Valuable Secondary Habitats or Hazardous Ecological Traps? Environmental Risk Assessment of Minor and Trace Elements in Fly Ash Deposits across the Czech Republic

Deposits of coal combustion wastes, especially fly ash, are sources of environmental and health risks in industrial regions. Recently, fly ash deposits have been reported as habitat surrogates for some threatened arthropods in Central Europe. However, the potential environmental risks of fly ash have not yet been assessed in the region. We analysed concentrations of 19 minor and trace elements in 19 lignite combustion waste deposits in the Czech Republic. We assessed their environmental risks by comparison with the national and EU legislation limits, and with several commonly used indices. Over 50% of the samples exceeded the Czech national limits for As, Cu, V, or Zn, whilst only V exceeded the EU limits. For some studied elements, the high-risk indices were detected in several localities. Nevertheless, the measured water characteristics, the long-term presence of fly ash, previous leaching by acid rains, and the low amount of organic matter altogether can infer low biological availability of these elements. We presume the revealed high concentrations of some heavy metals at some studied sites can be harmful for some colonising species. Nevertheless, more ecotoxicological research on particular species is needed for final decision on their conservation potential for terrestrial and freshwater biota.info:eu-repo/semantics/publishedVersio

Bioaccumulation of chemical elements at post-industrial freshwater sites varies predictably between habitats, elements and taxa: A power law approach

Elevated environmental levels of elements originating from anthropogenic activities threaten natural communities and public health, as these elements can persist and bioaccumulate in the environment. However, their environmental risks and bioaccumulation patterns are often habitat-, species- and element-specific. We studied the bioaccumulation patterns of 11 elements in seven freshwater taxa in post-mining habitats in the Czech Republic, ranging from less polluted mining ponds to highly polluted fly ash lagoons. We found nonlinear, power-law relationships between the environmental and tissue concentrations of the elements, which may explain differences in bioaccumulation factors (BAF) reported in the literature. Tissue concentrations were driven by the environmental concentrations in non-essential elements (Al, As, Co, Cr, Ni, Pb and V), but this dependence was limited in essential elements (Cu, Mn, Se and Zn). Tissue concentrations of most elements were also more closely related to substrate than to water concentrations. Bioaccumulation was habitat specific in eight elements: stronger in mining ponds for Al and Pb, and stronger in fly ash lagoons for As, Cu, Mn, Pb, Se, V and Zn, although the differences were often minor. Bioaccumulation of some elements further increased in mineral-rich localities. Proximity to substrate, rather than trophic level, drove increased bioaccumulation levels across taxa. This highlights the importance of substrate as a pollutant reservoir in standing freshwaters and suggests that benthic taxa, such as molluscs (e.g., Physella) and other macroinvertebrates (e.g., Nepa), constitute good bioindicators. Despite the higher environmental risks in fly ash lagoons than in mining ponds, the observed ability of freshwater biota to sustain pollution supports the conservation potential of post-industrial sites. The power law approach used here to quantify and disentangle the effects of various bioaccumulation drivers may be helpful in additional contexts, increasing our ability to predict the effects of other contaminants and environmental hazards on biota.info:eu-repo/semantics/publishedVersio

Marihuana: drug or medicine?

Diploma thesis "Marihuana: drug or medicine?" deals with recent change of a medicine law and with process enabling treatment by marihuana. It identifies stakeholders and advocacy coalitions involved in the law and public policy enforcement and explains what is the motivation for these coalitions and on which values is the motivation based. Using event analysis this thesis shows timeline of events moving towards the change of the law and reveals the stakeholders who are significant for the change. Their public speeches are analyzed and stakeholders are divided into advocacy coalitions on the basis of the analysis. The conclusion of the qualitative content analysis is verified by half structured interviews with stakeholders representing the coalitions. Three coalitions were identified in cannabis subsystem. First of them is liberal and tries to get the legalization trough, the second one tries to enable a treatment by marihuana for patients and the third coalition is skeptic to cannabis treatment. The thesis explains a participation of these coalitions on the change and their relations to each other

Development of professional and public policy discourse in certain documents of antidrug policy in the Czech Republic

This paper deals with a development of certain aspects of discourse between authors of technical and policy science papers pertaining to antidrug policies in time period of 1993 - 2010. The basic question of my research is: What kind of discourse has been taking place among the authors of these documents? I try to asses whether this discourse has changed over the years and how. I analyze those selected documents that were essential for establishing of antidrug policy and development this policy has undergone from the beginning until now. My paper examines progress and changes in labeling the problem itself, labeling of actual users and approach to proposed solutions. Analysis of content focuses on hidden meanings in the language used and uncovers attitudes and opinions of the authors in regard of drug problem. My study also describes the development of antidrug policy in Czech Republic during the above mentioned period and in this context describes and labels those aspects of system of values that have served as basis for key documents of antidrug policy. As a theoretical framework I have chosen a theory based on premiss that language used by authors of the documents also has impact on the situation of the actual users themselves

Are Reproductive Traits Related to Pollen Limitation in Plants? A Case Study from a Central European Meadow

The deficiency of pollen grains for ovule fertilization can be the main factor limiting plant reproduction and fitness. Because of the ongoing global changes, such as biodiversity loss and landscape fragmentation, a better knowledge of the prevalence and predictability of pollen limitation is challenging within current ecological research. In our study we used pollen supplementation to evaluate pollen limitation (at the level of seed number and weight) in 22 plant species growing in a wet semi-natural meadow. We investigated the correlation between the pollen limitation index (PL) and floral traits associated with plant reproduction or pollinator foraging behavior. We recorded significant pollen limitation for approximately 41% of species (9 out of 22 surveyed). Seven species had a significant positive response in seed production and two species increased in seed weight after pollen supplementation. Considering traits, PL significantly decreased with the number of pollinator functional groups. The relationship of PL with other examined traits was not supported by our results. The causes of pollen limitation may vary among species with regard to (1) different reproductive strategies and life history, and/or (2) temporary changes in influence of biotic and abiotic factors at a site