Environmental Engineering Reference
In-Depth Information
11
Aquatic Chemistry
Controlling Nutrient
Cycling: Redox and O
2
Chemicals in Freshwaters
Redox Potential, Potential Energy, and Chemical Transformations
Oxygen: Forms and Transformations
Photosynthesis
Distribution of Dissolved Oxygen in the Environment
Summary
Questions for Thought
The way chemicals move through the environment is an essential as-
pect of ecosystem function. Nutrients often control primary production,
and understanding nutrient cycling is central to understanding the influ-
ence of nutrient pollution. On a larger scale, nutrient cycling is tied to
global-scale patterns of climate and production. Understanding nutrient cy-
cling requires careful study of the concept of oxidation-reduction state (re-
dox). The dynamics of oxygen are related closely to redox, so both are dis-
cussed in this chapter. In following chapters, additional nutrients (carbon,
nitrogen, phosphorus, sulfur, and iron) are discussed. The material in this
chapter forms a conceptual foundation for treatment of all biogeochemical
discussions in this topic.
CHEMICALS IN FRESHWATERS
Among the chemical parameters of interest to the aquatic ecologist,
some of the most important are the total number of ions (charged mole-
cules) in solution and the absolute concentrations of specific ions and
gasses dissolved in solution. The total amount of dissolved and suspended
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