The fate and behavior of pollutants is often dictated by the coupling of chemical and biologically-mediated reactions. Both hydrophobic organic pollutants and toxic transition metals are strongly sorbed to soil surfaces at Superfund sites. Sorption reactions together with the hindered diffusion of pollutants. through small pores appear to control the concentrations to which biological populations (including indigenous soil microorganisms) are exposed. Reactions which act to enhance pollutant release kinetics can both exacerbate exposure and can be deliberately employed to enhance aquifer clean-up procedures. Bacterial polymers naturally occur in soil solution and have documented binding.properties for both transition metals and hydrophobic organic contaminants. Project research to date has demonstrated that bacterial polymers will act to enhance metal desorption and mobility in porous media, and related research has similarly shown that the bacterial polymers will act to enhanced sorption and mobility of hydrophobic organic pollutants in porous media. Therefore, bacterial polymers may enhance the bioavailability of both toxic transition metals and organic contaminants in soil. The proposed continuation of this research will quantify the desorption kinetics of a radio-labeled transition metal (109Cd) and a polynuclear aromatic hydrocarbon (PAH), 14C.phenanthrene, in the presence and absence of selected extracellular polymers, including several produced by isolates of indigenous soil bacteria. The research will use a novel kinetic model that employs a statistical distribution of release rates to reflect the multiplicity of binding site types and pore sizes that collectively act to control contaminant release. Techniques using fluorescent antibody (Fab) staining and microautoradiography (MARG), developed during prior phases of this NIEHS- sponsored research, will be employed to view the distribution of radiolabeled organic compounds, polymers, and bacterial cells at the microscale and will provide an improved understanding of polymer-mediated contaminant release mechanisms. MARG methods will also be adapted for use in assessing the bioavailability of sorbed metals and PAH to soil bacteria that adhere to soil surfaces through production of extracellular polymers. The project results will yield basic information on the micro- and macro-scale influence of extracellular polymers on the bioavailability of contaminants. in porous media. A range of experimental scales will be considered from the macroscopic behavior of pollutant sorbates in suspensions or columns of sorbent material to direct microscopic measurements at the scale of bacterial cells in their microhabitats. This range in experimental scale will facilitate construction and verification of environmentally relevant models that employ mechanistic descriptions of reaction and transport at the pore scale to make predictions of macroscopic behavior.

Project Start
1999-04-20
Project End
2001-03-31
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
8
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Cornell University
Department
Type
DUNS #
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Smith, Donald; Strupp, Barbara J (2013) The scientific basis for chelation: animal studies and lead chelation. J Med Toxicol 9:326-38
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Stangle, Diane E; Smith, Donald R; Beaudin, Stephane A et al. (2007) Succimer chelation improves learning, attention, and arousal regulation in lead-exposed rats but produces lasting cognitive impairment in the absence of lead exposure. Environ Health Perspect 115:201-9
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Chen, Suping; Golemboski, Karen; Piepenbrink, Michael et al. (2004) Developmental immunotoxicity of lead in the rat: influence of maternal diet. J Toxicol Environ Health A 67:495-511
Stangle, Diane E; Strawderman, Myla S; Smith, Donald et al. (2004) Reductions in blood lead overestimate reductions in brain lead following repeated succimer regimens in a rodent model of childhood lead exposure. Environ Health Perspect 112:302-8
Lee, Ji-Eun; Dietert, Rodney R (2003) Developmental immunotoxicity of lead: impact on thymic function. Birth Defects Res A Clin Mol Teratol 67:861-7
Savage, Wesley K; Quimby, Fred W; DeCaprio, Anthony P (2002) Lethal and sublethal effects of polychlorinated biphenyls on Rana sylvatica tadpoles. Environ Toxicol Chem 21:168-74
Tang, Jixin; Liste, Hans-Holger; Alexander, Martin (2002) Chemical assays of availability to earthworms of polycyclic aromatic hydrocarbons in soil. Chemosphere 48:35-42

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