Models of Sorptive Toxic Substances in Freshwater Systems. III: Streams and Rivers

Abstract

Equations defining the steady‐state distributions of solids and sorptive substances in freshwater streams and rivers are developed and solved analytically. The spatial variations of the flow and suspended solids are incorporated in the chemical equations, which take into account the kinetic and transfer routes of the dissolved and particulate components. The sorptive interaction between these components is characterized by instantaneous equilibrium. The solution for the total concentration of the chemical from which the dissolved and particulate components follow, is developed. Various relationships between the partition coefficient and the solids are incorporated into the equations. The exchange of both the dissolved and particulate components of the chemical between the water column and the bed is a key factor. The calculated spatial profiles of heavy metals and organic chemicals are compared to observed data under different flow and wastewater discharge conditions in freshwater rivers.