Letteratura scientifica selezionata sul tema "Volcanic dust"

On 19 September 2021, a volcanic eruption began on the island of La Palma (Canary Islands, Spain). The eruption has allowed the assessment of an unprecedented multidisciplinary study on the effects of the volcanic plume. This work presents the estimation of the spectral direct radiative forcing (ΔF) and efficiency (ΔFEff) from solar radiation measurements at the Izaña Observatory (IZO) located on the island of Tenerife (∼140 km from the volcano). During the eruption, the IZO was affected by different types of aerosols: volcanic, Saharan mineral dust, and a mixture of volcanic and dust aerosols. Three case studies were identified using ground-based (lidar) data, satellite-based (Sentinel-5P Tropospheric Monitoring Instrument, TROPOMI) data, reanalysis data (Modern-Era Retrospective Analysis for Research and Applications, version 2, MERRA-2), and backward trajectories (Flexible Trajectories, FLEXTRA), and subsequently characterised in terms of optical and micro-physical properties using ground-based sun-photometry measurements. Despite the ΔF of the volcanic aerosols being greater than that of the dust events (associated with the larger aerosol load present), the ΔFEff was found to be lower. The spectral ΔFEff values at 440 nm ranged between −1.9 and −2.6 Wm−2nm−1AOD−1 for the mineral dust and mixed volcanic and dust particles, and between −1.6 and −3.3 Wm−2nm−1AOD−1 for the volcanic aerosols, considering solar zenith angles between 30∘ and 70∘, respectively.

Abstract. The polarization lidar photometer networking (POLIPHON) method introduced to separate coarse-mode and fine-mode particle properties of Eyjafjallajökull volcanic aerosols in 2010 is extended to cover Saharan dust events as well. Furthermore, new volcanic dust observations performed after the Grimsvötn volcanic eruptions in 2011 are presented. The retrieval of particle mass concentrations requires mass-specific extinction coefficients. Therefore, a review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is given. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

Abstract. The lidar-photometer method introduced to separate volcanic coarse-mode and fine-mode particle properties is extended to cover Saharan dust events as well. A review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is presented. These mass-specific extinction coefficients are required in the retrieval of particle mass concentration profiles. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to Central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

This review paper contrasts volcanic ash and mineral dust regarding their chemical and physical properties, sources, atmospheric load, deposition processes, atmospheric processing, and environmental and climate effects. Although there are substantial differences in the history of mineral dust and volcanic ash particles before they are released into the atmosphere, a number of similarities exist in atmospheric processing at ambient temperatures and environmental and climate impacts. By providing an overview on the differences and similarities between volcanic ash and mineral dust processes and effects, this review paper aims to appeal for future joint research strategies to extend our current knowledge through close cooperation between mineral dust and volcanic ash researchers.

Abstract. A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. We show an example, how the characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometer size-range in the ambient air. The low real part of the water's refractive index around 2700–2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range and this feature can be used for the particle identification. The two-wavelength measurement setup was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (R value) for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice) showed at least 9 times higher values (on average 70 times) for water droplets than for the dust types at any diameter within the particle size range of 2–20 μm. The envisaged measurement setup was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and Ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations, the median experimental R value is 8–21 times higher for water than for the "dust" particles.

Abstract. A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single-particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. The characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometre size range in the ambient air. The low real part of the water's refractive index around 2700–2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range, and this feature can be used for the desired particle identification. The two-wavelength measurement set-up was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (visible-to-IR (infrared), R value) for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice) showed at least 9-times-higher values (on average 70 times) for water droplets than for the dust types at any diameter within the particle size range of 2–20 μm. The envisaged measurement set-up was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders, simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations; the median experimental R value is 8–21 times higher for water than for the "dust" particles.

The direct solar radiation data over India have been examined for depletion of solar energy due to the volcanic dust clouds produced by the Mexican volcano El Chichon in 1982. At Bhavnagar and Pune the depletion of 20-25% of solar energy starting from about 20 April 1982 till the onset of monsoon has been noticed.

Abstract. New information on the PM10 mineral dust from site-specific (Rome area, Latium) outcropped rocks, and on the microphysics, optical properties and radiative effects of mineral dust at local level were gained in this work. A multi-disciplinary approach was used, based on individual-particle scanning electron microscopy with X-ray energy-dispersive microanalysis (SEM XEDS), X-ray diffraction (XRD) analysis of dust, size distribution of mineral particles, and radiative transfer modelling (RTM).The mineral composition of Rome lithogenic PM10 varies between an end-member dominated by silicate minerals and one exclusively composed of calcite. The first is obtained from volcanic lithotypes, the second from travertine or limestones; lithogenic PM10 with intermediate composition derives mainly from siliciclastic rocks or marlstones of Rome area. Size and mineral species of PM10 particles of silicate-dominated dust types are tuned mainly by weathering and, to lesser extent, by debris formation or crystallization; chemical precipitation of CaCO3 plays a major role in calcite-dominated types. These differences are evidenced by the diversity of volume distributions, within either dust types, or mineral species. Further differences are observed between volume distributions of calcite from travertine (natural source) and from road dust (anthropic source), specifically on the width, shape and enrichment of the fine fraction (unimodal at 5 μm a.d. for travertine, bimodal at 3.8 and 1.8 μm a.d. for road dust). Log-normal probability density functions of volcanics and travertine dusts affect differently the single scattering albedo (SSA) and the asymmetry parameter (g) in the VISible and Near Infrared (NIR) regions, depending also on the absorbing/non-absorbing character of volcanics and travertine, respectively. The downward component of the BOA solar irradiance simulated by RTM for a volcanics-rich or travertine-rich atmosphere shows that volcanics contribution to the solar irradiance differs significantly from that of travertine in the NIR region, while similar contributions are modelled in the VIS.

