6.2

Airborne particles can come from a variety of sources and contain variable chemical constituents. Some particles are formed by natural processes, such as volcanoes, erosion, sea spray, and forest fires, while other are formed by anthropogenic processes, such as industrial- and motor vehicle-related combustion, road-related wear, and mining. In general, larger particles (those greater than 2.5 μm) are formed by mechanical processes, while those less than 2.5 μm are formed by combustion processes. The chemical composition of particles is highly influenced by the source: for combustion-related particles, factors such as temperature of combustion, fuel type, and presence of oxygen or other gases can also have a large impact on PM composition. These differences can often be observed at a regional level, such as the greater sulphate-composition of PM in regions that burn coal for electricity production (which contains sulphur) versus regions that do not. Most countries maintain air monitoring networks, and studies based on the resulting data are the most common basis for epidemiology studies on the health effects of PM. Data from these monitoring stations can be used to evaluate the relationship between community-level exposure to ambient particles and health outcomes (i.e., morbidity or mortality from various causes). Respiratory and cardiovascular outcomes are the most commonly assessed, although studies have also considered other related specific outcomes such as diabetes and congenital heart disease. The data on particle characteristics is usually not very detailed and most often includes some combination of PM2.5, PM10, sulphate, and NO2. Other descriptors that are less commonly found include particle number (ultrafine particles), metal components of PM, local traffic intensity, and EC/OC. Measures of association are usually reported per 10 μg/m3 or interquartile range increase in pollutant concentration. As the exposure data are taken from regional monitoring stations, the measurements are not representative of an individual's exposure. Particle size is an important descriptor for understanding where in the human respiratory system the particles will deposit: as a general rule, smaller particles penetrate to deeper regions of the lungs. Initial studies on the health effects of particulate matter focused on mass of the particles, including either all particles (often termed total suspended particulate or TSP) or PM10 (all particles with an aerodynamic diameter less than 10 μm). More recently, studies have considered both PM10 and PM2.5, with the latter corresponding more directly to combustion-related processes. UFPs are a dominant source of particles in terms of PNC, yet are negligible in terms of mass. Very few epidemiology studies have measured the effect of UFPs on health; however, the numbers of studies on this topic are increasing. In addition to size, chemical composition is of importance when understanding the toxicity of particles. Some studies consider the composition of particles in addition to mass; however this is not common, in part due the cost and labour involved in such analyses.

Zona volcànica catalana

Esta excursión pretende ofrecer una visión esquemática y puntual de uno de los rasgos principales de la geología del noreste de la Península Ibénca, como es el vulcanismo neógeno-quaternario de la Zona Volcánica Catalana (ZVC). En concreto se plantea un recorrido, por el Parque Natural de la Zona Volcánica de la Garrotxa (PNZVG), que muestre los rasgos más significativos del vulcanismo reciente de la PenínsulaIbérica

Els volcans a l'aula i les aules de volcans

Article que es refereix a com estudiar els volcans a l' aula

Statistical evidences of cyclic changes in volcanic gas chemistry composition by inverse modelling

The identification of compositional changes in fumarolic gases of active and quiescent volcanoes is one of the most important targets in monitoring programs. From a general point of view, many systematic (often cyclic) and random processes control the chemistry of gas discharges, making difficult to produce a convincing mathematical-statistical modelling. Changes in the chemical composition of volcanic gases sampled at Vulcano Island (Aeolian Arc, Sicily, Italy) from eight different fumaroles located in the northern sector of the summit crater (La Fossa) have been analysed by considering their dependence from time in the period 2000-2007. Each intermediate chemical composition has been considered as potentially derived from the contribution of the two temporal extremes represented by the 2000 and 2007 samples, respectively, by using inverse modelling methodologies for compositional data. Data pertaining to fumaroles F5 and F27, located on the rim and in the inner part of La Fossa crater, respectively, have been used to achieve the proposed aim. The statistical approach has allowed us to highlight the presence of random and not random fluctuations, features useful to understand how the volcanic system works, opening new perspectives in sampling strategies and in the evaluation of the natural risk related to a quiescent volcano

Els volcans a l'aula i les aules de volcans

Article que es refereix a com estudiar els volcans a l' aula

Los Volcanes: un enfoque sistémico de un tema clásico

Si consideramos nuestro planeta como un conjunto de subsistemas interdependientes las relaciones que se establecen entre todos sus elementos definen un sistema complejo donde cualquiera de sus partes puede influir en la evolución del resto. En este escenario de interconexiones los volcanes asumen un papel muy importante

Dos nous afloraments volcànics a l'Alt Empordà (Girona)

Two unknown volcanic outcrops in the Alt Emporda (Girona) are described in this paper . We present their exact situation and a description of their occurrence and their mineralogical and petrological characteristics. Bothhave been classified as alkali-olivine basalts and they probably extruded during the Neogen period

