表层沉积物(生物膜)非残渣态组分的选择性萃取分离及其吸附铜/锌的特性

采用化学萃取技术对表层沉积物(生物膜)的非残渣态组分(铁、锰氧化物及有机质)进行了分离, 并研究了表层沉积物(生物膜)非残渣态和残渣态组分吸附铜、锌的特性. 结果表明, 0.1 mol/L NH2OH·HCl+0.1 mol/L HNO3, (NH4)2C2O4-H2C2O4缓冲溶液和体积分数为30%的H2O2可选择性地萃取分离表层沉积物(生物膜)非残渣态的锰氧化物、铁锰氧化物和有机质, 萃取率为63.15%～97.59%, 同时对非目的组分影响较小; 表层沉积物(生物膜)及其各组分对铜的吸附能力均大于对锌的吸附能力, 且生物膜及其各组分对铜、锌的吸附能力均高于表层沉积物及其相应组分对铜、锌的吸附能力; 表层沉积物(生物膜)非残渣态组分对铜、锌的吸附能力均大于残渣态组分, 且非残渣态组分中锰氧化物的单位吸附能力最强, 其次是铁氧化物, 而有机质的单位吸附能力较弱, 比锰氧化物低2个数量级, 说明生物膜对水体中痕量重金属的迁移转化作用强于表层沉积物, 而表层沉积物(生物膜)中金属(铁、锰)氧化物对水中痕量重金属起主要控制作用.

Selective Extraction and Separation of Non-residual Components in the Surficial Sediments(Surface Coatings) and Adsorption Characteristics of Cu and Zn

The selective separation of non-residual components of surficial sediments(surface coatings) was performed via chemical extraction techniques and then Cu and Zn adsorption to the non-residual components and residual component of surficial sediments(surface coatings) were investigated. The results indicate that 0.1 mol/L NH2OH·HCl+0.1 mol/L HNO3, (NH4)2C2O4-H2C2O4 buffer solution and 30% H2O2 could remove Mn oxides, Fe/Mn oxides and organic materials from the non-residual components of surficial sediments(surface coatings) with the efficiency ranging from 63.15% to 97.59%, and the effects of extraction on non-target components were negligible. Cu adsorption to the surficial sediments(surface coatings) and the individual component of surficial sediments(surface coatings) were much greater than those of Zn, and the adsorption capability of surficial sediments was much smaller than that of surface coatings. Furthermore, Cu and Zn adsorption to the non-residual components of surficial sediments(surface coatings) were much greater than those to residual component, and that the greatest contribution to metals adsorption on a molar basis was from Mn oxides in the non-residual component. Metals adsorption capacities of Mn oxides exceeded those of organic materials by two orders of magnitude, and the estimated contribution of the residual component to metals adsorption was insignificant. These results imply that the role of surface coatings in transformation and cycling of heavy metals in aquatic environments was more important than that of surficial sediments, and the relative importance for controlling heavy metals in aquatic environments was attributed to metal(Fe and Mn) oxides.