A hipóxia ocorre quando a demanda de oxigênio molecular necessário para gerar ATP é insuficiente. Os genes ativados por hipóxia compreendem o gene Hif-1a (Hipóxia-fator induzível 1a), Vegf-a (fator de crescimento endotelial vascular a), Arnt e Vhl (von Hippel-Lindau). Neste estudo foram utilizadas linhagens de camundongos geneticamente selecionados para alta (AIRmax) ou baixa (AIRmin) resposta inflamatória aguda (AIR). Foram realizados testes biológicos para caracterizar as reações inflamatórias produzidas por Biogel e TPA, bem como o tipo PAH cancerígeno. Testamos a expressão de mRNA de genes de hipóxia e caracterização de polimorfismo da região codificadora do Hif-1a no cromossomo 12. Camundongos AIRmax demonstraram uma maior reação inflamatória que os AIRmin para biogel e TPA enquanto o inverso foi observado com o DMBA. Os conjuntos de dados de fenótipos, expressão gênica e polimorfismo candidatam a região do cromossomo 12, que contém, entre outros, o gene Hif-1a, como participante da regulação da AIR. / Hypoxia occurs when the demand for molecular oxygen necessary to generate ATP is insufficient. Genes activated by hypoxia comprise the Hif-1a gene (Hypoxia-Inducible Factor 1a), Vegf-a (Vascular Endothelial Growth Factor a), Arnt and Vhl (von Hippel-Lindau). In this study we used lines of mice genetically selected for high (AIRmax) or low (AIRmin) acute inflammatory response (AIR). We conducted biological tests to characterize the inflammatory reactions produced by Biogel and TPA, and the type PAH carcinogen. We tested the mRNA expression of genes of hypoxia and characterization of polymorphism of the coding region of Hif-1a gene on chromosome 12. We found that the mice AIRmax had greater intensity of the inflammatory reaction that AIRmin to biogel and TPA while the reverse was observed with the DMBA. The data sets of phenotypes, gene expression and polymorphism applying the region of chromosome 12 that contains, among others, the gene Hif-1a, as part of the regulation of AIR.

Made available in DSpace on 2017-07-24T19:38:07Z (GMT). No. of bitstreams: 1 FABIOMALINOSKI.pdf: 1967487 bytes, checksum: a8c89b1d9584a90151895d2cdcb1b6d6 (MD5) Previous issue date: 2012-05-07 / This work presents the compilation and analysis of several analytical data obtained in the characterization of shale fine and lime schist, two abundant residuals in the Petrosix process. In order to ensure better representativeness of results, samples of lime schist extracted from complete vertical cuts of the layer were analyzed, and indirect analysis procedure was adopted for the shale fine residual, which basically consists of the characterization of samples obtained from complete vertical sections of superior and inferior shale layers in the Mine Rio das Pedras pit, within the Irati formation, in São Mateus do Sul PR. Analytical results obtained though Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) revealed that the lime schist layer presents mass predominance of the elements: Calcium, Silicon and Magnesium, and that this predominance, as indicated by the X-Ray Diffraction analysis (XRD), is due to the significant presence of Dolomite (CaMg(CO3)2) and Quartz (SiO2), and that the great reduction of mass after the Fixed Mineral Residue analysis is mainly related to CO2 elimination, in the dolomite thermal decomposition process. In the shale fine characterization, analytical results obtained through ICP-AES demonstrated that superior and inferior shale layers presented mass predominance of the elements silicon and iron, and this predominance, as indicated by the XRD is mainly due to the presence of Quartz (SiO2) and Pyrite (FeS2), and that the mass reduction after Fixed Mineral Residue analysis is related to the elimination of organic matter and the Pyrite thermal decomposition, with the former as the most relevant factor. Shale layers also presented Albite, Microcline and Muscovite, particle density similar values, crude oil with chromatographic profile of relative elevation in mass between the Heptane and Undecane peaks, uniform distribution between Dodecane and Octacosane peaks, decreasing distribution between the Nonacosane and C72 peaks, with normal spare paraffins in an unresolved complex organic mixture. These results indicate that the fine shale residue has a composition that oscillates between the narrow parameters of superior and inferior shale. / Neste trabalho apresentamos a compilação e a análise de diversos