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Данный
перечень содержит статьи (в основном
на
украинском языке),
связанные со специфическими проблемами питьевой воды
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Статьи
на украинском
языке:
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Некоторые общие положения, перед тем, как прибегать к
деталям:
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How
is our drinking water?
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This
is usually the first question which people ask a water
expert, when they meet him. The information level of the
population is rather low. In the past, contradicting
information has been spread. This is understandable, if
taken into account, that the level of analytical
techniques and reliability of analytical results, are not
always as high as one could wish. Further, the treatment
technique has several times been changed leading to
different water quality.
This
article was written to describe some facts and
consequences without going to much into specific details.
The majority of the people know, that drinking water in
Kiev and in the majority of other Ukrainian cities, is
prepared from river water. River water contains many
organic substances. The bigger amount of them can be
classified as humic substances of natural origin. During
the summer, the concentration of organics can be increased
because of plankton (algae, bacteria), plankton excretes
and degradation products. If this type of water is mixed
with chlorine for disinfection, chlororganic compounds
will be formed. To reduce the necessary doses of chlorine
ammonia (NH3) can be added leading to the formation of
chloramines. Chloramines have a negative impact on aquatic
organisms and can be found even after sewage treatment.
The
formation of chlororganics because of disinfection is
known already more than 20 years. Type and quantity depend
on many factors as for example: type and concentration of
organic matter, temperature, time of contact and so on.
Some compounds, as chloroform, will be formed in higher
concentration only during the vegetation period. Others
can only be found using analytical instruments that are
not available to the analytical control services or that
are not included into standard surveys. Because of the big
amount of dangerous compounds, one has to admit, that the
volume of work for a permanent control would be by far too
high.
A
possible solution of this problem would be, to determine
the amount of chlorine bound in organic compounds. Such
analytical results that were collected by the author of
this article in the past, showed, that chlororganics were
present in the drinking water all over the year. Their
concentration could be evaluated as "very high" but have
decreased in recent years. What is meant by the assessment
"very high" ? The quotation marks were set to point out
that this is an evaluation, based on actual knowledge and
assumptions. The assumptions have to be made for the
quantity of daily water consumption, for the number of
years of consumption and for adults and children
separately. One also has to ask if there are other factors
important for the health, as various harmful substances in
air and food products, wrong nutrition, smoking, etc.
These remarks should point out that a reliable health
evaluation for the Ukrainian population is still not
possible. We can however take into consideration some
American studies. MORRIS, CHALMERS and some other
colleagues from Harvard University (1997) summarized the
results from several studies. They conclude, that people
drinking chlorinated water more than 10 - 15 years, have
an increased risk to get bladder cancer (21 %) and rectal
cancer (38 %). Many other publications show in the same
direction. These results are important also for Ukraine.
It can be assumed that the situation here is even worse.
Other harmful compounds that occur in drinking water are
obviously less important. Nitrate and heavy metals, for
example, can be found but only in “small” concentrations,
radioactive substances and pesticides occur at certain
times, but information about these substances is rather
insufficient and therefore not reported here.
Perspectives
The aim of a future drinking water policy should be to
give up the direct use of surface water and
chlorination. As soon as possible, water protection
zones should be selected and protected within
the river valleys; they also will serve for nature
protection purposes. When ground water is extracted
here, it can be enriched with river water already
filtered through the underground or by artificial
infiltration of river water. The raw water from these
places will contain less organic matter and a much
smaller quantity of bacteria than river water itself.
In this case, disinfection will be necessary only
after treatment and filtration in the water work.
Expenses for technical changes are rather small, in
comparison with the economic damage caused by illness
and reduced life expectance.
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