. In addition to complementary techniques that allow us to quantify and identify iron compounds using magnetometry, extraction, and electron microscopy, we are utilizing a powerful combined mapping/characterization approach with synchrotron X-rays. This has enabled the location and characterization of iron accumulations containing magnetite and ferritin in human Alzheimer's disease (AD) brain tissue sections in situ at micron-resolution. It is hoped that such approaches will contribute to our understanding of the role of unusual iron accumulations in disease pathogenesis, and optimise the potential to use brain iron as a clinical biomarker for early detection and diagnosis.

  6. The Ksp-Solubility Conundrum.

    ERIC Educational Resources Information Center

    Clark, Roy W.; Bonicamp, Judith M.

    1998-01-01

    Argues that there are only a few cases in which solubility and Ksp are related in a simple way. States that illustrations of the solubility product principle for one-to-one salts are adequate for students. Contains 23 references. (DDR)

  7. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; Prévôt, A. S. H.; El Haddad, I.

    2015-08-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make impractical its deployment at sufficient sites to determine regional characteristics. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, PM10) collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g. AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 μg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon, oxygen containing and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g. filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially-resolved long-term datasets.

  8. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; El Haddad, I.; Prévôt, A. S. H.

    2016-01-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.

  9. Recombinant soluble adenovirus receptor

    DOEpatents

    Freimuth, Paul I.

    2002-01-01

    Disclosed are isolated polypeptides from human CAR (coxsackievirus and adenovirus receptor) protein which bind adenovirus. Specifically disclosed are amino acid sequences which corresponds to adenovirus binding domain D1 and the entire extracellular domain of human CAR protein comprising D1 and D2. In other aspects, the disclosure relates to nucleic acid sequences encoding these domains as well as expression vectors which encode the domains and bacterial cells containing such vectors. Also disclosed is an isolated fusion protein comprised of the D1 polypeptide sequence fused to a polypeptide sequence which facilitates folding of D1 into a functional, soluble domain when expressed in bacteria. The functional D1 domain finds application for example in a therapeutic method for treating a patient infected with a virus which binds to D1, and also in a method for identifying an antiviral compound which interferes with viral attachment. Also included is a method for specifically targeting a cell for infection by a virus which binds to D1.

  10. Modeling the processing of mineral iron during dust transport

    NASA Astrophysics Data System (ADS)

    Vogelsberg, Ulrike; Wolke, Ralf; Tilgner, Andreas; Tegen, Ina; Herrmann, Hartmut

    2014-05-01

    The Saharan desert and the Gobi desert are the main contributors to Aeolian desert dust, which is a major source of micronutrients to the remote ocean regions. Micronutrients, such as transition metals like iron or copper, are regarded essential for biological processes of different marine species. In this context recent studies have shown that soluble iron, since it is generally the most abundant transition metal in dust particles, has the ability to control marine productivity and thereby likely influence the CO2- budget. Nevertheless, the processing of desert dust leading to the release of soluble iron still lacks sufficient understanding since several factors control the solubilization process. Especially anthropogenic emissions are regarded to significantly add to the amount of soluble iron by acidification of dust particles or by the direct emission of soluble iron comprised, e.g. in coal fly ash. For the investigation of the dissolution process of iron that takes place during dust transportation the spectral air parcel model SPACCIM is used. A mechanism describing the precipitation and dissolution of mineral particles by heterogeneous surface reactions has been implemented. Trajectory properties were derived from COSMO-MUSCAT simulations or from re-analysis data by HYSPLIT. Differences in the chemical composition and the amount of anthropogenic and naturally emitted species on the North African continent and the highly industrialized region of South-East Asia have considerable impact on the acidification of the desert dust. Under this aspect, special cases of dust outbreaks of the Saharan desert and the Gobi desert are investigated and compared with focus on soluble iron produced.

  11. Comparative Calculations of Solubility Equilibria

    SciTech Connect

    Beahm, E.C.