Volcanic eruptions often have an impact on the environment. In the context of the environmental problem of global warming, a large amount of carbon dioxide released by volcanic eruptions will aggravate the greenhouse effect, which has aroused widespread concern. This article first explains the volcano's cone-shaped structure with several craters, cones, and vents. Although each volcano is unique, most volcanoes can be separated into three major types, the first type is a cinder cone, the second type is a composite volcano, and the third type is a shield volcano. Furthermore, this article interprets the causes of volcanic eruptions by decompression melting, and crustal movement. In addition to this, the environmental impacts of volcanic eruptions from three different angles are explained in the article. The First is the environmental impact of volcanic eruptions at different latitudes. It not only examines the sea surface temperatures' responses to volcanic forcing but also mentions a phenomenon of wind (El Niño de Navidad) caused by volcanic. The second argument is the impact of volcanic eruption on climate. It explains the effects of volcanic dust, Sulphur dioxide, and greenhouse gases, these three main volcanic substances that contribute to environmental cooling, acid rain, and global warming respectively. The final point is the impact of volcanic eruption on the benefits and disadvantages of plant cultivation, hoping this article could raise awareness of volcanoes and global environmental problems and prevent them.

Abstract. Iron is a key limiting micro-nutrient for marine primary productivity. It can be supplied to the ocean by atmospheric dust deposition. Volcanic ash deposition into the ocean represents another external and so far largely neglected source of iron. This study demonstrates strong evidence for natural fertilisation in the iron-limited oceanic area of the NE Pacific, induced by volcanic ash from the eruption of Kasatochi volcano in August 2008. Atmospheric and oceanic conditions were favourable to generate a massive phytoplankton bloom in the NE Pacific Ocean which for the first time establishes a causal connection between oceanic iron-fertilisation and volcanic ash supply.

The economy of the Commonwealth of Dominica is primarily agrarian based with banana production as one of the key export commodities, notwithstanding its preferential loss in the European Union market. However, banana productivity like most other crops has been severely impacted by a general low native soil nutrient status coupled with low application rates of phosphate (P) fertilizers in particular. The latter can be partly attributed to the low purchasing power on the international market as is evident in the long term trends of increaseprices for nitrogenous and phosphate fertilizers. The volcanic soils of the Commonwealth of Dominica were first studied in a relatively detailed way in 1967 with these soils showing high phosphate retention capacities. As a consequence, although P application is an integral part of profitable agricultural systems, improving soil fertility and plant nutrient management is a complex challenge. This challenge is amplified by the fact that a high ability to adsorb P is one of the characteristics of volcanic soils making P sparingly available for plant uptake. Hence although the world’s high reserves of phosphate ores are declining the demand for P fertilizers in the humid tropics are constantly increasing. If not managed properly, increase and continued input of P fertilizers and manure P may eventually lead to environmental rather than agronomic concerns. This research examines the influence of soil properties from some major agricultural soils in the Commonwealth of Dominica in order to obtain an improved comprehension of soil fertility limitations with the goal of developing nutrient management and farm developmental strategies geared towards increased crop production and overall farm productivity. In this regard special attention is given to the use of pyroligenous acid as a low molecular weight organic acid (LMWOA) in catalysing the dissolution of secondary P minerals. Hence the aim is to understand how native P stocks as well as applied fertilizer can potentially become more plant available thus reducing P fertilizer applications to a required minimum.

Thesis advisor: Rudolph Hon
Pleistocene-age terra rossa paleosols are situated on and are intercalated with eolianite and marine carbonate units across the Bermuda Islands. These clay-rich soils were originally thought to the derived from weathering of the volcanic seamount and/or from dissolution of the carbonate units, the paleosols are now believed to be primarily the result of atmospheric dust deposition from Saharan North Africa and the Sahel via long range transport, with some local inputs. If so, these soil units are mixtures of atmospheric deposition during one or more glacial- interglacial cycles. Previous investigations have been conducted on the paleosols to determine their provenance, age, and to identify unique characteristics for island wide mapping. We conducted comprehensive geochemical analyses to determine the degree of chemical weathering and diagenesis, and to identify processes responsible for their formation and development. The paleosols were found to be geochemically similar across all ages, and to show an increased degree of alteration with age rather than with their duration of subaerial exposure, indicating diagenesis by infiltrating meteoric waters as well subaerial weathering. Evidence of paleosol diagenesis suggests vadose flow across the island may not be limited to preferential pathways and that while flow through the limestones is complex, infiltrating waters appear to have allowed for additional alteration of the soils. In addition to the paleosols, clay-rich deposits with paleosol-like textures were identified during coring operations in Harrington Sound and Hungry Bay, beneath present-day sea level. The source and development histories of these materials were previously unknown. Since these clay deposits are situated beneath present-day sea level it is likely that they were deposited and chemically weathered exclusively during glacial low-sea level climate conditions. Geochemical analyses were conducted on the submarine clay samples to determine if they were related to the above-sea level paleosol and to identify their sources. Major and trace element signatures showed the submarine clay deposits to be chemically similar to the paleosols and to be derived from a similar upper continental crust-like parent. Trace element fingerprinting showed the samples to be derived from a parent similar to that of the paleosols; primarily atmospheric dust with some volcanic contributions. These findings provide additional evidence that trade wind vectors for dust transport were present during Pleistocene glacial climate conditions. Weathering indicators reveal the submarine clay samples to be somewhat less weathered than paleosols of similar age and comparable periods of exposure. Like the paleosols, the submarine clays underwent an initial period of rapid subaerial weathering which suggests warm humid climate conditions during glacial low sea level periods. However, the submarine clays did not experience extended periods of diagenesis, which may explain the somewhat lower degree of weathering. Evidence of inputs from the volcanic platform to the paleosols was limited, but comparisons with shallow volcanic rock and highly weathered volcanic residual known as the Primary Red Clay showed some similarities, suggesting that in-situ chemical weathering of the volcanic platform could produce a laterite with some characteristics similar to the Bermuda paleosols. Geochemical analysis of volcanic sands collected at Whalebone Bay showed the igneous fragments to be a result of mechanical weathering and sorting of heavy refractory minerals and we interpret these sediments to be best described as a beach placer deposit. These materials are enriched in insoluble trace elements and REE, and their contribution to the paleosols is limited
Thesis (MS) — Boston College, 2020
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences

