Transmission electron microscopy of the natural organic matter of surface waters

Some components of aquatic natural organic matter (NOM) can be analysed effectively by methods of particle analysis employing transmission electron microscopy in conjunction with multi-method analytical approaches in the field, minimum perturbation techniques for sample handling and technology transfer from the biomedical sciences. The NOM components, include fulvic acids, colloidal fibrils and organic polymers of MW > 30 000. The use of a water-compatible embedding resin permits shape and size analyses of colloidal NOM (1–1000 nm) in ultrathin sections which minimize the misleading dehydration artifacts of the past. Experimentally induced perturbations allow one to follow aggregation/coagulation events at 1 nm resolution, while permitting the analyst to relate some components of coagulum structure to chemical entities. This review presents the current status of attempts to optimize a combination of analytical chemistry and transmission electron microscopy for describing NOM and its behaviour in surface waters.