    2000-07-25

    The uncertainties in calculated solubilities in the Na-F-PO{sub 4}-HPO{sub 4}-OH system. at 25 C for NaOH concentrations up to 5 mol/kg were assessed. These uncertainties were based on an evaluation of the range of values for the Gibbs energies of the solids. Comparative calculations using the Environmental Simulation Program (ESP) and SOLGASMIX indicated that the variation in activity coefficients with NaOH concentration is much greater in the ESP code than in SOLGASMIX. This resulted in ESP calculating a higher solubility in water and a lower solubility in NaOH concentrations above 1 mol/kg: There was a marked discrepancy in the solubilities of the pure components sodium fluoride and trisodium phosphate predicted by ESP and SOLGASMIX. In addition, different solubilities for these components were obtained using different options in ESP. Because of these observations, a Best Practices Guide for ESP will be assembled.

  12. The impacts of aerosol loading, composition, and water uptake on aerosol extinction variability in the Baltimore-Washington, D.C. region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2016-01-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type - such as composition, size, and hygroscopicity - and to the surrounding atmosphere, such as temperature, relative humidity (RH), and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in situ atmospheric profiling in the Baltimore, MD-Washington, D.C. region was performed during 14 flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties, and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed, with high-loading days having a proportionally larger percentage of sulfate due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of inorganics increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity, causing an increase in the water content of the aerosol. Conversely, low-aerosol-loading days had lower sulfate and higher black carbon contributions, causing lower single-scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km, decreasing to 35 ng m-3 in the free troposphere (above

  13. Biological aerosol background characterization

    NASA Astrophysics Data System (ADS)

    Blatny, Janet; Fountain, Augustus W., III

    2011-05-01

    To provide useful information during military operations, or as part of other security situations, a biological aerosol detector has to respond within seconds or minutes to an attack by virulent biological agents, and with low false alarms. Within this time frame, measuring virulence of a known microorganism is extremely difficult, especially if the microorganism is of unknown antigenic or nucleic acid properties. Measuring "live" characteristics of an organism directly is not generally an option, yet only viable organisms are potentially infectious. Fluorescence based instruments have been designed to optically determine if aerosol particles have viability characteristics. Still, such commercially available biological aerosol detection equipment needs to be improved for their use in military and civil applications. Air has an endogenous population of microorganisms that may interfere with alarm software technologies. To design robust algorithms, a comprehensive knowledge of the airborne biological background content is essential. For this reason, there is a need to study ambient live bacterial populations in as many locations as possible. Doing so will permit collection of data to define diverse biological characteristics that in turn can be used to fine tune alarm algorithms. To avoid false alarms, improving software technologies for biological detectors is a crucial feature requiring considerations of various parameters that can be applied to suppress alarm triggers. This NATO Task Group will aim for developing reference methods for monitoring biological aerosol characteristics to improve alarm algorithms for biological detection. Additionally, they will focus on developing reference standard methodology for monitoring biological aerosol characteristics to reduce false alarm rates.

  14. Genetics Home Reference: iron-refractory iron deficiency anemia

    MedlinePlus

    ... refractory iron deficiency anemia iron-refractory iron deficiency anemia Enable Javascript to view the expand/collapse boxes. ... All Close All Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...

  15. MISR UAE2 Aerosol Versioning

    Atmospheric Science Data Center

    2013-03-21

    ... the MISR aerosol microphysical properties are "Beta." Uncertainty envelopes for the aerosol optical depths are given in  Kahn et ... particle microphysical property validation is in progress, uncertainty envelopes on particle size distribution, shape, and ...

  16. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  17. Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations

    PubMed Central

    Martínez-Garay, Carlos Andrés; de Llanos, Rosa; Romero, Antonia María; Martínez-Pastor, María Teresa

    2016-01-01

    Iron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains of S. cerevisiae isolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels. PMID:26773083

  18. Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations.

    PubMed

    Martínez-Garay, Carlos Andrés; de Llanos, Rosa; Romero, Antonia María; Martínez-Pastor, María Teresa; Puig, Sergi

    2016-01-15

    Iron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains of S. cerevisiae isolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels.

  19. Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations.

    PubMed

    Martínez-Garay, Carlos Andrés; de Llanos, Rosa; Romero, Antonia María; Martínez-Pastor, María Teresa; Puig, Sergi

    2016-03-01

    Iron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains of S. cerevisiae isolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels. PMID:26773083

  20. Cloud Nucleating Properties of Aerosols During TexAQS - GoMACCS 2006: Influence of Aerosol Sources, Composition, and Size

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Coffman, D. J.; Covert, D. S.; Onasch, T. B.; Alllan, J. D.; Worsnop, D.

