Greinar - LBHÍ

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Effect of a high-palmitic acid fat supplement on milk production in Icelandic dairy cows fed grass silage-based diet
(Agricultural University of Iceland, 2020) Sveinbjörnsson, Jóhannes; Baldursdóttir, Hrafnhildur; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Thirty-seven dairy cows of the Icelandic breed were used in a change-over design experiment. The aim was to analyse the effects of moderate addition of high-palmitic acid (C16:0) fat supplement to a grass silage-based diet. There were three experimental treatments: a treatment with the fat supplement as powder (FAPOW); a treatment with the fat supplement in pelleted concentrate (FAPEL); and a control treatment (CONTROL). Milk protein content was significantly lower, and there was a tendency (p<0.10) toward a higher milk fat content in the fat treatments. This resulted in significantly higher milk fat:protein ratio in the fat treatments compared to the control (FAPOW 1.21 and FAPEL 1.20; CONTROL 1.15). A significant reduction in the ratio of casein in milk protein due to fat addition explains the reduction in milk protein. The concentration of free fatty acids in milk was higher in the fat treatments, especially FAPEL. The ratio of C16:0 in total fatty acids was increased by the fat treatments.
Reviews and syntheses: Greenhouse gas exchange data from drained organic forest soils: A review of current approaches and recommendations for future research
(Copernicus GmbH, 2019-12-10) Jauhiainen, Jyrki; Alm, Jukka; Bjarnadóttir, Brynhildur; Callesen, Ingeborg; Christiansen, Jesper R.; Clarke, Nicholas; Dalsgaard, Lise; He, Hongxing; Jordan, Sabine; Kazanavičiūtė, Vaiva; Klemedtsson, Leif; Lauren, Ari; Lazdins, Andis; Lehtonen, Aleksi; Lohila, Annalea; Lupikis, Ainars; Mander, Ülo; Minkkinen, Kari; Kasimir, Åsa; Olsson, Mats; Ojanen, Paavo; Óskarsson, Hlynur; Sigurdsson, Bjarni D.; Søgaard, Gunnhild; Soosaar, Kaido; Vesterdal, Lars; Laiho, Raija; Kennaradeild (HA); Faculty of Education (UA); Hug- og félagsvísindasvið (HA); School of Humanities and Social Sciences (UA)
Drained organic forest soils in boreal and temperate climate zones are believed to be significant sources of the greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), but the annual fluxes are still highly uncertain. Drained organic soils exemplify systems where many studies are still carried out with relatively small resources, several methodologies and manually operated systems, which further involve different options for the detailed design of the measurement and data analysis protocols for deriving the annual flux. It would be beneficial to set certain guidelines for how to measure and report the data, so that data from individual studies could also be used in synthesis work based on data collation and modelling. Such synthesis work is necessary for deciphering general patterns and trends related to, e.g., site types, climate, and management, and the development of corresponding emission factors, i.e. estimates of the net annual soil GHG emission and removal, which can be used in GHG inventories. Development of specific emission factors also sets prerequisites for the background or environmental data to be reported in individual studies. We argue that wide applicability greatly increases the value of individual studies. An overall objective of this paper is to support future monitoring campaigns in obtaining high-value data.We analysed peer-reviewed public cations presenting CO2, CH4 and N2O flux data for drained organic forest soils in boreal and temperate climate zones, focusing on data that have been used, or have the potential to be used, for estimating net annual soil GHG emissions and removals. We evaluated the methods used in data collection and identified major gaps in background or environmental data. Based on these, we formulated recommendations for future research.
