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Public
Health and Environmental Bureaux. Municipality
of Luján, José María Pérez y Champgnat, 6700-Luján, Buenos Aires.
Aquatic
Ecology and Chemical Division Research Programme, Basic Sciences
Department, National University of Luján, C.C. 221-6700, Luján, Buenos
Aires.
Introduction
The district of Luján occupies
one part of the accumulation flatland known as pampasia, made up of
Quaternary period deposits. The
area has a series of geological soils containing the ground aquifers from
where drinking water is obtained . They
are the Hipopuelche aquifer
(non-potable), the Puelche acquifer
(where drinking water supplies are extracted) and the Pampeano
or Epipuelche aquifer which is the most superficial and provides water
for rural areas and household wells.
The objectives of this work
were: to prepare a map
showing the pollution of Pampeano and Puelche aquifers, in the district of
Luján, and to help devise alternatives for the management of water
resources and, finally, to produce information for the development of
preventive steps to improve health.
Methodology
267 perforations were selected (100 in the Puelche aquifer and 167
in the Pampeano aquifer). Samples
were taken from each perforation in order to conduct bacteriological and
physical-chemical analyses. The
results were pH, alkalinity, hardness, chlorides, sulphates, ammonia,
nitrites, nitrates, phosphates, total chrome and cadmium.
In addition, information on the perforations and their geographical
location was registered.
A map on the current state of the aquifers was drawn by means of
representing all analyses conducted on a district map, using the scale
1:50000. Later on, an
analysis of the main components was conducted and mapped; this allowed for
the identification of risk areas in terms of water quality.
Finally, a survey was conducted to gather information on
consumption habits and neighbours perception as to the quality of water
in neighbourhoods that are totally or partially supplied with piped water
and in areas where water is only obtained from household wells.
Results
In the case of the Puelche aquifer, 7% of the samples revealed
bacteria contamination and, in a similar percentage, the presence of heavy
metals was detected despite the fact that, in all cases, this was within
accepted values.
In the case of the Pampeano aquifer, 70% of the samples revealed
levels of nitrates that exceeded the limits set by the Argentine Food
Code. The rest of ions were
within the accepted limits though in some cases the presence of heavy
metals was detected.
In the analysis of the main components, the first three components
explained nearly 70% of the
variance in both aquifers. Values
with higher quality in the case of the Pampeano aquifer, were found toward
its southern area, while toward the north-east of the urban area lower
quality values were registered (indicated by the negative values of the
component). In the Puelche
aquifer the high-quality values were also found toward the south of the
district while those of lower quality were detected in the northern urban
sector, and a intermediate quality was detected in the eastern zone.
In our case, high concentrations of sulphates and chlorides were
associated to better-quality water while high concentrations of nitrates
and nitrites were associated with lesser-quality water.
In consequence, a simple quality index was prepared; it allowed for
the rapid evaluation of water quality in the Luján district area and
could be extrapolated to other areas after a preliminary regional study.
Surveys revealed that neighbourhoods supplied by piped water show
higher consumption rates that those that are not.
The latter, in turn, reveal a higher energy consumption in order to
extract water. It was clear
in all cases that neighbourhoods do not have information about the quality
of the water, the presence of household polluting problems caused by lack
of hygiene and care in water tanks and pipes.
In general, potable water is not considered a priority service.
Conclusions
The quality of water extracted from the Puelche aquifer is worse in
the northern and eastern zones of the district and in some areas of the
urban sector and this is probably due to a higher extraction for household
and industrial consumption. In
the urban area, perforations providing a better-quality water are
generally the most recent ones. This
reveals that old perforations need to be controlled in order to avoid
contamination risks produced by inadequate or deteriorated insulation or
containment devices.
Water quality in the Pampeano aquifer
is highly at risk throughout the district, and presents high-risk
values in the northern sector. In
general, its deterioration could be due to the percolation of fertilisers
used in agriculture to deeper layers of the soil.
All the information gathered will contribute to protect the health
of the population as it will allow the discouragement of installing food
industries that use water to process their products in risk areas.
This will also help to plan water pipelines in new neighbourhoods
and the closing down of improper perforations.
There is a proposal which in some cases has become a
realityto generate standards in order to:
a)
reduce water consumption at the level of industry, encouraging
and recommending water-recycling practices.
b)
Create awareness and regulate household use of large quantities
of good-quality water to fill swimming pools, wash cars and water
gardens.
c)
Control the construction of perforations for irrigation in areas
devoted to agriculture, to avoid mixing water of different qualities.
d)
Allow for the development of new neighbourhoods only in areas
where water is good and with adequate perforations.
e)
Give priority to the construction of running water pipelines in
neighbourhoods and areas where a significant presence of
water-originated diseases or poor-quality ground water are detected.
f)
Keep a register of and give a licence to all well-drillers
working in the district, after they pass a training course with
specialists. This last
standard has already been approved as municipal regulation.
Information
has been disseminated to teachers at different levels as water is
part of the education curricula and criss-crosses several subjects.
A newsletter has been produced to this end and news reports
appeared in the local press. A
round table was organised with the participation of specialists from the
National University of Luján.
Finally, contacts have been made with nearby municipalities who are
interested in replicating this experience.
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