Trends in Water Quality in Laborec River, Slovakia

Abstract

The Water Framework Directive (2000/60/EC) demands new approaches for managing and improving surface and groundwater quality across the European Union, with emphasis shifting from chemical towards ecological water quality standards. The variation of pollutant concentrations in surface waters shares broad interest by scientists and researchers in the field of water pollution control. Changes in water quality resulting from land-use activities on a watershed can make water unusable for some purposes although it can still be acceptable for other. In some instances, we are required by laws or regulations to prevent water-quality characteristics from being degraded from natural or background conditions, and these characteristics are a key provision in the water-quality standards. Most important environmental problems in river water quality are eutrophication, acidification and emission dispersion. Monitoring of river quality is primarily done to detect the status and trends and to identify whether observed trends are due to natural or anthropogenic causes. Trend analyses were conducted for data on concentrations of pollutants provided by Slovak Water Management Enterprise. Concentration data series of CHSK, NO2, NO3, NH4, and P with a monthly time step were generated for each parameter in seven river profiles in river Laborec (eastern Slovakia). Trends were identified using the Mann-Kendall (MK) test, which is a non-parametric statistical test widely employed for identifying monotonic trends in water quality time series. Mostly decreasing trends were classified.