dados analíticos obtidos na caracterização do Finos de Xisto e do Calcário de Xisto, dois resíduos abundantes do processo Petrosix. Para garantir maior representatividade de resultados, analisam s amostras de Calcário de Xisto extraídas de cortes verticais completos da camada, e adotamos um procedimento de análise indireta para o resíduo denominado Finos de Xisto, que consiste basicamente na caracterização de amostras obtidas de secções verticais completas das camadas de Xisto Superior e Xisto Inferior das cavas da Mina Rio das Pedras, dentro da Formação Irati, na cidade de São Mateus do Sul – PR. Os resultados analíticos obtidos por Espectrometria de Emissão Atômica por Plasma Indutivamente Acoplado (EEA-PIA) demonstraram que a camada denominada Calcário de Xisto apresenta predomínio mássico dos elementos: Cálcio, Silício e Magnésio, que este predomínio, conforme indicado na análise de Difração de Raios X (DRX), deve-se a presença expressiva de Dolomita (CaMg(CO3)2) e Quartzo (SiO2), e que a grande redução de massa após a análise de Resíduos Minerais Fixos está relacionada principalmente a eliminação de CO2, no processo de decomposição térmica da Dolomita. Na caracterização do Finos de Xisto, os resultados analíticos obtidos por EEA-PIA demonstraram que as camadas de Xisto Superior e Xisto Inferior apresentam predomínio mássico dos elementos Silício e Ferro, que este predomínio, conforme indicado na análise de DRX, deve-se em grande parte a presença de Quartzo (SiO2) e Pirita (FeS2), que a redução de massa após a análise de Resíduos Minerais Fixos está relacionada a eliminação da matéria orgânica e a decomposição térmica da Pirita, sendo o primeiro fator muito mais relevante. As camadas de Xisto também apresentaram Albita, Microclínio e Muscovita, valores semelhantes de massa específica de partículas, óleo bruto com perfil cromatográfico de relativa elevação em massa entre os picos de Heptano e Undecano, distribuição uniforme entre os picos de Dodecano e Octacosano, distribuição decrescente entre os picos de Nonacosano e C72, com normais parafinas sobressalentes numa mistura orgânica complexa não resolvida. Estes resultados indicam que o resíduo Finos de Xisto tem composição oscilante entre os estreitos parâmetros do Xisto Superior e do Xisto Inferior.

This dissertation examines the relationship between resource nationalism and energy integration, and uses Bolivia and Brazil as a test case. Essentially, does resource nationalism affect energy integration? The findings nest within more expansive questions on international political economy and export-driven models of development. Why do populist regimes, historically operating under an economic nationalist cum protectionist paradigm, simultaneously pursue policies of economic integration? What is the relationship between resource nationalists and open markets, especially in the hydrocarbons sector? What is the relationship between populists, who are typically resource nationalists, and their decision to choose policies of energy integration? The most common responses to the above are that resource nationalists pursue protectionist policies in the hydrocarbon sector. This dissertation demonstrates that once in power, resource nationalists do not always pursue protectionist policies in the hydrocarbon sector, but instead rely on market forces. Another common response is that populists pursue policies of resource nationalism in the hydrocarbon sector. This dissertation demonstrates that populists do not always pursue policies of resource nationalism in the hydrocarbon sector, but instead choose policies of integration. Policies of integration are compelled by market forces, and at times ironically provide the foundation for resource nationalism to later flourish. This dissertation develops a case-study of Bolivia and Brazil to assess the relationship between resource nationalism and energy integration. The case is selected based on each country having energy resources or derivative products for exploitation and use, an energy trade relationship between the countries, the presence of government-run natural resource firms in each country, and a specific period where resource nationalism is present. Bolivia and Brazil are important for this study because of their proximity, particularly where the supply of natural gas is concerned. Proximity is of great importance as natural gas infrastructure is concomitant with energy integration, particularly supply.

