Hygroscopic growth of atmospheric aerosol particles based on active remote sensing and radiosounding measurements: selected cases in southeastern Spain

A new methodology based on combining active and passive remote sensing and simultaneous and collocated radiosounding data to study the aerosol hygroscopic growth effects on the particle optical and microphysical properties is presented. The identification of hygroscopic growth situations combines the analysis of multispectral aerosol particle backscatter coefficient and particle linear depolarization ratio with thermodynamic profiling of the atmospheric column. We analyzed the hygroscopic growth effects on aerosol properties, namely the aerosol particle backscatter coefficient and the volume concentration profiles, using data gathered at Granada EARLINET station. Two study cases, corresponding to different aerosol loads and different aerosol types, are used for illustrating the potential of this methodology. Values of the aerosol particle backscatter coefficient enhancement factors range from 2.1 ± 0.8 to 3.9 ± 1.5, in the ranges of relative humidity 60–90 and 40–83%, being similar to those previously reported in the literature. Differences in the enhancement factor are directly linked to the composition of the atmospheric aerosol. The largest value of the aerosol particle backscatter coefficient enhancement factor corresponds to the presence of sulphate and marine particles that are more affected by hygroscopic growth. On the contrary, the lowest value of the enhancement factor corresponds to an aerosol mixture containing sulphates and slight traces of mineral dust. The Hänel parameterization is applied to these case studies, obtaining results within the range of values reported in previous studies, with values of the γ exponent of 0.56 ± 0.01 (for anthropogenic particles slightly influenced by mineral dust) and 1.07 ± 0.01 (for the situation dominated by anthropogenic particles), showing the convenience of this remote sensing approach for the study of hygroscopic effects of the atmospheric aerosol under ambient unperturbed conditions. For the first time, the retrieval of the volume concentration profiles for these cases using the Lidar Radiometer Inversion Code (LIRIC) allows us to analyze the aerosol hygroscopic growth effects on aerosol volume concentration, observing a stronger increase of the fine mode volume concentration with increasing relative humidity.

Investigation of the Hygroscopic and Morphological Properties of Atmospheric Aerosols

The first objective of this thesis was to examine the hygroscopic and morphological nature of various substances through the use of an Environmental Scanning Electron Microscope (ESEM). The hygroscopic growth and changes in morphology for pure-component aerosols were studied for particles greater than 2 µm in size. Hygroscopic growth was observed through changes in relative humidity (RH) and hygroscopic growth curves were created. The second objective of this thesis, the hygroscopic growth of multi-component aerosol mixtures, was studied using Hygroscopic Tandem Differential Mobility Analysis(HTDMA). The size distribution for an aerosol stream was determined before and after the stream was subjected to an increase in relative humidity.

Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity

Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. We have measured and characterized CCN at water vapor supersaturations in the range of S=0.10-0.82% in pristine tropical rainforest air during the AMAZE-08 campaign in central Amazonia. The effective hygroscopicity parameters describing the influence of chemical composition on the CCN activity of aerosol particles varied in the range of kappa approximate to 0.1-0.4 (0.16+/-0.06 arithmetic mean and standard deviation). The overall median value of kappa approximate to 0.15 was by a factor of two lower than the values typically observed for continental aerosols in other regions of the world. Aitken mode particles were less hygroscopic than accumulation mode particles (kappa approximate to 0.1 at D approximate to 50 nm; kappa approximate to 0.2 at D approximate to 200 nm), which is in agreement with earlier hygroscopicity tandem differential mobility analyzer (H-TDMA) studies. The CCN measurement results are consistent with aerosol mass spectrometry (AMS) data, showing that the organic mass fraction (f(org)) was on average as high as similar to 90% in the Aitken mode (D <= 100 nm) and decreased with increasing particle diameter in the accumulation mode (similar to 80% at D approximate to 200 nm). The kappa values exhibited a negative linear correlation with f(org) (R(2)=0.81), and extrapolation yielded the following effective hygroscopicity parameters for organic and inorganic particle components: kappa(org)approximate to 0.1 which can be regarded as the effective hygroscopicity of biogenic secondary organic aerosol (SOA) and kappa(inorg)approximate to 0.6 which is characteristic for ammonium sulfate and related salts. Both the size dependence and the temporal variability of effective particle hygroscopicity could be parameterized as a function of AMS-based organic and inorganic mass fractions (kappa(p)=kappa(org) x f(org)+kappa(inorg) x f(inorg)). The CCN number concentrations predicted with kappa(p) were in fair agreement with the measurement results (similar to 20% average deviation). The median CCN number concentrations at S=0.1-0.82% ranged from N(CCN,0.10)approximate to 35 cm(-3) to N(CCN,0.82)approximate to 160 cm(-3), the median concentration of aerosol particles larger than 30 nm was N(CN,30)approximate to 200 cm(-3), and the corresponding integral CCN efficiencies were in the range of N(CCN,0.10/NCN,30)approximate to 0.1 to N(CCN,0.82/NCN,30)approximate to 0.8. Although the number concentrations and hygroscopicity parameters were much lower in pristine rainforest air, the integral CCN efficiencies observed were similar to those in highly polluted megacity air. Moreover, model calculations of N(CCN,S) assuming an approximate global average value of kappa approximate to 0.3 for continental aerosols led to systematic overpredictions, but the average deviations exceeded similar to 50% only at low water vapor supersaturation (0.1%) and low particle number concentrations (<= 100 cm(-3)). Model calculations assuming aconstant aerosol size distribution led to higher average deviations at all investigated levels of supersaturation: similar to 60% for the campaign average distribution and similar to 1600% for a generic remote continental size distribution. These findings confirm earlier studies suggesting that aerosol particle number and size are the major predictors for the variability of the CCN concentration in continental boundary layer air, followed by particle composition and hygroscopicity as relatively minor modulators. Depending on the required and applicable level of detail, the information and parameterizations presented in this paper should enable efficient description of the CCN properties of pristine tropical rainforest aerosols of Amazonia in detailed process models as well as in large-scale atmospheric and climate models.

A study on the sensitivities of simulated aerosol optical properties to composition and size distribution using airborne measurements

We present a flexible framework to calculate the optical properties of atmospheric aerosols at a given relative humidity based on their composition and size distribution. The similarity of this framework to climate model parameterisations allows rapid and extensive sensitivity tests of the impact of uncertainties in data or of new measurements on climate relevant aerosol properties. The data collected by the FAAM BAe-146 aircraft during the EUCAARI-LONGREX and VOCALS-REx campaigns have been used in a closure study to analyse the agreement between calculated and measured aerosol optical properties for two very different aerosol types. The agreement achieved for the EUCAARI-LONGREX flights is within the measurement uncertainties for both scattering and absorption. However, there is poor agreement between the calculated and the measured scattering for the VOCALS-REx flights. The high concentration of sulphate, which is a scattering aerosol with no absorption in the visible spectrum, made the absorption measurements during VOCALS-REx unreliable, and thus no closure study was possible for the absorption. The calculated hygroscopic scattering growth factor overestimates the measured values during EUCAARI-LONGREX and VOCALS-REx by ∼30% and ∼20%, respectively. We have also tested the sensitivity of the calculated aerosol optical properties to the uncertainties in the refractive indices, the hygroscopic growth factors and the aerosol size distribution. The largest source of uncertainty in the calculated scattering is the aerosol size distribution (∼35%), followed by the assumed hygroscopic growth factor for organic aerosol (∼15%), while the predominant source of uncertainty in the calculated absorption is the refractive index of organic aerosol (28–60%), although we would expect the refractive index of black carbon to be important for aerosol with a higher black carbon fraction.

Aerosol scattering and absorption during the EUCAARI-LONGREX flights of the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146: can measurements and models agree?

