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Low energy electrons in nanotechnology and cancer therapy
No full textThe interaction of low-energy electrons (LEEs) with neutral molecules plays an important role in various applications. In focused electron beam induced deposition
(FEBID), a direct-write 3D nanofabrication technique, a high-energy focused electron
beam is used to induce nanostructured deposition from precursor molecules (usually
organometallic complexes) adsorbed onto a surface. At the current stage, this technique
faces some challenges in regard to deposit purity and resolution. These limitations are
mainly attributed to the low-energy secondary electrons generated by the impact of the
primary electron beam on the surface. They are emitted with a large spatial distribution
and can initiate electron-induced reactions that lead to incomplete fragmentation of the
precursor molecules.
Low-energy electron interactions are expected to play an important role also in chemoradiotherapy, i.e., concomitant chemotherapy and radiotherapy. In this cancer treatment,
radiosensitizing agents are used to sensitize cancer cells to radiation. It has been shown
that LEEs, generated by the interaction of ionizing radiation with biological tissues, can
interact with a radiosensitizer producing radicals that can induce DNA damage.
In order to improve the performance of FEBID precursors and radiosensitizers, it is
important to study the energy dependence of the electron-induced processes.
Low-energy electrons (LEEs) can induce fragmentation through four distinct processes:
dissociative electron attachment (DEA), dissociative ionization (DI), dipolar dissociation
(DD) and neutral dissociation (ND). Low-energy electron interactions are commonly
investigated in gas phase experiments, under single electron-molecule collision conditions, with crossed molecular/electron beam instruments.
In this Ph.D. project, the LEE-induced decomposition of FEBID precursors and some
model compounds for application in chemoradiotherapy was investigated in the gasphase, specifically focusing on DEA and DI processes.
The FEBID precursors that have been selected for this work are (η
3
-C3H5)Ru(CO)3Br
and cis-Pt(CO)2Br2. For (η
3
-C3H5)Ru(CO)3Br , an extensive DI study was conducted
as a follow-up of previous studies of this compound. For cis-Pt(CO)2Br2, both DEA
and DI were investigated, with more emphasis on DEA, and the results were compared
with previous gas-phase DEA studies on cis-Pt(CO)2Cl2 and cis-Pt(NH3)2Cl2, with
surface studies on cis-Pt(CO)2Cl2 and with FEBID experiments on cis-Pt(CO)2Br2 and
cis-Pt(CO)2Cl2.
With the aim of enhancing the susceptibility of radiosensitizers towards LEEs, extensive
DEA studies on the model compounds pentafluorothiophenol, 2-fluorothiophenol and
pentafluorobenzoic acid, were conducted, where we explored the perfluorination and
neutral HF formation as potential means to promote DEA reactions. The results were
compared with previous work on DEA to pentafluorophenol and benzoic acid
Modeling of energy and mass balance using remote sensing for seasonal snow and glaciers in Iceland
Get PDFSnow and glacier research is important in Iceland for a variety of reasons. Water
resource forecasting for hydro-power production is important and monitoring of long-term changes and trends provide guidance for adoption strategies due to climate change.
Activity in glacier-covered volcanoes can cause volcanic ash and tephra deposits leading
to enhanced melt or in some cases glacier surface isolation reducing melt significantly.
The high natural climate variability can pose a risk to the reliability of the energy
production and delivery systems as drought conditions, low-flow periods, and years with
low summer melt are challenging to predict. Many Earth observing satellites provide
data that can improve estimations of physical processes that can be challenging to model
accurately, such as snow cover and surface albedo of snow and ice-covered surfaces.
In this research, satellite data were used to create gap-filled products of daily snow cover
and surface albedo in Iceland from 2000 to 2021 at a 500 m horizontal resolution. The
products relied on data collected from the two satellites carrying the MODIS sensor,
Aqua and Terra, providing sub-daily overpass. A process pipeline was developed to
merge the daily data and apply temporal aggregation to reduce the high number of
cloud-obscured pixels. Due to high cloud cover, yielding many pixels obscured by
clouds even after merging and temporal aggregation, machine learning models were
further developed to fully reclassify the remaining unclassified data. The output from
this process was a spatio-temporal product with capabilities for further analysis and
extraction of various statistical parameters describing snow cover and albedo properties
in Iceland. To better understand the seasonal and inter-annual variability and possible
trends, a surface energy balance model was developed utilizing remotely sensed snow
cover and albedo as prognostic variables. Surface albedo was used to constrain net short wave radiation forced at a snow-covered surface and fractional snow cover provides an aerial constraint for seasonal snow outside of glaciers by estimating the fractional snow cover of pixels, scaling the calculated melt energy accordingly. Large-scale atmospheric circulation anomalies and surface energy balance were analyzed to study relationships of the data and understanding the drivers of variability.
