Реферат на тему UnH1d Essay Research Paper Phosphates may be
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Untitled Essay, Research Paper
Phosphates may be created by substituting some or all of the hydrogen of a phosphoric acid
by metals. Depending on the number of hydrogen atoms that are replaced, the resulting
compound is described as a primary, secondary or tertiary phosphate. Primary and secondary
phosphates contain hydrogen and are acid salts. Secondary and tertiary phosphates, with
the exception of those of sodium, potassium and
ammonium are insoluble in water. Tertiary sodium phosphate is valuable as a detergent and
water softener. The primary phosphates tend to be more soluble.
Phosphates, which are an important component to metabolism in both plants and animals,
help in the first step in oxidation of glucose in the body. Primary calcium phosphate is
an ingredient of plant fertilizer.
Phosphates have caused increasing attention recently. The focus is on the environmentally
harmful effects in household detergents. Wastewater, from laundering agents, contains
phosphates, which are said to be a water pollutant.
Most laundry detergents contain approximately 35% to 75% sodium
triphosphate (Na5P3O10), which serves two purposes. Providing an alkaline solution (pH 9.0
to 10.5) is necessary for effective cleansing and also to tie up calcium and magnesium
ions found in natural waters and prevent them from interfering with the cleansing role of
the detergent.
Eutrophication is the progressive over-fertilization of water, in which festering masses
of algae’s blooms, choking rivers and lakes. Phosphorus compounds act as a fertilizer for
all plant life, whether free-floating algae or more substantial rooted weeds, and are
implicated in eutrophication. Many countries control phosphate levels, whereas
Switzerland has banned the use of phosphates.
The marine environment is both fragile and more resistant than the terrestrial ecosystem.
It is fragile for the reasons that nutrients are generally present in very low
concentrations, permanently consumed by living organisms and pollutants diffuse rapidly.
Lakes and rivers are extremely complex ecosystems. Nutrients are taken up by both algae
and rooted weeds. The weeds act as a shelter for fish larvae and zooplankton, both of
which eat algae and are, in turn, eaten by larger fish. Scientists have concluded that
unpolluted lakes can absorb surprisingly large amounts of phosphates without uncertainty.
When a fertilizer, such as a phosphate, is added more algae will grow,
and consequently will the populations of zooplankton and fish. Difficulties only arise
when the lake is already impure. Zooplankton are sensitive to their environment and many
substances are toxic to them. If any of these substances, including phosphates, are
present the zooplankton population cannot increase. Adding phosphates to this polluted
system will case algae growth. The floating masses cut off the light supply. Weeds die and
decompose using up dissolved oxygen, and causing sulfurous smells and plagues. Deprived of
shelter and food, the fish larvae starve. The lake is well on the way to catastrophe.
Without wetlands there would be a minimal amount of fresh drinking water due to the fact
that wetlands filter the waters of our lakes, rivers and streams, sequentially reducing
contamination of water. The plant growth in wetlands removes phosphates and other plant
nutrients washed in from the surrounding soil, consequently restricting
the growth of algae and aquatic weeds. This growth is a serious problem in some of
Canada’s major waterways, where dead and decaying algae deprive the deeper waters of their
oxygen.
Researches at Lancaster University have studied lakes whose plant and animal life has been
killed by acid rain. The excess acid in the lakes can be neutralized easily by adding
lime, but this makes the waters rich in calcium. Life will gradually return to the lake
but, as these lakes should have low calcium levels, it will not be the same kind
of life that existed in lakes before pollution. The answer, they have concluded, is to add
phosphates.
These phosphates work by shielding the water. This depends upon nitrate ions in the lake.
Contradictory, these ions also are produced by acid rain, contain oxides of nitrogen from
combustion sources. These fertilizers do not alter the pH level of the water. Instead,
they stimulate the growth of plants. The plants absorb the dissolved nitrates, generating
hydroxide ions, which in return neutralize the excess acid.
Removal of phosphates from detergent is not likely to slow algae growth in containing
substances. It may actually prove disastrous. Its replacement with borax will definitely
be disastrous. Scientists are unsure of borax role in plant growth. It is not required by
algae and other micro plants, but it is essential to higher plants. However in
excessive quantities, about 5 micrograms of boron per gram of water, b