Effects of Interactions Between Sediment Components on Copper Sorption in EstuariesEPA Grant Number: U915359
Title: Effects of Interactions Between Sediment Components on Copper Sorption in Estuaries
Investigators: Dukenfield, Kea
Institution: College of William and Mary-VA
EPA Project Officer: Michaud, Jayne
Project Period: August 1, 1998 through August 1, 2001
Project Amount: $83,462
RFA: STAR Graduate Fellowships (1998) RFA Text | Recipients Lists
Research Category: Fellowship - Geochemistry , Ecological Indicators/Assessment/Restoration , Academic Fellowships
The objective of this research project is to demonstrate the significance of relationships between iron oxide and humic acid coatings and quartz and kaolinite substrates as they affect the uptake and release of aqueous copper. This will allow a more accurate assessment of the impact of sediment-bound copper on estuarine environments.
This project is comprised of three stages: (1) construction and characterization of environmentally relevant sediment phase composites; (2) determining potential causes of different sorptive behavior between these composites, their components, and an estuarine sediment; and (3) tests of these potential causes using parallel sorption experiments. The project focuses on mineral-phase coatings. Two important copper-reactive phases, iron oxide and humic acid, will be coated onto two common mineral phase substrates, quartz and kaolinite. The iron oxide will be synthesized in the laboratory; the humic acid will be extracted from a relatively clean surface sediment collected from the York River Estuary, Virginia. The sediment used for comparison will be from the same site, collected at the same time. The quartz and kaolinite are natural minerals; they will be cleaned to remove impurities and contaminants, and they also will be size-fractionated to control for grain-size related effects. Classic wet chemistry techniques will be combined with spectroscopic methods to elucidate copper sorption behavior. Batch adsorption and desorption experiments will be conducted under typical estuarine conditions, and the results will be analyzed using spectrophotometric methods. The molecular structures of the solid surfaces and adsorbed copper complexes will be investigated using x-ray absorption fine structure spectroscopy. Physical characteristics will be determined using scanning electron microscopy and energy dispersive x-ray spectroscopy, BET-N2 surface area analysis, potentiometric titration, and x-ray diffraction. Carbon, hydrogen, and nitrogen elemental analysis also will be used to examine the chemical characteristics of the humic acid.