Impact of calcium peroxide dosage on the control of nutrients release from sediment in the anoxic landscape water
2019
Wang, Yi | Wang, Wen-Huai | Lu, Xin-Xin | Feng, Lin-Lin | Xue, Fu-Rong | Sun, Lu-Qin
The anoxic and reductive aquatic environment is formed easily in summer due to the global warming, which may accelerate endogenous release. In this experiment, four different dosages of calcium peroxide (CaO₂) were adopted to study the control effects of nutrients release from the sediments in the simulated landscape waters. The results demonstrated that CaO₂ addition could effectively improve the physicochemical properties and microbial composition in sediments, and an obvious improvement was achieved with a larger dosage. It was observed that the surface sediments of experiment groups were oxidized to form a capping barrier between the sediment and overlying water, which might cut off the pollutant diffusion in sediment. Meanwhile, CaO₂ could decrease the nutrients concentration in water obviously, and the reduced effect was positively correlated with the CaO₂ dosage. Compared with the nutrients release fluxes in CK (105.89 mg-TN m⁻² day⁻¹, 106.48 mg-NH₄⁺-N m⁻² day⁻¹, 4.14 mg-TP m⁻² day⁻¹, and 4.30 mg-SRP m⁻² day⁻¹), the CaO₂ dosages of 0.12 and 0.18 kg m⁻² could entirely inhibit the nutrients release from sediment, and partially reduce the original pollutants in the overlying water. However, 0.18 kg m⁻² CaO₂ would cause a higher increase of pH value and NO₂⁻-N concentration, and bring potential risk to the aquatic ecosystem. Therefore, 0.12 kg-CaO₂ m⁻²-sediment was selected as the optimal dosage by considering the control effect, economic cost, and potential risk comprehensively. In general, this study provided a quantitative usage method of CaO₂, which is convenient and effective to prevent or control the nutrients release from sediment caused by anoxic and reductive condition in summer.
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