DGT法原位测量水体中金属有效态组分及动力学研究

In situ measurements of available composition and dissociation kinetics of metals in water using DGT

根据不同厚度扩散膜DGT(梯度扩散薄膜)对金属络合易解离态解离能力差异性这一原理,提出了一套计算金属解离动力学及有效态组分方法,并将其应用于水体Zn、Ni、Cu、Fe、Mn、Cd、Pb等金属形态及运移动力学特征差异性计算中。结果表明,研究提出的计算方法,克服了原有方法过拟合的缺点,可以不借助第三方金属形态分析软件一次性计算出金属有效态含量、组分构成及K-1值,且计算结果更好地体现出有效态中络合易解离部分的贡献,计算公式假设参数少,避免了金属价态、有机质组分构成差异性等因素对有效态含量计算的影响。

The principles of different diffusion layer thickness of diffusive gradients in thin films（DGT）with different dissociation abilities of metal complexes were used to determine the dissociation rate constants and the component composition of metal concentrations. A theoretical model based on this principle was developed to analyze the differences in metal forms and dissociation kinetic constants of Zn, Ni,Cu,Fe, Mn, Cd, and Pb in freshwater. The results showed that the new calculation method overcame the overfitting problem of the original method. Labile concentrations, components, and kinetic constants（K-1）of seven metals in water solution can be calculated in one system without auxiliary morphological analysis software. The contribution of metal complexes to labile concentrations was reflected easily. The theoretical model had a smaller number of parameters, hypothesis and the effects of the metal valence, organic components can be neglected in our system.