Persistent albedo reduction on southern Icelandic glaciers due to ashfall from the 2010 Eyjafjallajökull eruption
(Elsevier BV, 2019-11) Möller, Rebecca; Dagsson-Waldhauserova, Pavla; Möller, Marco; Kukla, Peter; Schneider, Christoph; Gudmundsson, Magnus Tumi; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
In April and May 2010 the Icelandic volcano Eyjafjallajökull experienced an explosive eruption that led to substantial ashfall across the central-southern parts of the island. The resulting ash deposits covered Eyjafjallajökull, Mýrdalsjökull and parts of Vatnajökull ice caps. In order to quantify the influence of these deposits on albedo, we analyzed albedo evolution across Eyjafjallajökull and Mýrdalsjökull ice caps over the period 2001–2016 using the MOD10A1 and MCD43A3 data products of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the Terra and Aqua satellites. A geostatistical model with a daily temporal resolution was used to delineate areas on the ice caps that show distinct ash cover-related albedo reductions over the post-eruption period. Results suggest that despite an overall decrease of the ash cover-related albedo reductions with time, noticeable albedo reductions persist on both, Eyjafjallajökull and Mýrdalsjökull over the entire post-eruption period. These reductions show means of 0.19 ± 0.11 and 0.17 ± 0.10, respectively, and occur most prominently during the summer seasons. Persistent albedo reductions are in agreement with and limited to areas of higher ash deposition during the volcanic eruption such as the southern parts of Eyjafjallajökull and Mýrdalsjökull ice caps. In addition, redistribution of Eyjafjallajökull ash deposited on the lowlands in southern Iceland contributed to dust storm events in the years after the eruption and caused additional albedo reductions.
Uptake and surface chemistry of SO2 on natural volcanic dusts
(Elsevier BV, 2019-11) Urupina, Darya; Lasne, Jerome; romanias, manolis; Thiery, Vincent; Dagsson-Waldhauserova, Pavla; THEVENET, Frederic; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
V-dust (v-dust) is a highly variable source of natural particles in the atmosphere, and during the period of high volcanic activity it can provide a large surface for heterogeneous interactions with other atmospheric compounds. Icelandic v-dust was chosen as a case study due to frequency of volcanic eruptions and high aeolian activity in the area. In this study, we focus on the kinetics and mechanism of the reaction of sulfur dioxide (SO2) with natural v-dust samples under atmospheric conditions using coated wall flow tube reactor and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Steady state uptake coefficients determined are in the range of 10−9 to 10−8 depending on the considered v-dust. Concomitantly with SO2 uptake, both sulfites and sulfates are monitored on the surface of v-dust, with sulfates being the final oxidation product, attesting of SO2 surface reaction. Surface hydroxyl groups play a crucial role in the conversion of SO2 to sulfites as evidenced from both flow tube and DRIFTS experiments. Based on these experimental results, a mechanism for SO2 interaction with different surface sites of v-dust is proposed and discussed. This study provides original insights in the kinetics of SO2 uptake under simulated atmospheric conditions and its mechanism and transformation on volcanic material. To that regards, it brings an accurate perspective on SO2 heterogeneous sinks in the atmosphere.
Interactions between the atmosphere, cryosphere, and ecosystems at northern high latitudes
(Copernicus GmbH, 2019-02-14) Boy, Michael; Thomson, Erik; Acosta Navarro, Juan C.; Arnalds, Olafur; Batchvarova, Ekaterina; Bäck, Jaana; Berninger, Frank; Bilde, Merete; Brasseur, Zoé; Dagsson-Waldhauserova, Pavla; Castarède, Dimitri; Dalirian, Maryam; de Leeuw, Gerrit; Dragosics, Monika; Duplissy, Ella-Maria; Duplissy, Jonathan; Ekman, Annica; Fang, Keyan; Gallet, Jean-Charles; Glasius, Marianne; Gryning, Sven-Erik; Grythe, Henrik; Hansson, Hans-Christen; Hansson, Margareta; Isaksson, Elisabeth; Iversen, Trond; Jonsdottir, Ingibjorg; Kasurinen, Ville; Kirkevåg, Alf; Korhola, Atte A.; Krejci, Radovan; Kristjánsson, Jón Egill; Lappalainen, Hanna K.; Lauri, Anniina; Leppäranta, Matti; Lihavainen, Heikki; Makkonen, Risto; Massling, Andreas; Meinander, Outi; Nilsson, Douglas; Olafsson, Haraldur; Pettersson, Jan B.C.; Prisle, Nønne; Riipinen, Ilona; Roldin, Pontus; Ruppel, Meri; Salter, Matthew; Sand, Maria; Seland, Øyvind; Seppä, Heikki; Skov, Henrik; Soares, Joana; Stohl, Andreas; Ström, Johan; Svensson, Jonas; Swietlicki, Erik; Tabakova, Ksenia; Thorsteinsson, Throstur; Virkkula, Aki; Weyhenmeyer, Gesa; Wu, Yusheng; Zieger, Paul; Kulmala, Markku; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI); Raunvísindadeild (HÍ); Faculty of Physical Sciences (UI); Jarðvísindastofnun (HÍ); Institute of Earth Sciences (UI); Umhverfis- og auðlindafræði (HÍ); Environment and Natural Resources (UI); Verkfræði- og náttúruvísindasvið (HÍ); School of Engineering and Natural Sciences (UI)
