Diffusion principles

Abstract

Ever since contamination of the marine environment began, the processes by which the concentrations of these contaminants increase or decrease have been a subject of investigation. Currents, with their turbulent (eddy) diffusion, are the main cause of distribution and dilution in marine systems, while sorption, precipitation and co-precipitation processes may cause local accumulations, usually in bottom sediments. A process of molecular diffusion cannot be of great significance in the sea, but remains crucial for migration of molecules or ions in interstitial water of bottom sediments, where movement of the pore water itself is negligible.