Ces travaux de thèse portent sur l’étude des interactions du dioxyde de soufre (SO2) gazeux avec des poussières volcaniques islandaises. Ils intègrent cinq échantillons naturels de poussières volcaniques: Hagavatn, Mýrdalssandur, Maelifellssandur, Dyngjusandur and Eyjafjallajökull. Les interactions hétérogènes entre SO2 et les poussières volcaniques sont abordées avec plusieurs techniques expérimentales complémentaires. Les profils temporels associés à la capture de SO2, caractérisés par les coefficients de capture en régime stationnaire ont été renseignés expérimentalement. Ces paramètres sont des données d’importance pour les modèles atmosphériques. Des mécanismes réactionnels décrivant la formation des espèces de surface résultant de l’interaction de SO2 avec la surface des poussières sont proposés. Une nouvelle méthode analytique permettant l’extraction et la quantification d’espèces soufrées de surface a été développée et validée. Cette méthode est à présent disponible tant pour l’étude de processus hétérogènes en laboratoire que pour la caractérisation d’échantillons de terrain. Il a été mis en évidence que l’interaction de SO2 avec les poussières volcaniques est un processus de long terme. Les produits formés en surface sont stables et influencent les propriétés des particules minérales. Il a été démontré expérimentalement que l’humidité relative présente une influence marquée sur la capture et la transformation de SO2. La composition de surface des particules minérales est aussi un élément clé, particulièrement pour des humidités relatives inférieures à 30%. Enfin, ces travaux montrent l’importance d’avoir recours à des échantillons minéraux naturels pour assurer une bonne représentativité des études portant sur les processus atmosphériques hétérogènes impliquant des particules minérales
This thesis investigates the interactions of sulfur dioxide (SO2) gas with Icelandic Volcanic Dusts. Five natural volcanic dust samples were used for the study: Hagavatn, Mýrdalssandur, Maelifellssandur, Dyngjusandur and Eyjafjallajökull. The heterogeneous interactions of gas-phase SO2 with volcanic dusts are investigated using a number of complimentary techniques. Temporal profiles of SO2 uptake and, more precisely, the steady state uptake coefficients have been determined experimentally. These are important kinetic parameters that can be implemented in models. Mechanisms of formation of various surface species resulting from the interactions of SO2 with the surface of dusts are proposed. A new method for quantification of surface sulphur species has been developed and validated. This method can now be used both for further laboratory investigations and in field measurements. It is evidenced that the interactions of SO2 gas with the volcanic dust is a long continuous process. The products formed on the surface are stable and definitely influence the mineral particle properties. It is evidenced that the interactions of SO2 gas and volcanic particles are highly influenced by humidity and by UV light. The influence of surface composition also plays an important role especially at levels of humidity equal or lower than 30% RH. This work emphasizes the importance of using relevant natural dust samples in order to study the heterogeneous atmospheric phenomena involving natural solid particles

Les aérosols constituent une source importante de macro- et micronutriments pour l’océan hauturier. Cependant, uniquement les nutriments dissous sont considérés comme biodisponibles, c’est-à-dire assimilables par le phytoplancton. Ainsi, la quantification de leur solubilité se révèle primordiale pour (i) estimer l’influence d’un dépôt d’aérosols sur le phytoplancton, et (ii) boucler les cycles biogéochimiques de ces éléments. Dans le cadre de cette thèse, nous avons établi des gammes de solubilité de deux types d’aérosols (désertique ou volcanique) selon le mode de dépôt (sec et humide), en intégrant la variabilité en fonction de l’origine des aérosols. Ainsi, le macronutriment silicium issu des poussières désertiques est plus soluble comparé aux cendres volcaniques (jusqu’à 0.7 % contre 0.2 %), notamment via la dissolution du quartz. Le micronutriment fer se dissout majoritairement dans l’eau de pluie lors d’un dépôt humide des aérosols à l’océan via la dissolution d’aluminosilicates, avec une solubilité généralement inférieure à 0.14 % et 0.02 %, dans l’eau de pluie et eau de mer respectivement, et ce indépendamment du type d’aérosol. L’ensemble de ces résultats permet ainsi une révision des flux de nutriments atmosphériques à l’océan de surface qui pourra être in fine intégrée dans les estimations globales de modélisation biogéochimique. La réponse biologique suite à un apport de nutriments par voie atmosphérique a été déterminée dans l’Océan Indien Austral et les nutriments ont majoritairement profité à la communauté de diatomées, notamment au niveau du plateau de Kerguelen
Aerosols are an important source of macro- and micronutrients for the open ocean. However, only dissolved nutrients are considered bioavailable, i.e. assimilable by phytoplankton. Thus, the quantification of their solubility is essential to (i) estimate the influence of aerosol deposition on phytoplankton, and (ii) closing the biogeochemical cycles of these elements. We thus established the solubility ranges of two types of aerosols (desert or volcanic) according to the deposition mode (dry and wet), by integrating the variability depending on the aerosol origin. Thus, the macronutrient silicon found in desert dust is more soluble compared to volcanic ash (up to 0.7 % against 0.2 %), in particular via the dissolution of quartz. The micronutrient iron dissolves mainly in rainwater during wet deposition of aerosols in the ocean via the dissolution of aluminosilicates, with solubilities generally below 0.14% and 0.02%, in rainwater and seawater respectively, regardless of the type of aerosol. Thus, these results allow a re-estimation of atmospheric nutrients fluxes to the surface ocean which could ultimately be integrated into global biogeochemical models. Finally; the biological response to an atmospheric nutrient input has been determined in the Southern Indian Ocean and the nutrients have mainly benefited the diatom community, especially at the Kerguelen plateau