Scattering and absorption by aerosol in anthropogenically perturbed air masses over Europe has been measured using instrumentation flown on the UK’s BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM) on 14 flights during the EUCAARI-LONGREX campaign in May 2008. The geographical and temporal variations of the derived shortwave optical properties of aerosol are presented. Values of single scattering albedo of dry aerosol at 550 nm varied considerably from 0.86 to near unity, with a campaign average of 0.93 ± 0.03. Dry aerosol optical depths ranged from 0.030 ± 0.009 to 0.24 ± 0.07. An optical properties closure study comparing calculations from composition data and Mie scattering code with the measured properties is presented. Agreement to within measurement uncertainties of 30% can be achieved for both scattering and absorption,but the latter is shown to be sensitive to the refractive indices chosen for organic aerosols, and to a lesser extent black carbon, as well as being highly dependent on the accuracy of the absorption measurements. Agreement with the measured absorption can be achieved either if organic carbon is assumed to be weakly absorbing, or if the organic aerosol is purely scattering and the absorption measurement is an overestimate due to the presence of large amounts of organic carbon. Refractive indices could not be inferred conclusively due to this uncertainty, despite the enhancement in methodology compared to previous studies that derived from the use of the black carbon measurements. Hygroscopic growth curves derived from the wet nephelometer indicate moderate water uptake by the aerosol with a campaign mean f (RH) value (ratio in scattering) of 1.5 (range from 1.23 to 1.63) at 80% relative humidity. This value is qualitatively consistent with the major chemical components of the aerosol measured by the aerosol mass spectrometer, which are primarily mixed organics and nitrate and some sulphate.

A multi-model evaluation of aerosols over South Asia: common problems and possible causes

Atmospheric pollution over South Asia attracts special attention due to its effects on regional climate, water cycle and human health. These effects are potentially growing owing to rising trends of anthropogenic aerosol emissions. In this study, the spatio-temporal aerosol distributions over South Asia from seven global aerosol models are evaluated against aerosol retrievals from NASA satellite sensors and ground-based measurements for the period of 2000–2007. Overall, substantial underestimations of aerosol loading over South Asia are found systematically in most model simulations. Averaged over the entire South Asia, the annual mean aerosol optical depth (AOD) is underestimated by a range 15 to 44% across models compared to MISR (Multi-angle Imaging SpectroRadiometer), which is the lowest bound among various satellite AOD retrievals (from MISR, SeaWiFS (Sea-Viewing Wide Field-of-View Sensor), MODIS (Moderate Resolution Imaging Spectroradiometer) Aqua and Terra). In particular during the post-monsoon and wintertime periods (i.e., October–January), when agricultural waste burning and anthropogenic emissions dominate, models fail to capture AOD and aerosol absorption optical depth (AAOD) over the Indo–Gangetic Plain (IGP) compared to ground-based Aerosol Robotic Network (AERONET) sunphotometer measurements. The underestimations of aerosol loading in models generally occur in the lower troposphere (below 2 km) based on the comparisons of aerosol extinction profiles calculated by the models with those from Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) data. Furthermore, surface concentrations of all aerosol components (sulfate, nitrate, organic aerosol (OA) and black carbon (BC)) from the models are found much lower than in situ measurements in winter. Several possible causes for these common problems of underestimating aerosols in models during the post-monsoon and wintertime periods are identified: the aerosol hygroscopic growth and formation of secondary inorganic aerosol are suppressed in the models because relative humidity (RH) is biased far too low in the boundary layer and thus foggy conditions are poorly represented in current models, the nitrate aerosol is either missing or inadequately accounted for, and emissions from agricultural waste burning and biofuel usage are too low in the emission inventories. These common problems and possible causes found in multiple models point out directions for future model improvements in this important region.

