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HYPOXIA EFFECT ON THE TRANSFORMATION, SPECIATION, BIOAVAILABILITY AND TOXICITY OF CHEMICAL CONTAMINANTS IN THE HYPOXIC ZONE
Citation:
Bailey, G W. HYPOXIA EFFECT ON THE TRANSFORMATION, SPECIATION, BIOAVAILABILITY AND TOXICITY OF CHEMICAL CONTAMINANTS IN THE HYPOXIC ZONE. Presented at Sixth International Symposium on Fish Physiology, Toxicology, and Water Quality, La Paz, B.C.S., Mexico, January 22-26, 2001.
Impact/Purpose:
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological, and geochemical) that describe the species-specific transformation and transport of organic contaminants and nutrients in environmental and biological systems. Develop and integrate chemical behavior parameterization models (e.g., SPARC), chemical-process models, and ecosystem-characterization models into reactive-transport models.
Description:
This Symposium seeks to understand the direct effect of hypoxia on aquatic biota at the individual population, and the ecosystem levels. Another concern, however, is the indirect effect of varying oxygen levels on the thermodynamics and kinetics of biogeochemical processes and the effect of these changes on the transformations, speciation, bioavailability and toxicity of particulate-bound or dissolved forms of inorganic and organic contaminants as they pass through or reside in the hypoxia water column and in the underlying sediment. The basic tenets of redox chemistry are presented and reviewed. The redox potential (Eh) is used as a tool to assess the speciation of redox sensitive metals -- Cr, Fe, Mn, Cu, Ni, Zn, Cd, Pb, Hg -- and metalloids --As, S, and, Se-- and the transformation rates of organic C-, N-, P-, S-, constituents in both organic matter and in anthropogenic chemicals both in the hypoxic water column and the underlying sediment. Both literature findings and calculations from MINTEQA2, a geochemical equilibrium model, will be used to make the individual evaluations. Possible adverse effects of that redox-sensitive chemically active forms on aquatic biota present in the hypoxic zone will be presented.