Two eruptions from Icelandic volcanoes have in the last years caused widespread dispersalof volcanic ash in the atmosphere. The transportation of tephra from Iceland to mainlandEurope is not an uncommon event and it can cause large disruptions to society. In thisthesis I present the ndings of a tephrochronological study of recent sediment from a bogcalled Trolls mosse in southern Sweden. The results show the presence of recent tephrafrom what is most likely the Grímsvötn eruption in May 2011, but geochemical analysisof the tephra could not conrm the exact origin of it, and a possibility that the Eyafjal-lajökull eruption also has contributed exists. By correlating atmospheric data about thelocation of the ash clouds produced during the eruptions and tephrochronological studiesof where tephra fallout has occurred could improve our understanding of tephra falloutdynamics and could help understand complex fallout patterns for past eruptions.

Iceland is the land-based expression of the Mid-Atlantic Ridge and is one of the most volcanically active regions of the world. Volcanic eruptions on Iceland are a source of geological hazard to humans and the environment due to the release of ash, gases and lava. The composition of the material released is determined by the chemical composition of the surrounding bedrock and the magma upwelling from the Earth’s crust. The effects of historical eruptions on Iceland have been locally devastating and of global impact. The eruption of Lakagígar in 1783-1784 is known to have been the largest eruption in historical time, and is responsible for the death of ~22 % of theIcelandic population. Skeletal fluorosis is a disease that is sometimes observed following large volcanic eruptions. Volcanic ash can travel great distances in the upper atmosphere and spread over vast areas far away from the erupting volcano. Volcanic ash can change incomposition in the atmosphere, and bring about climate-changing effects. Most notably in recent times, violent ash eruptions can also cause problems to the aviation industry, when ash enters and damages airplane engines. Iceland has many active volcanoes and needs to ensure plans for future eruptions are in place. One such measure is an evacuation plan that protects people living close to an active volcano, such as the most lively on Iceland: Hekla, Katla and Eyjafjallajökull.

The diploma thesis focuses on position of Iceland as an international tourism destination. The first chapter defines theoretical framework for the thesis, whereas the second chapter introduces essential information about the country and its macroeconomic environment. The third chapter deals with the topic of Icelandic tourism and its importance for the economy. The influence of the Eyjafjallajökull eruption in 2010 for tourism is taken into account. The following chapter number four is based on questionnaire about attractiveness of Iceland for Czech tourists. The final chapter sumps up trends of Iceland tourism and focuses on other possibilities of development in this field. In the end the forecast of Icelandic inbound tourism is calculated with a method called regression analysis.

Iodine is an important element essential for higher animals. A large part of the global human population suffers from a lack of iodine; elucidation of transfer and mobility of this element in the environment, water, soil, air and in organisms is thus very important. The aim of this work was the elaboration and optimisation of the method for determination of very low concentrations of iodine in the waters. The mass spectrometry with inductively coupled plasma (ICP-MS) technique was used. It has been shown that using of different filter types during sample preparation had no significant effect on the content of impurities in the filtered sample. Antimony was recommended as an internal standard, despite commonly used elements (indium or tellurium). Samples were not preserved because nitric acid caused volatilization of iodine from the sample and the addition of aqueous ammonia had no significant effect. The optimised method was tested on several groups of water samples, including precipitation, surface water and lysimetric waters. From autumn 2009 to summer 2010, a part of the Blanice River (Šumava Mountains, South Bohemia) was sampled. The average content of iodine in samples ranged from 1.48 ? 0.30 ?g?dm-3 (April 2010) to 3.05 ? 0.38 ?g?dm-3 (July 2010). The average content of iodine in samples from all tributaries of the Blanice River ranged between 2.52 ? 1.63 ?g?dm-3 (March 2010) and 3.67 ? 1.37 ?g?dm-3 (July 2010). The concentration of iodine in the monitored surface waters did not change significantly along the flow of the river. The other two streams were sampled near Rapotín village (Jeseníky Mountains, north Moravia). The average contents of iodine were as follow: Annov (upper stream) 1.60 ? 0.65 ?g?dm-3, Annov (lower stream) 1.88 ? 1.18 ?g?dm-3, Salaš (upper stream) 1.77 ? 0.92 ?g?dm-3, Salaš (lower stream) 1.42 ? 0.58 ?g?dm-3. Generally, the data showed that considering iodine, the area of Šumava had slightly higher levels than those observed in the Jeseníky Mountains. Precipitation collected in the South Bohemia (Arnoštov village and city of České Budějovice) and in Jeseníky (Rapotín) contained less iodine compared to surface waters, and rarely exceeded 3 micrograms per liter of water. The situation has changed in the spring of 2010, because of the occurrence of volcanic dust and ash over the Czech Republic. This volcanic cloud came from the sudden activity of the Eyjafjallajökull Volcano (Iceland). In the mentioned period, the contents of iodine in precipitation were increased several times at all sample collection sites. This is an indirect evidence that iodine could be released during volcanic eruptions and transferred over long distances through the atmosphere. It turned out that the wastewater treatment plant can eliminate iodine in wastewater only partially. However, the wastewater treatment plants in the monitored region were too small to evaluate the overall impact on the environment. The maximum iodine content at the outlet of the wastewater treatment plant Prachatice town (South Bohemia) was 28.5 ?g?dm-3, which is several times higher than natural levels in the Živný stream, to which the treated water flows. Lysimetric water samples were collected from lysimeters installed in three nearby plots in Arnoštov village (Šumava, South Bohemia). The highest concentrations of iodine were found on plot where cattle were grazed. These values were significantly higher (average 4.38 ? 1.74 ?g?dm-3) than those obtained from a site used as hay meadow (average 2.69 ? 1.19 ?g?dm-3) or an untreated meadow (average 2.25 ? 1.39 ?g?dm-3). Iodine therefore probably originated from the urine and feces of grazed cattle. This thesis contributes to the total knowledge of iodine, particularly to the part concerning determination of iodine in the hydrosphere.

This master's thesis deals with the issue of volcanic ash as a complex and its impact on aviation, including the volcanic activity itself (conditions for its existence, for existence of eruptions and their basic products). In addition, the thesis also deals with effect of volcanic ash on aircraft and airports, possibilities of its detection or monitoring as well as mechanism of its spreading in airspace. The emphasis is laid mainly on air incidents related to volcanic ash and on danger it poses to the airspace of the Czech Republic.