A Modeling and Experimental Investigation of Metal Release from Contaminated Sediments The Effects of Metal Sulfide Oxidation and ResuspensionEPA Grant Number: R825277
Title: A Modeling and Experimental Investigation of Metal Release from Contaminated Sediments The Effects of Metal Sulfide Oxidation and Resuspension
Investigators: Di Toro, Dominic M. , Mahony, John D.
Institution: Manhattan College
EPA Project Officer: Hahn, Intaek
Project Period: November 15, 1996 through November 14, 1999 (Extended to November 14, 2000)
Project Amount: $544,463
RFA: Risk-Based Decisions for Contaminated Sediments (1996) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Description:The objective of this research project is to construct and validate a mechanistically realistic model of the release of potentially toxic metals from contaminated sediments. These are: cadmium, copper, nickel, lead, and zinc, all of which form metal sulfides more insoluble than iron sulfide. The model is intended to be used in conjunction with water column fate and transport models. The model is intended to be compatible with sediment quality criteria based on simultaneously extracted metals (SEM) and acid volatile sulfide (AVS) concentrations in sediments as well as interstitial water toxic units.
The presently available model formulations for computing the metal flux from sediments are incomplete since they take no account of the critical and central importance of metal sulfide formation, dissolution and oxidation. They are based on partition coefficients. As a consequence they provide only a rough approximation to what is actually controlling the release of metals from sediments. The purpose of this project is to remedy this situation.
This research project will produce a model which calculates the flux of metals from the sediment to the overlying water. The model can be incorporated into presently available water quality models for metals. The features to be incorporated in the proposed model are: a) The oxidation of metal sulfides as a source of dissolved metals, b) Partitioning of metals to iron oxyhydroxide, c) The effects of sediment resuspension as a mechanism to facilitate transport of metal from the surface layers of the sediment to the overlying water, d) The impact of surface shear stress on particle mixing in the sediment, e) Partitioning of metals to particulate organic carbon, f) Bioturbation, g) Pore water diffusion.
The experiments are designed to support the model development. The topics are: a) The oxidation kinetics of the metal sulfides, b) Measurements of metal fluxes from spiked and intact field collected cores, c) The effects of resuspension on metal flux and particle mixing.