GEO Brasil - UNEP

Barreiras Group, sandy re-covering
which exists along the Brazilian coast
from Amapá to the State of Espírito
Santo
In this hydro-geologic context, the
shallow water level (WL) from
excavated depth in the plateau might
be temporary, which means it dries out
along the period when there are no
rains or it disappears when a deep well
is perforated in its surroundings
Thus, the deep or tubular well crossed
the hydro -geologic substratum which
supported the accumulation of
shallow underground water, the
suspended aquifer (Figure 2b)
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Contamination Agents
Underground water is “hidden” under
a layer of non saturated filtrating
material of high purifying power Due
to local and occasional geological
characteristics, the deepening of the
well could be the solution for
obtaining a larger flow and better
which affect the waters stocked in
dams (Santiago, 1984) Thus, based
on the results of 500 analyzed samples,
it is observed that only 37 percent
present total dissolved solid content
(STD) similar or inferior to 2000 mg/L
(Cruz & Melo, 1968; Rebouças, 1973)
However, the studies developed by
EMBRAPA-CPTSA (2000) show that
there are several alternatives for using
brine generated by mineral processes
of well-drawn waters, which draw the
fractured rocky areas under the
crystalline substratum water in the
semi-arid Northeast Among viable
alternatives, the irrigation of forrage,
which are of great economical and
social reach in the development of
caprine-raising, stands out
Consequently, the use of water
desalinisation agents in inverse
osmosis processes has been growing
in the last decade In this case, the
collection or inadequate deposits of
garbage, which is produced in the
cities mainly, the disordered
implementation of service posts,
cemeteries, the installation of buried
or semi-buried tanks of dangerous
products without proper
consideration regarding corrosion
risks-specially in a country where there
is a great amount of rain and hot
weather for most of the year are
frequent agents which affect the good
natural quality of underground water
(Hassuda, 1997, Hirata, 1994, Hirata et
al, 1997)
Among the agents of underground
water contamination in Brazil, the
nitrogen series (NH4, NO2 and NO3)
stands out and is brought about by
the chaotic dominant sanitation
situation of our cities (Parissot, 1983,
Pacheco, 1984, Mello, 1995,
Cavalcante, 1998, Santos, 2000)
the state of the environment in Brazil
quality of drawn water, while in other
places this alternative may result in
substantial reduction of obtained
flows and worsening of its quality
Also, due to lack of appropriate
foundation to the ringed space,
sanitation stamp and other technical
deficiencies such as constructive,
operational, maintenance and
abandonment of wells, there may be
processes of crossed contamination
caused by polluted waters from
main problems faced result in:
a) lack of monitoring of the quality
of water extracted from wells and
which tends to improve after 2 - 3
years use as the intensive well
pumping engenders greater
renewal dynamics to the water
drawn from the underground;
b) lack of equipment maintenance;
and
In addition, among the risks of binomial
underground soil-water contamination
in Brazil, the growing industrialization
and development of agricultural
activities with intensive use of chemical
inputs-fertilizers, herbicides, pesticides
results in, the existence of inorganic and
organic synthetic chemical micro
pollutants (Hirata, 1994) Among the
most frequent, we emphasize the
following:
neighbouring or shallower layers
In the areas of fractured aquifer rocks
c) lack of rational use of brine
generated this way
a) inorganic non metallic
chemicals, such as phosphorus,
selenium, nitrogen, sulphur and
and alluvial patches of geological
basis from the Pre-Cambrian Age in
the semi-arid Northeast there are
processes of climatic underground
water salinisation similar to those
The construction, operation and
disordered abandonment of wells, the
chaotic forms of occupation of urban
and rural environment, the non
fluorine;
b) poisonous metals, such as
mercury, chrome, cadmium, lead
and zinc;
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