A new depth-based method of seismic imaging is used to provide insights into the 3D structural geometry of faults, and to facilitate a detailed structural interpretation of the Penola Trough, Otway Basin, South Australia. The structural interpretation is used to assess fault kinematics through geological time and to evaluate across-fault juxtaposition, shale gouge and fault reactivation potential for three selected traps (Zema, Pyrus and Ladbroke Grove) thus providing a full and systematic assessment of fault seal risk for the area. Paper 1 demonstrates how a depth-conversion method was applied to two-way time seismic data in order to redisplay the seismic in a form more closely representative of true depth, here termed ‘pseudo-depth’. Some apparently listric faults in two-way time are demonstrated to be planar and easily distinguishable from genuine listric faults on pseudo-depth sections. The insights into fault geometry provided by pseudo-depth sections have had a significant impact on the new structural interpretation of the area. Paper 2 presents the new 3D structural interpretation of the area. The geometry of faulting is complex and reflects variable stress regimes throughout structural development and the strong influence of pre-existing basement fabrics. Some basement-rooted faults show evidence of continual reactivation throughout their structural history up to very recent times. Structural analysis of all the live and breached traps of the area demonstrate that traps associated with a basement rooted bounding fault host breached or partially breached accumulations, whereas non-basement rooted faults are associated with live hydrocarbon columns. Papers 3 and 4 demonstrate that for all the traps analysed (Zema, Pyrus and Ladbroke Grove), initial in-place seal integrity was good. The initial seal integrity was provided by a combination of both favourable across fault juxtaposition (Ladbroke Grove) and/or sufficiently well developed shale gouge over potential leaky sand on sand juxtaposition windows to retain significant hydrocarbon columns (Zema, Pyrus). The palaeocolumns observed at Zema and Pyrus indicate that there has been subsequent post-charge breach of seal integrity of these traps while Ladbroke Grove retains a live hydrocarbon column. Evidence of open, permeable fracture networks within the Zema Fault Zone suggest that it is likely to have recently reactivated, thus breaching the original hydrocarbon column. Analysis of the in-situ stress tensor and fault geometry demonstrates that most of the bounding faults to the selected traps are at or near optimal orientations for reactivation in the in-situ stress tensor. The main exception being the Ladbroke Grove Fault which has a NW-SE trending segment (associated with a relatively high risk of fault reactivation and possible leakage at the surface) and an E-W trending segment (associated with a relatively low risk of fault reactivation and a present day live column). The free water level of the Ladbroke Grove accumulation coincides with this change in fault orientation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339545 / Thesis (Ph.D.) - University of Adelaide, Australian School of Petroleum, 2008

Τα τελευταία χρόνια, η φασματοσκοπία πλάσματος επαγόμενο από λέιζερ (LIBS) έχει προσελκύσει μεγάλο ερευνητικό ενδιαφέρον καθώς αποτελεί μία πειραματικά απλή και αποτελεσματική τεχνική, η οποία παρέχει τη δυνατότητα λήψης μετρήσεων για απευθείας ποιοτική και ποσοτική στοιχειακή ανάλυση. Η τεχνική LIBS στηρίζεται στη δημιουργία σπινθήρα/πλάσματος μέσω ισχυρά εστιασμένης δέσμης λέιζερ στην επιφάνεια ή στο εσωτερικό του δείγματος, στην ακόλουθη διέγερση και ατομοποίηση των στοιχείων του στόχου και στην τελική καταγραφή και φασματοσκοπική ανάλυση της εκπεμπόμενης ακτινοβολίας του πλάσματος. Λόγω των πολλών πλεονεκτημάτων που συγκεντρώνει η τεχνική, το LIBS έχει προταθεί για πληθώρα πρακτικών, τεχνικών και τεχνολογικών εφαρμογών σε ένα ευρύ φάσμα ερευνητικών πεδίων. Από την άλλη μεριά, στον