The results show high seasonal and inter-annual variability in surface energy balance,
snow cover and surface albedo for snow- and ice-covered surfaces in Iceland. The high
variability in surface energy balance reflects the high variability of albedo, especially
for glaciers. The impacts of light-absorbing particles (LAPs), both from tephra deposits
due to volcanic eruptions and dust deposits from airborne dust, were estimated to
provide understanding of the extent, magnitude and impact on surface energy balance
and showed a significant melt enhancement for years with high LAPs deposits. Sea
surface temperature impacts cloud cover in Iceland during the melting season. Recent
abrupt changes in the sea surface conditions near Greenland and SST south of Iceland
correlate strongly with cloud cover in Iceland during the melt season. Cloud cover
acts as a modulator on the incoming short-wave radiation available for surface forcing,
i.e., surface energy balance. Large-scale patterns such as the Greenland Base Index
(GBI) and the North Atlantic Oscillation (NAO) also showed significant correlation to
controlling parameters relating to the surface energy balance
Things from the Past. People’s Possessions and Museum Collection from 19th Century.
No full textDoktorsverkefnið var unnið innan öndvegisverkefnisins Heimsins hnoss. Söfn efnismenningar, menningararfur og merking.Viðfangsefni doktorsritgerðarinnar er að draga fram heimildasöfn (e. archives) og greina þá efnismenningu (e. material culture) sem þau búa yfir, eða með öðrum orðum að kanna samband manna og hluta. Rannsóknaraðferðin krefst þess að víða sé leitað fanga eins og á sviði sagnfræði, fornleifafræði, safnafræði, þjóð- og þjóðháttafræði og menningarfræði. Við úrvinnslu flókinna og stórra heimildagrunna er sérstaklega stuðst við aðferð einsögunnar (e. microhistory) eða einvæðingu sögunnar (e. singularization of history), sögu hluta (e. history of things) og gagnrýninnar menningararfsfræða (e. critical heritage studies). Markmið rannsóknarinnar er að draga fram hversdagslíf alþýðunnar á 19. öld með rannsókn á efnismenningu tveggja ólíkra heimildasafna. Hugmyndin var að nálgast heimildirnar með eiginleika þeirra í huga til að fá sem fyllstu mynd af fortíðinni og dýpka skilning á þeim álitamálum sem upp koma við notkun ólíkra heimilda. Í fyrsta lagi er um að ræða dánarbúsuppskriftir sem varðveittar eru á Þjóðskjalasafni Íslands og eru rúmlega 33.000 talsins. En það eru gögn sem innihalda upptalningu og virðingu á eigum látinna einstaklinga ef þau skildu eftir sig ólögráða erfingja, skulduðu öðrum eða ef deilur um skiptingu dánarbúsins ríktu meðal erfingja. Í öðru lagi var safnkostur Þjóðminjasafns Íslands frá sama tíma tekinn fyrir eins og hann birtist í Sarpi, stafrænum gagnagrunni sem safnið notar til að skrá muni og halda utan um safnkostinn.
Umfjöllun ritgerðarinnar er fjórþætt. Í inngangskafla er fjallað um helstu hugtök og kenningar sem notaðar eru í doktorsrannsókninni og hvernig þær mótuðu aðferðafræði verksins. Þar er einnig fjallað um heimildirnar sem notaðar eru þar sem eiginleikum, kostum og göllum er velt upp á gagnrýninn hátt. Nokkur hugtök eru rædd sérstaklega eins og efnismenning, efnisheimur, menningararfur, nýja efnishyggjan (e. new materialism), skráning, heimildasöfn og varðveisla og tengingar þeirra við efnið og umræða um þau í öðrum fræðigreinum. Hér kemur fram þverfræðileg nálgun verkefnisins sem og aðferðafræði rannsóknarinnar. Hún byggir á heimildasöfnunum þar sem stórir gagnagrunnar eru teknir fyrir og efni þeirra bútað smátt og smátt niður eftir tímabili, stöðu fólks, aldri, meðaltalsvirði dánarbúanna, landfræðilegri dreifingu og að lokum hlutirnir sjálfir skoðaðir – eigurnar og safngripirnir.