Les travaux de cette thèse reposent sur l’étude des processus hétérogènes à la surface desparticules minérales en présence d’irradiation UV-A. Nous savons que les poussièresminérales contiennent des oxydes métalliques pouvant absorber la radiation solaire et ainsiactiver une chimie très différente de celle observée à l’obscurité. Un réacteur à écoulementd’aérosols a été utilisé pour étudier les interactions des gaz (SO2, NO2 et O3) avec devéritables poussières minérales, évitant ainsi les artéfacts de mesure liés à la naturemacroscopique des films comme dans les études précédentes.La mise en suspension des poussières minérales a permis d’observer une formation inattenduede nouvelles particules ultrafines en présence de SO2. Le mécanisme proposé pour expliquerce phénomène de nucléation suggère une désorption de radicaux OH photoproduits à lasurface des minéraux vers la phase gazeuse. Ce mécanisme a pu être corroboré par descampagnes de mesure en atmosphère réelle. Nous avons étudié la chimie des échantillons de réelles cendres volcaniques issus de la dernière éruption du volcan Eyjafjallajökull en Islande (2010). Ceci nous a permis d’élaborerdes cinétiques de capture du SO2 sur des films macroscopiques de cendres aboutissant à descoefficients de capture de l’ordre de 10-7. Ces cinétiques couplées à des analyses chimiquesont permis de proposer un mécanisme réactionnel expliquant la formation de sulfate de fer àla surface des cendres. Finalement, nous avons étudié les interactions photochimiques de O3 et NO2 sur les poussièresminérales dans le réacteur à écoulement mettant en évidence un bon accord avec des étudesantérieures sur des surfaces macroscopiques
The objective of this work is to study the heterogeneous processes of mineral dust surfacesunder UV-A radiation. It is know that mineral dust containing metal oxides which can absorbsolar radiation and therefore activate a different chemistry compared to that observed in thedark. In order to avoid measurement artifacts related to the nature of macroscopic films, anaerosol flow tube was developed during this work and applied to study the interactions ofSO2, NO2 and O3 with real mineral dust.An unexpected formation of new particles in the presence of SO2 was observed. In order toexplain this phenomenon, we suggest the desorption of OH radicals from the mineral dustsurface to the gas phase. This mechanism has also been supported by field campaigns.Using real samples of volcanic ash from the last eruption of Eyjafjallajökull in Iceland (2010)allowed us study capture of SO2 on macroscopic ashes films with uptake coefficient around10-7. Associated kinetic experiments combined with chemical analysis allowed us to propose areaction mechanism explaining the formation of iron sulfate on the surface of ashes.Finally, we investigated the photochemical interactions of O3 and NO2 with minerals dustaerosols in the flow tube reactor showing a good agreement with previous data obtained onmacroscopic surfaces

Occupational exposure to dust generated by quarrying siliceous rocks (i.e. sandstone, coal) is a well documented respiratory hazard. Hazard of volcanic ash inhalation is also routinely studied (although less well understood), but the specific respiratory hazard of quarried volcanic deposits is entirely under-researched and is the focus of this study. The two main factors potentially implicated in respiratory toxicity of volcanic quarry dust are: i) crystalline silica content implicated in silicosis and lung cancer; and ii) iron-catalysed hydroxyl radical generation, implicated in inflammation and carcinogenesis. Twelve sites (in New Zealand, Montserrat and Greece), quarrying a range of volcanic deposits, were investigated and compared with volcanic ash samples (to test suitability as an analogue) and dust from non-volcanic quarries (greywacke and sandstone) in an investigation of the physicochemical characteristics which may influence particle surface reactivity. Samples of deposited dust (<1mm size fraction) were collected and 11 of these separated to ≤10μm for further analyses. Compositional analyses (XRF) showed the samples spanned the range of magmatic compositions from mafic to felsic (44-76 wt.% SiO2). The finest material was generated by drilling lava flows (8.3-27.5 cu.vol% <10 μm diameter particles in <1mm fraction), however, several other sample types (i.e. dust on processor) contained high levels of respirable material, akin to volcanic ash from equivalent eruption settings. SEM analyses confirmed particles to be blocky and angular, having aspect ratios between 0.59-0.70 (<10μm fraction). Crystalline silica content was highest (up to 28 wt. %) in dusts from intermediate and felsic quarries where lava domes (or collapse deposits) are mined. Similar levels were observed for dome-collapse ash and greywacke quarry dusts; however, the sandstone quarry dust was 99 wt.% crystalline silica. Hydroxyl radical generation was lower for quarried volcanic samples than for either volcanic ash or sandstone (significant to p≤0.01 for mafic ash/quarry dust). Haemolysis (erythrocyte membrane rupture, an indicator of quartz reactivity) was exhibited by six samples from three quarries, and comparable to the DQ12 quartz positive standard, when adjusted for surface area. These findings may be influenced by the presence of clays, however, as haemolytic samples included those with little crystalline silica. Airborne dust levels (both role-specific and ambient) were measured in the quarries and were mostly within international exposure limits, however, interpretations were limited by the duration of measurements so further work is required. Some workers’ shifts were longer than 8 hours, and workers on Montserrat may also be simultaneously exposed to volcanic ashfall, which should be considered with respect to adherence to regulations in those quarries. Mitigation measures were variable and workers would benefit from better awareness regarding use of non-mandatory respiratory protection. Volcanic quarries pose a hazard distinct from volcanic ash and from non-volcanic quarries. Overall, hazard may be lower than for quarrying other rock types, but further research is needed to better constrain the potential hazards. Until then, a precautionary approach might be taken in quarries where respirable dust levels are high and deposits may contain crystalline silica or iron.

This study utilizes major-, trace- and rare earth elements, as well as radiogenic isotopes (Rb-Sr, Sm-Nd, Pb), in bulk sediment, extracted glass shards, and discrete ash layers, at Ocean Drilling Program Site 1149 (Izu-Bonin Arc), Deep Sea Drilling Project Site 52 (Mariana Arc), and Integrated Ocean Drilling Program Sites C0011 and C0012 (Nankai Trough) in order to characterize and quantify the abundance of dispersed ash, rather than discrete ash layers, in sediments from the Northwest Pacific Ocean. Combination of the geochemical methods with multivariate statistical techniques, such as Q-mode Factor Analysis and multiple linear regressions, allows for differentiation of unique chemistries of the dispersed ash, and the terrigenous components. Therefore, we can document sources that change through time and space. At Site 1149 the bulk sediment is a mixture of two dust and two dispersed ash sources. The two dust sources show contrasting accumulation patterns changing over at a tectonically and climactically active time in Earth's past (~22 Ma) and yield a more complete history of Asian aridity than has been previously considered. We interpret the source of the ashes as basalt from the Izu-Bonin Front Arc (IBFA) and rhyolite from the Honshu Arc (HR). Comparison of the dispersed ash component to the discrete ash layers suggests that eruption frequency, rather than eruption size, drives the dispersed ash record. In contrast, at Site 52 Chinese Loess, IBFA, dispersed boninite from the Izu-Bonin arc, and a dispersed felsic ash of unknown origin are the sources. Interestingly, there are no boninite layers, yet boninite is dispersed within the sediment. Changes in the volcanic and eolian inputs through time indicate strong arc- and climate-related controls. The bulk sediment at Site C0011 is characterized by eolian dust, HR, and a dacite of unknown origin. Site C0012 is comprised of eolian dust, a dacite of unknown origin, as well as dacite and andesite from the Izu-Bonin Arc. Analysis of the total ash record at these two sites provides insight into subduction zone mass balance and water budgets as well as information about the changes in physical properties that result from the alteration of volcanic ash.

