Geology Reference
In-Depth Information
3.
Iron and chloride are major inorganic substances that
adversely affect drinking water. Are they health hazards
according to the USEPA tables in this exercise?
varied with the annual average temperature (Table 13.3).
An excess of fluoride is associated with excessive bone
formation and calcification of ligaments. Fluoride is
now included in both the primary and secondary
drinking water standards (Tables 13.1 and 13.2).
NITRATE (N0
3
).
Nitrate may be leached from some
rocks by water, but certain plants, plant debris, animal
excrement, sewage wastes, and inorganic nitrate
fertilizers are probably the major contributors of nitrate.
Nitrate concentration (measured as N) in water in excess
of 10 mg/L, the maximum limit set by the USEPA (Table
13.1), causes infantile methemoglobinemia (blue babies).
4.
a. What are the health hazards of excessive fluoride?
b. Why is fluoride listed in Tables 13.1 and 13.2?
IRON (Fe).
Iron compounds are very common in rocks
and they are easily leached by water, particularly water
with a low pH. Concentrations of iron in excess of 0.3
mg/L will cause staining of laundry and utensils; it is
usually objectionable for food processing, beverages, ice
manufacturing, and many other processes. It may cause a
metallic taste. Streams draining coal or other mining areas
commonly contain excessive iron concentrations. Various
other industrial processes, such as steel production, may
also contribute to excessive iron concentrations.
Minor and trace inorganic substances are
included in Tables 13.1 and 13.2 and microbiological
and organic chemical data are in Table 13.1. Consult
the footnotes for these tables for additional informa-
tion on the nature, occurrence, and health effects of
these substances in drinking water.
5. For each of the following contaminants in drinking water,
list the potential health effects and their sources.
Arsenic
Asbestos
Atrizine
Bromate
Carbofuran
Chlordane
QUESTIONS 13, PART A
1.
Which of the major inorganic substances might indicate
contamination by sewage?
Chlorine (as Cl
2
)
Chromium
Cryptosporidium
Dioxin
Diquat
2.
What are the major inorganic substances discussed in Part
A that may be detrimental to human health?
Lead
Nitrate
PCBs
TABLE 13.3 Former Recommended Fluoride Limits
(USPHS, 1962)
Selenium
Tetrachloroethylene
Annual Average Of Maximum
Daily Air Temperatures (*F)
Recommended Flu-
oride Limit (mg/L)
Vinyl chloride
50.0-53.7
1.7
6.
Use the information in Table 13.1 to help answer the
following.
a. What is the purpose or role of adding disinfectants to
drinking water?
53.8-58.3
1.5
58.4-63.8
1.3
63.9-70.6
1.2
70.7-79.2
1.0
79.3-90.5
0.8
