A chronosequence approach to estimate the regional soil organic carbon stock on moraines of two glacial fore-fields in SE-Iceland

Post-print (lokagerð höfundar)SOC has received increased attention over the last decades because of its role as an option to mitigate the effects of increased anthropogenic greenhouse gas emissions. In Iceland, the loss of vegetation and soil due to land-use and natural processes has left large areas as barren deserts. Land restoration actions have the primary goals to prevent land degradation and restore lost ecosystems but the ancillary benefits of SOC accumulation with regard to COP 21 are obvious. Natural vegetation succession is active in areas being exposed by glacial recession since the end of the Little Ice Age in ∼1890. Here, we attempt to estimate the current regional SOC stock on undisturbed moraines in front of two glaciers in SE-Iceland, using surface age, soil properties and vegetation cover data. RapidEye images were used to estimate the surface area of two vegetation classes with 50% cover. Regional SOC stock was calculated using soil data and the sum of the area of each cover class for each time-zone. The rates of SOC accretion reached the maximum values of 0.004−0.009 kg C m−2 yr−1. The regional SOC stock for the two glacier fore-fields was estimated at 1605 Mg C (0−10 cm) for Skaftafellsjökull (396 ha) and 1106 Mg C (0−5 cm) for Breiðamerkurjökull (632 ha). The current annual increase in the moraine SOC stocks was estimated at 20.7 Mg C yr−1 for Skaftafellsjökull and 19.7 Mg C yr−1 for Breiðamerkurjökull.This research was supported by the University of Iceland Trust Fund, The University of Iceland Research Fund, the Icelandic Research Fund, Rannís, Grant of Excellence No. 152266-052 (Project EMMIRS), the Landvirkjun Energy Research Fund No. 04-2010, the Vinir Vatnajökuls Fund No. 11 and the Icelandic Research Fund [No. 1201211021].Peer Reviewe

Of mosses and men: Plant succession, soil development and soil carbon accretion in the sub-Arctic volcanic landscape of Hekla, Iceland

Post-print (lokagerð höfundar)Lava flows pose a hazard in volcanic environments and reset ecosystem development. A succession of dated lava flows provides the possibility to estimate the direction and rates of ecosystem development and can be used to predict future development. We examine plant succession, soil development and soil carbon (C) accretion on the historical (post 874 AD) lava flows formed by the Hekla volcano in south Iceland. Vegetation and soil measurements were conducted all around the volcano reflecting the diverse vegetation communities on the lavas, climatic conditions around Hekla mountain and various intensities in deposition of loose material. Multivariate analysis was used to identify groups with similar vegetation composition and patterns in the vegetation. The association of vegetation and soil parameters with lava age, mean annual temperature, mean annual precipitation and soil accumulation rate (SAR) was analysed. Soil carbon concentration increased with increasing lava age becoming comparable to concentrations found on the prehistoric lavas. The combination of a sub-Arctic climate, gradual soil thickening due to input of loose material and the specific properties of volcanic soils allow for continuing accumulation of soil carbon in the soil profile. Four successional stages were identified: initial colonization and cover coalescence (ICC) of Racomitrium lanuginosum and Stereocaulon spp. (lavas 600 years); and highland conditions/retrogression (H/R) by tephra deposition (70−860 years). The long time span of the SC stage indicates arrested development by the thick R. lanuginosum moss mat. The progression from SC into VPD was linked to age of the lava flows and soil depth, which was significantly deeper within the VPD stage. Birch was growing on lavas over 600 years old indicating the development towards birch woodland, the climax ecosystem in Iceland.The Icelandic Research Fund, Rannís, Grant of Excellence no. 152266-052 (Project: EMMIRS).Peer Reviewe

Hekla Volcano, Iceland, in the 20th Century: Lava Volumes, Production Rates, and Effusion Rates

