科研之友
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摘要
Treatment of lake sediments with salts is a promising approach for preventing phosphorus release from sediments. Five 35-d treatments of undisturbed sediment cores in the East Lake, Wuhan, China were applied under anoxic conditions: nothing added (control), Al(2)(SO(4))(3) added, FeCl(3) added, CaCl(2) added, and NaNO(3) added. To identify changes in the P binding sites in the sediment caused by the treatments, different P binding forms were extracted from the sediment before and after the treatments. We found that the mean P release rates for anoxic treatments with Al(2)(SO(4))(3), FeCl(3), CaCl(2) and NaNO(3) were -0.6, 0.03, 0.6 and 2.6 mg/(m(2)center dot d), respectively, while the P release rate with no additives was 7.3 mg/(m(2)center dot d). In suboxic conditions, the concentration of total phosphorus (TP(average) 657 mg/kg) in sediment was much lower than that of untreated sediment (TP(average) 688 mg/kg) and treatments with salts (TP(Al(2)(SO(4))(3)) 793 mg/kg, TP(FeCl(3)) 781 mg/kg, TP(NaNO(3)) 802 mg/kg, TP(CaCl(2)) 747 mg/kg). We also found that adding CaCl(2) prevented P release because of apatite formation and because P(Ca) (Ca bound P) increased at the sediment surface. Addition of Fe(3 ) and NO (3) (-) to the sediment increased the amounts of P(Fe, Mn) (Redox-sensitive P, mostly Fe and Mn compounds), since iron oxide has the ability to combine P. Addition of Al(2)(SO(4))(3) increased the fraction of P(Al, Fe) (P bound to metal oxides (Al, Fe)) and decreased the P and Fe in the water above the anoxic sediment, showing the greater ability of Al in binding P. The results showed that Al(2)(SO(4))(3), FeCl(3), CaCl(2) and NaNO(3) all had an effect in controlling phosphorus release. The effect was related to the forms of phosphorus existing in the sediment before treatment and the forms resulting after adding the four reagents. The combination of Al(3 ) or Fe(3 ) with NO (3) (-) promises to be a reasonable chemical treatment for increasing the P retention capacity of sediments in eutrophic lakes. If chemical treatment is combined with bioremediation, the aim of environmental repair may be achieved.
- 出版日期2009-9
- 单位武汉大学
