This paper presents the impact of salinisation on the aquatic mollusc fauna in flooded mine subsidences in the Karvina region (Czech Republic). The results of the previous research on salinity in flooded mine subsidences show that some of them contain a high content of dissolved inorganic substances (above 1000 mg·l-1). These substances can affect the vegetation and animals occurring in the water and the surrounding area. The phylum of Mollusca was selected as a model group for the fieldwork as it includes species with the proven bioindication potential.
The occurrence of aquatic mollusc species was studied at 10 sites. The sites were selected based on the content of dissolved substances (the salinity gradient from <500 to >1000 mg·l-1. A total of 12 aquatic mollusc species were found, including one species identified as a potential bioindicator of the negative effect of salinisation on aquatic biota.
The analysis showed statistically significant positive correlations between the content of dissolved inorganic substances and the presence of alien species Potamopyrgus antipodarum (J.E. Gray, 1843). The gradient of salinity significantly affects the species composition of the mollusc fauna in flooded mine subsidences and may affect the biodiversity of this group.
Ethnic return migration is a widespread strategy for migrants from economically disadvantaged coun-tries. This article is about those ethnic return migrants who might successfully migrate thanks to their ancestors; their decision is based upon economic, pragmatic or rationalistic incentives aside from their diasporic feeling of belonging. Although this phenomenon has already been studied, scholars still mostly refer only to the benefits proposed by immigration policy as a key to understanding it. The impact of policy in the country of emigration on ethnic return migration is understudied. This article fills this gap. I found that when the Soviet Union introduced an attractive policy for Ukrainians/Russians in terms of study or work opportunities and the inhabitants in the Ukrainian Soviet Republic were quick to proclaim themselves as Ukrainians or Russians, the dissolution of the Soviet Union quickly changed this motiva-tion. Ukrainians with Czech ancestors started to aim at obtaining official status as Czech members of the diaspora because of the benefits proposed by the Czech government (mainly permanent residency). However, it is difficult to prove the required link to one’s Czech ancestors due to Soviet-era documents in which the column with the Czech nationality of people’s ancestors is often missing. These observa-tions lead to the conclusion that an attractive immigration policy aimed at the diaspora should not be treated as the only comprehensive explanation for ethnic return migration. Ethnic policy in the country of emigration also shapes this kind of migration and – in this concrete case – could even discourage ethnic return migrants.
The ground source of drinking water for the village of Skalice nad Svitavou is located 35 km North of Brno (Czech Republic). An evaluation of developments in selected indicators of water quality in this groundwater source in the period 2013–2017 was the essence of this work. The data was provided by Vodárenská akciová společnost, a.s., i.e. the operator. At the same time, annual monitoring of water quality in the Úmoří stream, which flows through the catchment area and can affect the quality of groundwater, was carried out. Water samples were collected in 2017–2018 from 6 profiles on the Úmoří stream and its two tributaries. Raw water from the groundwater source does not meet the requirements for drinking water in some indicators and needs to be treated. Monitoring of surface water shows that the most problematic indicator is total phosphorus, the concentration of which exceeded limit values on all sampling profiles. The highest values were found in the tributaries, where total phosphorus concentrations exceeded 10 mg∙dm–3. There are 12 municipalities in the area of interest, only two of which have their own sewage treatment plant. It is clear from the results that wastewater in some municipalities is discharged directly into the recipient and is the cause of above-limit concentrations of both phosphorus and nitrogen. Intensively used agricultural land is another major source of pollution. Based on an analysis of sources of pollution, corrective measures have been proposed to improve the quality of surface and groundwater in the area.
The article examines the language biographies of two generations of a family of German origin in the Czech Republic from the end of World War II to the present day. The content analysis of the biographies is based on the application of the narrative interview method developed in qualitative sociology. The analysis of the data obtained by this method follows the stages in the language use of the two informants in coping with the challenge of the language policies of the state.