Publisher's version (útgefin grein)Lava flow thicknesses, volumes, and effusion rates provide essential information for understanding the behavior of eruptions and their associated deformation signals. Preeruption and posteruption elevation models were generated from historical stereo photographs to produce the lava flow thickness maps for the last five eruptions at Hekla volcano, Iceland. These results provide precise estimation of lava bulk volumes: V1947–1948 = 0.742 ± 0.138 km3, V1970 = 0.205 ± 0.012 km3, V1980–1981 = 0.169 ± 0.016 km3, V1991 = 0.241 ± 0.019 km3, and V2000 = 0.095 ± 0.005 km3 and reveal variable production rate through the 20th century. These new volumes improve the linear correlation between erupted volume and coeruption tilt change, indicating that tilt may be used to determine eruption volume. During eruptions the active vents migrate 325–480 m downhill, suggesting rough excess pressures of 8–12 MPa and that the gradient of this excess pressure increases from 0.4 to 11 Pa s−1 during the 20th century. We suggest that this is related to increased resistance along the eruptive conduit.Icelandic Research Fund. Grant Number: 152266‐052Peer Reviewe

Historical lava flow fields at Hekla volcano, South Iceland

Publisher's version (útgefin grein)Hekla volcano is known to have erupted at least 23 times in historical time (last 1100 years); often producing mixed eruptions of tephra and lava. The lava flow volumes from the 20th century have amounted 80% to almost 100% of the entire erupted volume. Therefore, evaluating the extent and volume of individual lava flows is very important when assessing the historical productivity of Hekla volcano. Here we present new maps of the historical lava flow fields at Hekla in a digital format. The maps were produced at a scale of 1:2000–10000 using a catalogue of orthophotos since 1945, acquired before and after each of the last five eruptions, combined with field observation of stratigraphy, soil profiles, tephra layers and vegetation cover. The new lava flow maps significantly improve the historical eruptive history of Hekla, prior to the 1947 eruption. The historical lava flow fields from Hekla cover 233 km2 and the lavas reach up to 16 km from Hekla volcano. Flow lengths up to 20 km are known, though lava flows only travelled up to 8–9 km from Hekla in the last 250 years. Identified historical vents are distributed between 0 and 16 km from Hekla volcano and vents are known to have migrated up to 5 km away from Hekla during eruptions. We have remapped the lava flow fields around Hekla and assigned the identified flow fields to 16 eruptions. In addition, ca. 60 unidentified lava units, which may be of historical age, have been mapped. It is expected that some of these units are from known historical Hekla eruptions such as the 1222, 1341, 1510, 1597, 1636 and potentially even from the previously excluded eruptions such as 1436/1439.Hekla hefur gosið 23 sinnum svo vitað sé síðan land byggðist. Oftast hafa gosin verið blandgos og framleitt bæði gjósku og hraun. Í gosum 20. aldar var hlutfall hrauns á milli 80–100% af gosefnunum svo þau skipta verulegu máli þegar framleiðni eldstöðvarkerfisins er metin. Í þessari grein eru birtar niðurstöður stafrænnar kortlagningar á Hekluhraunum frá sögulegum tíma eins langt aftur í tímann og unnt er. Þetta er engan veginn auðvelt viðfangsefni á svo virku eldfjalli sem Hekla er, því ný hraun hylja þau sem fyrir eru. Hraunakortin eru gerð í mælikvarða 1:2000–10000 og styðjast við uppréttaðar loftmyndir sem teknar hafa verið síðan 1945, bæði fyrir og eftir síðustu fimm eldgos. Einnig er stuðst við innbyrðis afstöðu hraunanna, landslagsform, jarðvegssnið, gjóskulög og gróðurþekju. Tekist hefur að bæta talsvert hraunakort Heklu og gert hefur verið kort af hraunum sem runnu fyrir gosið mikla 1947. Hraun frá eldstöðvarkerfi Heklu á sögulegum tíma þekja u.þ.b. 233 km2 lands. Hraun hafa runnið allt að 16 km vegalengd frá megineldstöðinni og hraunstraumar hafa náð 20 km lengd. Á síðustu 250 árum hafa hraun þó aðeins runnið 8–9 km frá megineldstöðinni. Eldvörp á sögulegum tíma dreifast allt að 16 km út frá megineldstöðinni. Í sumum gosum hefur eldvirknin færst um allt að 5 km út frá eldstöðinni þega leið á gosið. Borin hafa verið kennsl á hraun frá 16 gosum og að auki hafa um 60 hraunflákar verið kortlagðir sem gætu verið frá gosum á sögulegum tíma. Þessi hraun eru líklega frá þekktum gosum, s.s. 1222, 1341, 1510, 1597 og 1636 en þau gætu líka verið að einhverju leyti frá gosum sem þótt hafa vafasöm, á árunum 1436–1439.Icelandic Research fund, Grant of Excellence No. 152266-052 (Project EMMIRS)Peer Reviewe

