One-Dimensional Model of Water Quality and Aquatic Ecosystem/Ecotoxicology in River Systems

Abstract

A one-dimensional water quality and aquatic ecology/ecotoxicology model has been incorporated into a package for the modeling of hydrodynamic, sediment transport, contaminant transport, water quality, aquatic ecosystem, and ecotoxicology in river systems. The water quality model alone can be used to determine water temperature, dissolved oxygen, biological oxygen demand, nitrogen, phosphorus, and conservative chemical such as chloride. The aquatic ecosystem model considers a basic food web structure consisting of four trophic levels: phytoplankton, zooplankton, forage fish, and predatory fish, undergoing various biological processes such as photosynthesis, grazing, respiration, excretion, defecation, mortality, gamete, and reproduction. The model simulates the bioaccumulation of toxic chemicals in organisms by uptake, depuration and dietary, and takes into account the effects of toxicity on organisms through modification factors of photosynthesis, grazing, and gamete mortality. The modeling package has been tested by simulating the water quality parameters in the Tualatin River, Oregon and the water quality, aquatic ecosystem, polychlorinated biphenyl (PCB) transport and bioaccumulation in the Upper Hudson River, New York. The simulated water quality parameters, phytoplankton and zooplankton biomass, fish populations, and PCB concentrations in fish are in generally good agreement with the measurement data.