    2006-12-01

    TexAQS - GoMACCS 2006 was conducted from July to September 2006 in the Gulf of Mexico and Houston Ship Channel to investigate sources and processing of gas and particulate phase species and to determine their impact on regional air quality and climate. As part of the experiment, the NOAA R.V. Ronald H. Brown transited from Charleston, S.C. to the study region. The ship was equipped with a full compliment of gas and aerosol instruments. To determine the cloud nucleating properties of aerosols, measurements were made of the aerosol number size distribution, aerosol chemical composition, and cloud condensation nuclei (CCN) concentration at five supersaturations. During the transit and over the course of the experiment, a wide range of aerosol sources and types was encountered. These included urban and industrial emissions from the S.E. U.S. as the ship left Charleston, a mixture of Saharan dust and marine aerosol during the transit around Florida and across the Gulf of Mexico, urban emissions from Houston, and emissions from the petrochemical industries, oil platforms, and marine vessels in the Gulf coast region. Highest activation ratios (ratio of CCN to total particle number concentration at 0.4 percent supersaturation) were measured in anthropogenic air masses when the aerosol was composed primarily of ammonium sulfate salts and in marine air masses with an aerosol composed of sulfate and sea salt. A strong gradient in activation ratio was measured as the ship moved from the Gulf of Mexico to the end of the Houston Ship Channel (values decreasing from about 0.8 to less than 0.1) and the aerosol changed from marine to industrial. The activation ratio under these different regimes in addition to downwind of marine vessels and oil platforms will be discussed in the context of the aerosol size distribution and chemical composition. The discussion of composition will include the organic mass fraction of the aerosol, the degree of oxidation of the organics, and the water

  1. Predicting the Mineral and Chemical Composition of Dust Aerosols: Evaluation and Implications

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2014-12-01

    Soil dust aerosols in Earth system models are typically assumed to have globally uniform properties. However, important climate processes related to dust depend on the aerosol mineral and chemical composition, which varies regionally. Such processes include aerosol radiative forcing, transport of bioavailable iron that catalyzes marine photosynthesis, heterogeneous chemistry, ice nucleation, and cloud condensation.We have implemented a new version of the soil dust aerosol scheme in the NASA GISS Earth System ModelE that takes into account the mineral composition of the dust particles. Dust aerosols are represented as an external mixture of minerals such as illite, kaolinite, smectite, carbonates, quartz, feldspar and gypsum, as well as iron oxides and accretions of iron oxides with each of the these minerals.We present a new publically available compilation of measurements of mineral fractions derived from ca. 50 references from the literature. This compilation is used to evaluate our new model of mineral and elemental composition within ModelE. We discuss the challenges of comparing simulated mineral fractions to measurements, which often come from field campaigns and ship cruises of limited duration. Despite uncertainties of the measurements, we show the importance of estimating the undisturbed size distribution of the parent soil prior to wet sieving, along with the modification of this size distribution during emission. In particular, our new model reproduces measurements showing greater amount of aerosols at silt sizes (whose diameters exceed 2 μm) including significant amounts of clay mineral aerosols (like illite) at silt sizes. Our model also reduces the systematic overestimation of quartz, while allowing iron to be transported farther from its source as impurities than in its pure, crystalline form.

  2. Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-10-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to

  3. Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-02-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, coating by heterogeneous uptake of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the resulting aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent in a soil whose aggregates are dispersed by wet sieving during analysis. We reconstruct the undispersed size distribution of the original soil that is subject to wind erosion. An empirical constraint upon the relative emission of clay and silt is applied that further differentiates the soil and aerosol mineral composition. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to measurements from North Africa shows that the extension brings the model into better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.