Annar hluti ritgerðarinnar, sem er fyrirferðarmesta efni rannsóknarinnar, eru dánarbúsuppskriftir 104 einstaklinga frá 19. öld sem eru skoðaðar og spurt: hvaða eigur átti fólkið við andlát sitt og hvað geta þær sagt okkur um hversdagslíf eigenda sinna? Til að nálgast umfangsmiklar heimildir (33.000 einstaklingar) er viðfangsefnið afmarkað í nokkrum þrepum. Fyrsta skrefið er tímabilið – 19. öld. Annað skrefið er að kalla fram fólk sem endurspeglaði þorra almennings á þessum tíma eftir stöðu þess. Þetta voru þrír hópar: bændur, ekkjur og vinnuhjú. Innan þessara hópa er þriðja skrefið tekið, sem er að nota aldurshópa sem sýndi fólkið í byrjun, miðju og við lok lífsferil þeirra. Með þessari afmörkun var ég enn með þúsundir manns í höndunum svo að fjórða leiðin byggði á því að koma böndum á fjölda þeirra sem teknir voru fyrir. Þar var farin sú leið að nýta meðaltal verðmæta eigna. Lokaskrefið er svo að handvelja „meðaljónana“ með því að dreifa þeim yfir alla 19. öldina og landið til þess að fá sem gleggsta mynd af efnisveruleika tímabilsins. Í doktorsrannsókninni koma fyrir 37 vinnuhjú, 34 bændur og 33 ekkjur sem fjallað er um út frá eigum þeirra eða eftir gripaflokkum dánarbúsuppskriftanna. Sú flokkun var gerð af virðingarmönnum dánarbúanna við úttekt dánarbúsins þar sem eigunum var skipt í til dæmis fatnað, búsgögn, reiðtygi og svo framvegis.
Heimildirnar sjálfar – dánarbúsuppskriftirnar – eru einnig greindar og eiginleikar þeirra dregnir fram til að fá sem fyllsta mynd af fortíðinni. Hvaða hagsmunir liggja þeim að baki? Dánarbúsuppskriftirnar gáfu innsýn í líf þeirra einstaklinga sem þar komu fyrir enda var þar að finna alls konar hluti, allt frá slitnum sokkum yfir í verðmætar mjólkurkýr. Sú efnismenning sem fram kom endurspeglaði stöðu, aldur, áhuga og sérhæfingu, kyn og daglegt líf fólksins og tilraunir þess til að bæta líf sitt. Á sama hátt gáfu dánarbúsuppskriftirnar sjálfar vísbendingar um fólkið og viðhorf embættismanna til þess.
Í þriðja hluta ritgerðarinnar er fjallað um safnkost Þjóðminjasafnsins sem er skráður inn í Sarp, og talinn vera frá tímabilinu 1740–1900. Það er, þeir gripir sem líklegast hafa verið notaðir á sama tíma og þeir einstaklingar sem komu fyrir í dánarbúsuppskriftunum voru uppi. Skoðað er hvaða munir hafa varðveist og af hvaða tagi eru þeir? Safnkostur tímabilsins var greindur út frá þeirri skráningu sem hann fékk í Sarpi og þannig er reynt að rýna í hvers konar gripir þetta eru og hvaðan þeir koma. Úr þeim upplýsingum sem mátti draga úr skráningu þeirra var ljóst að þar voru á ferðinni munir sem varpa upp fremur fegraðri mynd af fortíðinni. Söfnunin ber þess merki að þjóðernisleg áhrif á seinni hluta 19. aldar og í byrjun þeirrar 20. hafi markað safnkost tímabilsins svo um munar. Þetta kemur fram í munum sem bera listræn og fagurfræðileg gildi og flokkast oft til alþýðulistar eins og útskurður í horn, tré og járn. Hlutur yfirstéttarinnar var einnig stór í safnkosti tímabilsins bæði sem gefenda og eigenda gripanna.
Í lok ritgerðar er gerður samanburður á þeirri efnismenningu sem er að finna í eigu einstaklinganna og þeirrar sem birtist í skráningu og varðveislu Þjóðminjasafnsins. Þetta er gert á þann hátt að eigum einstaklinganna er skipt í gripaflokka sem virðingarmenn dánarbúanna notuðu til að gera upp búið. Á sama hátt er safnkosti tímabilsins skipt upp, en með því gefst tækifæri til að draga fram líkindin og það sem er ólíkt með þeim. Eru sambærilegir gripir í báðum heimildasöfnum eða vantaði einhverja sérstaka gripaflokka? Tilgangurinn með þessari greiningu er að takast á við þann vanda sem fylgir því að fjalla um fortíðina ásamt því að varpa fram ályktunum um á hvaða fræðilegu stoðum hinn svokallaði menningararfur stendur á.
Rannsóknin leiðir í ljós hið síbreytilega samband manna og hluta – efnismenningu fortíðar og þeirri sem varðveitt er í samtímanum. Frá því að vera hlutur í dánarbúsuppskrift sem kom við sögu á hverjum degi í lífi fólks á einn eða annan hátt yfir í að vera safngripur sem er í vernduðu umhverfi varðveisluhúsnæðis og rætt er um sem menningararf Íslendinga bæði í almennri umræðu og á vettvangi safna. Samanburðurinn á dánarbúsuppskriftum og safnkosti Þjóðminjasafns Íslands sýnir stigveldi gripa, íslenska list og handverk, hið hversdagslega og einstaklingsbundna. Allt eru þetta þættir sem koma fram á mismunandi hátt í heimildarsöfnunum og veita óvænta og nýja innsýn í tímabil 19. aldar.
