The Masters day of Natural Sciences

Master students at the Faculty of Life and Environmental Sciences and Faculty of Earth Sciences will present their masters projects.

Following students will present their masters projects:

13:05   Sunna Harðardóttir

Title: Spatial distribution and geochemical characterization of Icelandic mantle end-members

Faculty: Faculty of Earth Sciences

Advisor:  Sæmundur Ari Halldórsson, Research Scholar at the Institute of Earth Sciences

Also in the masters committee: Matthew G. Jackson, Professor at UCSB

Abstract

Radiogenic isotopic ratios and major element contents in Icelandic lavas are used to evaluate mantle end-member compositions and their spatial distribution in the Icelandic mantle. A database, entitled the Icelandic Volcanics Isotopic Database (IVID), which includes previously reported 87Sr/86Sr, εNd, εHf, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 187Os/188Os, 3He/4He, δ18O and U-Th decay series isotopic ratios measured in Icelandic lavas, was compiled. Major and trace element contents were also included in the IVID. Isotopic ratios were evaluated, and filter based on improvements in analytical methods, major element chemistry and sample characteristics. The filtered database was used to map the radiogenic isotopic composition of Icelandic lavas by creating isoscapes superimposed on a map of Iceland. Spatial analyses demonstrate that lavas from the off-rift volcanic zones tend to be more geochemically enriched (higher 87Sr/86Sr and 206Pb/204Pb and lower 143Nd/144Nd and 176Hf/177Hf) in their radiogenic isotopic composition than lavas from the axial rift zones. High-MgO (≥ 8 wt%) lavas demonstrate correlations between major elements and isotopic ratios, where the more enriched off-rift volcanic zone lavas are characterized by higher TiO2, Na2O, K2O, FeOT and K2O/TiO2 and lower, SiO2, CaO and Na2O/TiO2. PRIMELT calculations demonstrate that the enriched off-rift volcanic zone lavas are generally produced at lower temperatures and by lower melt fractions, consistent with preferential sampling of geochemically enriched and fertile “plums” at lower degrees of melting; more geochemically depleted lavas on the axial rift zones show higher degrees of melting at higher temperatures, consistent with dilution of enriched plum melts by melts of more depleted and refractory mantle. Isotopically distinct components have been identified in the Icelandic mantle, but major element chemistry cannot distinguish between all of the components. Mixing of mantle components within the Icelandic mantle and melting conditions such as mantle potential temperature, pressure and degree of melting control which mantle component(s) are sampled spatially throughout Iceland.

13:25   Hermann Dreki Guls

Title: Accumulation and biomarker responses in the Atlantic rock crab (Cancer irroratus) exposed to Benzo(a)Pyrene through ingestion of contaminated mussels (Mytilus edulis)

Faculty:  Faculty of Life and Environmental Sciences

Advisor:  Halldór Pálmar Halldórsson, Director of the University of Iceland´s Research Centre in Sudurnes

Also in the masters committee: Jörundur Svavarsson, Professor at the Faculty of Life and Environmental Sciences

Abstract

The aims of this study were to estimate suitability of the Atlantic rock crab (Cancer irroratus) for environmental monitoring through investigation of 7-ethoxyresorufin O-deethylase (EROD), glutathione peroxidase (GPx) and glutathione (GSH) biomarker responses to Benzo(a)Pyrene (BaP) exposure through ingestion, i.e. as potential monitoring tool for Polycyclic Aromatic Hydrocarbons (PAHs) through a laboratory exposure to contaminated prey items. Biomarker responses were measured in hepatopancreas tissue shortly after starvation period as well as after long-term exposure. Blue mussels (Mytilus edulis) were exposed to 2, 20 and 50 µg BaP/L for 14 days after which they had accumulated 11.5, 192 and 417 µg BaP/g tissue dw., respectively. Subsequently, mussels were fed to crabs for 21 days in daily portions of about 4.7 g soft tissue ww. per crab. Assimilation rate of BaP through ingestion in crabs was estimated at < 1%.

Biomarker responses were measured at days 3 and 21 of the experiment. Biomarker values were generally lower than their relative control levels on day 3, likely reflecting degradation of xenobiotic defence systems induced by prolonged starvation. After 21 day of exposure the crabs exhibited significant biomarker response in the highest exposure group, where significantly higher EROD activity and GSH content as well as significantly lower protein content were observed. Biomarker responses proved insufficiently sensitive for implementation in environmental monitoring. This study provides first insight into physiological responses of Cancer irroratus to PAH induced stress post starvation and during long-term exposure

 

13:45   Rúna Björk Smáradóttir

Title: Bacterial community structure and function of Anthelia biological soil crust

Faculty:Faculty of Life and Environmental Sciences

Advisor:  Ólafur S. Andrésson, Professor at the Faculty of Life and Environmental Sciences

Also in the masters committee: Ingibjörg Svala Jónsdóttir, Professor at the Faculty of Life and Environmental Sciences

Abstract:
Biological soil crust (biocrust) dominated by the liverwort Anthelia juratzkana is widespread in the Icelandic highlands. In this study the bacterial community structure and function of the biocrust in various habitats within four areas in the highlands was analysed using high-throughput metagenomic sequencing. A clear difference was found between the biocrust and underlying soil strata both in taxonomic analysis and functional gene analysis.
The most abundant phyla of the biocrust were Acidobacteria, Actinobacteria and Proteobacteria. The phyla Acidobacteria, Armatimonadetes, Bacteroidetes, Chloroflexi and Cyanobacteria were enriched in the biocrust compared to subsurface soil. The most abundant genera were Ktedonobacter of the phylum Chloroflexi, Bradyrhizobium of the phylum Proteobacteria and the Acidobacterial genus Candidatus Solibacter.
No statistical difference in the bacterial composition was found between different habitat types, sample areas or seasons.
Genes encoding various functional pathways were enriched in the biocrust compared to lower soil strata including carbohydrate metabolism, which was among the most abundant functional systems, photosynthesis, motility and chemotaxis, and potassium and sulfur metabolism.

 

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