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 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 ...