Einn af áhersluþáttum verkefnisins er að færa fram á sjónarsviðið mikilvægi efnismenningar sem og að beita nýjum aðferðum til þess að nálgast viðfangsefnið. Forðast var að dvelja við hlutina í heimildunum eina og sér heldur leitast við að færa þunga greiningarinnar yfir á eiginleika sjálfra heimildanna og hvað þær hafa um fortíðina að segja. Vísindalegt gildi rannsóknarinnar er því ekki aðeins fólgið í notkun á nýjum heimildum heldur er aðferðin nýstárleg að því leyti að hún miðar að því að greina hlutina út frá mörgum sjónarhornum. Fram að þessu hefur sagnfræðin nálgast viðfangsefni sitt út frá afstöðu mannanna og lítið skeytt um efnisheiminn sem hefur veigamikil áhrif á daglega framgöngu fólks. Nýlunda verkefnisins er því fólgin í því að efnismenning eða hlutir eru notuð sem mikilvægt greiningartæki á fortíðina.The object of the thesis is to bring archives to light and to analyse the material culture they embody – in other words to explore the relationship between people and things. The research method requires a broad-based approach, embracing such fields as history, archaeology, museum studies, folkloristics and ethnology, and culture studies. In working with large and complex collections of sources, the methods of microhistory or singularization of history, the history of things and critical heritage studies are applied. The objective of the study is to illuminate the daily life of the people of Iceland in the 19th century through study of material culture as preserved in two different archives. The principle was to approach the sources with their attributes in mind, in order gain the fullest possible picture of the past and to deepen understanding of moot points that may arise when different sources are used. The first archive explored consists of probate inventories, preserved by the National Archives of Iceland, which number about 33,000. These are documents that contain inventories and valuations of the estates of deceased individuals, carried out if they left heirs of minor age or died in debt, or in cases where the division of assets among heirs was disputed. The other archive is the collection of the National Museum of Iceland for the same period, which is examined via catalogue entries on Sarpur, an online digital database cataloguing Icelandic museums‘ collections.
The content of the thesis is made up of four parts. The introduction discusses the principal concepts and theories applied in the doctoral study, and how these influenced the research methodology. The sources used in the study are also addressed, with a critical discussion of their qualities, strengths and weaknesses. There is specific discussion of several concepts, such as material culture, materiality, cultural heritage, new materialism, cataloguing, archives and preservation, together with their relevance to the project and discussion of them in other scholarly disciplines. This explains the cross-disciplinary approach of the project and the methodology of the study. It is grounded in the archives: large databases are examined and their content is gradually divided up by period, social status, age, average value of probate inventories, geographical distribution, and finally the things themselves – the possessions and the museum pieces.
The second part of the thesis, the bulk of the study material, comprises an examination of probate inventories of 104 individuals who lived in the 19th century. The questions are asked: what possessions did people own when they died, and what can those possessions tell us about the daily lives of their owners? In order to approach the extensive sources (on 33,000 individuals), the content was narrowed down in a number of stages. The first stage was the period: the 19th century. The second stage was to identify by social status individuals who were representative of the Icelandic population at the time. These comprised three social groups: farmers, widows and farm workers. Within these categories the third stage was applied: to pick age groups that were examples of people in early or middle life or in old age. After this process of selection, I was still left with thousands of people; the fourth stage consisted of winnowing out the cases to be included. Here the average value of the probate inventory was used. The final stage was to hand-pick “typical” individuals representing all periods of the 19th century and regions of the country, in order to gain the clearest possible impression of the materiality of the time. The doctoral study thus examined 37 farm workers, 34 farmers and 33 widows, who are discussed on the basis of their possessions, or categories of possessions, in the probate inventories. This categorisation of assets was carried out by the valuers of the estate, who classed the assets in such categories as clothing, domestic equipment, riding gear, etc.
The sources themselves – probate inventories – are also analysed, and their attributes are discussed, in order to gain the fullest possible image of the past. What interests lie behind them? The probate inventories provided insight into the lives of the individuals concerned, listing possessions from worn-out socks to valuable dairy cows. The material culture documented in them reflects the social status, age, interests and skills, gender and daily life of the people concerned, and their efforts to improve their lives. At the same time the probate inventories themselves provided clues to the individuals and how they were viewed by officials.
The third part of the thesis is concerned with objects in the collection of the National Museum of Iceland, catalogued on the Sarpur database, and believed to date from the period 1740–1900. In other words, these are objects which appear to have been in use during the lifetimes of the people whose possessions are documented in the probate inventories. An examination is made of the objects preserved in the museum collection, and their nature. The museum pieces of the period were analysed, based on the catalogue entries on Sarpur, seeking to identify the kinds of objects and where they were from. The information derived from the catalogue entries led to the conclusion that these objects give a far more idealised image of the past than is seen in the probate inventories. The way in which the items were collected indicates that nationalist fervour in the later 19th century and the early 20th has clearly made its mark upon the collection for that period. This is seen in objects of artistic/aesthetic value, often classified as folk art, such as carvings in horn or wood and ironwork. The social élite is also disproportionately represented in the collection for that period, both as owners and donors of objects.