The Nordic Centre of Excellence CRAICC (Cryosphere–Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011–2016, is the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual centre with the objectives of identifying and quantifying the major processes controlling Arctic warming and related feedback mechanisms, outlining strategies to mitigate Arctic warming, and developing Nordic Earth system modelling with a focus on short-lived climate forcers (SLCFs), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special issue of the journal Atmospheric Chemistry and Physics. This paper presents an overview of the main scientific topics investigated in the centre and provides the reader with a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Faced with a vast amount of scientific discovery, we do not claim to completely summarize the results from CRAICC within this paper, but rather concentrate here on the main results which are related to feedback loops in climate change–cryosphere interactions that affect Arctic amplification.
Vertical distribution of aerosols in dust storms during the Arctic winter
(Springer Science and Business Media LLC, 2019-11-06) Dagsson-Waldhauserova, Pavla; renard, jean-baptiste; Olafsson, Haraldur; VIGNELLES, Damien; Berthet, Gwenael; Verdier, Nicolas; Duverger, Vincent; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
High Latitude Dust (HLD) contributes 5% to the global dust budget, but HLD measurements are sparse. Dust observations from Iceland provide dust aerosol distributions during the Arctic winter for the first time, profiling dust storms as well as clean air conditions. Five winter dust storms were captured during harsh conditions. Mean number concentrations during the non-dust flights were <5 particles cm−3 for the particles 0.2–100 µm in diameter and >40 particles cm−3 during dust storms. A moderate dust storm with >250 particles cm−3 (2 km altitude) was captured on 10th January 2016 as a result of sediments suspended from glacial outburst flood Skaftahlaup in 2015. Similar concentrations were reported previously in the Saharan air layer. Detected particle sizes were up to 20 µm close to the surface, up to 10 µm at 900 m altitude, up to 5 µm at 5 km altitude, and submicron at altitudes >6 km. Dust sources in the Arctic are active during the winter and produce large amounts of particulate matter dispersed over long distances and high altitudes. HLD contributes to Arctic air pollution and has the potential to influence ice nucleation in mixed-phase clouds and Arctic amplification.
Comparison of test-day and lactation models for genetic evaluations of Icelandic dairy cows for production traits and somatic cell score
(Agricultural University of Iceland, 2019) Eiríksson, Jón Hjalti; Sigurdsson, Agust; Jóhannesson, Guðmundur; Eythorsdottir, Emma; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Predicted genetic progress in production traits was compared using three different models for genetic evaluation of Icelandic dairy cows. The models were: a random regression (RR) test-day model, model using lactation yields until day 305 from calving (LAC1), and the model currently used for the national evaluation, based on lactation yield from calving to the end of lactation regardless of the length of the lactation (LAC2). Additionally, genetic evaluation for somatic cell score with RR and LAC1 were compared. Predicted genetic progress for protein yield was highest when using RR, or 0.170 σa/yr, compared with 0.167 σa/yr and 0.158 σa/yr for LAC1 and LAC2, respectively. Results for other production traits were similar. The main reason could be the shorter generation interval when records can be utilized before the end of lactation and reliable estimated breeding values thus obtained earlier. Application of an RR model will be beneficial for genetic evaluation for production traits and somatic cell score.
