Florence T M, Morrison G M, Stauber J L
CSIRO Centre for Advanced Analytical Chemistry, Menai, N.S.W., Australia.
Sci Total Environ. 1992 Sep 7;125:1-13. doi: 10.1016/0048-9697(92)90377-5.
Knowledge of trace element speciation in waters is essential to an understanding of aquatic toxicity and bioaccumulation, as well as to the partitioning of elements between water and colloidal and particulate phases. In natural waters, only very small percentages of the dissolved heavy metals, such as copper, lead cadmium or zinc, are present as free (aquo) metal ion; most of the metal is adsorbed to colloidal particles or combined in complexes. For aquatic toxicity studies, the aim of the speciation measurement is to determine the fraction of total dissolved metal (the 'toxic fraction') that will react with, and be transported across, a biological membrane such as a fish gill. In this review, a range of trace element speciation techniques is discussed and compared. A simple anodic stripping voltammetric method is recommended for the measurement of the fraction of electroactive metal in a sample, i.e. the fraction of total dissolved metal that can be deposited into a mercury electrode at the natural pH of the sample. The electroactive fraction is believed to approximate the toxic fraction. A rapid ion exchange method, suitable for field use, is proposed for the determination of the toxic fraction of copper in waters.
了解水中微量元素的形态对于理解水生毒性和生物累积以及元素在水相、胶体相和颗粒相之间的分配至关重要。在天然水中，溶解态重金属（如铜、铅、镉或锌）中只有非常小的百分比以游离（水合）金属离子的形式存在；大部分金属被吸附到胶体颗粒上或结合在络合物中。对于水生毒性研究，形态测量的目的是确定总溶解态金属中会与生物膜（如鱼鳃）发生反应并穿过该膜的部分（“毒性部分”）。在本综述中，对一系列微量元素形态分析技术进行了讨论和比较。推荐一种简单的阳极溶出伏安法来测量样品中电活性金属的比例，即在样品的自然pH值下可沉积到汞电极中的总溶解态金属的比例。据信电活性部分近似于毒性部分。提出了一种适用于现场使用的快速离子交换法来测定水中铜的毒性部分。
