Environmental Engineering Reference
In-Depth Information
CHAPTER
8
Th
e Phosphorus Cy
cle
Elena M. Bennett
1
and Meagan E. Schipanski
2
1
McGill School of Environment and Department of Natural Resource Sciences,
McGill University, Canada;
2
Plant Sciences Department, Pennsylvania State University,
University Park, PA
INTRODUCTION
Phosphorus (P) is essential for all organisms since it is an important component
of DNA, RNA, ATP, and the phospholipids that form cell membranes. Relative to its
biological importance, P is present in only small quantities on Earth (
Filippelli 2008
).
P plays a crucial role in limiting or colimiting primary production in many ecosystems,
including agricultural ecosystems where it is needed for production of crops and livestock.
It also plays an important role in the productivity of inland waters and estuaries. Inland
waters with low P concentrations generally have not only low primary production, but
also low secondary production of invertebrates and fish. Consequently, inland waters are
extremely sensitive to increases in P concentrations that often lead to eutrophic (high
productivity) conditions associated with low water clarity, decline of rooted plants, anoxic
bottom waters, fish kills, and algal blooms. Phosphorus' critical role in agricultural
production as well as eutrophication has triggered much of the ecological research on
P over the past 50 years.
In this chapter, we present information about the key processes in P cycling in terrestrial
and aquatic systems, followed by a discussion of the interactions between terrestrial and
aquatic P cycles at the global, watershed, and local scales. We conclude with a discussion of
human management of the P cycle.
BACKGROUND
Literally, phosphorus means “bearer of light”; elemental P (P
o
) glows in the presence of
oxygen and is easily combustible.
In 1669,
the German alchemist Henning Brandt
