The
eutrophication is an excessive fertilization of water which had with a massive
contribution of nitrogenized and phosphorated compounds coming from the agricultural
activity and the domestic and industrial rejections. These compounds support the
development of the microalgae (phytoplanktons) and the macro-algae which constitutes the
first link of the near total of the maritime food chains.
The
eutrophication induces an abnormal operation of the ecosystem. In roads of Brest, the data
of the RNO show that the nitrogen contributions were multiplied by two since 1975 and four
since 1950, thus certain Bretonnes bays are covered with a dense layer of green algas as
of the appearance of conditions favorable of sunning to the primary production. The local
nutritive salt contributions of agricultural origins are directly responsible for these
green tides inparticular hydrodynamic zones and do not allow the fast dispersion of these
contributions with water the broad one.
As
an example , it is worth to study the seas which border the dimensions
Italians. One cash counts 644 communes along the 7 200 km of shores of the peninsula a
total population of 16 million inhabitants. During the tourist season, it increases to 50
million beings. More over, 130 miles
production facilities unequally distributed are established in these same communes and
produce a quantity of polluting materials being equivalent to that which would reject 30
million additional in habitants. There exists in more 137 ports making forward 200 million
freight and 20 million passengers. One can thus estimate that water which bathes the
coasts Italians receives each year a pollution equivalent to that poured by a population
of 120 million in habitants.
On
has a present currently brought up to date the figures of oneof the pollutants: phosphorus
coming from metabolic residues (28%);detergents (33%); installation of breedings (13%);
agriculturalexcesses of manure (18%) and industry (6%). Once arrived in water,phosphorus
exerts there the action for which it is used inagriculture, i.e. like a fertilizer. Water
thus fattened becomesunfortunately eutrophic: she produce an abnormal quantity
ofmicroalgae which alive or dead produce different type of harmfuleffects. The principal consequence of thisproliferation is
that it consumes all oxygen available in water. Oncedead posed on the bottom, these algae
still needs much oxygen fortheir decomposition. This
one is withdrawnmassively from water, which involves the asphyxiation of manyvegetable and
animal species.
The
eutrophication is also responsible for the redtides which corresponds to a massive
proliferation of microalgae until concentrations of several million cells per liter of
water led to acolouring of sea water This
phenomenon is of tennatural, but favoured and is amplified by the nutritive contribution
of element in the medium.
The eutrophication thus begin with an abnormal
proliferation from un questionable algae and ends in the asphyxiation and the destruction
of the whole of the ecosystem. I would like to say a word on what I estimate to be a true
scandal. It is the business of phosphate and
the handling of the science which is responsible today for part of eutrophication of our
seas. The quarrel on the role of phosphate in the water scour has lasted formore than
forty years. Supported by certain not very scrupulous scientists, his role in the eutrophication of the seas and
water levels in general underwent many controversies and handling.
The
end of our century bursts the war of phosphates on the ecological level. At the end of the second world war, it was
established in an irrefutable way that it is well phosphorus and not the nitrogen which is
responsible for the excess of algae. One thus concluded from it that had of-to be
phosphated the effluents. The lessiviers are then reflected to seek substitute products to
the tpp. But the industrialists of phosphorus felt threatened and stated several arguments
to save their activity. They then advanced the fate of their employees, but this social
argument not giving anything, they resorted to the medical argument. They attacked the
more credible substitute product lme: the NTA. It was shown to be a carcinogenic product,
without never to have brought the proof of it, but this A is enough to condemn it. It
should be known that phosphorus is a very toxic product and that its excess in the feeding
causes the osteoporosis, which was never retained against him. There after, the medical
argument hardly being useful, the combat moved then on the ground of the environment. It
was then a question of discrediting phosphorus in the causes of eutrophication. It then
announced with the assistance of certain "scientists " that the phosphate limits
the growth alguale and that the first person in charge of eutrophication was carbon. But
certain scientists, after this advertisement, undertook full-scale experiments on lakes
(whose celebrates it lake 226), and concluded that had to be tracked phosphorus. But in
1980, Rhône-Poulenc seeing of an evil eye the arrival of the detergents without
phosphate, showed this time nitrogen like the first person in charge of eutrophication.
Step which resulted in to put confusion in the spirits on the respective role of nitrogen,
carbon and phosphorus in eutrophication. Lastly, in 1993, to sell at the same time tpp and
substitute products, it was necessary to clear phosphates while preaching their
elimination in the stations of purification; node of inconsistencies for a maximum of
profits... under cover of scientific controversies!!!