The thesis concludes with a comparison of the material culture found in the individuals’ possession according to the probate inventories, and that which is preserved and catalogued by the National Museum of Iceland. The comparison was made by dividing the individuals’ possessions into the categories of assets used by the valuers of states for probate. The museum pieces of the period are classified in the same way, providing the opportunity to discern similarities and dissimilarities. Do comparable objects feature in both archives, or are some categories lacking? The objective of this analysis is to address the problems that arise with discussing the past, while also drawing inferences regarding the scholarly basis of “cultural heritage.”
The study revealed the mutable relationship between people and things – the material culture of the past, and that which is preserved in the present: from being an object in a probate inventory that featured in people’s everyday life in one way or another, to being a museum piece in the secure setting of a museum facility, cited as part of Iceland’s heritage, both in general discourse and in the museum environment. The comparison of probate inventories and the National Museum of Iceland collection demonstrates a hierarchy of objects, Icelandic art and crafts, the commonplace and the personal. These are all factors which emerge in different ways in archives and provide a new and unexpected perspective on the 19th century.
One of the priorities of the project is to highlight the importance of material culture, and to apply new methods in approaching the subject. The principle was to avoid devoting excessive attention to individual objects in the sources, focussing instead on the qualities of the sources themselves and what they can tell us about the past. The scholarly value of the study thus lies not only in the use of new sources: the method is innovative in that it sets out to analyse objects from various perspectives. Hitherto history has approached its subjects in terms of people, paying little attention to materiality, which has a major influence on people’s daily lives. The novelty of this project thus consists in using material culture or things as an important analytical tool about the past.Ranní
Reikningar á rafeindabyggingu spunavíxlverkaðra járnsúlfíðsklasa
No full textIron-sulfur clusters are integral to the biochemistry of living organisms and
a lot of effort has been devoted to research their structure and function.
However, describing these polynuclear iron-sulfur clusters with computa tional chemistry poses a challenge due to their complicated open-shell
electronic structure and the fact they are embedded within a protein. Many
electronic structure methods (e.g. DFT) struggle with describing correctly
the phenomena encountered in these clusters, such as their spin coupling.
The overarching goal is to model these systems (QM or QM/MM), in
particular the cofactors of the nitrogenase enzymes, and understand their
electronic structure within the language of DFT. Firstly, the resting state
of the iron-vanadium cofactor as it appears in the 1.35 Å resolution X-ray
structure is found to be best described as [VFe7S8C(CO3)]2−. Secondly,
a test set of 11 dimeric spin-coupled Fe or Mo clusters and a test set of
5 dimeric Fe closed shell clusters are introduced and are demonstrated to
behave differently w.r.t. density functional choice. Thirdly, the calculated
nuclear resonance vibrational spectra (NRVS) of iron-sulfur proteins mod elled by QM/MM is shown to be sensitive to functional choice and model
size. NRVS is additionally a promising method in the study of nitrogenase
and calculations suggest that a combined experimental-computational ap proach could help characterize the isolable states in the catalytic cycle of
nitrogenase.Prótein sem innihalda járn-brennisteins hjálparþætti gegna mikilvægu
hlutverki í lífverum og mikil rannsóknarvinna hefur farið í að skilja hvernig
þessi prótein virka. Reikniefnafræðilega er þó ekki einfalt að lýsa þessum
hjálparþáttum vegna þess hve flókin rafeindabygging þeirra er, sem og
vegna áhrifa frá próteinumhverfinu. Þéttnifellafræði (DFT) á erfitt með
að lýsa rétt rafeindabyggingu þessa hjálparþátta vegna fyrirbæra eins og
spunavíxlerkun. Markmið rannsóknanna sem lýst er í þessu verkefni er
að kortleggja hve vel mismunandi þéttnifelli (DF) lýsa þessum kerfum,
svo og skilja undirliggjandi rafeindabyggingu þeirra ásamt því að lýsa
umhverfisáhrifum út frá fjölskala reiknilíkönum (QM/MM). Þessa þekkingu
má síðan nota til að lýsa betur hjálparþáttum nítrógenasa ensímanna sem
eru oft taldir vera meðal flóknustu málm hjálparþáttum sem finna má í
próteinum. Niðurstöðum verkefnisins má skipta í þrennt. Í fyrsta lagi var
fjölskalareiknilíkan af vanadíum-járn hjálparþætti vanadíum nítrógenasa
borið saman við kristalbyggingu ensímsins og fundið að hjálparþættinum er
best lýst sem [VFe7S8C(CO3)]2− klasa. Í öðru lagi voru tvö sameindasöfn
útbúin þar sem eitt innihélt 11 spunakúplaða tvíjárns-komplexa og annað 5
tvíjárns-komplexa með allar rafeindir paraðar og sýnt fram á að mismunandi
þéttnifelli lýsa þeim misvel. Í þriðja lagi voru kjarntitringshermiróf (NRVS)
af járn-brennisteins hjálparþáttum reiknuð með fjölskalareiknilíkönum þar
sem áhrif vals á þéttnifellis, fjölda atóma lýst með skammtafræði og fjölda
atóma í reikningum á annarri afleiðu orkunnar var rannsakað. Niðurstöður
benda til að lífrænir tenglar frá próteininu séu næmari fyrir þessum þáttum
en ólífrænir tenglar og að NRVS-tilraunir ásamt reikningum ætti að vera góð
aðferð til að greina ástönd sem hægt er að einangra í hvarfgangi nítrógenasa
Magmatic olivine as a tool to investigate geochemical mantle heterogeneities beneath Iceland
Get PDFThe extent of compositional and lithological heterogeneity in Earth’s convecting mantle, caused by the recycling of oceanic and continental lithosphere, has long been a subject of interest to geochemists and geophysicists. A fundamental outstanding question that is still widely debated is: how is recycling of crustal material preserved in ocean island basalts?