Η περιοχή Κω – Νισύρου βρίσκεται στο ανατολικότερο άκρο του ενεργού ηφαιστειακού τόξου του νοτίου Αιγαίου, Τεταρτογενούς ηλικίας και περιλαμβάνει τα νησιά Κω και Νίσυρο και τις νησίδες του Γυαλιού, της Στρογγύλης, της Παχειάς και της Πυργούσας. Η ηφαιστειακή δραστηριότητα στη Κω χαρακτηρίζεται από Άνω – Μειοκαινικές ιγκνιμβριτικές (πυρομβριτικές) αποθέσεις και από Πλειοκαινικά – Πλειστοκαινικά ηφαιστειακά προϊόντα όπως τους ηφαιστειακούς δόμους, την πυροκλαστική ακολουθία της Κεφάλου, τους υδρομαγματικούς τόφφους και τον σε μεγάλη έκταση πυροκλαστικό σχηματισμό «τόφφο της Κω» (Kos Plateau Tuff) αποθέσεις του οποίου εντοπίζονται και στα νησιά της Καλύμνου, της Ψερίμου και της Τήλου. Η Νίσυρος είναι ένα στρωματοηφαίστειο δομημένο από Πλειοκαινικά ηφαιστειακά προϊόντα που αποτελούνται κυρίως από ανδεσίτες και βασαλτικούς ανδεσίτες πάνω στους οποίους αποτέθηκαν ασβεσταλκαλικά ηφαιστειακά προϊόντα δακιτικής – ρυοδακιτικής σύστασης με την μορφή πυροκλαστικών αποθέσεων, ροών λάβας και δόμων λάβας. Οι νησίδες του Γυαλιού, της Στρογγύλης, της Παχειάς και της Πυργούσας αποτελούνται από Πλειοκαινικούς δόμους ρυολιθικής (Γυαλί), ανδεσιτικής (Στρογγύλη) και δακιτικής σύστασης (Παχειά και Πυργούσα) οι οποίοι φιλοξενούν πυροκλαστικές αποθέσεις της ανώτερης κίσσηρης του Γυαλιού (Στρογγύλη) και ενότητες του τόφφου της Κω (ΚΡΤ) και της Παναγιάς Κυράς (Παχειά και Πυργούσα). Στη παρούσα διδακτορική διατριβή στόχος είναι η πετρογραφική, ορυκτοχημική και γεωχημική μελέτη των ηφαιστειακών προϊόντων της ευρύτερης περιοχής Κω-Νισύρου και η αποτύπωση ηφαιστειακών δομών και μορφολογικών στοιχείων. Σκοπός είναι η κατανόηση της ηφαιστειακής εξέλιξης με την εξαγωγή συμπερασμάτων που αφορούν τη συγγενετική σχέση των μαγματικών προϊόντων, φαινόμενα μίξης, τους μαγματικούς θαλάμους και την επιφανειακή έκφραση αυτών (καλδέρες). Για το σκοπό αυτό μελετήθηκε η γεωχημική συγγενετική σχέση του τόφφου της Κω (Kos Plateau Tuff) στην Κω – Κάλυμνο – Τήλο και η γεωχημική διαφοροποίηση των πιο βίαιων και εκρηκτικών μονάδων D και E του ιγκνιμβρίτη της Κω επιβεβαιώνοντας τη στρωματογραφική συσχέτιση των αποθέσεων αυτών όπως έχει παρουσιαστεί από δεδομένα κυρίως φυσικής ηφαιστειολογίας. Από την πετροχημική μελέτη της περιοχής Κω – Νισύρου ως ένα ενιαίο «ηφαιστειακό σύμπλεγμα» προκύπτει ότι η ηφαιστειότητα της περιοχής διαχωρίζεται σε Μειοκαινική με προϊόντα όπως ο μονζονίτης και οι Μειοκαινικοί ιγκνιμβρίτες της Κω και σε Πλειο – Πλειοστοκαινική με ηφαιστειακά προϊόντα όπως οι δόμοι και τα πυροκλαστικά από την Κω, το Γυαλί και την Νίσυρο όπου διαφαίνεται η συγγενετική μαγματική σχέση των πετρωμάτων αυτών. Από τη μέθοδο της Συμβολομετρίας «Nomarski» προκύπτει ότι φαινόμενα μαγματικής μίξης/ανάδευσης είναι αναμφισβήτητα και παρέχουν αποδείξεις ότι τα φαινόμενα αυτά ήταν ενεργά καθ’ όλη την διάρκεια της εξέλιξης του ηφαιστείου της Νισύρου. Με την χρήση υπαίθριων παρατηρήσεων και τηλεπισκοπικών μεθόδων εντοπίστηκαν μορφές καλδερών στην ευρύτερη περιοχή Κω – Νισύρου οι οποίες χαρακτηρίσθηκαν και ταξινομήθηκαν σύμφωνα με νέες αντιλήψεις επί της ηφαιστειακής εξέλιξης. Στη συνέχεια μελετήθηκαν οι ηφαιστειακές δομές του ηφαιστείου της Νισύρου με την χρήση της Τηλεπισκόπησης μέσω της φωτοερμηνείας από δορυφορικές εικόνες και ψηφιακά υψομετρικά μοντέλα εδάφους και με την χρήση της γεωμορφομετρικής ανάλυσης συνδυάζοντας γεωμορφο-τεκτονικά χαρακτηριστικά του ηφαιστείου της Νισύρου όπως αυτά παρουσιάζονται από άλλους ερευνητές και νέες αντιλήψεις επί της ηφαιστειακής ανάπτυξη. Επίσης, παρουσιάζεται ένα μοντέλο πρωτο-καλδερικής, καλδερικής και μετα-καλδερικής εξέλιξης του ηφαιστείου της Νισύρου με βάση νέες αντιλήψεις επί της ηφαιστειακής εξέλιξης και σε σχέση με την στρωματογραφική του εξέλιξη. Τέλος, μελετήθηκαν οι υποηφαιστειακοί μαγματικοί θάλαμοι της περιοχής Κω – Νισύρου και τα φαινόμενα μίξης στο ηφαίστειο της Νισύρου με τη μέθοδο της Συμβολομετρίας «Nomarski» και την κατανομή των κύριων στοιχείων, ιχνοστοιχείων και σπανίων γαιών παρουσιάζοντας τον συγγενετικό χαρακτήρα αυτών των κέντρων, ορίζοντας την ευρύτερη ηφαιστειακή περιοχή Κω – Νισύρου ως ένα κύριο ηφαιστειακό κέντρο το οποίο χαρακτηρίζεται από ένα σύνθετο καλδερικό σύστημα. Η αειφορική διαχείριση του ηφαιστείου της Νισύρου είναι το μέσο με το οποίο μπορεί νε συνδυαστεί η ηφαιστειολογική εξέλιξη με την περιβαλλοντική διατήρηση και προβολή της ευρύτερης περιοχής ως γεωτόπου. Από την διερεύνηση της υφιστάμενης κατάστασης του νησιού διαπιστώνεται ότι ενώ η Νίσυρος διαθέτει ένα υψηλό περιβαλλοντικό, ενεργειακό, κοινωνικό, πολιτιστικό και οικονομικό δυναμικό, αυτό παραμένει ανεκμετάλλευτο και αναξιοποίητο λόγω της έλλειψης ενός ολοκληρωμένου σχεδίου αειφορικής διαχείρισης βάση του οποίου θα λαμβάνονται οι αποφάσεις ισότιμα, ισοδύναμα, ταυτόχρονα και αρμονικά. Με βάση την μελέτη των υδατικών πόρων, την καταγραφή του ενεργειακού δυναμικού από ανανεώσιμες πηγές ενέργειας, την διαχείριση του φυσικού και δομημένου περιβάλλοντος του ηφαιστείου της Νισύρου, την μελέτη των επιπτώσεων, θετικών και αρνητικών, της ύπαρξης εξορυκτικής βιομηχανίας στην περιοχή προτάθηκε ένα ολοκληρωμένο σχέδιο αειφόρου ανάπτυξης, προσαρμοσμένο στις απόψεις και τοποθετήσεις, της άμεσα ενδιαφερόμενης, τοπικής κοινωνίας. Από αυτό το ολοκληρωμένο σχέδιο προκύπτουν προτάσεις για την ολοκληρωμένη διαχείριση του ηφαιστείου της Νισύρου οι οποίες ικανοποιούν ισότιμα, ισοδύναμα, ταυτόχρονα και αρμονικά τις αρχές της αειφόρου ανάπτυξης στοχεύοντας στον επαναπροσανατολισμό της τοπικής οικονομίας, την διαχείριση του φυσικού και δομημένου περιβάλλοντος και την κοινωνική ανάπτυξη.
