Characterization of aquatic colloids and macromolecules. 1. Structure and behavior of colloidal material.

Parts 1 and 2 of this series are tutorial feature articles exceptionally published as Critical Reviews for editorial reasons. They intend to give to the nonspecialist an overview of the major aspects of the characterization of aquatic colloids in perspective of their properties. For this reason, there is a close link between parts 1 and 2, which in reality form one single paper. In these papers, the words colloids and macromolecules refer to any organic or inorganic entity in the size range of 1 nm to 1 μm. In aquatic systems, they form inherently unstable suspensions due to their propensity to undergo conformational changes, aggregate, and then sediment. These factors should be considered carefully in the development of any procedure for the characterization of colloidal material. In this context, part 1 of this series describes the chemical composition and morphology of aquatic colloids and their aggregates, their size distribution, and the main factors that influence the aggregate structure and formation kinetics. Emphasis is placed on structure-behavior relationships of the colloidal material of surface waters. Part 2 discusses some commonly used characterization procedures on the basis of the above properties.