Olivine is usually the first mineral to crystallise during the ascent of mantle-derived melts and is stable over a large range in pressure, temperature, and melt composition. Because of this, the chemistry of olivine is often used as a proxy for primitive melt compositions prior to secondary modifications occurring in the uppermost part of the mantle and the crust. Iceland is the largest subaerial section of the global mid-ocean-ridge system and reflects the current location of the Iceland mantle plume. Previous work has shown that the mantle beneath Iceland is chemically heterogenous, and this has been attributed in part to the presence of recycled crust entrained within the upwelling plume. The recognition of a chemically heterogenous plume, together with the widespread occurrence of primitive basalts, makes Iceland an ideal location to identify the properties of recycled crust in a mantle plume from the chemical composition of high-forsterite olivine.
This thesis is in three parts where I present a detailed study of high-forsterite olivine from the active rift and flank zones as well as older crust in Iceland. I apply a combination of in-situ and bulk digestion analytical techniques to produce an internally-consistent, high-precision dataset for distinguishing mantle-derived variability from the effect of secondary processes, such as fractional crystallisation and assimilation. In the first part of the thesis, I use minor and trace elements in olivine and previously published He isotopes to show, that the geochemical heterogeneity beneath Iceland is mainly caused by the Iceland plume entraining pyroxene-rich mantle components, formed from recycled oceanic crust. In the second part, I use oxygen isotopic ratios in the same olivine crystals to show, that the amount of entrained recycled crust has increased since the initiation of the plume (~ 60 Ma). This is related to an increase in plume flux and melt production, which was likely facilitated by the coincidence of the Iceland mantle plume and the North Atlantic Rift starting at ~ 25 Ma and resulted in the formation of the Iceland plateau around the same time. In the final part, I explore the use of bulk digestion methods to determine Mg and Fe isotopic ratios in olivine from the same samples of Icelandic basalts to further assess the nature of this recycled component. Here, I find that variations in Mg and Fe isotopes in Icelandic olivine are mostly controlled by magma transport timescales which, going forward, could enable us to estimate residence times for olivine in the various volcanic regions.Nordic Volcanological Center
Icelandic Research Fund (Grant #196084-051 and Grant #196139-051
Controls on andesitic glaciovolcanism at ice-capped volcanoes from field and experimental studies
Get PDFPost-printGlaciovolcanic deposits at Tongariro and Ruapehu volcanoes, New Zealand, represent diverse styles of interaction between wet-based glaciers and andesitic lava. There are iceconfined lavas, and also hydroclastic breccia and subaqueous pyroclastic deposits that formed during effusive and explosive eruptions into meltwater beneath the glacier; they are rare among globally reported products of andesitic glaciovolcanism. The apparent lack of hydrovolcanically fragmented andesite at ice-capped volcanoes has been attributed to a lack of meltwater at the interaction sites because either the thermal characteristics of andesite limit meltwater production or meltwater drains out through leaky glaciers and down steep volcano slopes. We used published field evidence and novel, dynamic andesite-ice experiments to show that, in some cases, meltwater accumulates under glaciers on andesitic volcanoes and that meltwater production rates increase as andesite pushes against an ice wall. We concur with models for eruptions beneath ice sheets showing that the glacial conditions and pre-eruption edifice morphology are more important controls on the style of glaciovolcanism and its products than magma composition and the thermal properties of magmas. Glaciovolcanic products can be useful proxies for paleoenvironment, and the range of andesitic products and the hydrological environments in which andesite erupts are greater than hitherto appreciated.R.P. Cole received funding from the Geological Soci-ety of New Zealand Wellman Research Award and the University of Otago Polar Environments Research Theme. The New Zealand Department of Conserva-tion provided logistical assistance in the field. Brent Pooley and Luke Easterbrook assisted with making the experimental apparatus. Matteo Demurtas helped Cole in using MatLab. Kelly Russell, John Smellie, and Alison Graettinger provided constructive reviews.Peer Reviewe
The explosive, basaltic Katla eruption in 1918, south Iceland II. Isopach map, ice cap deposition of tephra and layer volume
