底泥轻组有机质对镧沸石控磷效果的影响

底泥中轻组有机质对其中磷的吸附-释放行为影响显著。镧沸石可有效地控制底泥磷释放，但轻组有机质对控磷效果的影响尚不清楚。因此，考察了镧沸石对原底泥(raw sediment，简称R-S)和去除轻组有机质底泥(light fraction organic removal sediment，简称LFOR-S)中磷释放的控制效果及机理。R-S和LFOR-S的最大磷吸附量分别为2 568 mg·kg⁻¹和2 071 mg·kg⁻¹，投加镧沸石可将其提高到4 054 mg·kg⁻¹和4 014 mg·kg⁻¹。LFOR-S在24 h内磷释放量为R-S的1.61倍。温度从5 ^oC上升到30 ^oC时，镧沸石对R-S的磷释放控制率逐渐升高，而对LFOR-S的磷释放控制率由90%下降到76%后又回到原水平。XPS表征发现，配体交换是镧沸石控制2种底泥磷释放的主要机制。镧沸石可将底泥中非稳定态磷转化为稳定态，但LFOR-S中减少的非稳定磷的并未完全转化为稳定态，而是进入了水相中使其磷释放量高于R-S，导致控磷效果变差。在原位钝化实际工程中，温度升高引起底泥轻组有机质含量下降时，需提高镧沸石投量以获得稳定的控磷效果。

Effect of light fraction organic matter in sediment on its phosphate releasing controlling by lanthanum modified zeolite

Light fraction organic matter in sediment has a significant impact on its phosphorus releasing behavior. Lanthanum Modified Zeolite (LMZ) could effectively control phosphorus release from sediment, but the effect of light fraction organic matter in sediment on its performance was still unclear. Therefore, control of phosphate release from raw sediment (R-S) and light fraction organic removal sediment (LFOR-S) by LMZ were investigated in the present study. The results showed that the maximum phosphate adsorption capacities of R-S and LFOR-S were 2568 and 2071 mg·kg−1, respectively, and they could increase to 4054 and 4014 mg·kg−1 after dosing LMZ, respectively. Phosphate release amount of LFOR-S was 1.61 times of that of R-S within 24 hours, leading to a lower controlling efficiency of LMZ in LFOR-S. Controlling performance of LMZ on phosphate release from R-S gradually became better when the temperature rose from 5 oC to 30 oC, while that of LFOR-S decreased from 90% to 76% and then returned to the original level under the same condition. XPS characterization showed that ligand exchange was the main mechanism of phosphate releasing inhibition by LMZ. LMZ could convert unstable phosphorus in R-S to stable forms, while a completely conversion of decreased liable phosphorus did not occur in LFOR-S, some unstable phosphorus entered water phase which led to a higher release than RS and worse phosphorus release control effect of LMZ. In engineering practice, it is necessary to increase the dosage of LMZ to maintain a stable controlling performance when the amount of light fraction organic matter in the sediment decreased under elevated temperature.