| 1. |
- Andrén, Margareta, et al.
(författare)
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Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland
- 2016
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Ingår i: Journal of Geophysical Research - Solid Earth. - 2169-9313 .- 2169-9356. ; 121:4, s. 2315-2337
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Tidskriftsartikel (refereegranskat)abstract
- Chemical analysis of groundwater samples collected from a borehole at Hafralækur, northernIceland, from October 2008 to June 2015 revealed (1) a long-term decrease in concentration of Si and Naand (2) an abrupt increase in concentration of Na before each of two consecutive M > 5 earthquakes whichoccurred in 2012 and 2013, both 76 km from Hafralækur. Based on a geochemical (major elements and stableisotopes), petrological, and mineralogical study of drill cuttings taken from an adjacent borehole, we areable to show that (1) the long-term decrease in concentration of Si and Na was caused by constant volumereplacement of labradorite by analcime coupled with precipitation of zeolites in vesicles and along fracturesand (2) the abrupt increase of Na concentration before the first earthquake records a switchover tononstoichiometric dissolution of analcime with preferential release of Na into groundwater. We attributedecay of the Na peaks, which followed and coincided with each earthquake to uptake of Na along fracturedor porous boundaries between labradorite and analcime crystals. Possible causes of these Na peaks are anincrease of reactive surface area caused by fracturing or a shift from chemical equilibrium caused by mixingbetween groundwater components. Both could have been triggered by preseismic dilation, which was alsoinferred in a previous study by Skelton et al. (2014). The mechanism behind preseismic dilation so far from thefocus of an earthquake remains unknown.
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| 2. |
- Eliaeson, Karin, et al.
(författare)
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Relationships of geochemistry and multiple sclerosis
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main aim of this study has been to investigate how registers and databases of geochemistry can be combined with registers of patient data in epidemiological studies. By testing the hypothesis that Multiple Sclerosis (MS) varies with geography and investigating if the variation can be explained by natural variability of zinc in different media, difficulties have been identified and recommendations for future epidemiological studies with similar scope are given. Multiple sclerosis (MS) is a chronic neurological illness that affects nerve cells in the central nervous system (CNS). It belongs to a group of illnesses called autoimmune diseases where the immune system attacks the body's own tissue. The onset of autoimmune reactions is not fully understood. Autoimmune diseases are believed to be multifactorial where both intrinsic factors (e.g. genetics, age, hormones) and environmental factors (e.g. infections, diet, drugs, chemicals etc.) may contribute to the induction, development and progression of the disease. There is a general believe that the epidemiological pattern of MS vary with geography, but even though the systematic study of MS started in 1929 the comparison of prevalence studies over the world still is very difficult and the results are not reliable. Iron, zinc, manganese, copper and molybdenum are examples of important building blocks for almost all living organisms and are thus termed essential elements. They originally derive from the Earth's crust and are taken up in organisms from soil, air and water. For some metals, no biological, nutritional or biochemical function has been established (yet) and they are thus termed non-essentials. The level of exposure to essential and non-essential elements is of crucial importance for the effect on living organisms. A too high dose can be toxic while a too low dose of essential elements will cause deficiency and consequent higher vulnerability for the exposure to toxic compounds or non-essential elements. In this study we have initially focused to check if the occurrence of MS could be correlated to background levels of zinc (Zn) since zinc is an element that participates in several important reactions in the body. We used the Swedish MS-register, which includes almost all MS-patients in Sweden. The best resolution on where the patients live is given on post code areas. Spatially distributed census data over postcode areas, valid for December 2005 and compiled by Official Statistics of Sweden, Statistics Sweden (SCB), were used in this study. Geochemical data from soil (till), stream-water and groundwater from the Swedish Geological Survey have been compiled into postcode areas. The analyzed data on the distribution of MS-patients indicate that a geographical pattern could be found with higher prevalence of MS in the county of Västerbotten and clusters around larges cities. No north -south or east-west gradient of the prevalence was found. However, visual interpretation of prevalence measures is strongly biased towards large post code areas, masking the variation of prevalence measures of small areas. This effect is striking in larger cities always having a large number of small post code areas. Combination of the patient registers and the geochemical registers was evaluated with multivariate analysis (MVA) and as a univariate study for zinc solely, but no correlation between the prevalence of MS and the occurrence of natural background levels of elements were found. Registers were analyzed both separately and together, but none of these models increased the degree to which variance was explained. This does not mean that no relationship between MS and geochemistry is possible but that correlations could not be found with the data, methods and models used in this project. The most important conclusion from this study is that to combine patient data with any kind of exposure data with a geographical variation, the administrative division (i.e. parishes, post code areas etc) are less appropriate. Divisions with respect to natural (geographical) borders such as catchment areas would be more useful for epidemiological purposes where a geographic component is of interest. To fulfil this, population data for catchment areas is needed. The density of the patient data and the exposure data is also of crucial importance. Moreover, there must be a variation in the exposure data large enough to result in a difference between areas. It is recommended that also the areas where no disease is found to be included in epidemiological studies. In these regions high or low levels of elements can also be present. The use of average values over districts is problematic. A high density of sampling in an area does not necessarily mean that the calculated mean value is representative for the whole area. How well an average value for a district describes the actual value depends both on the natural variability of substances in the media as well as the sampling density (i.e. high variance but many samples could give the same average value as low variance and few samples).