Get PDFDue to poor preservation and lack of proximal tephra thickness data, no comprehensive isopach map has existed for the tephra layer from the major eruption of the Katla volcano in 1918. We present such a map obtained by combining existing data on the thickness of the 1918 tephra in soil profiles with newly acquired data from the 590 km2 Mýrdalsjökull ice cap which covers the Katla caldera and its outer slopes. A tephra thickness of 20–30 m on the ice surface proximal to the vents is inferred from photos taken in 1919. The greatest thicknesses presently observed, 30–35 cm, occur where the layer outcrops in the lowermost parts of the ablation areas of the Kötlujökull and Sólheimajökull outlet glaciers. A fallout location within the Katla caldera is inferred for the presently exposed tephra in both outlet glaciers, as estimates of balance velocities imply lateral transport since 1918 of ∼15 km for Kötlujökull, ∼11 km for Sólheimajökull and about 2 km for
the broad northern lobe of Sléttjökull. Calculations of thinning of the tephra layer during this lateral transport indicate that the presently exposed tephra layers in Kötlujökull and Sólheimajökull were respectively over 2 m and about 1.2 m thick where they fell while insignificant thinning is inferred for the broad northern lobe of Sléttjökull. The K1918 layer has an estimated volume of 0.95±0.25 km3 (corresponding to 1.15±0.30×1012 kg) whereof about 50% fell on Mýrdalsjökull. About 90% of the tephra fell on land and 10% in the sea to the south and southeast of the volcano. The volume estimate obtained contains only a part of the total volume erupted as it excludes water-transported pyroclasts and any material that may have been left on the glacier bed at the vents. While three main dispersal axes can be defined (N, NE and SE), the distribution map is complex in shape reflecting tephra dispersal over a period of variable wind directions and eruption intensity. In terms of airborne tephra, Katla 1918 is the largest explosive eruption in Iceland since the silicic eruption of Askja in 1875.MTG, ÞH: University of Iceland Research Fund, Chief of Police in South Iceland, The Icelandic Road Authority.
MHJ: EU Marie Sklodowska-Curie fellowship
JG: Landsvirkjun, Fræðslusjóður Suðurlands
TJ: GOSVÁ program on volcanic hazard assessment in IcelandPeer Reviewe
Simulation of a Small Scale Biowaste Gasification System for Energy Production
Get PDFSeveral waste incinerators in Iceland were closed down in 2011/2012 due to environmental problems and health concerns. To date no cost effective and environmentally acceptable replacement has been found for disposing of the waste that was combusted at these facilities up to 2012. As a result, large amounts of waste have been transported by ferry and road to be landfilled or incinerated hundreds of kilometers away (for example routes include from Vestmannaeyjar to Reykjavik or even in some cases Blönduós, with similar long journeys in other remote locations, for example Vestfirðir). The aim of this PhD project was to take steps towards adapting a greener solution developed elsewhere for waste disposal to Iceland. The process is called gasification which is a waste-to-energy technology. The challenges for waste gasification are its adaption to the Icelandic scale, using waste as feedstock and determining operational parameters. Downscaling must be done while still eliminating the pollution problems of incinerators and the cost constraints of small-scale plants.
To overcome these challenges, the experimental and pilot work at the University in Iceland was conducted by modeling and simulation. Described in this thesis is the following modelling and simulation work: An integrated small-scale gasification system with power production unit was simulated by using ASPEN Plus. This model helps to understand under what conditions and in which ways the system can operate. The system’s model was used to analyze and assess the potential of adapting gasification-based waste to power systems for conditions in Iceland. The analysis and assessment includes techno-economic and environmental perspectives.
The project’s contribution to the field of gasification is the knowledge regarding simulation of small-scale gasifiers as well as the assessment of their performance and various operating parameters. This knowledge is valuable for developing gasification solutions for smaller communities that have similar waste streams and waste disposal challenges.
The results indicate that electricity production from waste gasification could be technically feasible, environmentally, and economic acceptable option replacing incinerators and landfilling sites for waste disposal in Iceland. Among all the studied feedstock alternatives, timber and wood waste are the most beneficial when certain factors are considered. The production of 1 kWh electricity from timber gasification comes with the relatively low global warming potential of 0.07 kgCO2eq, acidification potential of 0.09 kgSO2eq, and eutrophication potential of 0.36 kgNO3eq. The results of techno-economic assessment show that the net present value is positive for a gasification system with the capability to generate greater than 45 kW. Discounted payback period (DPP) will be also lower than 2 years for a gasification with capacity higher than 75 kW. However, it could be lower than 6 months if gasification is applied in capacity greater than 200 kW.