Aboveground woody biomass of natural birch woodland in Iceland – Comparison of two inventories 1987-1988 and 2005-2011
(Agricultural University of Iceland, 2019) Snorrason, Arnór; Jónsson, Þorbergur Hjalti; Eggertsson, Ólafur; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
The only native tree species in Iceland forming woodland is the mountain birch. Since human settlement in the 9th century AD, natural birch woodlands have decreased from around 28% to 1.5% of the terrestrial area. In this paper we estimated and compared aboveground woody biomass stocks of two sample inventories from 1987-1988 and 2005-2011. Total above- ground woody biomass stocks in 1987-1988 and 2005-2011 were 1503 Gg (SE = 175, n= 272) and 1455 Gg (SE = 180, n= 181), respectively, for the woodland already existing in 1987-1988. The biomass estimates in 2005-2011were not significantly different from the 1987-1988 estimates in the < 2 m height class (P = 0.282) nor in the 2 - 4 m height class (P = 0.673). We concluded that the aboveground woody biomass of the natural birch woodland already existing in 1987-1991 had not changed between the two inventories. Additionally, we estimated an aboveground woody biomass increment of 37 Gg for the woodland expansion occurring between these two inventories.
Effects of reduced water availability and insecticide on damage caused by cabbage root fly larvae
(Agricultural University of Iceland, 2019) Baba, Abdul-Salam Mahamud; Barrio, Isabel C; Halldórsson, Guðmundur; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
The incidence of horticultural pests in combination with increased frequency of extreme weather events, like summer drought, can compromise crop production in Nordic agricultural systems during the already short summer growing season. In particular, rootfeeding insects can severely damage plants when combined with water deficits because root herbivores reduce plant water and nutrient uptake (Zvereva & Kozlov 2012). The cabbage root fly Delia radicum (L.) (Diptera: Anthomyiidae) is a major pest of cauliflower Brassica oleracea (L.) (Brassicales: Brassicaceae) crops in Iceland (Halldorsson 1989). Its larvae feed on roots of brassica plants, initially on root hairs and then by tunnelling into the taproot. Cabbage root flies overwinter as pupae in diapause in the soil around brassica plant roots (Bažok et al. 2012). In Iceland, adults emerge in June and females lay eggs between late June and early July (Halldorsson 1989). Eggs are laid on the soil surface around the base of the stems of brassica plants and are relatively resistant to desiccation (Lepage et al. 2012). In contrast, survival of first-instar larvae is compromised at low levels of soil moisture (Lepage et al. 2012). The aim of this study was to investigate the potential effects of reduced water supply on damage by cabbage root fly on cauliflower plants using a field experiment in Iceland. Specifically, we assessed the effect of reduced water supply on larval densities and on early-season growth of cauliflower plants. We expected reduced biomass production in plants that were not treated with insecticides; we hypothesized that this effect would be aggravated during periods of reduced water availability because the water deficit imposed by root damage would be stronger when combined with reduced water supply.
Genetic parameters for Icelandic dairy cows using a random regression test-day model
(Agricultural University of Iceland, 2019) Eiríksson, Jón Hjalti; Sigurdsson, Agust; Jóhannesson, Guðmundur; Eythorsdottir, Emma; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
A total of 480,495 test-day yield records of 33,052 cows were used to estimate the genetic parameters for daily milk yield (MY), fat yield (FY), protein yield (PY) and somatic cell score (SCS) of Icelandic dairy cows in the first three lactations with a random regression model. Heritability of all traits was lowest in early lactation in all lactations and highest in mid- or late lactation. Heritability of lactation yields for the first lactation was 0.43, 0.39 and 0.41 for MY, FY and PY, respectively, but was estimated as lower when using a lactation model. Heritability of SCS in the first lactation was 0.23 using the random regression model but 0.15 using the lactation model. Heritability of persistency of lactation MY, FY and PY were 0.14-0.24 in all lactations and genetic correlations to the whole lactation SCS were -0.08 to -0.13. Heritability of yields had increased from previous estimates for the breed. Genetic variation of persistency in the population makes change of the lactation curve possible through selection.
Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses
(Wiley, 2019-03-06) Ekman, stina; Lindahl, Anders H.; Rüetschi, Ulla; Jansson, Anna; Björkman, K.; Abrahamsson-Aurell, K.; Björnsdóttir, Sigríður; Löfgren, Maria; Mattsson Hultén, Lillemor; Skiöldebrand, Eva; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Molecular serum markers that can identify early reversible osteoarthritis (OA) in horses are lacking. Objectives: We studied serum concentrations of a novel cartilage oligomeric matrix protein (COMP) neo-epitope in horses subjected to short-term exercise and with acute lameness. The effects of circadian rhythm and age were also evaluated. Study design: Longitudinal studies in healthy horses and cross-sectional comparison of lame and non-lame horses. Methods: Sera were collected from five horses before and after short-term interval exercise and during full-day box rest. Sera from 32 acutely lame horses were used to evaluate age-related effects. Independent samples from control horses (n = 41) and horses with acute lameness (n = 71) were included. COMP neo-epitope concentrations were analysed using custom-developed inhibition ELISAs validated for equine serum. The presence of COMP neo-epitope was delineated in healthy and osteoarthritic articular cartilage with immunohistochemistry. Results: COMP neo-epitope concentrations decreased after speed training but returned to baseline levels post-exercise. No correlations between age and serum COMP neo-epitope concentrations were found (r = 0.0013). The mean (±s.d.) serum concentration of COMP neo-epitope in independent samples from non-lame horses was 0.84 ± 0.38 μg/mL, and for lame horses was 5.24 ± 1.83 μg/mL (P<0.001). Antibodies against COMP neo-epitope did not stain normal articular cartilage, but intracytoplasmic staining was found in superficial chondrocytes of mild OA cartilage and in the extracellular matrix of moderately osteoarthritic cartilage. Main limitations: ELISA was based on polyclonal antisera rather than a monoclonal antibody. There is a sex and breed bias within the groups of horses, also it could have been of value to include horses with septic arthritis and tendonitis and investigated joint differences. Conclusions: This COMP neo-epitope can be measured in sera, and results indicate that it could be a biomarker for pathologic fragmentation of cartilage in connection with acute joint lameness.
A 60 Year Examination of Dust Day Activity and Its Contributing Factors From Ten Icelandic Weather Stations From 1950 to 2009
(Frontiers Media SA, 2019-01-09) Nakashima, Miye; Dagsson-Waldhauserova, Pavla; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
High latitude dust is an important contributor to the global dust cycle, which affects the radiative balance of the atmosphere. The frequency and severity of dust events are driven by variables such as wind speed, precipitation, temperature, surface cover type, and volcanic activity. The extent of impact of glacial retreat is yet to be determined, but glacial outburst floods, known as jökulhlaups, have been suggested to be a significant factor in the seasonal pattern of dust activity, with major jökulhlaups being attributed as a cause for an increase in dust activity in their subsequent year. However, in examination of ten meteorological stations from 1950 to 2009, there does not appear to be sufficient evidence that jökulhlaups are a significant driver of Iceland’s dust activity. Additionally, taking into account a larger range of dust codes, contributions from Icelandic dust plumes are found to be greater than previously assumed, with an average of 128 dust days per year as compared to a previously determined average of 34 dust days annually.
Identification of Ideal Allele Combinations for the Adaptation of Spring Barley to Northern Latitudes
(Frontiers Media SA, 2019-05-03) Göransson, Magnus; Hallsson, Jon; Lillemo, Morten; Orabi, Jihad; Backes, Gunter; Jahoor, Ahmed; Hermannsson, Jónatan; Christerson, Therese; Tuvesson, Stine; Gertsson, Bo; Reitan, Lars; Alsheikh, Muath; Aikasalo, Reino; Isolahti, Mika; Veteläinen, Merja; Jalli, Marja; Krusell, Lene; Hjortshøj, Rasmus L.; Eriksen, Birger; Bengtsson, Therese; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
The northwards expansion of barley production requires adaptation to longer days, lower temperatures and stronger winds during the growing season. We have screened 169 lines of the current barley breeding gene pool in the Nordic region with regards to heading, maturity, height, and lodging under different environmental conditions in nineteen field trials over 3 years at eight locations in northern and central Europe. Through a genome-wide association scan we have linked phenotypic differences observed in multi-environment field trials (MET) to single nucleotide polymorphisms (SNP). We have identified an allele combination, only occurring among a few Icelandic lines, that affects heat sum to maturity and requires 214 growing degree days (GDD) less heat sum to maturity than the most common allele combination in the Nordic spring barley gene pool. This allele combination is beneficial in a cold environment, where autumn frost can destroy a late maturing harvest. Despite decades of intense breeding efforts relying heavily on the same germplasm, our results show that there still exists considerable variation within the current breeding gene pool and we identify ideal allele combinations for regional adaptation, which can facilitate the expansion of cereal cultivation even further northwards.