  4. Predicting the Mineral Composition of Dust Aerosols. Part 1; Representing Key Processes

    NASA Technical Reports Server (NTRS)

    Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

    2015-01-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wetsieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to

  5. Characterizing Aerosolized Particulate As Part Of A Nanoprocess Exposure Assessment

    SciTech Connect

    Jankovic, John Timothy; Ogle, Burton R; Zontek, Tracy L; Hollenbeck, Scott M

    2010-01-01

    The purpose of this effort was to propose important aerosol characterization parameters that should be gathered as part of a nanomaterial hazard assessment and to offer a methodology for applying that data to daily operations. This study documents different ways of characterizing nanoscale materials using an aerosol from a process simulation consisting of a vacuum cleaner motor operating inside an enclosure. The aerosol is composed of insoluble carbon particles plus environmental background constituents. The average air concentration is 2.76E+5 p/cm3. Size measurements of the aerosol indicate > 70% of the particulate is blade-like in shape, 50% of which have a height dimension 100 nm. In terms of an equivalent spherical diameter 0.8% of the particulate is 100 nm in size. The carbon blades are characterized as having a root-mean-square roughness of 75 nm, and average fractal dimension of 2.25. These measures: aerosol chemistry, solubility, shape and size, surface area, number concentration and size distribution are important parameters to collect for current exposure assessment and toxicology and epidemiology studies.

  6. Photochemistry of Glyoxal in Wet Aerosols: Smog Chamber Study

    NASA Astrophysics Data System (ADS)

    Lim, Y. B.; Kim, H.; Turpin, B. J.

    2015-12-01

    Aqueous chemistry is an important pathway for the formation of secondary organic aerosol (SOA). Reaction vessel studies provide evidence that in the aqueous phase photooxidation of water soluble organic compounds (e.g., glyoxal, methylglyoxal) form multifunctional organic products and oligomers. In this work, we extend this bulk-phase chemistry to the condensed-phase chemistry that occurs in/on aerosols by conducting smog chamber experiments — photooxidation of ammonium sulfate and sulfuric acid aerosols containing glyoxal and hydrogen peroxide in the presence of NOx under dry/humid conditions. Particles were analyzed using ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). In the irradiated chamber, photooxidation products of glyoxal as seen in reaction vessel experiments (e.g., oxalic acids and tartaric acids) were also formed in both ammonium sulfate aerosols and sulfuric acid aerosols at humid and even dry conditions. However, the major products were organosulfurs (CHOS), organonitrogens (CHON), and nitrooxy-organosulfates (CHONS), which were also dominantly formed in the dark chamber. These products were formed via non-radical reactions, which depend on acidity and humidity. However, the real-time profiles in the dark chamber and the irradiated chamber were very different, suggesting photochemistry substantially affects non-radical formation in the condensed phase.

  7. Surfactants in atmospheric aerosols and rainwater around lake ecosystem.

    PubMed

    Razak, Intan Suraya; Latif, Mohd Talib; Jaafar, Shoffian Amin; Khan, Md Firoz; Mushrifah, Idris

    2015-04-01

    This study was conducted to determine the composition of surfactants in atmospheric aerosols and rainwater in the vicinity of Lake Chini, Malaysia. Samples of atmospheric aerosol and rainwater were collected between March and September 2011 using a high volume air sampler (HVAS) and glass bottles equipped with funnel. Colorimetric analysis was undertaken to determine the concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). The water-soluble ionic compositions were determined using inductively coupled plasma mass spectrometry for cations (Na, K, Mg and Ca) and ion chromatography equipped with a conductivity detector for anions (F(-), Cl(-), NO3(-), and SO4(2-)) and the Nessler Method was used to obtain the NH4(+) concentrations. The source apportionment of MBAS and DBAS in atmospheric aerosols was identified using a combination of principal component analysis (PCA) and multiple linear regression (MLR). The results revealed that the concentrations of surfactants in atmospheric aerosols and rainwater were dominated by anionic surfactants as MBAS. The concentration of surfactants as MBAS and DBAS was dominated in fine mode compared to coarse mode aerosols. Using PCA/MLR analysis, two major sources of atmospheric surfactants to Lake Chini were identified as soil dust (75 to 93%) and biomass burning (2 to 22%).