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| 3. |
- Skelton, Alasdair, et al.
(författare)
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Changes in groundwater chemistry before two consecutive earthquakes in Iceland
- 2014
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 7:10, s. 752-756
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Tidskriftsartikel (refereegranskat)abstract
- Groundwater chemistry has been observed to change before earthquakes and is proposed as a precursor signal. Such changes include variations in radon count rates(1,2), concentrations of dissolved elements(3-5) and stable isotope ratios(4,5). Changes in seismicwave velocities(6), water levels in boreholes(7), micro-seismicity(8) and shear wave splitting(9) are also thought to precede earthquakes. Precursor activity has been attributed to expansion of rock volume(7,10,11). However, most studies of precursory phenomena lack sufficient data to rule out other explanations unrelated to earthquakes(12). For example, reproducibility of a precursor signal has seldom been shown and few precursors have been evaluated statistically. Here we analyse the stable isotope ratios and dissolved element concentrations of groundwater taken from a borehole in northern Iceland between 2008 and 2013. We find that the chemistry of the groundwater changed four to six months before two greater than magnitude 5 earthquakes that occurred in October 2012 and April 2013. Statistical analyses indicate that the changes in groundwater chemistry were associated with the earthquakes. We suggest that the changes were caused by crustal dilation associated with stress build-up before each earthquake, which caused different groundwater components to mix. Although the changes we detect are specific for the site in Iceland, we infer that similar processes may be active elsewhere, and that groundwater chemistry is a promising target for future studies on the predictability of earthquakes.
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| 4. |
- Tengvall, Katarina, 1980-
(författare)
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Genetic Studies in Dogs Implicate Novel Genes Involved in Atopic Dermatitis and IgA Deficiency
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents genetic studies of atopic dermatitis (AD) and IgA deficiency in dogs.AD is a chronic inflammatory and pruritic skin disorder caused by allergic reactions against environmental allergens. Both genetic and environmental factors are involved in the development of Canine AD (CAD) and human AD. In Paper I, we performed genome-wide association studies (GWAS) and identified a locus on chromosome 27 significantly associated with CAD in German shepherd dogs (GSDs). The locus contains several genes and fine-mapping indicated strongest association close to the candidate gene PKP2. In Paper II, we performed additional fine-mapping and identified four highly associated SNPs located in regions with transcriptional regulatory potential in epithelial and immune cells. The risk alleles were associated with increased transcriptional activity and the effect on expression was cell-type dependent. These data indicate that multiple cell-type specific enhancers regulate the expression of PKP2, and/or the neighboring genes YARS2, DNM1L and FGD4, and predispose GSDs to CAD.IgA deficiency is the most common primary immune deficiency disorder in both humans and dogs, characterized by a higher risk of recurrent mucosal tract infections, allergic and other immune-mediated diseases. In Paper III, we performed the widest screening (to date) of serum IgA levels in dog breeds (Ndogs=1267, Nbreeds=22) and defined eight breeds as predisposed to low IgA levels. In Paper IV, we performed GWAS in four of the breeds defined as prone to low IgA levels. We used a novel percentile groups-approach to establish breed-specific cut-offs to perform analyses in a close to continuous manner. In total, 35 genomic loci were suggestively associated (p<0.0005) to IgA levels, and three genomic regions (including the genes KIRREL3 and SERPINA9) were genome-wide significantly associated with IgA levels in GSDs. A ~20kb long haplotype on chromosome 28, significantly associated to IgA levels in Shar-Pei dogs, was positioned within the first intron of the gene SLIT1 overlapping with a possible dog domestication sweep.This thesis suggests novel candidate genes involved in two immune-mediated disorders in the dog. Hopefully, these results will become an important resource for the genetic research of the corresponding human diseases.
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