Background: Secondary salinity of river water reduces the value of ecosystem services, negatively impacting the entire aquatic ecosystem and reducing the possibility of water use. In Poland, significant anthropogenic salinity of rivers and water reservoirs is usually associated with mining activity consisting of pumping salty mine water into settling ponds or often directly into rivers. However, to assess the reasons for the salinity of the Vistula waters, it is necessary to identify all sources of salt in surface waters, enabling the assessment of the salt load in the waters. Methods: The paper presents four sources of data which have been compiled to propose a valuable method for analyzing the threat of the river. Patrol monitoring was one method of data acquisition, and State Environmental Monitoring data ware also used. Clustering and correlation statistical techniques were used for analysis. Results: Of the 20 physical and chemical parameters analyzed, chloride, calcium sulphate and magnesium ions are important for salinity. Measurements with multi-parameter probes allowed for the identification of increased salinity pressure sites, while flow analyses were required to calculate the load. Conclusions: The Vistula River had the highest concentrations of the analyzed ions in the Silesia Region. The use of patrol monitoring can be highly useful in determining the causes of emerging problems with water quality and supporting State Environmental Monitoring.

Plankton assemblages can be altered to different degrees by mining. Here, we test how diatoms and cladocerans in ponds along a river in southern Poland respond to the cessation of the long-term Pb-Zn mining. There are two groups of subsidence ponds in the river valley. One of them (DOWN) was contaminated over a period of mining, which ceased in 2009, whereas the other (UP) appeared after the mining had stopped. We used diatoms and cladocerans (complete organisms in plankton and their remains in sediments) to reveal the influence of environmental change on the structure and density of organisms. The water of UP pond was more contaminated by major ions (SO₄²⁻, Cl⁻) and nutrients (NO₃⁻, PO₄³⁻) than the DOWN ponds. Inversely, concentrations of Zn, Cd, Cu and Pb were significantly higher in sediment cores of DOWN ponds in comparison to those in the UP pond. Ponds during mining had higher diversity of diatoms and cladocerans than the pond formed after the mining had stopped. CCA showed that diatom and cladoceran communities related most significantly to concentrations of Pb in sediment cores. Comparison of diatom and cladoceran communities in plankton and sediment suggests significant recovery of assemblages in recent years and reduction of the harmful effect of mine-originating heavy metals. Some features of ponds such as the rate of water exchange by river flow and the presence of water plants influenced plankton communities more than the content of dissolved heavy metals.

Mining is recognized to deeply influence invertebrate assemblages in aquatic systems, but different invertebrates respond in different ways to mining cessation. Here, we document the response of the cladoceran assemblage of the Chechło river, S. Poland (southern Poland) to the cessation of Pb-Zn ore mining. The aquatic system includes the river and associated subsidence ponds in the valley. Some ponds were contaminated during the period of mining, which ceased in 2009, while one of the ponds only appeared after mining had stopped. We used Cladocera to reveal how the cessation of mine water discharge reflected on the structure and density of organisms. A total of 20 Cladocera taxa were identified in the sediment of subsidence ponds. Their density ranged from 0 to 109 ind./1 cm³. The concentrations of Zn, Cd, Cu and Pb were much higher in sediments of the ponds formed during peak mining than in the ponds formed after the closure of the mine. Statistical analysis (CCA) showed that Alonella nana, Alona affinis, Alona sp. and Pleuroxus sp. strongly correlated with pond age and did not tolerate high concentrations of heavy metals (Cu and Cd). This analysis indicated that the rate of water exchange by the river flow and the presence of aquatic plants, affect species composition more than pond age itself.

Coal mining activity contributes to energy security and employment occupation, but is associated with environmental deterioration. Coal combustion leads to GHG emissions, while coal mining results in the generation of saline effluents. These effluents are discharged in inland surface waters, applying significant pressure on their quality, with a negative impact on aquatic life and the economy of a region. This study includes water samples that were analyzed in order to investigate the organic compounds, heavy metals, and other physicochemical parameters. Biological monitoring was done according to the Water Framework Directive methodology. The results from an aquatic area in Southern Poland, which indirectly receives coal mine effluents, indicate elevated salinity with excessive chlorides, sulfates, and sodium ions. The water quality of another non-polluted aquatic area was also assessed to examine the impact of indirect coal mine wastewater discharge on this area. The high salinity levels hinder the use of river water for drinking, agricultural, or industrial purposes. The results obtained show high pressure on the ecological status of streams and rivers that receive mine effluents, and on the density and diversity of aquatic invertebrates. This pressure is clearly visible in the structure of benthic communities and in invertebrate diversity. It also contributes to the appearance of invasive species and increasing water salinity. Limiting discharges of mine water transporting large loads of saline substances would reduce the negative impact on the quality of river waters and biological life.