  8. A study on major inorganic ion composition of atmospheric aerosols.

    PubMed

    Salve, P R; Krupadam, R J; Wate, S R

    2007-04-01

    Atmospheric aerosol samples were collected from Akola and Buldana region covering around 40 sqkm area during October-November 2002 and were analyzed for ten major inorganic ions namely F-, Cl-, NO3-, SO4(2-), PO4(2-), Na+, K+, Ca2+, Mg2+ and NH4+ using ion chromatographic technique. The average mass of aerosols was found to be 225.81 microg/m3 with standard deviation of 31.29 and average total water soluble load of total cations and anions was found to be 4.32 microg/m3. The concentration of ions in samples showed a general pattern as SO4(2-) > NO3- > Cl- > PO4(2-) > F- for anions and Na+ > Ca2+ > NH4+ > Mg2+ > K+ for cations. The overall composition of the aerosols was taken into account to identify the sources. The trend showed higher concentration of sodium followed by calcium, sulfate, nitrate, phosphate and ammoinum and found to be influenced by terrestrial sources. The presence of SO4(2-) and NO3- in aerosols may be due to re-suspension of soil particles. Ca2+, Mg2+ and Cl- are to be derived from soil materials. The presence of NH4+ may be attributed to the reaction of NH3 vapors with acidic gases may react or condense on an acidic particle surface of anthropogenic origin. The atmospheric aerosol is slightly acidic due to neutralization of basicity by SO2 and NO(x).

  9. New Particle Formation and Secondary Organic Aerosol in Beijing

    NASA Astrophysics Data System (ADS)

    Hu, M.; Yue, D.; Guo, S.; Hu, W.; Huang, X.; He, L.; Wiedensohler, A.; Zheng, J.; Zhang, R.

    2011-12-01

    Air pollution in Beijing has been a major concern due to being a mega-city and green Olympic Games requirements. Both long term and intensive field measurements have been conducted at an Urban Air Quality Monitoring Station in the campus of Peking University since 2004. Aerosol characteristics vary seasonally depending on meteorological conditions and source emissions. Secondary compositions of SNA (sum of sulfate, nitrate, and ammonium) and SOA (secondary organic aerosol) become major fraction of fine particles, which may enhance aerosol impacts on visibility and climate change. The transformation processes of new particle formation (NPF) and secondary organic aerosol have been focused on. It was found that gaseous sulfuric acid, ammonia, and organic compounds are important precursors to NPF events in Beijing and H2SO4-NH3-H2O ternary nucleation is one of the important mechanisms. The contributions of condensation and neutralization of sulfuric acid, coagulation, and organics to the growth of the new particles are estimated as 45%, 34%, and 21%, respectively. Tracer-based method to estimate biogenic and anthropogenic SOA was established by using gas chromatography-mass spectrometry. Secondary organic tracers derived from biogenic (isoprene, α-pinene, β-caryophyllene) and anthropogenic (toluene) contributed 32% at urban site and 35% at rural site, respectively. Other source apportionment techniques were also used to estimate secondary organic aerosols, including EC tracer method, water soluble organic carbon content, chemical mass balance model, and AMS-PMF method.

  10. Nickel decreases cellular iron level and converts cytosolic aconitase to iron-regulatory protein 1 in A549 cells

    SciTech Connect

    Chen Haobin; Davidson, Todd; Singleton, Steven; Garrick, Michael D.; Costa, Max . E-mail: costam@env.med.nyu.edu

    2005-08-15

    Nickel (Ni) compounds are well-established carcinogens and are known to initiate a hypoxic response in cells via the stabilization and transactivation of hypoxia-inducible factor-1 alpha (HIF-1{alpha}). This change may be the consequence of nickel's interference with the function of several Fe(II)-dependent enzymes. In this study, the effects of soluble nickel exposure on cellular iron homeostasis were investigated. Nickel treatment decreased both mitochondrial and cytosolic aconitase (c-aconitase) activity in A549 cells. Cytosolic aconitase was converted to iron-regulatory protein 1, a form critical for the regulation of cellular iron homeostasis. The increased activity of iron-regulatory protein 1 after nickel exposure stabilized and increased transferrin receptor (Tfr) mRNA and antagonized the iron-induced ferritin light chain protein synthesis. The decrease of aconitase activity after nickel treatment reflected neither direct interference with aconitase function nor obstruction of [4Fe-4S] cluster reconstitution by nickel. Exposure of A549 cells to soluble nickel decreased total cellular iron by about 40%, a decrease that likely caused the observed decrease in aconitase activity and the increase of iron-regulatory protein 1 activity. Iron treatment reversed the effect of nickel on cytosolic aconitase and iron-regulatory protein 1. To assess the mechanism for the observed effects, human embryonic kidney (HEK) cells over expressing divalent metal transporter-1 (DMT1) were compared to A549 cells expressing only endogenous transporters for inhibition of iron uptake by nickel. The inhibition data suggest that nickel can enter via DMT1 and compete with iron for entry into the cell. This disturbance of cellular iron homeostasis by nickel may have a great impact on the ability of the cell to regulate a variety of cell functions, as well as create a state of hypoxia in cells under normal oxygen tension. These effects may be very important in how nickel exerts phenotypic

