Impact of lignite mine waters from deep seated drainage on water quality of the Noteć River

Abstract

Open-pit lignite mines affect many compartments of the environment. Surface mines cause changes in the catchment basin, re-shaping the land relief, modifying soil properties and depressing lake water levels as well as the groundwater table. Although the environmental concerns raised by this type of mines have been widely surveyed, we lack sufficient information provided by research reports on regarding the influence of lignite mines there on surface water bodies. In general, there are two types of mine waters from brown coal mining: runoff from the surface and water percolating from deep seated drainage. This paper discusses the impact of lignite mine waters from a deep seated drainage system in the Lubstow Mine on the quality of water in a lowland river. Lignite had been excavated in Lubstow until 2009, and untreated mine waters had been discharged to the Notec River. The aim of the study was to assess possible changes of the river water quality after the long-term contamination with mine waters. For the assessment, three sites were selected (one above and two below the mine water inflow) for water sampling in order to perform chemical analyses according to standard methods (spectrophotometry, atomic absorption spectroscopy). Properties of mine waters, such as pH, conductivity, phosphorus, nitrates, sulphates, alkalinity and heavy metals, were analysed in samples taken directly from the canal which carried discharged mine waters to the Notec River. The results showed that lignite mine waters from deep seated drainage generally caused minor changes in river water quality, except alkalinity, in which the water quality below the discharge point (site B) was significantly worse than at the upper site (A). Chemically, site C was similar to site A.