Hygroskopische Eigenschaften atmosphärischer Partikel in kontinentalen Luftmassen

Die hygroskopischen Eigenschaften sind wichtige Parameter des atmosphärischen Aerosols. Sie beeinflussen sowohl direkt über den Strahlungsantrieb, als auch indirekt über die Wechselwirkung von Aerosol und Wolken die globale Strahlungsbilanz und somit das Klima. Auch die Sichtweiteveränderung ist von ihnen abhängig. Sie beeinflussen die Partikeldeposition in der Lunge und müssen zur Vermeidung von Artefaktbildung bei der Aerosolmessung berücksichtigt werden.
Die vorliegende Dissertation beinhaltet Messungen des wasserlöslichen Volumenanteils und des hygroskopischen Wachstumsfaktors des atmosphärischen Aerosols. Mit diesen Untersuchungen konnte der überwiegende Teil (50 nm bis 4 µm Partikeldurchmesser) des für atmosphärische Prozesse relevanten Größenbereichs gleichzeitig größenaufgelöst und detailliert erfasst werden. Messungen wurden in ruralen, semi-urbanen und frei-troposphärischen Luftmassen durchgeführt. Messverfahren sind die SoFA (Water-Soluble Fraction of Large and Giant Atmospheric Particles)-Methode und der HTDMA (Hygroscopic Tandem Differential Mobility Analyzer). Im Rahmen dieser Arbeit wurde die SoFA-Methode weiterentwickelt.
Ein umfangreiches Messprogramm zeigt, dass der mittlere lösliche Volumenanteil des Aerosols mit Werten von ca. 59 % geringe Variationen zwischen den Messstandorten aufweist, lediglich in frei-troposphärischen Luftmassen liegt er mit 66 % erwartungsgemäß höher. Betrachtet man die Daten größenaufgelöst, so zeigt sich, dass im Größenbereich zwischen 200 und 500 nm Partikeldurchmesser der lösliche Volumenanteil ein Maximum aufweist. Ein in semi-urbanem Aerosol gemessener Jahresgang weist, vor allem für Partikel kleiner 300 nm, im Sommer geringere Werte als im Winter auf. Unterhalb 300 nm Partikeldurchmesser treten üblicherweise zwei, oberhalb bis zu drei Partikeltypen unterschiedlicher Hygroskopizität auf: der fast unlösliche Partikeltyp mit löslichen Volumenanteilen bis 12 %, der wahrscheinlich aus Ruß, sekundärem organischem, mineralischem und biologischem Material besteht; der teilweise lösliche Partikeltyp (50 bis 75 %), der als Mischpartikel anzusprechen ist; schließlich der überwiegend lösliche Partikeltyp (ca. 90 %), der wahrscheinlich durch Wolkenprozessierung entsteht. Der Unterschied zwischen den Messstandorten ist auch hier gering. Üblicherweise dominieren die löslicheren Partikeltypen mit relativen Anteilen von 60 bis 95 %, wobei sich ein Minimum der Häufigkeit der löslicheren Partikel zwischen 1.5 und 2.5 µm zeigt. Abschließende größenaufgelöste Modellrechnungen zum Aerosol-Feuchtewachstum unterstreichen die Relevanz dieser Untersuchungen für Strahlungs- und Wolkenprozesse.

