Keywords: Yellow River, nitrogen transport, flux, pollution monitoring, Bohai Sea, China, nitrogen concentrations, water pollution, environmental pollution, domestic sewage, fertilisers, industrial wastewater, total nitrogen, dissolved nitrogen, solid nitrogen, nitrate nitrogen, water regulation, sediment regulation
Variations of nitrogen transport in the mainstream of the Yellow River, China
Three sections along the mainstream of the Yellow River were chosen as sites for monitoring the concentration variations of nitrogen species. First, the nitrogen in the water was mainly dissolved and dominated by nitrate–nitrogen. Second, the nitrogen concentrations in the middle stream were much higher than those in the upper stream, and close to those in the lower stream. Third, the nitrogen species in the upper stream were mainly related to fertiliser, mostly connected with domestic sewage and fertiliser in the middle stream, and principally induced by industrial wastewater in the lower stream. Fourth, the amount of total nitrogen, dissolved nitrogen, solid nitrogen, and nitrate nitrogen transported to the Bohai Sea by the Yellow River averaged 101.2, 94.6, 6.6, and 81.8 thousand tons, respectively, during the period of 2005 to 2007. Finally, water and sediment regulation had important effects on the nitrogen transport in the Yellow River.