The Kos - Nisyros study area is located at the easternmost edge of the active Quaternary volcanic arc of the southern Aegean Sea and includes the islands of Kos and Nisyros and the islets of Gyali, Strongyli, Pachia and Pyrgoussa. The volcanic activity of Kos island is characterized by Upper – Miocene ignimbrite deposits and Pliocene - Pleistocene volcanic products such as volcanic domes, the Kefalos pyroclastic sequence of hydromagmatic tuffs and the large-scale pyroclastic formation Kos Plateau Tuff (KPT) deposits which is also found on the Kalymnos, Pserimos and Tilos islands. Nisyros is a calcalkaline stratovolcano which consists of Pliocene volcanic products such as andesite and basaltic andesite lavas that are overlain by pyroclastic deposits, lava flows and lava domes of dacitic – rhyodacitic composition. The islets of Gyali, Strongyli, Pachia and Pyrgoussa represent Pliocene lava domes of rhyolitic (Gyali), andesitic (Strogyli) and dacitic composition (Pachia and Pyrgoussa) On these domes, pyroclastic deposits of the Upper Pumice unit of Gyali (in Strogyli) and pyroclastic deposits of the Kos Plateau Tuff (KPT) and Panayia Kyra formation (in Pachia and Pyrgoussa) have been identified. In this thesis, the volcanic products of the Kos-Nisyros area are examined using mineral chemistry, geochemical and petrographical methods, while volcanic structures and morphological features are identified and mapped using remote sensing techniques. The aim of this thesis is to understand the volcanic evolution of the study area, by drawing conclusions regarding the consanguineous relationship of the magmatic products, magma mixing phenomena and the magma chamber system of the area, as well as, the surface expression of this magma chamber system in the form of caldera structures. For this purpose, in this thesis, it is investigated the consanguineous relationship of the Kos Tuff (Kos Plateau Tuff) found on Kos, Tilos and Kalymnos islands, as well as, the geochemical differentiation of the most violent and explosive ignimbrite units D and E of the Kos Tuff, confirming the stratigraphic correlation of these deposits as it was previously presented by physical volcanology data. The petrochemical study of the Kos - Nisyros area as a single "volcanic complex" reveals that the volcanism of the study area is divided into a Miocene and a Pliocene – Pleistocene activity. The Miocene activity is characterized by magmatic and volcanic products such as the monzonite of Kos and the Miocene ignimbrites of Kos and the Pliocene – Pleistocene volcanic activity consists of volcanic products such as lava domes and pyroclastic deposits from Kos, Gyali and Nisyros volcanoes where it is revealed the consanguineous magmatic relationship of these Pliocene – Pleistocene products. Using “Nomarski” interferometry method it is revealed that magma mixing/mingling phenomena are unquestionable for the magma chamber system of Nisyros and provide evidence that these phenomena were active throughout the volcanic evolution of Nisyros volcano. Field observations and remote sensing methods revealed caldera structures in the Kos - Nisyros area which are identified and classified according to new perceptions regarding the volcanic evolution. The volcanic structures of Nisyros volcano are examined using remote sensing methods such as satellite image and digital elevation models interpretation, as well as, the geomorphometric analysis of the Nisyros terrain in combination with geomorphotectonic features of the volcano as presented by other researchers and new perceptions on the volcanic evolution. It is also presented a model of proto-caldera, caldera and post-caldera evolution of Nisyros volcano based on new perceptions on the volcanic evolution in relation to the stratigraphic evolution. Finally, it is studied the subvolcanic magma chamber system of the Kos - Nisyros area, as well as, mixing phenomena in the volcano of Nisyros using the “Nomarski” interferometry method and the distribution of major, trace and rare earth elements revealing the consanguineous nature of these volcanic centers by providing the widest volcanic area of Kos - Nisyros as a major volcanic center characterized by a complex caldera system. Sustainable development of Nisyros volcano represents a management tool which combines the volcanic evolution with the environmental preservation and can promote volcanic regions as geotopes. The investigation of the present conditions of the island reveals, despite the fact that Nisyros is characterized by a strong environmental, energy, social, cultural and economic potential, it remains undeveloped and unexploited due to lack of an integrated sustainable development management plan, based on which, decisions should be equal, equivalent simultaneously and in harmony. Based on the study of the Nisyros water resources, the energy potential from renewable energy sources, the management of natural and urban environment of the volcano of Nisyros and the study of the positive and/or negative effects of the mining industry in Gyali volcanic islet it is proposed an integrated sustainable development according to the views and the perspectives of the local community. From this intergraded plan are generated recommendations for an integrated management of the volcano of Nisyros which satisfy equal, equivalent, simultaneously and in harmony the principles of sustainable development aiming to refocus the local economy, the management of natural and urban environment and the social development.