Numerical simulations of microphysical processes in pyro-convective clouds

Hochreichende Konvektion über Waldbränden ist eine der intensivsten Formen von atmosphärischer Konvektion. Die extreme Wolkendynamik mit hohen vertikalen Windgeschwindigkeiten (bis 20 m/s) bereits an der Wolkenbasis, hohen Wasserdampfübersättigungen (bis 1%) und die durch das Feuer hohen Anzahlkonzentration von Aerosolpartikeln (bis 100000 cm^-3) bilden einen besonderen Rahmen für Aerosol-Wolken Wechselwirkungen.Ein entscheidender Schritt in der mikrophysikalischen Entwicklung einer konvektiven Wolke ist die Aktivierung von Aerosolpartikeln zu Wolkentropfen. Dieser Aktivierungsprozess bestimmt die anfängliche Anzahl und Größe der Wolkentropfen und kann daher die Entwicklung einer konvektiven Wolke und deren Niederschlagsbildung beeinflussen. Die wichtigsten Faktoren, welche die anfängliche Anzahl und Größe der Wolkentropfen bestimmen, sind die Größe und Hygroskopizität der an der Wolkenbasis verfügbaren Aerosolpartikel sowie die vertikale Windgeschwindigkeit. Um den Einfluss dieser Faktoren unter pyro-konvektiven Bedingungen zu untersuchen, wurden numerische Simulationen mit Hilfe eines Wolkenpaketmodells mit detaillierter spektraler Beschreibung der Wolkenmikrophysik durchgeführt. Diese Ergebnisse können in drei unterschiedliche Bereiche abhängig vom Verhältnis zwischen vertikaler Windgeschwindigkeit und Aerosolanzahlkonzentration (w/NCN) eingeteilt werden: (1) ein durch die Aerosolkonzentration limitierter Bereich (hohes w/NCN), (2) ein durch die vertikale Windgeschwindigkeit limitierter Bereich (niedriges w/NCN) und (3) ein Übergangsbereich (mittleres w/NCN). Die Ergebnisse zeigen, dass die Variabilität der anfänglichen Anzahlkonzentration der Wolkentropfen in (pyro-) konvektiven Wolken hauptsächlich durch die Variabilität der vertikalen Windgeschwindigkeit und der Aerosolkonzentration bestimmt wird. rnUm die mikrophysikalischen Prozesse innerhalb der rauchigen Aufwindregion einer pyrokonvektiven Wolke mit einer detaillierten spektralen Mikrophysik zu untersuchen, wurde das Paketmodel entlang einer Trajektorie innerhalb der Aufwindregion initialisiert. Diese Trajektore wurde durch dreidimensionale Simulationen eines pyro-konvektiven Ereignisses durch das Model ATHAM berechnet. Es zeigt sich, dass die Anzahlkonzentration der Wolkentropfen mit steigender Aerosolkonzentration ansteigt. Auf der anderen Seite verringert sich die Größe der Wolkentropfen mit steigender Aerosolkonzentration. Die Reduzierung der Verbreiterung des Tropfenspektrums stimmt mit den Ergebnissen aus Messungen überein und unterstützt das Konzept der Unterdrückung von Niederschlag in stark verschmutzen Wolken.Mit Hilfe des Models ATHAM wurden die dynamischen und mikrophysikalischen Prozesse von pyro-konvektiven Wolken, aufbauend auf einer realistischen Parametrisierung der Aktivierung von Aerosolpartikeln durch die Ergebnisse der Aktivierungsstudie, mit zwei- und dreidimensionalen Simulationen untersucht. Ein modernes zweimomenten mikrophysikalisches Schema wurde in ATHAM implementiert, um den Einfluss der Anzahlkonzentration von Aerosolpartikeln auf die Entwicklung von idealisierten pyro-konvektiven Wolken in US Standardamtosphären für die mittleren Breiten und den Tropen zu untersuchen. Die Ergebnisse zeigen, dass die Anzahlkonzentration der Aerosolpartikel die Bildung von Regen beeinflusst. Für geringe Aerosolkonzentrationen findet die rasche Regenbildung hauptsächlich durch warme mikrophysikalische Prozesse statt. Für höhere Aerosolkonzentrationen ist die Eisphase wichtiger für die Bildung von Regen. Dies führt zu einem verspäteten Einsetzen von Niederschlag für verunreinigtere Atmosphären. Außerdem wird gezeigt, dass die Zusammensetzung der Eisnukleationspartikel (IN) einen starken Einfluss auf die dynamische und mikrophysikalische Struktur solcher Wolken hat. Bei sehr effizienten IN bildet sich Regen früher. Die Untersuchung zum Einfluss des atmosphärischen Hintergrundprofils zeigt eine geringe Auswirkung der Meteorologie auf die Sensitivität der pyro-konvektiven Wolken auf diernAerosolkonzentration. Zum Abschluss wird gezeigt, dass die durch das Feuer emittierte Hitze einen deutlichen Einfluss auf die Entwicklung und die Wolkenobergrenze von pyro-konvektive Wolken hat. Zusammenfassend kann gesagt werden, dass in dieser Dissertation die Mikrophysik von pyrokonvektiven Wolken mit Hilfe von idealisierten Simulation eines Wolkenpaketmodell mit detaillierte spektraler Mikrophysik und eines 3D Modells mit einem zweimomenten Schema im Detail untersucht wurde. Es wird gezeigt, dass die extremen Bedingungen im Bezug auf die vertikale Windgeschwindigkeiten und Aerosolkonzentrationen einen deutlichen Einfluss auf die Entwicklung von pyro-konvektiven Wolken haben.

