Contributions of commercial fertilizer, mineralized soil nitrate, and animal and human waste to the nitrate load in the Upper Elbe River Basin, Czech Republic

Abstract

Nitrate contamination in the upper Elbe River basin in the Czech Republic is high and has remained relatively constant since monitoring began in the 1960's. Long-term NO3− and discharge data for 138 locations in the Labe, Berounka, Ohře, and Vltava sub-basins has been analyzed. Fifty nine of the locations were sampled for δ15N during low flow conditions. The nitrate, flow, and stable isotopic data were used to evaluate the source term contributions associated with commercial fertilizer, mineralized soil nitrate, and animal and human waste. The relationship between city size and nitrate loading was also examined. The stable isotopic data indicate that about 76% of the nitrate load is from animal and human waste and that human waste water is the major source of river nitrate. Keywords: Nitrogen isotopes, Pollutant source identification, Surface water