Comparative study of phosphorus adsorption behaviors in lake sediments over short and long periods of time: implication for the prediction of the release of phosphorus by CaCl2 and NaHCO3 extraction

Huang, Lidong; Li, Zhenxuan; Li, Renying; Wu, Hongsheng

Comparative study of phosphorus adsorption behaviors in lake sediments over short and long periods of time: implication for the prediction of the release of phosphorus by CaCl2 and NaHCO3 extraction

2016

Huang, Lidong | Li, Zhenxuan | Li, Renying | Wu, Hongsheng

Ten sediments were collected from the northern part of Taihu Lake, China. They were incubated for 24 h and 80 days to analyze the adsorption characteristics. After adsorption, the residual sediments were extracted with 0.01 M CaCl₂ and 0.5 M NaHCO₃ separately. Maximum buffer capacities of the Langmuir and Freundlich functions of 80-day incubation were highly correlated with 24 h (R ² = 0.97). A longer time would enhance the resistance of the sediments to P changes in the water. Adsorption and NaHCO₃-P were highly linearly related with R ² > 0.969, but the relationships between 24 h and 80 days were different. The relationships between adsorption and CaCl₂-P could be better explained (97 %) by segmented line models, but the fitting results were affected by incubation time. An interesting finding is that when we plotted the NaHCO₃-P and CaCl₂-P together by a segmented line model, the data showed a uniform trend unrelated to the incubation time. NaHCO₃-P is seldom used to evaluate P status in sediments in comparison with soils. Yet, our results suggested NaHCO₃-P is a good bridge to link the sediments P retention ability and P release risk. Due to its simplicity, NaHCO₃-P has promising potential in predicting the transfer of P from sediments.

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