Critical body residues and ion-exchange membranes as measures of heavy metal bioavailability and toxicity in soilEPA Grant Number: U915465
Title: Critical body residues and ion-exchange membranes as measures of heavy metal bioavailability and toxicity in soil
Investigators: Conder, Jason
Institution: Oklahoma State University - Main Campus
EPA Project Officer: Manty, Dale
Project Period: August 17, 1998 through January 1, 2000
Project Amount: $47,458
RFA: STAR Graduate Fellowships (1998) RFA Text | Recipients Lists
Research Category: Fellowship - Toxicology , Health Effects , Academic Fellowships
The objective of this research project is to better understand the bioavailability and toxicity of cadmium, lead, and zinc to soil organisms, both as individual contaminants and as a mixture.
Two methods of measuring metal bioavailability in soils will be investigated: (1) earthworm metal residues; and (2) ion-exchange membrane uptake. Single- and multiple-metal toxicity tests using the earthworm Eisenia fetida and ion-exchange membrane exposures will be conducted in artificial soil spiked with metal salts. Toxic units will be calculated from the single-metal tests to evaluate mixture toxicity of the multiple-metal test. During all toxicity tests, dead earthworms will be analyzed to determine critical body residues (CBRs) for lethality for each metal. A CBR is the concentration of toxicant in an organism associated with a toxic endpoint, providing a link between the measure of bioavailability (the residue) and toxicity. CBRs also will serve to further investigate mixture toxicity. Plant root simulators (PRS), ion-exchange membranes coated with a heavy metal chelating agent, will be exposed to artificial soils at the same concentrations as the earthworm toxicity tests. PRS uptake will be compared to toxicity (mortality) and CBRs to investigate their suitability as surrogates for earthworm bioassays.