The configuration, sensitivity and rapid retreat of the Late Weichselian Icelandic ice sheet

The fragmentary glacial-geological record across the Icelandic continental shelf has hampered reconstruction of the volume, extent and chronology of the Late Weichselian ice sheet particularly in key offshore zones. Marine geophysical data collected over the last two decades reveal that the ice sheet likely attained a continental shelf-break position in all sectors during the Last Glacial Maximum, though its precise timing and configuration remains largely unknown. Within this context, we review the available empirical evidence and use a well-constrained three-dimensional thermomechanical model to investigate the drivers of an extensive Late Weichselian Icelandic ice-sheet, its sensitivity to environmental forcing, and phases of deglaciation. Our reconstruction attains the continental shelf break across all sectors with a total ice volume of 5.96×105km3 with high precipitation rates being critical to forcing extensive ice sheet flow offshore. Due to its location astride an active mantle plume, a relatively fast and dynamic ice sheet with a low aspect ratio is maintained. Our results reveal that once initial ice-sheet retreat was triggered through climate warming at 21.8 ka BP, marine deglaciation was rapid and accomplished in all sectors within c. 5 ka at a mean rate of 71 Gt of mass loss per year. This rate of ice wastage is comparable to contemporary rates observed for the West Antarctic ice sheet. The ice sheet subsequently stabilised on shallow pinning points across the near shelf for two millennia, but abrupt atmospheric warming during the Bølling Interstadial forced a second, dramatic collapse of the ice sheet onshore with a net wastage of 221 Gt a−1 over 750 years, analogous to contemporary Greenland rates of mass loss. Geothermal conditions impart a significant control on the ice sheet's transient response, particularly during phases of rapid retreat. Insights from this study suggests that large sectors of contemporary ice sheets overlying geothermally active regions, such as Siple Coast, Antarctica, and NE Greenland, have the potential to experience rapid phases of mass loss and deglaciation once initial retreat is initiated

Unclear boundaries between the Directorate of Internal Revenue and the Directorate of Tax Investigations: Boundaries between „tax planning“, „tax avoidance“ and „tax evasion“

Ritgerð þessi ber heitið: Óljós mörk eftirlitsskrifstofu ríkisskattstjóra og embættis skattrannsóknarstjóra ríkisins: Mörkin á milli: „skattahagræðis“, „skattasniðgöngu“ og „skattsvika“. Í ritgerðinni leitast höfundur við að svara þeirri spurningu: Hvar mörkin liggja á milli skattahagræðis og skattasniðgöngu annars vegar og skattasniðgöngu og skattsvika hins vegar? Höfundur leitast við að svara rannsóknarspurningunni samkvæmt hinni „dogmatísku“ lögfræðilegu aðferð með hliðsjón af dómum Hæstaréttar, úrskurðum yfirskattanefndar, lögum, reglugerðum, bókum og fræðiritum. Skoðaður er munurinn á skatteftirliti annars vegar og skattrannsókn hins vegar en ekki hafa verið lagðar skýrar línur um mörkin þar á milli. Skattahagræðing og skattasniðganga falla undir það fyrrnefnda og skattsvik það síðarnefnda. Höfundur telur því nauðsynlegt að gerður sé skýr greinarmunur á milli hugtakanna „skattahagræði“, „skattasniðganga“ og „skattsvik“ en í ritgerð þessari mun höfundur rýna í hvert hugtak fyrir sig og reyna að komast að niðurstöðu á því hvaða háttsemi fellur undir hvaða hugtak. Enda hefur það mikla þýðingu fyrir réttarstöðu skattaðila að rétt embætti vinni úr málefnum þess og sambærileg mál séu rannsökuð á sambærilegan máta. Eins og niðurstaða ritgerðarinnar leiðir í ljós er skýr greinarmunur á milli „skattahagræði“ annars vegar og „skattasniðgöngu“ og „skattsvika“ hins vegar, en mörkin eru óljósari á milli þeirra tveggja síðarnefndu. Það sem lestur ritgerðar þessarar mun leiða í ljós er annars vegar að skattahagræði er lögmæt hagræðing á greiðslu skatta og skattasniðganga er á skjön við lög. Hins vegar er munurinn á skattasniðgöngu og skattsvikum sá að skattasniðganga stangast ekki beint á við ákvæði skattalaga en fela frekar í sér misnotkun á ákvæðum laganna, en skattsvik eru bein brot á lögum og varða þau við refsingu.The name of this thesis is: Unclear boundaries between the Directorate of Internal Revenue and the Directorate of Tax Investigations: Boundaries between „tax planning“, „tax avoidance“ and „tax evasion“. The author seeks answers to the question: Where lie the boundaries between tax planning and tax avoidance on the one hand and tax avoidance and tax evasion on the other hand? The author seeks to write the thesis and answer the research question using the „dogmatic“ legal approach by reviewing judgments from the Supreme Court, Internal Revenue Board, law, regulations, books and literature. The difference between Directorate of Internal Revenue and Directorate of Tax Investigations will be examineded but the boundaries between these two have not been fully determined. Tax planning and tax avoidance falls under the scope of the former and tax evasion under the scope of the latter. The author finds it necessary that clear distinction is made between the concepts. It has great significance for legal status for taxpayers that the appropriate directorate will handle their affairs and that similar cases are investigated in a similar way. As the conclusion of the thesis reveals there is a clear distinction between „tax planning“ on one hand and „tax avoidance“ and „tax evasion“ on the other hand but the distinction of the latter two is less clear. What the thesis will revel is that tax planning is a legitimate streamlining of tax payments and tax avoidance is an effort made by taxpayers to mitigate taxes by illegal means. However, the difference between tax avoidance and tax evasion is that tax avoidance does not conflict directly with provisions of the tax law but is an abuse of the law, how ever tax evasion is a direct punishable violation of the law

