| Popis: |
The aim of this study was to examine if the sediments were washed out from the Jordán reservoir due to the rupture of the temporary dam to the Tismenický brook and then to the Lužnice river. The aim of the work was to assess the degree of their contamination with mercury and the possible environmental risk as well. The detailed literature research focused on determination of mercury in sediments was conducted at first. Then, the characteristics of the analytical method serving for mercury determination using an AMA 254 spectrometer were calculated. After that, the contents of mercury in individual samples of sediments were determinedand the degree of the environmental contamination was evaluated. Analytical andecological aspects of this study were taken into account. The measurements were related to samples taken from eight sampling sites during the six months from November 2013 to June 2014. The sediments were taken from four depths. Localities upstream the reservoir contained very low content of mercury. Its concentration corresponded to the natural background observed in sediments (the natural occurrence of Hg in the environment). The higher concentrations of Hg were determined in samples taken from sampling sites downstream the reservoir. However,these values corresponded to the natural occurrence of this element as well. The increased mercury concentrations (1.0365 mg/kg ? 0.0398) were obtained for samples taken from the site lying close ahead of the confluence of the Tismenický brook and the Lužnice river. This value exceeded the legislative limit (regulation No. 13/1994 Sb. The higher concentrations of mercury were determined for samples taken from the Lužnice river downstream the confluence compared to samples taken upstream the confluence. It is due to the rupture of the temporary dam (in December 2012 and June 2013) that resulted in washing out the sediments from the Jordán reservoir. This ecological disaster led to the change in natural mercury occurrence in localities downstream the reservoir. |