It is also worth to mention that, if cogeneration of heat and power (CHP) is used – instead of only power production – the DPP can be shortened even further (i.e., in cold locations where cheap geothermal hot water is not available) and that will make gasification even more feasible than shown in this thesis.Icelandic Research Fund, (in Icelandic: Rannsoknasjodur) with grant number of 196458-051, financially supported the work
Framework for Dealing with Uncertainty in the Port Planning Process: An Icelandic Case of the Ports of Isafjordur Network
Get PDFPorts have always been evolving to satisfy the new or changing demands of stakeholders. In this unstable world, ports as dynamic systems are developed under a high degree of uncertainty. Furthermore, black-swan events, for instance, the financial crisis in 2008, the avalanche in Flateyri (Iceland) in 2020, the COVID-19 pandemic in 2020-2021 make successful port planning a challenging task. Indeed, the ever-increasing complexity of a port system and its long technical lifetime make uncertainty considerations inevitable in the planning process. Therefore, this research presents a structured framework to deal with uncertainties, including opportunities and vulnerabilities, in the port planning process. To this end, a structured stakeholder analysis is performed to effectively and timely engage stakeholders in the planning process. Fuzzy logic 3-dimensional decision surface is used to identify the salient stakeholders. Subsequently, the success of the future port is defined in terms of the specific objectives of the stakeholders. To develop this definition, a problem structuring method and fuzzy multi-attribute group decision-making method are synthesized. Then, a port throughput forecast is conducted that accounts for epistemic uncertainty, including model and parameters uncertainties, and thus increases the reliability of forecast results. The method identifies the influencing macroeconomic variables on port throughput by mutual information and then applies the Bayesian statistical method to forecast the port throughput. Effective actions are planned to seize opportunities and manage vulnerabilities that manifest in the projected lifetime. Therefore, the port can adapt or better withstand the vagaries of the future. The nonlinearity of dealing with uncertainty by application of the framework provides a robust and better plan toward its success. The framework supports decision making under uncertainty and facilitates adaptive port planning. The framework is applied to the Ports of Isafjordur Network in Iceland. The results indicate that the uncertainties mainly present opportunities in the short-time horizon, while in the middle-time horizon the port network is confronted with multiple vulnerabilities.Hið öfluga og sívaxandi flókna eðli hafnarkerfa í margbreytilegum heimi skapar mikla
óvissu varðandi þróunaráætlanir hafna. Enn fremur þá leiða óvæntir atburðir, svonefndir
svartir svanir, eins og til dæmis efnahagshrunið 2008, snjóflóðið á Flateyri 2020 og
COVID-19 faraldurinn, til þess að skipulagsgerð hafna er sérstaklega krefjandi verkefni
sem er háð mikilli óvissu. Flækjustig hafnarkerfa og óvissa á löngum líftíma hafna gerir
það óumflýjanlegt að taka tillit til óvissu í skipulagsferlinu. Þessi rannsókn setur fram
skipulagsramma til að takast á við óvissu, þar á meðal tækifæri og veikleika, í
skipulagsferli hafnar. Þessi rannsókn kynnir skipulagða hagsmunagreiningu til að virkja
hagsmunaaðila hafna tímanlega í skipulagsferlinu. Þrívíddar ákvörðunaryfirborð byggt á
loðinni (e. fuzzy) rökfræði er notað til að bera kennsl á mikilvæga hagsmunaaðila með
mismunandi áhrif og hagsmuni. Í kjölfarið er árangur skipulagsins skilgreindur út frá
markmiðum hagsmunaaðila og með samtvinnun eldri aðferðar og loðinnar rökfræði. Notuð
er aðferð við gerð spár fyrir flæði um höfnina sem tekur tillit til þekkingaróvissu og eykur
þannig áreiðanleika niðurstaðna spárinnar. Aðferðin skilgreinir þjóðhagslega áhrifaþætti á
afkastagetu hafna með aðferð gagnkvæmra upplýsinga (e. mutual information) og beitir
síðan Bayesískri tölfræði til að spá fyrir um afköst hafnarinnar. Árangursríkar aðgerðir eiga
að geta nýtt tækifæri og takmarkað veikleika á áætluðum líftíma hafnarinnar, þar sem
höfnin getur aðlagast eða þolað duttlunga framtíðarinnar betur. Sá ólínuleiki í að takast á
við óvissu með því að beita skipulagsrammanum stuðlar að betra hafnarskipulagi.
Skipulagsamminn styður ákvarðanatöku í óvissu umhverfi með því að auðvelda
sveigjanlega skipulagsgerð fyrir hafnir. Skipulagsrammanum er beitt á hafnir Ísafjarðar.
Helstu niðurstöður benda til þess að óvissan feli aðallega í sér tækifæri til skamms tíma, en
til lengri tíma stendur hafnarkerfið frammi fyrir veikleikum.University of Iceland, Municipality of Isafjordur, Icelandic Road and Coastal AdministrationFina