τομέα της καύσης, η ποσότητα καυσίμου σε ένα εύφλεκτο μίγμα είναι αντικείμενο μείζονος σημασίας καθώς επηρεάζει σημαντικά την απόδοση των χημικών διεργασιών και την παραγωγή και εκπομπή ρύπων. Επομένως, δημιουργείται η ανάγκη ανάπτυξης μίας γρήγορης και μη παρεμβατικής διαγνωστικής τεχνικής για τη μέτρηση της περιεκτικότητας του καυσίμου τοπικά στη φλόγα με καλή τόσο χωρική όσο και χρονική ανάλυση. Στα πλαίσια της παρούσας διδακτορικής διατριβής, η τεχνική LIBS η οποία συγκεντρώνει όλα αυτά τα πλεονεκτήματα χρησιμοποιήθηκε για αυτό το σκοπό. Κατά τη διάρκεια των πειραμάτων, χρησιμοποιήθηκαν πηγές λέιζερ διάρκειας παλμών ns και fs, ενώ τα συστήματα καύσης που μελετήθηκαν ήταν φλόγες υδρογονανθράκων-αέρα, στρωτής και τυρβώδους ροής, απλής και συνθετότερης γεωμετρίας. Από τα LIBS φάσματα φλογών διαφορετικής σύστασης, προέκυψε λοιπόν ότι υπάρχει μία ισχυρή εξάρτηση μεταξύ των εντάσεων διαφόρων φασματικών γραμμών με το λόγο ισοδυναμίας. Επομένως, μέσω της συσχέτισης αυτής μπορεί να επιτευχθεί με μεγάλη ακρίβεια τόσο η μέτρηση της περιεκτικότητα σε καύσιμο φλογών άγνωστης σύστασης όπως επίσης και η μέτρηση της κατανομής του καυσίμου τοπικά μέσα σε όλη την έκταση της φλόγας παρέχοντας σημαντικές πληροφορίες για την δομή της. Τέλος, εφαρμόστηκε μία παραπλήσια διαγνωστική τεχνική, κατά την οποία η διηλεκτρική κατάρρευση του μέσου ήταν αποτέλεσμα ενός ηλεκτρικού σπινθήρα: electrical Spark Induced Breakdown Spectroscopy (SIBS) όπου και πραγματοποιήθηκε η συγκριτική μελέτη της ακτινοβολίας του πλάσματος επαγόμενο μέσω οπτικής και ηλεκτρικής διέγερσης. / Laser induced breakdown spectroscopy (LIBS) has attracted a lot of scientific interest during the last two decades as it is generally considered to be an experimentally simple and efficient laser-based technique which can perform real-time, qualitative and quantitative elemental analysis. The basic idea of LIBS is the creation of spark/plasma through tight focusing of a laser beam on the surface or into a sample, the subsequent excitation and atomization of the species of the sample at the location where the spark is formed and the final detection and spectroscopic analysis of the emitted radiation from the decaying plasma. Seeing the numerous advantages holding the technique, LIBS has been proposed for many practical, technical and technological applications in various scientific areas. On the other hand, in the field of combustion, the proportion of fuel in a combustible mixture is of great importance as it strongly affects the efficiency of the chemical processes and the production of soot emissions. Therefore, there is a continuously increasing need for the development of a rapid and non-perturbative diagnostic technique for the determination of the fuel content locally in the flame structure with good spatial and temporal resolution. Ιn the present dissertation, LIBS technique which offers such advantages has been applied for combustion diagnostics purposes. During the experiments, laser systems with pulse duration in the scale of ns and fs have been applied as excitation sources, while the combustible mixtures under investigation were hydrocarbon-air flames, of laminar and turbulent flow with simple and more complicated structures. From the LIBS spectra in flames of different compositions, it was exhibited that there is a strong dependence of the intensities of various spectral lines on the equivalence ratio, which demonstrates that the precise determination of the amount of fuel can be performed. Also based on this correlation, the determination of the equivalence ratio locally everywhere within the flame can be achieved giving useful information about its structure. Finally, a similar diagnostic technique has been employed. The dielectric breakdown is held using a spark generator and the technique is called electrical Spark Induced Breakdown Spectroscopy (SIBS). The emitted light of the two plasmas induced by optical and electrical excitation was collected and a comparative study was performed.

