Yamashita Youhei, Jaffé Rudolf
Southeast Environmental Research Center, and Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
Environ Sci Technol. 2008 Oct 1;42(19):7374-9. doi: 10.1021/es801357h.
Natural dissolved organic matter (DOM) is composed of a variety of organic compounds, which can interact with metals in aquatic environments. The interactions between DOM and two metals of environmental concern (Cu(II) and Hg(II)) were studied using fluorescence quenching titrations combined with excitation-emission matrix (EEM) spectra and parallel factor analysis (PARAFAC). This allowed characterizing the specific interactions between eight fluorescent components in DOM and two metals. Triplicate titration experiments showed good reproducibility when assessing the interactions between humic-like components with Cu(ll). Our data show clear differences in metal-DOM interaction for samples of different DOM composition and between two different metals. The results demonstrate that the combination of fluorescence quenching titrations with EEM-PARAFAC was reproducible and sensitive to determine the binding properties of humic-like components with trace metals. The enhancement in fluorescence intensity after its initial decrease for the protein-like components with addition of Cu(II) was observed at mangrove-dominated sites, suggesting changes in the molecular environments of protein-like components due to increased Cu(II) interaction. The application of EEM-PARAFAC in fluorescence quenching studies is a useful tool to evaluate intermolecular DOM and DOM-trace metals interactions.
天然溶解有机物（DOM）由多种有机化合物组成，其在水生环境中能与金属发生相互作用。采用荧光猝灭滴定法结合激发发射矩阵（EEM）光谱和平行因子分析（PARAFAC）研究了DOM与两种环境相关金属（Cu(II)和Hg(II)）之间的相互作用。这使得能够表征DOM中八种荧光成分与两种金属之间的特定相互作用。在评估类腐殖质成分与Cu(ll)之间的相互作用时，三次重复滴定实验显示出良好的重现性。我们的数据表明，不同DOM组成的样品以及两种不同金属之间的金属 - DOM相互作用存在明显差异。结果表明，荧光猝灭滴定与EEM - PARAFAC相结合对于确定类腐殖质成分与痕量金属的结合特性具有可重复性和敏感性。在以红树林为主的地点，观察到添加Cu(II)后，类蛋白质成分在荧光强度最初下降后出现增强，这表明由于Cu(II)相互作用增加，类蛋白质成分的分子环境发生了变化。EEM - PARAFAC在荧光猝灭研究中的应用是评估分子间DOM和DOM - 痕量金属相互作用的有用工具。
