Week 13

Structures, Properties, and Occurrence of Organic Compounds in Natural Waters - III

Overview

In the final week of lessons on organic geochemistry, we explore the roles of organic acids in aqueous environments. We will concentrate on simple carboxylic acids (e.g., acetate, oxalate, citrate) and more complex organic acids (humic substances). We will see that these may play important roles in determining the mobilities of heavy metals and organic contaminants. Finally, we will discuss briefly some transformations among organic compounds that can take place in the absence of biological activity.

Objectives

	Examine the role and importance of carboxylic acids in natural and contaminated waters.
	Define humic and fulvic acids and explore their roles in natural and contaminated waters.
	Investigate abiotic transformations of organic compounds in natural and contaminated waters.

Learning Resources

Read: Chapter 6 (p. 212-225) in Kehew (2001)

Optional Reading: Most of the material covered in this lecture is not covered in Kehew (2001). If you would like additional reading on this material, I suggest:

1) Wood, S.A. (1996) The role of humic substances in the transport and fixation of metals of economic interest (Au, Pt, Pd, U, V). Ore Geol. Rev. 11, 1-31.
2) Wood, S.A. (2000) Organic matter: Supergene enrichment and dispersion. In T.H. Giordano, R.M. Kettler and S.A. Wood, eds., Ore Genesis and Exploration: The Roles of Organic Matter. Reviews in Economic Geology, v. 9, p. 157-192.

Additional Questions to consider: Here are some study guide questions to contemplate as you consider the lecture notes.

	What are the potential roles for carboxylic acids in natural waters?
	List some natural sources of carboxylic acids.
	Why is oxalate a stronger complexer of metals than acetate?
	Distinguish between humic and fulvic acids.
	What are the potential roles for humic substances in natural waters?
	Draw a schematic diagram showing the general structure of fulvic acid.