The Chinese meteorological records could be traced back to the oracle-bone inscriptions of the Shang Dynasty (c. 1600 bc–c. 1046 bc). For the past 3,000 years, continuous meteorological records are available in official histories, chronicles, local gazetteers, diaries, and other historical materials. Ever since the Qin Dynasty (221–207 bc), precipitation reports to the central government were officially organized; however, only those of the Qing Dynasty (1644–1912 ad) are extant, and they have been widely used to reconstruct precipitation variability.Modern meteorological knowledge began to be introduced in China during the late Ming Dynasty (1368–1644 ad). Modern meteorological observation possibly began in the 17th century, whereas continuous meteorological observation records go back to the mid-19th century.Previous researches have reconstructed the chronologies of the temperature change in China during the past 2,000 years, and the Medieval Warm Period and Little Ice Age were identified. With regard to precipitation variability, yearly charts of dryness/wetness in China for the past 500 years were produced. Several chronologies of dust storm, plum rain (Meiyu), and typhoon were also established. Large volcanic eruptions resulted in short scale abrupt cooling in China during the past 2,000 years. Climatic change was significantly related to the war occurrences and dynastic cycles in historical China.

The chapter describes the important role aerosols may have played in the past and are still playing in today’s climate, discussing aerosol distribution, aerosol–climate interaction, aerosol–radiation interaction, aerosol–cloud interaction and aerosol–surface interaction. The biogeochemical aspects are illustrated using the CLAW hypothesis about feedback of dimethylsulphide on climate, and the role that volatile organic carbons may play in shaping today’s climate. Aerosol sources and sinks are shown and it is clear that a substantial part today originates from humans. The aerosols may interact with radiation through scattering and absorption and with clouds to change the availability of cloud condensation nuclei. The basic physics of these interactions are described. The role of volcanic explosions and dust is elucidated and, particularly, the role of dust and associated iron in glacial–interglacial transitions is discussed.

Carbon compounds on the early Earth were not the simple mixture previously referred to as a “prebiotic soup.” Instead, there was a continuing input of organic material synthesized by geochemical and photochemical reactions in the volcanic crust and atmosphere; organic compounds were also being delivered during late accretion by the infall of interplanetary dust particles (IDPs), impacting comets, and asteroid-sized bodies. Compounds from both sources (terrestrial and not) then underwent chemical processing by volcanism, photochemistry, and mineral-driven oxidation–reduction reactions. Some of these processes were synthetic reactions that led to increasing complexity, but this was balanced by other processes such as hydrolysis and pyrolysis that degraded organic material into simpler compounds or tar-like polymers. Because the atmosphere contained no molecular oxygen, the organic compounds that formed were relatively stable as a dilute solution in the global ocean, but were also dissolved in freshwater hydrothermal pools in contact with mineral surfaces of volcanic land masses. In either case, a process was required by which the organic compounds could become sufficiently concentrated to undergo chemical reactions. Questions to be addressed: What are plausible sources of organic compounds? What is their composition and abundance? How would organic material be chemically processed on the early Earth? How can dilute organic solutes become sufficiently concentrated to undergo chemical reactions? Chapter 1 described how virtually all of the carbon now circulating in the biosphere as organic and inorganic compounds was delivered during accretion of planetesimals as the Earth formed, and it is reasonable to assume that Mars had a similar addition of carbon compounds and water after it cooled from primary accretion. On the Earth, organic substances delivered during primary accretion would have been destroyed by the heat of impacts and the moon-forming event, so the carbon compounds necessary for the origin of life were necessarily added after the Earth had cooled sufficiently for a global ocean to appear.

Until the lunar explorations began in earnest in the 1960s, the Barringer crater in Arizona was believed to be one of the few, if not the only, impact crater on earth. Before the moon landings, many scientists thought that lunar craters were volcanic in origin and that the moon might be covered in a layer of volcanic dust meters thick so that astronauts would sink up to their eyeballs when disembarking from their space capsules. A pleasant sense of relief greeted the news that the first unmanned lunar spacecraft did not disappear into the dust. For a century or more it was doubted that lunar craters were produced by impacts because it was assumed that such craters would seldom be circular. It seemed obvious that circular craters could only be produced by objects falling straight down, a rare situation, since meteorites are likely to approach from random directions, especially on the moon where there is no atmosphere to slow them down before impact. W. M. Smart in 1928 stated this explicitly: “Objections to lunar craters being caused by meteors is that the craters are round and there is no a priori reason why meteors should fall vertically and in no other direction.” He also shuddered at the notion that the impactors would have to be as large as asteroids to create the lunar basins. At about the same time, Thomas Chamberlin ruled out impacts on the moon because there was no evidence for an appropriate population of objects anywhere in the solar system that could have made the craters That was in 1928 when near-earth asteroids had not yet been found, and when little was known about the history of the moon or the formation of the solar system. Richard A. Proctor in 1896, however, had concluded that because so many meteors continued to fall to earth that the planet and the solar system were still forming. To him, this made more sense than to blame the formation of the planets on “the creative fiats of the Almighty.” There is merit to his point of view, because today’s bombardment merely represents a faint, ongoing manifestation of the process of accretion that assembled the planets in the first place.