  11. Aerosol characterization with lidar methods

    NASA Astrophysics Data System (ADS)

    Sugimoto, Nobuo; Nishizawa, Tomoaki; Shimizu, Atsushi; Matsui, Ichiro

    2014-08-01

    Aerosol component analysis methods for characterizing aerosols were developed for various types of lidars including polarization-sensitive Mie scattering lidars, multi-wavelength Raman scattering lidars, and multi-wavelength highspectral- resolution lidars. From the multi-parameter lidar data, the extinction coefficients for four aerosol components can be derived. The microphysical parameters such as single scattering albedo and effective radius can be also estimated from the derived aerosol component distributions.

  12. Mixing state of aerosols over the Indo-Gangetic Plain: Radiative forcing and heating rate

    NASA Astrophysics Data System (ADS)

    Srivastava, R.; Ramachandran, S.

    2012-12-01

    ratio is calculated from the geometry of core-shell particles, which depends on the mass and density of the core and shell. The size distribution parameters and refractive indices of different aerosol species are taken from OPAC database [3]. Different fractions of black carbon, water soluble and mineral dust aerosols involved in core-shell mixing emerge as the most probable mixing states over the IGP. Aerosol forcing for external mixing shows higher deviations from those for probable mixing cases during winter and pre-monsoon. The heating rate over Kanpur and Gandhi College in the lower troposphere is similar during pre-monsoon (March-May) ( 0.75 K day^{-1}) and monsoon (June-September) ( 0.5 K day^{-1}), while differences occur in other seasons [4]. Aerosol heating rate profiles exhibit primary and secondary peaks over the IGP and exhibit seasonal variations. Details on the calculations of aerosol mixing states over IGP, the impact of aerosol mixing state on aerosol forcing and heating rate will be discussed. References: [1] Intergovernmental panel on climate change (2007), Solomon S. et al. (eds.), Cambridge Univ. Press, NewYork. [2] Holben B. N., et al. (2001), J. Geophys. Res., 106(D11), 12067-12097. [3] Hess M., P. Koepke, I. Schult (1998), Bull. Am. Meteorol. Soc., 79, 831-844. [4] Srivastava R., S. Ramachandran (2012), Q. J. R. Meteorol. Soc., 138, doi:10.1002/qj.1958.

  13. Aerosol Quality Monitor (AQUAM)

    NASA Astrophysics Data System (ADS)

    Liang, X.; Ignatov, A.

    2011-12-01

    The Advanced Clear-Sky Processor for Oceans (ACSPO) developed at NESDIS generates three products from AVHRR, operationally: clear sky radiances in all bands, and sea surface temperature (SST) derived from clear-sky brightness temperatures (BT) in Ch3B (centered at 3.7 μm), Ch4 (11 μm) and Ch5 (12 μm), and aerosol optical depths (AOD) derived from clear-sky reflectances in Ch1 (0.63), Ch2 (0.83) and Ch3A (1.61 μm). An integral part of ACSPO is the fast Community Radiative Transfer Model (CRTM), which calculates first-guess clear-sky BTs using global NCEP forecast atmospheric and Reynolds SST fields. Simulated BTs are employed in ACSPO for improved cloud screening, physical (RTM-based) SST inversions, and to monitor and validate satellite BTs. The model minus observation biases are monitored online in near-real time using the Monitoring IR Clear-sky radiances over Oceans for SST (MICROS; http://www.star.nesdis.noaa.gov/sod/sst/micros/). A persistent positive M-O bias is observed in MICROS, partly attributed to missing aerosol in CRTM input, causing "M" to be warmer than "O". It is thus necessary to include aerosols in CRTM and quantify their effects on AVHRR BTs and SSTs. However, sensitivity of thermal bands to aerosol is only minimal, and use of solar reflectance bands is preferable to evaluate the accuracy of CRTM modeling, with global aerosol fields as input (from e.g. Goddard Chemistry Aerosol Radiation and Transport, GOCART, or Navy Aerosol Analysis and Prediction System, NAAPS). Once available, the corresponding M-O biases in solar reflectance bands will be added to MICROS. Also, adding CRTM simulated reflectances in ACSPO would greatly improve cloud detection, help validate CRTM in the solar reflectance bands, and assist aerosol retrievals. Running CRTM with global aerosol as input is very challenging, computationally. While CRTM is being optimized to handle such global scattering computations, a near-real time web-based Aerosol Quality Monitor (AQUAM

