The goal of this research is to develop models for predicting the toxicity and mobilization of individual metals? and metal mixtures in sediments. These predictions are critical in evaluating the risk associated with? contaminated sediments at Superfund sites. In past Superfund basic research projects, we have developed? methods of assessing the toxicity of individual metals - Cd, Cu, Ni, Pb and Zn - for sediments with excess? acid volatile sulfides (AVS). We propose to develop a model that predicts the toxicity of metals in sediments? with little or no AVS. This requires a prediction of the partitioning of sediment metals to the other important? sediment phases - sediment organic carbon if it is in sufficient supply, and then the other phases (e.g. iron? oxyhydroxides) that are important in the aerobic layer of sediments. We also propose to develop the next? generation of models for the prediction of mobilization of metals from sediments that explicitly include the? mechanisms of mobilization. We intend to model the mechanisms of metal sulfide oxidation directly and to? relate them to the cycles of manganese and iron in sediments. We have included such a mechanism? nvolving the Fe(ll)-facilitated oxidation of arsenic in our present project. We propose to extend this work to? the oxidation of metal sulfides.? Our specific aims are:? 1. For cationic metals, to extend the sediment Biotic Ligand Model (BLM) so that it can predict the toxicity of? metals and metal mixtures by considering competitive interactions of metals and major ions to the organic? carbon, (hydrous) oxide surfaces, clays and to uptake sites on benthic organisms.? 2. For metals that form insoluble metal sulfides in sediments (Cd, Cu, Ni, Pb, Zn), to determine the rates of? metal sulfide oxidation and their dependence on solution parameters for inclusion in metal mobilization? models.? 3. For arsenic, to investigate the effects of inorganic and organic ligands present in sediments that affect? the rate of Fe(ll)-catalyzed oxidation of arsenite and ultimately the rates of arsenic mobilization from? sediments.? 4. For chromium, to investigate the effect of natural organic matter on the rates of chromium(lll) oxidation? by manganese oxide in sediments, and the subsequent release of chromium(VI) to the pore water and the? overlying water.? 5. For the metals discussed above, to construct an integrated model that combines the metal mobilization? and toxicity mechanisms, together with a model of the seasonal cycling of redox-sensitive species including? oxygen, organic matter, iron, manganese and sulfur in sediments.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES015444-02
Application #
7269935
Study Section
Special Emphasis Panel (ZES1-SET-A (P9))
Program Officer
Henry, Heather F
Project Start
2006-08-01
Project End
2009-05-31
Budget Start
2007-06-01
Budget End
2008-05-31
Support Year
2
Fiscal Year
2007
Total Cost
$315,266
Indirect Cost
Name
University of Delaware
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
059007500
City
Newark
State
DE
Country
United States
Zip Code
19716
Kipka, Undine; Di Toro, Dominic M (2011) A linear solvation energy relationship model of organic chemical partitioning to particulate organic carbon in soils and sediments. Environ Toxicol Chem 30:2013-22
Carbonaro, Richard F; Atalay, Yasemin B; Di Toro, Dominic M (2011) Linear Free Energy Relationships for Metal-Ligand Complexation: Bidentate Binding to Negatively-Charged Oxygen Donor Atoms. Geochim Cosmochim Acta 75:2499-2511
Kipka, Undine; Di Toro, Dominic M (2011) A linear solvation energy relationship model of organic chemical partitioning to dissolved organic carbon. Environ Toxicol Chem 30:2023-9
Phillips, Kathy L; Di Toro, Dominic M; Sandler, Stanley I (2011) Prediction of soil sorption coefficients using model molecular structures for organic matter and the quantum mechanical COSMO-SAC model. Environ Sci Technol 45:1021-7
Atalay, Yasemin B; Carbonaro, Richard F; Di Toro, Dominic M (2009) Distribution of proton dissociation constants for model humic and fulvic acid molecules. Environ Sci Technol 43:3626-31
McGrath, Joy A; Di Toro, Dominic M (2009) Validation of the target lipid model for toxicity assessment of residual petroleum constituents: monocyclic and polycyclic aromatic hydrocarbons. Environ Toxicol Chem 28:1130-48
Kipka, Undine; Di Toro, Dominic M (2009) Technical basis for polar and nonpolar narcotic chemicals and polycyclic aromatic hydrocarbon criteria. III. A polyparameter model for target lipid partitioning. Environ Toxicol Chem 28:1429-38
Shough, Anne Marie; Doren, Douglas J; Di Toro, Dominic M (2008) Polyfunctional methodology for improved DFT thermochemical predictions. J Phys Chem A 112:10624-34
Phillips, Kathy L; Sandler, Stanley I; Greene, Richard W et al. (2008) Quantum mechanical predictions of the Henry's law constants and their temperature dependence for the 209 polychlorinated biphenyl congeners. Environ Sci Technol 42:8412-8