Civil Engineering Reference
In-Depth Information
CHAPTER 2
Inorganic and Radionuclide
Contaminants
This chapter presents information on four classes of contaminants:
Inorganic constituents of health concern
•
Inorganic contaminants causing aesthetic problems
•
Residual disinfectants and inorganic disinfection by-products
•
Radionuclides
•
Information on current U.S. water quality standards for these contaminants is found
in Chapter 1.
INORGANIC CONTAMINANTS OF HEALTH CONCERN
Drinking water supplies are susceptible to contamination by a wide range of inorganic
constituents that are known or suspected to cause adverse health effects. These con-
taminants enter water supplies from natural sources or from pollutant sources. Also,
constituents such as lead and copper may be contributed from corrosion of piping and
plumbing materials in the distribution system. The following sections present infor-
mation on the source, occurrence, and health effects of 23 inorganic contaminants of
concern.
Aluminum
Sources
Aluminum is the most abundant metal found on the earth's crust—8.1 per-
cent—and the third most abundant element. It is found in nature as alumino silicates,
such as clay, kaolin, mica, and feldspar. Bauxite, an impure hydrated oxide ore, is a
major source of industrial production.
Occurrence
Aluminum occurs naturally in nearly all foods. Dietary intake varies
from 1.53 to 100 mg / day, with an average of 20 mg / day. Aluminum is common in
treated drinking water, especially water treated with alum; however, drinking provides
a relatively minor proportion of dietary intake compared with other sources
1
(see Table
2-1).
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