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Osmoregulation is the process of maintaining the delicate balance of
salts and minerals in their tissues. Acid molecules in the water cause mucus to
form in their gills and this prevents the fish to absorb oxygen as well. If the
buildup of mucus increases, the fish would suffocate. In addition, a low pH will
throw off the balance of salts in the fish tissue. Salts levels such as the
calcium (Ca+2) levels of some fish cannot be maintained due to pH change. This
results in poor reproduction - their eggs produced would be damaged; they are
either too brittle or too weak. Decreased Ca+2 levels also result in weak spines
and deformities. For example, crayfish need Ca+2 to maintain a healthy
exoskeleton; low Ca+2 levels would mean a weak exoskeleton. Another type of salt
N+ also influences the well-being of the fish.
As nitrogen- containing
fertilizers are washed off into the lakes, the nitrogen stimulates the growth of
algae, which logically would mean and increase in oxygen production, thus benefitting the fish. However, because of increased deaths in the fish
population due to acid rain, the decomposition process uses up a lot of the
oxygen, which leaves less for the surviving fish to take in. Indirectly,
sulfuric acid releases heavy metals present in soils to be dissociated and
released. For example, Aluminium (Al+2) is harmless as part of a compound, but
because acid rain causes Al+2 to be released into the soils and gradually into
the lakes, it becomes lethal to the health of the fish in the lakes. Al+2 burns
the gills of the fish and accumulates in their organs, causing much damage. So,
although many fish may be able to tolerate a pH of approximately 5.9, this acid
level is high enough to release Al+2 from the soils to kill the fish.
This
effect is further augmented by spring acid shock. The effect of acid rain can be
dynamically illustrated in a study done on Lake 223, which started in 1976.
Scientists monitored the pH and aquatic ecosystem of Lake 223. They observed
that as the pH of the Lake Decrease over the years, a number of crustaceans died
out because of problems in reproduction due to the acidity of the lake caused by
acid precipitation. At a pH of 5.6, algae growth in the lake was hindered and
some types of small died out. Eventually, it was followed by larger fish dying
out with the same problem in reproduction; there were more adult fish in the
lake than there were young fish. Finally, in 1983, the lake reached a pH of 5
and the surviving fish in the lake was thin and deformed and unable to
reproduce. This case study obviously illustrates the significant effect of acid
rain on lakes and its aquatic ecosystem.
Effect on Materials Acid rain also
damages materials such as fabrics. For example, flags that are put up are being
eaten away by the acidic chemicals in the precipitation. Books and age-old art
that are centuries old are also being affected; the ventilation systems of the
libraries and museums that hold them do not prevent the acidic particles from
entering the buildings and so, they get in and circulate within the building,
affecting and deteriorating the materials. Effect on Atmosphere Some of the
constituents of acid pollution are sulphates, nitrates, hydrocarbons and ozone.
These exists as dry particles in the air and contribute to haze, affecting
visibility. This makes navigation especially hard for air pilots. Acid haze also
interferes with the flow of sunlight from the sun to the earth and back.
In the
Arctic, this affects the growth of lichens which in turn, affect the caribou and
reindeer which feed on it. Effect on Architecture Acid particles are also
deposited on to buildings and statues, causing corrosion. For example, the
Capitol building in Ottawa has been disintegrating because of excess sulphur
dioxide in the atmosphere. Limestone and marble turn to a crumbling substance
called gypsum upon contact with the acid, which explains the corrosion of
buildings and statues. In addition, bridges are corroding at a faster rate, and
the railway industry as well as the airplane industry have to expend more money
in repairing the Corrosive damage done by acid rain.
Not only is this an
economically taxing problem caused by acid rain, but also a safety hazard to the
General public; as an illustration, in 1967, the bridge over the Ohio River
collapsed killing 46 people - the reason? Corrosion due to acid rain. Effects On
Humans Among one of the serious side effects of acid pollution on humans is
respiratory problems. The SO2 and NO2 emmisions give rise to respiratory
problems such as asthma, dry coughs, headaches, eye, nose and throat
irritations.
An indirect effect of acid precipitation on humans is that the
toxic metals dissolved in the water are absorbed in fruits, vegetables and in
the tissues of animals. Although these toxic metals do not directly affect the
animals, they have serious effects on humans when they are being consumed. For
example, mercury that accumulate in the organs and tissues of the animals has
been linked with brain damage in children as well as nerve disorders, brain
damage and death. Similarly, another metal, Aluminium, present in the organs of
the animals, has been associated with kidney problems and recently, was
suspected to be related to Alzheimer's disease.
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