Buffle Jacques, Zhang Zeshi, Startchev Konstantin
Analytical and Biophysical Environmental Chemistry (CABE), University of Geneva, Sciences II, 30 quai E. Ansermet, CH-1211 Geneva 4.
Environ Sci Technol. 2007 Nov 15;41(22):7609-20. doi: 10.1021/es070702p.
In the computation of metal flux in aquatic systems, at consuming surfaces like organism membranes, diffusion processes of metal ions, ligands, and complex species, as well as the kinetic and thermodynamic aspects of their chemical interactions, must be considered. The properties of many natural ligands, however, are complicated (formation of successive complexes for simple ligands, polyelectrolytic properties and chemical heterogeneity for macromolecular ligands, large size distribution and fractal structure for suspended aggregates). These properties should be properly modeled to get the correct values of the chemical rate constants and diffusion coefficients required for flux computations. The selection of the most appropriate models and parameter values is far from straightforward. This series of papers discusses the various models and compiles the parameters needed for the three most important types of complexants found in aquatic systems: the small, simple ligands, the fulvic and humic compounds, and the colloidal "particles" or aggregates. In particular, new approaches are presented to compute the rate constants of metal complex formation, with both fulvics/humics and particles/aggregates. The method to include the site distribution of fulvics/humics and the size distribution of particles/aggregates in metal flux computation at consuming interfaces is also discussed in detail. These models and parameters are discussed critically and presented in the same framework, forthe computation of metal flux in presence of any of the above complexants or mixtures. Such parameters, largely spread in the literature, are gathered here and selected specifically for environmental applications. The focus in Part I of the series is on simple ligands and fulvic/humic compounds. Part II deals with particulate and aggregate complexants.
在计算水生系统中的金属通量时，在诸如生物膜等消耗表面，必须考虑金属离子、配体和络合物的扩散过程，以及它们化学相互作用的动力学和热力学方面。然而，许多天然配体的性质很复杂（简单配体形成连续络合物，大分子配体具有聚电解质性质和化学不均一性，悬浮聚集体具有大尺寸分布和分形结构）。为了获得通量计算所需的化学速率常数和扩散系数的正确值，应该对这些性质进行适当的建模。选择最合适的模型和参数值绝非易事。这一系列论文讨论了各种模型，并汇编了水生系统中发现的三种最重要类型的络合剂所需的参数：小分子简单配体、富里酸和腐殖酸化合物以及胶体“颗粒”或聚集体。特别是，提出了计算与富里酸/腐殖酸以及颗粒/聚集体形成金属络合物的速率常数的新方法。还详细讨论了在消耗界面处的金属通量计算中纳入富里酸/腐殖酸的位点分布和颗粒/聚集体的尺寸分布的方法。对这些模型和参数进行了批判性讨论，并在同一框架内呈现，用于计算存在上述任何一种络合剂或混合物时的金属通量。这些在文献中广泛分布的参数在此收集，并专门为环境应用进行了选择。该系列第一部分的重点是简单配体和富里酸/腐殖酸化合物。第二部分涉及颗粒状和聚集体络合剂。