"Þó dáleiða blíðast og dilla mér sætast-draumarnir mínir sem aldrei rætast". (Úr Systurnar í Grænadal). Um ástina og trúna í skáldsögunum Gestir og Systurnar frá Grænadal.

Í ritgerðinni er fjallað um ástina og trúna í verkum Maríu Jóhannsdóttur og Kristínar Sigfúsdóttur, Systurnar frá Grænadal og Gestir. Ástin og trúin eru viðfangsefni sem verða ekki skilin að í verkunum, þau leggja grunninn hvort að öðru og eru gríðarlega mikilvæg. Þessi hugtök virðast hafa átt hug og hjarta margra höfunda í kringum tuttugustu öldina og eiga jafnvel enn. María og Kristín eru aðeins tvær af mörgum merkum kvenrithöfundum, sem hafa ekki fengið þá athygli sem þeim ber. Fórnin var áberandi í skáldsögum kvenna á fyrstu tveim áratugum tuttugustu aldarinnar, en hún tengist þeim hugtökum sem eru aðal umfjöllunarefni ritgerðarinnar, ástinni og trúnni. Fórnin er áberandi í samskiptum kynjanna og í hjónabandinu, konan fórnar sér fyrir hagsmuni eiginmanns og barna, það var köllun kvenna. Uppeldi kvenna og samfélagið allt var gegnsósa af þeim skilaboðum að hagsmunum þeirra væri best borgið með því að bæla drauma sína og þrár fyrir hið hefðbundna hlutverk sem þeim var ætlað – að vera eiginkonur, mæður og húsfreyjur. Þetta kemur skýrt fram í báðum sögunum. Fórnin tengist trúnni og ástin samskiptum kynjanna. Það er augljóst af skrifum þessara kvenna að þær velta fyrir sér hlutverki sínu í lífinu og það endurómar þá kvennabaráttu sem var að hefjast á Íslandi. Hugmyndin um hlutverk og köllun konunnar átti eftir að taka breytingum, sem gekk ekki þrautalaust fyrir sig eins og flestir vita

Stokkseyri - bærinn minn : sögurammi og fróðleikur

Eftirfarandi ritgerð er lokaverkefni til B.Ed. prófs við Menntavísindasvið Háskóla Íslands. Í henni er að finna greinargerð um Söguaðferðina þar sem fjallað er um upphaf söguaðferðinnar, tilgang hennar og uppbyggingu. Þar er einnig að finna kennismiði ásamt kenningum þeirra. Að lokum er að finna söguramma og fróðleik um Stokkseyri. Verkefnið er unnið út frá því að fræða nemendur um bæinn sinn og hvernig hann hefur breyst á 50 árum. Verkefnið miðast við nemendur í 2. - 4. bekk. Með notkun á Söguaðferðinni er auðvelt að samþætta kennslugreinar og þannig að skapa heildstæðari kennslu