Not a limitless resource: ethics and guidelines for destructive sampling of archaeofaunal remains
(The Royal Society, 2019-10-02) Palsdottir, Albina Hulda; Bläuer, Auli; Rannamäe, Eve; Boessenkool, Sanne; Hallsson, Jon; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
With the advent of ancient DNA, as well as other methods such as isotope analysis, destructive sampling of archaeofaunal remains has increased much faster than the effort to collect and curate them. While there has been considerable discussion regarding the ethics of destructive sampling and analysis of human remains, this dialogue has not extended to archaeofaunal material. Here we address this gap and discuss the ethical challenges surrounding destructive sampling of materials from archaeofaunal collections. We suggest ways of mitigating the negative aspects of destructive sampling and present step-by-step guidelines aimed at relevant stakeholders, including scientists, holding institutions and scientific journals. Our suggestions are in most cases easily implemented without significant increases in project costs, but with clear long-term benefits inthe preservation and use of zooarchaeologicalmaterial.
Can Volcanic Dust Suspended From Surface Soil and Deserts of Iceland Be Transferred to Central Balkan Similarly to African Dust (Sahara)?
(Frontiers Media SA, 2019-07-03) Đorđević, Dragana; Tosic, Ivana; Sakan, Sanja; Petrović, Srđan; Đuričić-Milanković, Jelena; Finger, David C.; Dagsson-Waldhauserova, Pavla; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI); Tækni- og verkfræðideild (HR); School of Science and Engineering (RU)
In this work we use chemical fingerprints as characteristics ratios of specific crustal elements Ca/Al, Fe/Al, K/Al, Mg/Al, Mn/Al, Ca/Fe, and Mg/Fe to investigate the long-range transport of volcanic aerosols from Iceland. Volcanic dust enters the atmosphere during suspension processes from Icelandic deserts, but mainly from the dust hot spots in remote areas in Iceland, and it is transmitted to the central Balkan area (Belgrade). For this purpose, backward trajectories from Belgrade (φ = 44°48′; λ = 20°28′) in 2012 and 2013, simultaneous with atmospheric aerosols measurements, were calculated by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. We found that about 17% of air masses passed over Icelandic territory and arrived to Balkan area. In almost all of these episodes ratios of some investigated elements in suburban aerosols of Balkan area corresponded to the ratios of elements investigated in surface soil of the Rangárvellir area – South Iceland in the vicinity of volcanoes. We identified several episodes, such as August 6–8, 2012; June 2–6, 2013; June 26–28, 2013; and September 18–20, 2013; with the characteristic ratios of the highest number of investigated elements in atmospheric aerosol of central Balkan corresponding to ratios from Icelandic soil material. This study provides evidence that Icelandic dust can travel long distances showing the importance of High Latitude Dust sources.
