Environmental Engineering Reference
In-Depth Information
radioactive metals and minerals that cause contamination). These radioac-
tive substances in water are of two types: radioactive minerals and radioac-
tive gas. The U.S. Environmental Protection Agency (USEPA) reports that
some 50 million Americans face increased cancer risk because of radioactive
contamination of their drinking water.
Because of their occurrence in drinking water and their effects on
human health, the natural radionuclides of chief concern are radium-226,
radium-228, radon-222, and uranium. The source of some of these naturally
occurring radioactive minerals is typically associated with certain regions
of the country where mining is active or was active in the past. Mining
activities expose rock strata, most of which contain some amount of radioac-
tive ore. Uranium mining, for example, produces runoff. Radioactive con-
tamination also occurs when underground streams flow through various
rockbed and geologic formations containing radioactive materials. Other
sources of radioactive minerals that may enter water supplies are smelters
and coal-fired electrical generating plants. Also contributing to radioactive
contamination of water are nuclear power plants, nuclear weapons facilities,
radioactive materials disposal sites, and mooring sites for nuclear-powered
ships. Hospitals contribute radioactive pollution when they dump low-level
radioactive wastes into sewers; some of these radioactive wastes eventually
find their way into water supply systems.
DID YoU KNoW?
In the prologue of this topic, we discussed sick water. We pointed out
that PPCPs are the primary ingredient in the sick conglomeration of
products we use each and every day. Why the concern, you might ask?
There is no one concern but instead many:
• Large quantities of PPCPs can enter the environment after use
by individuals or domestic animals.
• Wastewater systems are not equipped for PPCP removal.
Currently, no municipal wastewater treatment plants are engi-
neered specifically for PPCP removal or for other unregulated
contaminants. Effective removal of PPCPS from treatment
plants varies based on the type of chemical and on the indi-
vidual wastewater treatment facilities.
• The risks are uncertain. The risks posed to aquatic organisms
and to humans are unknown, largely because the concentra-
tions are so low.
• The number of PPCPs is growing. In addition to antibiotics
and steroids, over 100 individual PPCPs have been identified
in environmental samples and drinking water (USEPA, 2011a).