This chapter describes how air is a complex natural gaseous system essential to support life on Earth. Air pollution comes from a wide variety of sources, which discharge of harmful substances into the atmosphere, causing adverse effects to humans and the environment. They can be natural or anthropogenic. Natural air pollution sources are multiple and include volcanic eruption, fire, ocean vapors, dust storms and fermentation of organic materials. However, the range and quantities of chemicals discharged into the atmosphere from industry, transport, agriculture, energy production, domestic heating, and many other human activities, have increased dramatically. Some pollutants are emitted directly into the atmosphere and are known as primary pollutants (NOx, SOx, particulate matter, etc.). Others are formed in the air as a result of chemical reactions with other pollutants and atmospheric gases; these are known as secondary pollutants like ozone. This chapter provides an overview on air pollution sources as well as the ways in which pollutants can affect human health and the environment.

Abstract Pollutants may enter the air from natural or synthetic sources. Air always carries natural pollutants such as pollens, spores, molds, yeast, fungi, and bacteria; and forest fires, windstorms, volcanic eruptions, and droughts cause smoke, dust, and other pollutants to enter the air. Yet all the pollution wrought by nature counts for little when compared with the effects of pollutants associated with human activity (112). The major sources of synthetic air pollutants include the burning of fossil fuels, particularly coal; emissions from smelters, steel plants, and other heavy manufacturing facilities; and emissions from mobile sources such as automobiles, trucks, and airplanes. The primary pollutants from these major sources are sulfur dioxide (S02), nitrogen dioxide (N02), carbon monoxide (CO), suspended particulates, ozone, hydrocarbons, acid aerosols of sulfates and nitrates, and heavy metals. Although emissions from chemical manufacturing may affect the area immediately surrounding the source, they do not have the same impact on regional air pollution as the aforementioned pollutants.

The stratospheric volcanic dust cloud resulting from the eruption of Mt. Pinatubo in June 1991 has adversely affected the retrieval of sea surface temperature from the upwelling infrared radiances (≈3.7,10.8, and 11.9 µm) measured by the Advanced Very High Resolution Radiometer onboard the NOAA polar orbiting satellites. Correction algorithms to restore the capability of sea surface temperature retrieval during such volcanic dust episodes have been developed by combining model simulations of the radiative effects of volcanic aerosols with shipboard and buoy measurements of sea surface temperature and the NOAA operational aerosol product. The operational implementation of the correction algorithms will be discussed, accompanied by examples of the restored sea surface temperature fields.

Results are reported for a technology program designed to determine the behavior of gas turbine engines when operating in particle-laden clouds. There are several ways that such clouds may be created, i.e., explosive volcanic eruption, sand storm, military conflict, etc. The response of several different engines, among them the Pratt & Whitney JT3D turbofan, the Pratt & Whitney J57 turbojet, a Pratt & Whitney engine of the JT9 vintage, and an engine of the General Electric CF6 vintage has been determined. The particular damage mode that will be dominant when an engine experiences a dust cloud depends upon the particular engine (the turbine inlet temperature at which the engine is operating when it encounters the dust cloud), the concentration of foreign material in the cloud, and the constituents of the foreign material (the respective melting temperature of the various constituents). Further, the rate at which engine damage will occur depends upon all of the factors given above and the damage is cumulative with continued exposure. An important part of the Calspan effort has been to identify environmental warning signs and to determine which of the engine parameters available for monitoring by the flight crew can provide an early indication of impending difficulty. On the basis of current knowledge, if one knows the location of a particle-laden cloud, then that region should be avoided. However, if the cloud location is unknown, which is generally the case, then it is important to know how to recognize when an encounter has occurred and to understand how to safely operate, which is another part of the Calspan effort.

Ground-based lidar measurements of free tropospheric aerosols and stratospheric aerosols have been made since 1982 at Tsukuba (36.1°N, 140.2°E) in Japan. The purposes of aerosol measurements are knowing aerosol variations related with pressure pattern and studying some transport mechanisms of aerosols which are originated from explosive volcanic eruptions, dust storms in China and fires such as the Kuwait’s oil wells.

Rotorcraft operations in arid environments can result in the ingestion of large quantities of dust particles into turboshaft engines, where they can melt and deposit on high pressure turbine nozzle guide vanes. This can result in reduced engine life-span and in worst case scenarios, in-flight engine failure. Predicting the extent and rate at which this damage occurs has proven difficult owing to the wide range of variables relating to the dust cloud, engine and most importantly, the properties of the particulate encountered. Whilst significant work has been carried out to model the particle deposition process for both volcanic ash and coal fly-ash, there is scarce similar work for the different types of mineral dusts rotorcraft encounter. In this contribution, we assess the suitability of two opposing numerical approaches for use in a generalised, reduced-order deposition model of individual mineral particles depositing on a vane. Both models are seen to be heavily reliant upon empirical inputs, be this the thermo-mechanical properties of the particles such as their yield strength, or currently unknown experimentally determined constants. An alternative approach is therefore proposed whereby the particle yield strength is correlated using existing relationships to the Vickers hardness of the grain, a property more amenable to empirical determination. The results obtained represent the current applicability limits of the two models based upon existing empirical data and thus highlight the need for further experimentation relating to both the thermo-mechanical properties and probabilities of adhesion for both individual mineral grains and mineral dust blends.

On June 15, 1991, Mt. Pinatubo in the Philippines explosively erupted, injecting large quantities of SO2 and dust particles directly into the stratosphere. The SO2 slowly reacted to form a concentrated and fairly thick layer of aerosol particles in the 15 to 32 km region of the stratosphere. When this layer was transported to latitudes at which a number of stratospheric lidars were operating, signals which had been dependent only on molecular scattering began to have a very large component due to Mie scattering from aerosols. Unlike Rayleigh scattering, the wavelength dependence of this Mie component is not well known.

This study explores the impact of air pollution on adverse birth outcomes. The study focuses on the effect of breathable particulate matter with diameter of 10 micrometers or less (PM10) on the likelihood of premature birth and low birth weight (LBW). The study exploits the fact that in 2011 the ashes and dust resulting from the eruption of the Puyehue volcano in Chile substantially increased exposure to PM10 in Montevideo, Uruguay. Using prenatal and birth data from the Perinatal Information System for 2010-2012, it is found that increases in quarterly averages of PM10 concentrations beyond 50 µg/m3 decrease birth weight and increase the likelihood of LBW and prematurity at increasing rates. The results also suggest that the effect of PM10 on birth weight works mainly through a higher likelihood of prematurity, rather than through intrauterine growth retardation. The effects increase with each trimester of pregnancy: exposure during the third trimester is the most dangerous.