Evaluating the carbon sequestration potential of volcanic soils in southern Iceland after birch afforestation
(Copernicus GmbH, 2019-08-06) Hunziker, Matthias; Arnalds, Olafur; Kuhn, Nikolaus; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Afforestation is a strategy to sequester atmospheric carbon in the terrestrial system and to enhance ecosystem services. Iceland's large areas of formerly vegetated and now degraded ecosystems therefore have a high potential to act as carbon sinks. Consequently, the ecological restoration of these landscape systems is part of climate mitigation programmes supported by the Icelandic government. The aim of this study was to explore the change in the soil organic carbon (SOC) pools and to estimate the SOC sequestration potential during the re-establishment of birch forest on severely degraded land. Differently aged afforested mountain birch sites (15, 20, 25 and 50 years) were compared to sites of severely degraded land, naturally growing remnants of mountain birch woodland and grasslands which were re-vegetated using fertilizer and grass seeds 50 years ago. The soil was sampled to estimate the SOC stocks and for physical fractionation to characterize the quality of the SOC. The results of our study show that the severely degraded soils can potentially sequester an additional 20 t C ha−1 (0–30 cm) to reach the SOC stock of naturally growing birch woodlands. After 50 years of birch growth, the SOC stock is significantly lower than that of a naturally growing birch woodland, suggesting that afforested stands could sequester additional SOC beyond 50 years of growth. The SOC fractionation revealed that at all the tested sites most of the carbon was stored in the <63 µm fraction. However, after 50 years of birch growth on severely degraded soils the particulate organic matter (POM) fraction was significantly enriched most (+12 t POM-C ha−1) in the top 30 cm. The study also found a doubling of the dissolved organic carbon (DOC) concentration after 50 years of birch growth. Therefore and due to the absence of any increase in the tested mineral-associated SOC fractions, we assume that the afforestation process evokes a carbon deposition in the labile SOC pools. Consequently, parts of this plant-derived, labile SOC may be partly released into the atmosphere during the process of stabilization with the mineral soil phases in the future. Our results are limited in their scope since the selected sites do not fully reflect the heterogeneity of landscape evolution and the range of soil degradation conditions. As an alternative, we suggest using repeated plot measurements instead of space-for-time substitution approaches for testing C changes in severely degraded volcanic soils. Our findings clearly show that detailed measurements on the SOC quality are needed to estimate the SOC sequestration potential of restoration activities on severely degraded volcanic soils, rather than only measuring SOC concentration and SOC stocks.
Functional diversity of Collembola is reduced in soils subjected to short-term, but not long-term, geothermal warming
(Wiley, 2018-02-28) Holmstrup, Martin; Ehlers, Bodil; Slotsbo, Stine; Ilieva-Makulec, Krassimira; Sigurdsson, Bjarni D.; Leblans, Niki; Ellers, Jacintha; Berg, Matty P.; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
1. Human activities have caused global changes of atmospheric chemistry resulting in increased temperature especially in the colder regions of the northern hemisphere. Since warming of the environment can have drastic effects on terrestrial ecosys-tems it is important to experimentally evaluate the extent of such effects in long-term field-based experiments. In this study we make use of both recent (short-term) and long-term geothermal warming of Icelandic soils to examine the responses of Collembola, an ecologically important group of soil invertebrates, to warming. 2. On the basis of metabolic scaling theory, we hypothesized that species of small size would be more successful in warmed soils than species of larger size. Further we expected that top-soil-dwelling species would benefit more from warming than deep-soil-dwelling species. In order to test these hypotheses we sampled Collembola along replicated gradients of increasing temperature in areas that had been heated for about 6 years and more than 50 years respectively. Collembola were identified to species level, counted and the community-weighted mean trait scores for six functional and ecological traits were calculated. 3. Results show that both short-term and long-term soil warming caused a shift to-wards a higher relative abundance of species with small body size. Furthermore, abundance of top-soil-dwelling Collembola tended to increase after short-term warming, but the opposite was observed after long-term warming.4. Using trait-based diversity indices (FRic and RaoQ), we show that functional rich-ness and diversity of Collembola communities was significantly reduced (almost halved) as a result of short-term soil warming to about 10°C above normal, but this effect was not detected in plots equally warmed for more than 50 years. This in-dicates that the functional diversity of Collembola communities have high resil-ience towards soil warming in a long-term perspective.
Aerosol Concentrations in Relationship to Local Atmospheric Conditions on James Ross Island, Antarctica
(Frontiers Media SA, 2018-12-03) Kavan, Jan; Dagsson-Waldhauserova, Pavla; renard, jean-baptiste; Láska, Kamil; Ambrožová, Klára; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Several important ice-free areas (e.g., Seymour Island, Cape Lamb on Vega Island, Terrapin Hill) are located in the Eastern Antarctic Peninsula region. The largest of these ice-free areas can be found on the Ulu Peninsula, James Ross Island, where this study was undertaken. The Ulu Peninsula covers an area of 312 km2, and has been found to be an important active High Latitude Dust source. In this study, aerosol concentrations and local wind properties are described together with their linkages and typical synoptic situations. The highest aerosol concentrations of 57 μg m-3 for PM10 were detected during high wind speed events that exceeded 10 m s-1, which is also a threshold level for activating local mineral material sources. Surface deposition of dust particles can have significant environmental impacts such as changes in properties of atmosphere or enhanced snow melting.
