College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China.
College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China.
Sci Total Environ. 2019 Jan 1;646:144-157. doi: 10.1016/j.scitotenv.2018.07.281. Epub 2018 Jul 20.
There is generally a significant heterogeneity in the vertical distribution of mobile phosphorus (P) in sediments, but the previous studies concerning the effect of zirconium-modified zeolite (ZrMZ) addition on the mobilization of P in sediments neglected this feature. In this study, microcosm experiments were conducted to investigate the effect of ZrMZ addition on the mobilization of P in river surface sediments at different depths. A high-resolution diffusive gradients in thin films technology (DGT) was used to measure the concentration of labile P in the overlying water-sediment profiles at a submillimeter vertical resolution. Results showed that the ZrMZ amendment not only could reduce the concentration of soluble reactive P (SRP) in the overlying water, but also could decrease the concentrations of SRP in the pore water at different depths. Furthermore, the ZrMZ amendment resulted in the reduction of both the releasing flux of SRP from sediments to the overlying water and the diffusion flux of SRP from the pore water to the overlying water. After the addition of ZrMZ into the top sediment, the static layer with low DGT-liable P (DGT-P) concentration was observed in the upper sediment. The addition of ZrMZ into the upper sediment resulted in the reduction of mobile P (P) in the upper and lower sediments via the transformation of P to more stable NaOH-extractable P (NaOH-rP) and residual P (Res-P). In addition, the contents of bioavailable P (BAP) including water-soluble P (WSP), readily desorbable P (RDP) and iron oxide paper extractable P (FeO-P) in the upper sediment were greatly reduced by the ZrMZ addition. Results of this study show that the immobilization of pore water SRP, DGT-P, sediment P and sediment BAP by ZrMZ played a very important role in the control of P release from sediments to the overlying water by the ZrMZ amendment.
沉积物中移动磷（P）的垂直分布通常存在显著的异质性，但之前关于锆改性沸石（ZrMZ）添加对沉积物中 P 迁移的影响的研究忽略了这一特征。本研究通过微宇宙实验，研究了 ZrMZ 添加对不同深度河流表层沉积物中 P 迁移的影响。采用高分辨率扩散梯度薄膜技术（DGT），以亚毫米的垂直分辨率测量上覆水-沉积物剖面中可利用磷的浓度。结果表明，ZrMZ 改性不仅可以降低上覆水中可溶性反应磷（SRP）的浓度，还可以降低不同深度孔隙水中 SRP 的浓度。此外，ZrMZ 改性导致 SRP 从沉积物向上覆水的释放通量和 SRP 从孔隙水向上覆水的扩散通量均减少。ZrMZ 添加到顶部沉积物后，在顶部沉积物中观察到具有低 DGT-可利用磷（DGT-P）浓度的静态层。ZrMZ 添加到上覆沉积物中，通过将 P 转化为更稳定的 NaOH 可提取磷（NaOH-rP）和残留磷（Res-P），减少了上覆和下覆沉积物中的移动磷（P）。此外，ZrMZ 添加大大降低了上覆沉积物中生物有效磷（BAP）的含量，包括水溶性磷（WSP）、易解吸磷（RDP）和氧化铁纸可提取磷（FeO-P）。本研究结果表明，ZrMZ 对孔隙水 SRP、DGT-P、沉积物 P 和沉积物 BAP 的固定作用，在控制 ZrMZ 改性对沉积物向上覆水释放 P 方面起着非常重要的作用。