  14. Cantera Aerosol Dynamics Simulator

    SciTech Connect

    Moffat, Harry

    2004-09-01

    The Cantera Aerosol Dynamics Simulator (CADS) package is a general library for aerosol modeling to address aerosol general dynamics, including formation from gas phase reactions, surface chemistry (growth and oxidation), bulk particle chemistry, transport by Brownian diffusion, thermophoresis, and diffusiophoresis with linkage to DSMC studies, and thermal radiative transport. The library is based upon Cantera, a C++ Cal Tech code that handles gas phase species transport, reaction, and thermodynamics. The method uses a discontinuous galerkin formulation for the condensation and coagulation operator that conserves particles, elements, and enthalpy up to round-off error. Both O-D and 1-D time dependent applications have been developed with the library. Multiple species in the solid phase are handled as well. The O-D application, called Tdcads (Time Dependent CADS) is distributed with the library. Tdcads can address both constant volume and constant pressure adiabatic homogeneous problems. An extensive set of sample problems for Tdcads is also provided.

  15. Mass Measurements of Saharan Dust Aerosols in Puerto Rico

    NASA Astrophysics Data System (ADS)

    Armstrong, R. A.; Jimenez, B.; Detres, Y.

    2003-12-01

    During the summer months, Saharan dust aerosols reach maximum values throughout the Caribbean Region. The respirable fraction of this dust, measured as PM 2.5, has the potential to induce regional health impacts, such as asthma and allergic reactions in sensitive individuals. Surface measurements of dust aerosols were obtained at Fajardo, on the northeastern corner of Puerto Rico, since November 2000. The PM 2.5 and PM 10 size fractions from the filter samples were related to satellite and sunphotometer measurements of aerosol optical depth before, during, and after Saharan dust events. In 2002, PM 2.5 ranged from 2.5 to 18.4 ug/m-3 while PM 10 ranged from 11 to 60 ug/m-3. The PM 2.5 fraction was approximately 25% of the PM 10. Saharan dust aerosols are also responsible for substantial heavy metal deposition in the tropical western Atlantic. In 2001, Iron increase from less than 4 mg/g during the first four months of the year, to a maximum of 24 mg/g in June, with relatively high values from May through September. An AVHRR 4-year climatology of aerosol optical depth for northeastern Puerto Rico shows a well-defined maximum peak during the last week of June and first week of July.

  16. Novel Measurements of Aerosol Particle Interfaces Using Biphasic Microfluidics

    NASA Astrophysics Data System (ADS)

    Metcalf, A. R.; Dutcher, C. S.

    2014-12-01

    Secondary organic aerosol (SOA) particles are nearly ubiquitous in the atmosphere and yet there remains large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. These aerosol interfaces can profoundly affect the fate of condensable organic compounds emitted into the atmosphere by altering the way in which organic vapors interact with the ambient aerosol. Aerosol interfaces affect particle internal structure, species uptake, equilibrium partitioning, activation to cloud condensation or ice nuclei, and optical properties. For example, organic thin films can shield the core of the aerosol from the ambient environment, which may disrupt equilibrium partitioning and mass transfer. To improve our ability to accurately predict the fate of SOA in the atmosphere, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Few technologies exist to accurately probe aerosol interfaces at atmospherically-relevant conditions. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred. Chemical compositions of the liquid phases studied here span a range of viscosities and include electrolyte and water soluble organic acid species often observed in the atmosphere, such as mixtures

  17. Indian aerosols: present status.

    PubMed

    Mitra, A P; Sharma, C

    2002-12-01

    This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source re