|
|
Wei Jingsheng and the Democracy Wall Movement (1978 - 1979)
Michálková, Zuzana ; Klimeš, Ondřej (advisor) ; Černošová, Jitka (referee)
Thesis Abstract This thesis focuses on Wei Jingsheng, a Chinese activist, and his concept of demoracy during the Democracy Wall Movement in Beijing (1978 - 1979). It explores the development of democracy in China dating back to the late nineteenth century and until the Democracy Wall Movement. Moreover, it thoroughly introduces the Democracy Wall Movement, which took place in Beijing two years after Mao Zedong passed away and with rise of new leadership under the guidance of Deng Xiaoping. Apart from that, this thesis analyses the following essays, written and published by Wei Jingsheng during the Democracy Wall Movement; The Fifth Modernization: Democracy and Other Things, Qincheng: A Twentieth Century Bastille, Human Rights, Equality, and Democracy and finally Do We Want Democracy of New Dictatorship? The aim of this thesis is to identify the criteria of democracy for Wei Jingsheng. Keywords: China 中國; Wei Jingsheng 魏京生, Democracy 民主, Democracy Wall 西單民主牆, Tiananmen 天安門, Deng Xiaoping 鄧小平
|
|
|
The use of (nano)oxides for metal and metalloid stabilization in contaminated soils
Michálková, Zuzana ; Komárek, Michael (advisor) ; Luke, Luke (referee)
The main objective of the thesis was to evaluate the potential of selected Mn and Fe (nano)oxides for the stabilization of metals and metalloids in contaminated soils. The research was focused basically on three materials - commercial nanomaghemite (Fe III), nanomagnetite (Fe II,III) and a synthetic amorphous Mn oxide (AMO). The main aim of the work was to provide a complex view on the chosen stabilizing amendments regarding not just their direct influence on contaminants mobility and stabilization mechanisms, but also their stability and alterations in soil conditions together with influence on soil microorganisms and higher plants. Firstly, adsorption properties of the tested materials towards Cd, Cu, Pb and As were investigated. In this context, the most effective material showed to be the AMO reaching one to two orders of magnitude higher adsorption capacities than Fe III and Fe II,III under given experimental conditions. Interestingly, the rate of As(V) adsorption onto AMO was increasing with increasing pH as a result of high pHzpc of the AMO (8.1) and significant dissolution of this phase at lower pH values. As a next step, the influence of (nano)oxides on metal(loid)s mobility and other physico-chemical soil characteristics after application to contaminated soil was examined. Again, the AMO proved to be the most efficient in reducing mobile pools of Cd, Cu, Pb, Zn and As. On the other hand, Fe III and Fe II,III addition had generally less significant effects on contaminants mobility. AMO application further resulted in an increase of soil pH connected with AMO dissolution and unwanted decomposition of soil organic matter. When (nano)oxides alterations in soil conditions were observed, MnCO3 coatings were identified on AMO surface while no significant changes were recorded for Fe III and Fe II,III. As the MnCO3 formation was connected with increased AMO stability, AMO particles synthetically covered with MnCO3 coating (denoted as SM AMO) were prepared. Although the SM-AMO had a lower mass loss in soil than pure AMO, the stabilizing efficiency was almost the same for both materials. The differences in surface composition of both materials were decreasing with time as MnCO3 naturally precipitated on the AMO surface in soils while the SM AMO coating was gradually dissolving. When investigating the effect on soil microbiota, AMO efficiently promoted soil microbial activity while no significant changes were observed in the case of Fe III and Fe II,III. The AMO was also able to reduce the uptake of Cd, Pb and Zn by sunflower (Helianthus annuus L.), eliminate Zn phytotoxicity symptoms and increase biomass yield. On the other hand, toxic levels of Mn released from the AMO in an acidic soil were found in sunflower tissues. AMO application is thus recommended for contaminated neutral or slightly alkaline pH with a higher cation exchange capacity in order to avoid unwanted release of Mn. Finally, various types of AMO-biochar composite sorbents were recently prepared and field experiment focused on stabilization of Cd, Pb, Zn and As using studied materials is currently under preparation. The combined results from the thesis highlight the importance of a complex experimental approach dealing with all parts of the contaminated soil environment in order to obtain complete information about the efficiency and usefulness of any newly developed stabilizing amendment.
|
|
|
Zinc in environment and methods of remediation
Landová, Ludmila ; Michálková, Zuzana (advisor) ; Dvořáková Březinová, Tereza (referee)
Zinc and other heavy metals cause negative effects on both the environment and human health. Depending on the concentration of zinc in the ecosystem, it can produce unwanted effects in the environment and on the human. Due to pollution, vegetation may not be able to grow on the contaminated soils, which can further result in strong soil erosion. For these reasons, remediation of soils contaminated with risk elements is necessary to minimize their impact on ecosystems. This bachelor thesis describes properties, utilization, stability and behavior of zinc and other risk elements in the environment, including the removal from contaminated soils using remediation methods.
The experimental part aims at the influence of AMO and Sm-AMO on stability of zinc and risk elements in contaminated soil together with the adsorption kinetics of zinc onto these two materials. The results detected high efficiency of Sm-AMO on sorption of zinc and lead in the test kintetics of adsorption. For most heavy metals
having a similar effect, when Sm-AMO is as efficient as AMO, any cases, it has a higher efficiency.
|
guest ::
RSS feed.