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, boron severely
damages plant life. Highly alkaline substances, gel proteins and sodium hydroxide is
hazardous substances. Another concern is the fact that each year thousands of children
swallow detergents resulting in serious injuries or death.
In conclusion, the only way to overcome the disastrous effects of phosphates is
to find an alternate. However, an acceptable substitute for phosphates has not yet been
found. Washing only with synthetic detergents would require so much detergent that the
cost per wash would increase significantly. Another alternative is the substitution of
synthetic nonionic detergents for ionic detergents in use. Nonionic detergents are not
precipitated by Calcium of Magnesium ions. This would reduce the risk contaminating our
lakes and rivers.
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