[Effect of the first water-sediment regulation on the variations of dissolved inorganic nutrients' concentrations and fluxes in the lower main channel of the Yellow River].

The variations and fluxes of dissolved inorganic nutrients were studied, based on continuously monitored data in the lower main channel of Yellow River (Lijin) during the period of water-sediment regulation in July 2002. Concentrations rang from 169.3 to 273.2 micromol x dm(-3) for NO3- -N, 0.08 to 0.84 micromol x dm(-3) for NO2- -N, 1.39 to 5.04 micromol x dm(-3) for NH4+ -N, with average of 218.6, 0.16, 2.27 micromol x dm(-3), respectively. Concentrations rang from 0.36 to 0.56 micromol x dm(-3) for PO4(3-) -P, 161.4 to 195.8 micromol x dm(-3) for SiO3(2-) -Si, with average of 0.48, 166.7 micromol x dm(-3), respectively. No significant relationship was found between nitrate, phosphate and water discharge during the period of water-sediment regulation, while silicate correlated well with suspended sediment discharge. Water-sediment regulation has no significant effect on the variation of dissolved inorganic nutrients concentrations during 2002 to 2003. But the fluxes proportion of dissolved inorganic nutrients during water-sediment regulation to the whole year is about 50%.