The article discusses the range and course of changes in the thermal regime of 14 rivers in Poland over the period 1961-2010. Eleven rivers are located in the Central European Plain, and the others flow in the foothills of the Carpathians Mountains. Statistical analyses take into consideration the results of daily measurements of water temperature carried out at 16 hydrological stations by the Institute of Meteorology and Water Management-National Research Institute. In the first part of the analysed period water temperature in most rivers declined in relation to its mean value for the entire study period . In 1987 there was a reverse trend: the temperature started rising. The fastest increase in water temperature was recorded in the western part of the study area, and it became slower towards the east. In the southern part of the study area (the foothills) changes of that kind were not observed. The mean yearly temperature of fluvial waters in the Central European Plain showed a positive trend, ranging from 0.17 to 0.27°C (10 years) -1 , whereas it did not change in the rivers in the foothills of the Carpathians Mountains. Its fastest rise was recorded in spring, and it reached from 0.08 to 0.43°C (10 years) -1 . The increase in water temperature correlated strongly with rising air temperature. The temperature of river waters in the lowlands is believed to be a good indicator of climatic changes.

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Copper mining generates large quantities of waste, tailings, and acid outflows causing long-term environmental impacts and potential threats to human health. Valea Şesei is the largest tailing impoundment in Romania, created by flooding the valley (known as Valea Şesei) of the Metalliferous Mountains (a division of the Apuseni Mountains) with copper mining waste. The present study (i) estimated the total volume of tailings in this area; (ii) screened the concentration of 65 elements (rare earth and platinum group elements, alkali metals and alkali earth metals, transition and post-transition metals and metalloids) and cyanide concentrations in wastewater samples collected from tailing impoundment; (iii) evaluated the toxicity of these water samples using five in vitro bioassays employing human cells isolated from healthy donors and a short-term (1 h) exposure model. The sampled waters were highly acidic (pH 2.1–4.9) and had high electrical conductivity (280–1561 mS cm−1). No cyanides were detected in any sample. Water samples collected from the stream (AMD) inflowing to the tailing impoundment were characterized by the greatest concentrations of alkali metals, alkaline earth metals, transition and post-transition metals, metalloids, rare earth elements, and noble metal group. At other sites, the elemental concentrations were lower but remained high enough to pose a relevant risk. The greatest magnitude of in vitro toxic effects was induced by AMD. Observed alterations included redox imbalance in human neutrophils followed by lipid peroxidation and decreased cell survival, significant aggregation of red blood cells, and increased prothrombin time. The study highlights that Valea Şesei is a large sink for toxic elements, posing environmental and health risks, and requiring action to prevent further release of chemicals and to initiate restoration of the area.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-017-9782-y) contains supplementary material, which is available to authorized users.

The objective of this study is to determine the usefulness of results of hydrological observations (1961-2015) carried out in a deep lake for the assessment changes in the ice-thermal regime of a shallow lake. The paper is based on results of daily values of surface water temperature and ice phenomena in shallow Lake Łebsko and deep Lake Charzykowskie. Similar, statistically significant, positive trends of water temperature were determined in both lakes (0.26°C 10 year-1 in Lake Łebsko and 0.25°C 10 year-1 in Lake Charzykowskie). The fastest increase in mean monthly water temperature in the analysed period (1961-2015) occurred in May (3.37°C in Lake Charzykowskie) and April (2.76°C in Lake Łebsko). The majority of elements of the thermal regime of surface waters in shallow lakes were generally determined to be similar to the same elements in deep lakes, and the effect of climatic changes on the thermal regime of both lakes was found to be similar. Less similarity is observed between elements of the ice regime, particularly in date of decline of the ice cover.

Abstract. The paper discusses the course of air temperature in the years 1961-2014 in Chojnice (Central European Lowland), and its effect on water temperature and occurrence of ice cover on Lake Charzykowskie. An increase in mean annual air temperature was determined by 0.31 o C per 10 years, and its even faster increase in the winter season (December-March), by 0.37 o C per 10 years on average. An increase in mean annual water temperature in the lake by 0.24 o C per 10 years also occurred. An increase in air and water temperature in winter months caused a reduction of the period of occurrence of ice cover. In the years 1961-2014, the persistence of ice cover was subject to a decrease by 3.7 days per 10 years on average, and the mean thickness of the ice cover decreased from 30 to 19 cm.