凹凸棒黏土覆盖对沉积物磷赋存形态的影响

Influence of attapulgite clay capping on phosphorus forms in the sediment

通过实验室模拟实验,研究了800℃热处理凹凸棒黏土覆盖对沉积物中磷的赋存形态影响,采用连续化学提取法和31P核磁共振(31P NMR)分析了覆盖过程中磷的形态变化,并借助扫描电镜能谱仪(SEM-EDS)对磷的形态转化机理进行初步探讨.结果表明,热处理凹凸棒黏土覆盖使沉积物表层中的活性磷平均含量从308.6mg/kg降低到241.1mg/kg,钙磷的平均含量从204.9mg/kg增加到257.3mg/kg.31P NMR分析发现,黏土覆盖使有机磷中的DNA-P、焦磷酸盐和单脂磷的含量分别减少47.0%、36.8%和31.3%.扫描电镜能谱分析发现,沉积物表层附着的白色絮状物质主要为钙结合态磷.以上分析初步表明,磷形态转化机制是由于材料中具有较高的活性钙含量,竞争吸附沉积物中的活性磷,材料覆盖沉积物表层后改变了沉积物界面环境,促进了表层沉积物的活性磷向钙结合态磷(Ca-P)转化.

Influence of sediment capping on phosphorus speciations using 800℃-heated natural calcium-rich attapulgite were researched, sequential chemical extraction and 31p nuclear magnetic resonance （31p NMR） were used to analyze the changes of phosphorus speciations during sediment capping period, and mechanism of phosphorus forms transformation were analyzed by Scanning Electron Microscope （SEM-EDS）. The results indicated that active phosphorus content was reduced from 308.6mg/kg to 241.1 mg/kg, and calcium phosphorus content was increased from 204.9mg/kg to 257.3mg/kg Results from 31p NMR analysis showed that DNA-P, pyrophosphate and single lipid content were decreased by 47.0%, 36.8% and 31.3%, respectively. Results of SEM-EDS analysis indicated that the white flocculent deposits on the surface of sediment were mainly calcium phosphate. The above analysis preliminary showed that mechanisms of phosphorus forms transformation were due to the high content of active calcium in the material and the changes of surface sediment environment after sediment capping, which promoted phosphorus speciations transformed from active phosphorus to calcium phosphorus.