Un nou volcà a la vall d'Hostoles

Descripció del volcà anomenat 'Palou' a 1Km. al Sud d' Amer

El campo volcánico catalán

Catalan volcanic field, in Iberian Peninsula Northeast, has been made during Neogene and Quaternary. It is made up Empordà, la Selva and la Garrotxa Zones, the best volcanic morphology is in the last one because is the most recent. In this paper we explain the volcanic rocks general characteristics, what eruption activity generate it and the final volcanic edifice morphology. Finally, we propose some crops to visit

L'aflorament volcànic del mas Ventós (el Port de la Selva, Alt Empordà)

Es descriu un aflorament volcànic localitzat a la rodalia del mas Ventós (el Port de la Selva), a la part central de la serra de Rodes, dins el Pirineu axial. Es tracta d’una xemeneia volcànica enclavada en granodiorites gneissificades. Els materials que la componen són basalts olivínics alcalins amb textura traquítica, bastant alterats, els quals queden colgats per un dipòsit col·luvial sense consolidar. Les dimensions de la xemeneia són difícils de determinar pel recobriment que presenta: supera els 70 m en direcció nord-nord-est a sud-sud-oest i és d’uns 35 m en la perpendicular a aquesta. Aquest aflorament va ser citat per Teixidor fa més d’ un segle, i no s’ha retrobat fins ara

Aportacions al coneixement del vulcanisme neogen de l'Alt Empordà: tres afloraments volcànics inèdits al terme municipal de Roses

En aquest treball es descriuen les característiques litològiques principals de tres afloraments volcànics inèdits que han estat localitzats al terme municipal de Roses. Es tracta de materials basàltics, similars als que s'associen a altres manifestacions efusives neògenes de la comarca de l'Alt Empordà

Els afloraments volcànics a les comarques gironines

Es descriuen els afloraments volcànics de les comarques gironines, que segons la seva edat es poden subdividir en: manifestacions eruptives paleozoiques i afloraments relacionats amb el vulcanisme de l'era cenozoica

Selenium cycling in volcanic environments: the role of soils as reactive interfaces

Selenium (Se) is an element with important health implications that is emitted in significant amounts from volcanoes. Attracted by the fertility of volcanic soils, around 10% of the world population lives within 100 km of an active volcano. Nevertheless, the behaviour of Se in volcanic environments is poorly understood. Therefore, the main aim of this thesis is to investigate the role of soils in the Se cycling in volcanic environments. Prior to the geochemical studies, precise and accurate methods for the determination of Se contents, speciation and isotopic signatures were developed. Afterwards, a combination of field studies and lab controlled experiments were performed with soils from two contrasting European volcanic settings: Mount Etna in Sicily (Italy) and Mount Teide in Tenerife (Spain). The results showed a strong link between Se behaviour and soil development, indicating that Se mobility in volcanic soils is controlled by sorption processes and soil mineralogy.

Naturaleza, paisaje y memoria: alturas y ciudades del Reino de Qutio en la experiencia viajera del siglo XVIII (Estudios)

A mediados del siglo XVIII las alturas de los Andes del Reino de Quito, al igual que sus centros urbanos, fueron visitadas por viajeros naturalistas y misioneros. Este artículo explora cómo algunos de esos viajeros percibieron, construyeron y recordaron desde dos puntos de vista distintos la naturaleza y el paisaje. Tras exponer las categorías y enfoques empleados, el artículo explora dos tipos de percepción y memoria de la naturaleza: el sobrenatural y el naturalista. Finalmente, se analiza el paisaje urbano en cuya construcción escrita se combinaron las antiguas ideas del orden colonial con la perspectiva de la prosperidad terrenal, correlato del interés por las ciencias aplicadas que animaba la exploración de las alturas nevadas y de los volcanes.

Insights into processes and deposits of hazardous vulcanian explosions at Soufrière Hills Volcano during 2008 and 2009 (Montserrat, West Indies)

During the Soufrière Hills eruption, vulcanian explosions have generally occurred 1) in episodic cycles; 2) isolated during pauses in extrusion, and 3) after major collapses of the dome. In a different eruptive context, significant vulcanian explosions occurred on 29 July 2008, 3 December 2008, and 3 January 2009. Deposits are pumiceous except for the 3 December event. We reconstructed the dispersal pattern of the deposits and their textural characteristics to evaluate erupted volume and vesicularity of the magma at fragmentation. We discuss the implications of these explosions in terms of eruptive processes and chronology, and the hazards posed by their sudden and often unheralded occurrence. We suggest that overpressurization of the conduit can develop over time-scales of months to weeks by a process of self-sealing of conduit walls and/or the cooling dome by silica polymorphs. This work provides new insights for understanding the generation of hazardous vulcanian explosions at andesitic volcanoes.