Surface watercourses as sources of karst water pollution

Abstract

The water discharge and quality of three small watercourses entering the Moravian Karst Protected Landscape Area (Czech Republic) was evaluated and compared. The impact of the wastewater and agricultural management system employed in their catchment areas was assessed. The differences among the watercourses were related to the land use, presence of municipalities, and wastewater treatment plants in their basins. The parameters which showed good quality for all streams were temperature, pH, and organic compounds. The main difference was in the content of nutrients, namely nitrate nitrogen, ammonia nitrogen, and phosphorus. Agricultural run-offs caused an increase in nitrate nitrogen, while untreated sewage provoked a rise in ammonia nitrogen. All watercourses were rich in dissolved oxygen, and thus part of the ammonia nitrogen was probably nitrified, whereas the produced nitrates remained in the water column. Untreated sewage was identified as the main source of phosphorus. The land use in the vicinity of the watercourses affected not only the extent of pollution, but also the self-purifying ability of the streams, which was supported by environments like forests or meadows. However, in karst areas the self-purifying ability can be reduced due to the sinking of surface watercourses underground. The research showed the importance of adequately protecting the areas adjacent to the Protected Landscape Area, because small watercourses carrying pollution from their catchment areas beyond the geological border of the karst directly affect the karst water quality.

Spatial and Temporal Variations of Nitrogen and Phosphorus in Surface Water and Groundwater of Mudong River Watershed in Huixian Karst Wetland, Southwest China

“…In karst areas, where the hydraulic connection between surface water and shallow groundwater is complicated and variable, nitrogen and phosphorus pollution concerns both surface and groundwater. Non-point source pollution of nitrogen and phosphorus in karst areas have been reported across the world, for example, in China [4,10,11], Mexico [12], United States [13,14], Ireland [6], Czech Republic [15], and Turkey [16]. These studies help draw attention to the nitrogen and phosphorus pollution of surface water and groundwater in karst areas and provide some scientific guidance for controlling it.…”