Long-term and seasonal trends of water parameters in the karst riverine catchment and general literature overview based on CiteSpace.

Although Europe is the continent with the highest proportion of karst areas, where hydrological systems are essential but extremely sensitive, data on the ecological status of karst riverine catchments are scarce. The aim of the present study was to assess the spatial and temporal (long-term and seasonal) variability of the physico-chemical and organic water parameters in the headwaters of the Krka River and its tributaries, as representatives of a typical karst ecosystem, situated in one of the largest karst areas in Europe, Dinarides in Croatia. It is affected in its upper reaches by improperly treated wastewaters, so anthropogenic influences and ecological status were estimated with the aim to present consequences of pollution exposure and importance of strict monitoring of such sensitive karst ecosystems worldwide. Results indicated degraded water quality, poor ecological status, and disturbed seasonal fluctuations at wastewater-influenced sites, primarily due to high levels of nutrients and organic matter. However, improvement was observed downstream in the Krka National Park, confirming the self-purification as important processes in dynamic karst rivers. Natural seasonality, observed at sites without wastewater influence, was mainly driven by fluctuations in water levels and primary production during the year. Literature analysis by CiteSpace pointed to scarce data on this topic worldwide (China and the USA account for 49% of all publications) and in Europe (34%). Therefore, such study is a valuable contribution in presenting the long-term and seasonal variability of ecological water parameters and in providing a more comprehensive understanding of the health of catchment under influence of multiple stressors.