Phosphates in Water Pollution

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