摘要
To investigate the effects of wastewater treatment plant effluent on nutrient retention in streams, a case study in Modian Creek, which is a typical first-order stream of Ershibu River in Nanfei River basin and predominated by wastewater treatment plant effluent, was conducted. Potentials of ammonium nitrogen (NH4 +-N), nitrate nitrogen (NO3 --N) and soluble reactive phosphorus (SRP) retention were evaluated quantitatively by nutrient spiraling metrics and its influencing factors were identified by means of regression analysis based on tracer experiments and modeling of models. Results showed that the first-order uptake coefficients of NH4 +-N and SRP in the main channel (λ) were an order of magnitude higher than those in the transient storage zone (λs), while the values of λ-NH4 +-N and λs-NH4 +-N were similar to λ-SRP and λs-SRP values, respectively. The mean values of Sw-NH4, Sw-SRP and Sw-NO3 were significantly larger than the whole length of Modian Creek, suggesting that the studied stream had no any ability to retain or remove nitrogen and phosphorus. Since the uptake lengths of both NH4 +-N and SRP were longer than that of NO3 --N, but their uptake velocities were all lower than that of NO3 --N, indicating that NO3 --N retention potential was greater than those of NH4 +-N and SRP. Moreover, significantly adverse impacts of wastewater treatment plant effluent on nitrogen and phosphorus retention were not found through comparison with the published literature of nutrient spiraling studies in the studied stream. Regression analysis suggested that hydrological condition was key drivers influencing nutrient retention in the Modian Creek. Transient storage was significantly correlated with Vf-SRP and U-SRP (both P<0.05), but was independent on NH4 +-N and NO3 --N.
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