Abstract: A water culture experiment was conducted to study the uptake of nitrogen (N) in simulated eutrophic water by 2 Salix integra clones (‘Yizhibi’ and ‘Weishanhu’), and the routine depletion technique was adopted to approach the uptake kinetics of NH₄⁺-N and NO₃^--N by the root systems of these two clones. In low concentrations of eutrophic water, the 2 clones could effectively remove N, with the removal rate of total N being >90%, which was 2 times as that in high concentrations of eutrophic water. The 2 clones could also effectively remove phosphorous (P), with the removal rate of total P reached 80% and 92% in the low and high concentrations of eutrophic water, respectively. Compared with ‘Weishanhu’, ‘Yizhibi’ had a higher efficiency in removing total N and total P, and the 2 clones performed better in higher concentrations of the simulated eutrophic water. Under the conditions of only existing NH₄⁺-N or NO₃^--N, ‘Weishanhu’ had greater maximum N uptake rate and N affinity than ‘Yizhibi’; when the other N sources existed, the NH₄⁺-N or NO₃^--N uptake rate of the two clones fell down to 50%. It was concluded that these 2 clones performed well in the ecological remediation of eutrophic water, and could be chosen as the better tree species for non-point source pollution control.

Key words: Ecopath massbalance model, Yellow River estuary and adjacent waters, energy flow, swimming crab, ecological carrying capacity.