The topic of this thesis is the degradation of fuel cell electrodes in proton exchange membrane fuel cells (PEMFCs). In particular, the degradation associated with localized fuel starvation, which is often encountered during start-ups and shut-downs (SUs/SDs) of PEMFCs. At SU/SD, O2 and H2 usually coexist in the anode compartment. This situation forces the opposite electrode, i.e. the cathode, to very high potentials, resulting in the corrosion of the carbon supporting the catalyst, referred to as carbon corrosion. The aim of this thesis has been to develop methods, materials and strategies to address the issues associated to carbon corrosion in PEMFC.The extent of catalyst degradation is commonly evaluated determining the electrochemically active surface area (ECSA) of fuel cell electrode. Therefore, it was considered important to study the effect of RH, temperature and type of accelerated degradation test (ADT) on the ECSA. Low RH decreases the ECSA of the electrode, attributed to re-structuring the ionomer and loss of contact with the catalyst.In the search for more durable supports, we evaluated different accelerated degradation tests (ADTs) for carbon corrosion. Potentiostatic holds at 1.2 V vs. RHE were found to be too mild. Potentiostatic holds at 1.4 V vs. RHE were found to induce a large degree of reversibility, also attributed to ionomer re-structuring. Triangle-wave potential cycling was found to irreversibly degrade the electrode within a reasonable amount of time, closely simulating SU/SD conditions.Corrosion of carbon-based supports not only degrades the catalyst by lowering the ECSA, but also has a profound effect on the electrode morphology. Decreased electrode porosity, increased agglomerate size and ionomer enrichment all contribute to the degradation of the mass-transport properties of the cathode. Graphitized carbon fibers were found to be 5 times more corrosion resistant than conventional carbons, primarily attributed to their lower surface area. Furthermore, fibers were found to better maintain the integrity of the electrode morphology, generally showing less degradation of the mass-transport losses. Different system strategies for shut-down were evaluated. Not doing anything to the fuel cell during shut-downs is detrimental for the fuel cell. O2 consumption with a load and H2 purge of the cathode were found to give around 100 times lower degradation rates compared to not doing anything and almost 10 times lower degradation rate than a simple air purge of the anode. Finally, in-situ measurements of contact resistance showed that the contact resistance between GDL and BPP is highly dynamic and changes with operating conditions. / Denna doktorsavhandling behandlar degraderingen av polymerelektrolytbränslecellselektroder. polymerelektrolytbränslecellselektroder. Den handlar särskilt om nedbrytningen av elektroden kopplad till en degraderingsmekanism som heter ”localized fuel starvation” oftast närvarande vid uppstart och nedstängning av bränslecellen. Vid start och stopp kan syrgas och vätgas förekomma samtidigt i anoden. Detta leder till väldigt höga elektrodpotentialer i katoden. Resultatet av detta är att kolbaserade katalysatorbärare korroderar och att bränslecellens livslängd förkortas. Målet med avhandlingen har varit att utveckla metoder, material och strategier för att både öka förståelsen av denna degraderingsmekanism och för att maximera katalysatorbärarens livslängd.Ett vanligt tillvägagångsätt för att bestämma graden av katalysatorns degradering är genom mätning av den elektrokemiskt aktiva ytan hos bränslecellselektroderna. I denna avhandling har dessutom effekten av temperatur och relativ fukthalt studerats. Låga fukthalter minskar den aktiva ytan hos elektroden, vilket sannolikt orsakas av en omstrukturering av jonomeren och av kontaktförlust mellan jonomer och katalysator.Olika accelererade degraderingstester för kolkorrosion har använts. Potentiostatiska tester vid 1.2 V mot RHE visade sig vara för milda. Potentiostatiska tester vid 1.4 V mot RHE visade sig däremot medföra en hög grad av reversibilitet, som också den tros vara orsakad av en omstrukturering av jonomeren. Cykling av elektrodpotentialen degraderade istället elektroden irreversibelt, inom rimlig tid och kunde väldigt nära simulera förhållandena vid uppstart och nedstängning.Korrosionen av katalysatorbäraren medför degradering av katalysatorn och har också en stor inverkan på elektrodens morfologi. En minskad elektrodporositet, en ökad agglomeratstorlek och en anrikning av jonomeren gör att elektrodens masstransportegenskaper försämras. Grafitiska kolfibrer visade sig vara mer resistenta mot kolkorrosion än konventionella kol, främst p.g.a. deras låga ytarea. Grafitiska kolfibrer visade också en förmåga att bättre bibehålla elektrodens morfologi efter accelererade tester, vilket resulterade i lägre masstransportförluster.Olika systemstrategier för nedstängning jämfördes. Att inte göra något under nedstängning är mycket skadligt för bränslecellen. Förbrukning av syre med en last och spolning av katoden med vätgas visade 100 gånger lägre degraderingshastighet av bränslecellsprestanda jämfört med att inte göra något alls och 10 gånger lägre degraderingshastighet jämfört med spolning av anoden med luft. In-situ kontaktresistansmätningar visade att kontaktresistansen mellan bipolära plattor och GDL är dynamisk och kan ändras beroende på driftförhållandena. / <p>QC 20131104</p>

No description available.

