Environmental Engineering Reference
In-Depth Information
Radon Evaporates
from an Open Tank
Radon Remains in the
Water in a Sealed Tank
Figure 3.3
Radon.
occurring radioactive minerals move from underground rock strata and
geologic formations into the underground streams flowing through them
and primarily affect groundwater. In water, radium-226, radium-228, radon-
222, and uranium are the natural radionuclides of most concern. Uranium
is typically found in groundwater and, to a lesser degree, in some surface
waters. Radium in water is found primarily in groundwater. Radon, a color-
less, odorless gas and a known cancer-causing agent, is created by the natu-
ral decay of minerals. Radon is an unusual contaminant in water, because
the danger arises not from drinking radon-contaminated water but from
breathing the gas after it has been released into the air. Radon dissipates rap-
idly when exposed to air (see
Figure 3.3
). When present in household water,
it evaporates easily into the air, where household members may inhale it.
Some experts believe that the effects of radon inhalation are more danger-
ous than those of any other environmental hazard. Manmade radionuclides
(more than 200 are known) are believed to be potential drinking water con-
taminants. Manmade sources of radioactive minerals in water are nuclear
power plants, nuclear weapons facilities, radioactive materials disposal sites,
and docks for nuclear-powered ships.
National Secondary Drinking Water Regulations
The National Secondary Drinking Water Regulations are non-enforceable
guidelines regulating contaminants that may cause cosmetic effects (such as
skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color)