Factors controlling nitrous oxide emissions from managed northern peat soils with low carbon to nitrogen ratio
(Elsevier BV, 2018-07) Liimatainen, Maarit; Voigt, Carolina; Martikainen, Pertti; Hytönen, Jyrki; Regina, Kristiina; Oskarsson, Hlynur; Maljanen, Marja; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Managed northern peatlands are an important source of the strong greenhouse gas nitrous oxide (N2O). However, N2O emissions from these managed peatlands display a high spatial variability, and processes governing N2O production and emissions from these ecosystems are still not well understood. To constrain the factors regulating N2O emissions from managed northern peat soils, we determined a wide set of soil physical and chemical properties of peatlands with different management histories spread across Finland, Sweden and Iceland. We included eleven peatland sites with available in situ N2O flux data, and complemented our analyses with detailed measurements of soil nitrogen (N) cycling processes such as N2O production, gross N mineralization and gross nitrification and, in addition, soil microbial biomass. This study included drained peatlands with different land-use types and management intensities, comprising forested, cultivated or only drained peatlands and afforested or abandoned agricultural peatlands. All selected peatland sites displayed a low soil carbon to nitrogen (C/N) ratio of 15–27, traditionally used to predict high N2O emissions. Despite the narrow C/N range, the N2O emissions at our sites varied greatly within and between land-use groups, ranging from 0.03 to 2.38 g N m−2 y−1. Thus, our findings provide valuable insights into the regulatory factors underlying the variability in N2O emissions and show that a low C/N ratio in managed peatlands cannot be used to predict high N2O emissions. Instead, our results demonstrate that higher N2O emissions are linked to higher peat phosphorus (P) and copper (Cu) content, suggesting that low P and Cu concentrations can limit N2O production in peat even with sufficient N availability. While known factors such as soil moisture, oxygen content and the degree of peat humification partially explained the variability in N2O emissions, this study directly links soil P and Cu availability to N2O production processes. The availability of P and especially Cu seemed to promote nitrification activities, thereby increasing N2O production. Our study highlights the link between N2O emissions and soil P and Cu availability and the strong coupling of the soil N and P cycles in peatlands, which is to date severely understudied.
Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses
(Springer Nature, 2018-04-17) Marañón Jiménez, Sara; Soong, Jennifer; Leblans, Niki; Sigurdsson, Bjarni D.; Penuelas, Josep; Richter, Andreas; Asensio, Dolores; Fransén, Erik A.; Janssens, Ivan; Auðlinda- og umhverfisdeild (LBHÍ); Faculty of Natural Resources and Environmental Sciences (AUI)
Increasing temperatures can accelerate soil organic matter decomposition and release large amounts of CO2 to the atmosphere, potentially inducing positive warming feedbacks. Alterations to the temperature sensitivity and physiological functioning of soil microorganisms may play a key role in these carbon (C) losses. Geothermally active areas in Iceland provide stable and continuous soil temperature gradients to test this hypothesis, encompassing the full range of warming scenarios projected by the Intergovernmental Panel on Climate Change for the northern region. We took soils from these geothermal sites 7 years after the onset of warming and incubated them at varying temperatures and substrate availability conditions to detect persistent alterations of microbial physiology to long-term warming. Seven years of continuous warming ranging from 1.8 to 15.9 °C triggered a 8.6–58.0% decrease on the C concentrations in the topsoil (0–10 cm) of these sub-arctic silt-loam Andosols. The sensitivity of microbial respiration to temperature (Q10) was not altered. However, soil microbes showed a persistent increase in their microbial metabolic quotients (microbial respiration per unit of microbial biomass) and a subsequent diminished C retention in biomass. After an initial depletion of labile soil C upon soil warming, increasing energy costs of metabolic maintenance and resource acquisition led to a weaker capacity of C stabilization in the microbial biomass of warmer soils. This mechanism contributes to our understanding of the acclimated response of soil respiration to in situ soil warming at the ecosystem level, despite a lack of acclimation at the physiological level. Persistent increases in the respiratory costs of soil microbes in response to warming constitute a fundamental process that should be incorporated into climate change-C cycling models.

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