Investigation Of Leucine And Glutamic Acid Properties From The Nanoscale To The Macroscale

Aerosols are known to have important effects on climate, the atmosphere, and human health. The extent of those effects is unknown and largely depend on the interaction of aerosols with water in the atmosphere. Ambient aerosols are complex mixtures of both inorganic and organic compounds. The cloud condensation nuclei (CCN) activities, hygroscopic behavior and particle morphology of a monocarboxylic amino acid (leucine) and a dicarboxylic amino acid (glutamic acid) were investigated. Activation diameters at various supersaturation conditions were experimentally determined and compared with Köhler theoretical values. The theory accounts for both surface tension and the limited solubility of organic compounds. It was discovered that glutamic acid aerosols readily took on water both when relative humidity was less than 100% and when the supersaturation condition was reached, while leucine did not show any water activation at those conditions. Moreover, the study also suggests that Köhler theory describes CCN activity of organic compounds well when only surface tension of the compound is taken into account and complete solubility is assumed. Single parameter ¿ was also computed using both CCN data and hygroscopic growth factor (GF). The results of ¿ range from 0.17 to 0.53 using CCN data and 0.09 to 0.2 using GFs. Finally, the study suggests that during the water-evaporation/particle-nucleation process, crystallization from solution droplets takes place at different locations: for glutamic acid at the particles¿ center and leucine at the particles¿ boundary.

Surfactant coated aerosol powders and their properties

The hygroscopic growth of aerosols is an important factor effecting particle size. The consequence of the hygroscopic growth of pharrnaceutical aerosols is a change in their deposition characteristics, such that there is an increase in the total amount deposited in the lung. In this study the hygroscopic growth of disodium fluorescein (DF) aerosol powders was investigated by coating the powders with lauric and capric acids. The coating procedure was carried out in dichloromethane and chloroform, which acted as cosolvents for the fatty acids. An assessment of the extent and the nature of the coating was carried out. The qualitative assessment of the coating was achieved by infra-red spectroscopy, electronscanning chemical analysis and scanning electron microscopy. The quantitative analysis was carried out by differential refractometry, ultra-violet spectroscopy and gas liquid chromatography. These powders were generated under conditions approaching those in the lung, of 97 % relative humidity and 37"C. Coated and uncoated DF aerosol powders were introduced into a controlled temperature and relative humidity apparatus, designed and constructed for the investigation of hygroscopic growth in these studies. A vertical spinning disc device was used to generate the powders. Under conditions of controlled temperature and relative humidity mentioned, the growth ratio of disodium fluorescein alone was 1.45 compared with 1.68, for a nominal coating of DF with lauric acid of 0.12 gg-1, 1.0 for a nominal lauric acid coating of 0.2 gg-1, and 1.02 for a nominal capric acid coating of 0.18 gg-1. The range of control of hygroscopic growth of these aerosols has implications for the deposition of these preparations in the respiratory tract. These implications are discussed in the light of the current knowledge of the effects of hygroscopic growth on the deposition of pharmaceutical and environmental aerosols. A series of experiments in which pulmonary ventilation using a simple radioaerosol generator and delivery system are reported showing that particle size determination may be used to aid the design of diagnostic aerosol generators.

Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June, 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the N. E. Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm(-3), while background marine air aerosol concentrations were between 400-600 cm(-3). The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm(-3), was observed and attributed to open ocean particle formation. Continental air submicron chemical composition (excluding refractory sea salt) was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF) and cloud condensation nuclei (CCN) to total condensation nuclei (CN) concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40-50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water soluble organic carbon, which, in turn, was dominated by methanesulphonic acid (MSA). Sulphate concentrations were highest in marine tropical air - even higher than in continental air. MSA was present at twice the concentrations of previously-reported concentrations at the same location and the same season. Both continental and marine air exhibited aerosol GFs significantly less than ammonium sulphate aerosol pointing to a significant organic contribution to all air mass aerosol properties.

Condensational growth of atmospheric aerosol particles in an expanding water saturated air flow

Aerosol particles and water vapour are two important constituents of the atmosphere. Their interaction, i.e. thecondensation of water vapour on particles, brings about the formation of cloud, fog, and raindrops, causing the water cycle on the earth, and being responsible for climate changes. Understanding the roles of water vapour and aerosol particles in this interaction has become an essential part of understanding the atmosphere. In this work, the heterogeneous nucleation on pre-existing aerosol particles by the condensation of water vapour in theflow of a capillary nozzle was investigated. Theoretical and numerical modelling as well as experiments on thiscondensation process were included. Based on reasonable results from the theoretical and numerical modelling, an idea of designing a new nozzle condensation nucleus counter (Nozzle-CNC), that is to utilise the capillary nozzle to create an expanding water saturated air flow, was then put forward and various experiments were carried out with this Nozzle-CNC under different experimental conditions. Firstly, the air stream in the long capillary nozzle with inner diameter of 1.0~mm was modelled as a steady, compressible and heat-conducting turbulence flow by CFX-FLOW3D computational program. An adiabatic and isentropic cooling in the nozzle was found. A supersaturation in the nozzle can be created if the inlet flow is water saturated, and its value depends principally on flow velocity or flow rate through the nozzle. Secondly, a particle condensational growth model in air stream was developed. An extended Mason's diffusion growthequation with size correction for particles beyond the continuum regime and with the correction for a certain particle Reynolds number in an accelerating state was given. The modelling results show the rapid condensational growth of aerosol particles, especially for fine size particles, in the nozzle stream, which, on the one hand, may induce evident `over-sizing' and `over-numbering' effects in aerosol measurements as nozzle designs are widely employed for producing accelerating and focused aerosol beams in aerosol instruments like optical particle counter (OPC) and aerodynamical particle sizer (APS). It can, on the other hand, be applied in constructing the Nozzle-CNC. Thirdly, based on the optimisation of theoretical and numerical results, the new Nozzle-CNC was built. Under various experimental conditions such as flow rate, ambient temperature, and the fraction of aerosol in the total flow, experiments with this instrument were carried out. An interesting exponential relation between the saturation in the nozzle and the number concentration of atmospheric nuclei, including hygroscopic nuclei (HN), cloud condensation nuclei (CCN), and traditionally measured atmospheric condensation nuclei (CN), was found. This relation differs from the relation for the number concentration of CCN obtained by other researchers. The minimum detectable size of this Nozzle-CNC is 0.04?m. Although further improvements are still needed, this Nozzle-CNC, in comparison with other CNCs, has severaladvantages such as no condensation delay as particles larger than the critical size grow simultaneously, low diffusion losses of particles, little water condensation at the inner wall of the instrument, and adjustable saturation --- therefore the wide counting region, as well as no calibration compared to non-water condensation substances.

Impaired Compensatory Beta-cell Function And Growth In Response To High-fat Diet In Ldl Receptor Knockout Mice.