Emissions from light-duty passenger vehicles represent a significant portion of total criteria pollutant emissions in the United States. Since the 1970s, emissions testing of these vehicles has been required in many major metropolitan areas, including Atlanta, GA, that were designated to be in non-attainment for one or more of the National Ambient Air Quality Standards. While emissions inspections have successfully reduced emissions by identifying and repairing high emitting vehicles, they have been increasingly inefficient as emissions control systems have become more durable and fewer vehicles are in need of repair. Currently, only about 9% of Atlanta area vehicles fail emissions inspection, but every vehicle is inspected annually. This research addresses explores ways to create a more efficient emissions testing program while continuing to use existing testing infrastructure. To achieve this objective, on road vehicle emissions data were collected as a part of the Continuous Atlanta Fleet Evaluation program sponsored the Georgia Department of Natural Resources. These remote sensing data were combined with in-program vehicle inspection data from the Atlanta Vehicle Inspection and Maintenance (I/M) program to establish the degree to which on road vehicle remote sensing could be used to enhance program efficiency. Based on this analysis, a multi-parameter model was developed to predict the probability of a particular vehicle failing an emissions inspection. The parameters found to influence the probability of failure include: vehicle characteristics, ownership history, vehicle usage, previous emission test results, and remote sensing emissions readings. This model was the foundation for a proposed emissions testing program that would create variable timing for vehicle retesting with high and low failure probability vehicles being more and less frequently, respectively, than the current annual cycle. Implementation of this program is estimated to reduce fleet emissions of 17% for carbon monoxide, 11% for hydrocarbons, and 5% for nitrogen oxides in Atlanta. These reductions would be achieved very cost-effectively at an estimated marginal cost of $149, $7,576 and $2,436 per-ton-per-year for carbon monoxide, hydrocarbons, and nitrogen oxides emissions reductions respectfully.

If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.

If sufficiently persistent, semi-volatile organic contaminants (SVOCs) can travel long distances through the atmosphere from their points of release and become concentrated in cold, remote regions. As air is sampled for SVOCs to establish both their presence and the success of emission reduction efforts, it becomes helpful to determine sampling site proximity to sources and the origin of the sampled air masses. Comparing three increasingly sophisticated methods for quantifying source proximity of sampling locations, it was judged necessary to account for the actual history of the sampled air through construction of an airshed, especially if wind is highly directional and population distribution is very non-uniform. The airshed concept was improved upon by introducing a ‘geodesic’ grid of equally spaced cells, rather than a simple latitude/longitude grid, to avoid distortion near Earth’s poles and to allow for the comparison of airshed shapes. Assuming that a perfectly round airshed reveals no information about sources allows the significance of each cell of an airshed to be judged based on its departure from roundness. Combining air-mass histories with a 2 year-long series of SVOC air concentrations at Little Fox Lake in Canada’s Yukon Territory did not identify distinct source regions for most analytes, although γ-hexachlorocyclohexane appears to originate broadly in north-eastern Russia and/or Alaska. Based on this remoteness from sources, the site is judged to be well suited to monitor changes in the hemispheric background concentrations of SVOCs. A model-based exploration revealed wet-gaseous deposition as the dominant process responsible for cold-trapping SVOCs in mountain soils. Such cold trapping is particularly effective if precipitation rate increases with altitude and if temperature differences along the mountain are large. Considerable sensitivity of the modeled extent of cold-trapping to parameters as diverse as scale, mean temperature, atmospheric particle concentration and time relative to emission maxima is consistent with the wide variety of observed enrichment behaviour. Concentration gradients of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in air and soil measured on four Western Canadian mountains with variable distance from sources revealed source proximity as the main driver of concentrations at both the whole-mountain scale and along individual mountain transects.