In this study, we investigated the effect of low density lipoprotein receptor (LDLr) deficiency on gap junctional connexin 36 (Cx36) islet content and on the functional and growth response of pancreatic beta-cells in C57BL/6 mice fed a high-fat (HF) diet. After 60 days on regular or HF diet, the metabolic state and morphometric islet parameters of wild-type (WT) and LDLr-/- mice were assessed. HF diet-fed WT animals became obese and hypercholesterolaemic as well as hyperglycaemic, hyperinsulinaemic, glucose intolerant and insulin resistant, characterizing them as prediabetic. Also they showed a significant decrease in beta-cell secretory response to glucose. Overall, LDLr-/- mice displayed greater susceptibility to HF diet as judged by their marked cholesterolaemia, intolerance to glucose and pronounced decrease in glucose-stimulated insulin secretion. HF diet induced similarly in WT and LDLr-/- mice, a significant decrease in Cx36 beta-cell content as revealed by immunoblotting. Prediabetic WT mice displayed marked increase in beta-cell mass mainly due to beta-cell hypertrophy/replication. Nevertheless, HF diet-fed LDLr-/- mice showed no significant changes in beta-cell mass, but lower islet-duct association (neogenesis) and higher beta-cell apoptosis index were seen as compared to controls. The higher metabolic susceptibility to HF diet of LDLr-/- mice may be explained by a deficiency in insulin secretory response to glucose associated with lack of compensatory beta-cell expansion.

Genetic Predictors Of Long-term Response To Growth Hormone (gh) Therapy In Children With Gh Deficiency And Turner Syndrome: The Influence Of A Socs2 Polymorphism.

There is great interindividual variability in the response to GH therapy. Ascertaining genetic factors can improve the accuracy of growth response predictions. Suppressor of cytokine signaling (SOCS)-2 is an intracellular negative regulator of GH receptor (GHR) signaling. The objective of the study was to assess the influence of a SOCS2 polymorphism (rs3782415) and its interactive effect with GHR exon 3 and -202 A/C IGFBP3 (rs2854744) polymorphisms on adult height of patients treated with recombinant human GH (rhGH). Genotypes were correlated with adult height data of 65 Turner syndrome (TS) and 47 GH deficiency (GHD) patients treated with rhGH, by multiple linear regressions. Generalized multifactor dimensionality reduction was used to evaluate gene-gene interactions. Baseline clinical data were indistinguishable among patients with different genotypes. Adult height SD scores of patients with at least one SOCS2 single-nucleotide polymorphism rs3782415-C were 0.7 higher than those homozygous for the T allele (P < .001). SOCS2 (P = .003), GHR-exon 3 (P= .016) and -202 A/C IGFBP3 (P = .013) polymorphisms, together with clinical factors accounted for 58% of the variability in adult height and 82% of the total height SD score gain. Patients harboring any two negative genotypes in these three different loci (homozygosity for SOCS2 T allele; the GHR exon 3 full-length allele and/or the -202C-IGFBP3 allele) were more likely to achieve an adult height at the lower quartile (odds ratio of 13.3; 95% confidence interval of 3.2-54.2, P = .0001). The SOCS2 polymorphism (rs3782415) has an influence on the adult height of children with TS and GHD after long-term rhGH therapy. Polymorphisms located in GHR, IGFBP3, and SOCS2 loci have an influence on the growth outcomes of TS and GHD patients treated with rhGH. The use of these genetic markers could identify among rhGH-treated patients those who are genetically predisposed to have less favorable outcomes.

Growth And Body Composition In Brazilian Female Rhythmic Gymnastics Athletes.

The aim was to analyse the physical growth and body composition of rhythmic gymnastics athletes relative to their level of somatic maturation. This was a cross-sectional study of 136 athletes on 23 teams from Brazil. Mass, standing height and sitting height were measured. Fat-free and fat masses, body fat percentages and ages of the predicted peak height velocity (PHV) were calculated. The z scores for mass were negative during all ages according to both WHO and Brazilian references, and that for standing height were also negative for all ages according to WHO reference but only until 12 years old according to Brazilian reference. The mean age of the predicted PHV was 12.1 years. The mean mass, standing and sitting heights, body fat percentage, fat-free mass and fat mass increased significantly until 4 to 5 years after the age of the PHV. Menarche was reached in only 26% of these athletes and mean age was 13.2 years. The mass was below the national reference standards, and the standing height was below only for the international reference, but they also had late recovery of mass and standing height during puberty. In conclusion, these athletes had a potential to gain mass and standing height several years after PHV, indicating late maturation.