Measurement Parameter Series
WHAT IS
PHOSPHORUS,
AND HOW IS IT
MEASURED?
A COMPREHENSIVE GUIDE FOR PHOSPHORUS
AND HOW IT AFFECTS OUR WORLD
Written by Tyler Huelsman
Located in the Lower Great Lakes and Ohio River Valley region,
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when your
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demands
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Phosphorus | 2
WHY PHOSPHORUS MATTERS
Phosphorus is an important component for all living organisms;
it is responsible for many biological properties and functions,
including the double helix shape of DNA as well as cellular
respiration and metabolism. It is present in DNA, RNA,
phosphoproteins, adenosine triphosphate (ATP), adenosine
diphosphate (ADP), the esters of enzymes and vitamins, and
bones. Phosphorus is the second most abundant nutrient in
the human body, behind only calcium. It constitutes about one
percent of a human’s body mass.
CONTENTS
3
The Importance of Monitoring Phosphorus
4
What is Phosphorus?
6
The Phosphorus Cycle
8
How Phosphorus Enters the Envrionment
10
Effect of Phosphorus on the Environment and Human Health
12
How Phosphorus Concentration is Measured
14
Applications for Monitoring Phosphorus
15
Bibliography
16
Glossary
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Phosphorus | 3
THE IMPORTANCE of Monitoring Phosphorus
Due to the use of phosphorus in agriculture and its effects on
life in ecosystems, it is also the subject of important regulations,
management practices, and research programs. In fact, it is the
most extensively studied element in freshwater.
Phosphorus is an important nutrient for the growth and
metabolism of photosynthetic organisms. It is often a
limiting factor in biological productivity, especially in aquatic
ecosystems. Where there is little or no phosphorus in a lake
or pond, there is also little or no life.
However, some freshwater systems have too much
phosphorus. Excessive amounts lead to a phenomenon called
eutrophication, a condition in which algae overrun the system
and outcompete, poison, or asphyxiate other aquatic species.
Phosphorus is naturally occurring in land and is found in water
in much smaller concentrations. Human influences over the
years, however, have caused phosphorus concentrations to rise
in many of the world’s bodies of water. These contributions
have increased to such a point it is now necessary to monitor
the phosphorus concentration in many water systems in
order to prevent or minimize environmental consequences
and keep the world’s limited freshwater resources usable.
.
Phosphorus is an important catalyst for lighting matches.
Phosphorus is an important nutrient
for the growth and metabolism of
photosynthetic organisms.
Phosphorus | 4
WHAT IS PHOSPHORUS?
Phosphorus is a chemical element with symbol, P, and atomic
number 15. It is a nonmetal and is a solid in its elemental form
at typical ranges of temperature and pressure. As an element,
it generally exists as one of two main allotropes — white
phosphorus or red phosphorus, but it can also exist as violet
and black phosphorus.
White Phosphorus
White phosphorus molecules consist of four-atom
tetrahedrons, in which each phosphorus atom is bonded with
the three other atoms (Figure 1).
White phosphorus is the least stable of the phosphorus
allotropes. When it is exposed to light or heat, it gradually
changes into red phosphorus. White phosphorus is flammable
and pyrophoric when it is exposed to the oxygen in air. When
in contact with oxygen, it burns and glows green.This reaction
forms crystalline phosphorus pentoxide, as shown:
P4 + 5O2 → P4O10
White phosphorus is only slightly soluble in water. It is often
stored underwater in order to avoid contact with oxygen.
White phosphorus is commonly used in military munitions
due to its volatility. It is most frequently employed in bombs,
missiles, and mortars. Upon impact, phosphorus-based
weapons explode into small pieces of burning phosphorus
that are capable of producing lethal third degree burns. White
phosphorus is also utilized to create smokescreens.
Figure 1.
P4 Molecule
Phosphorus | 5
Red Phosphorus
The red phosphorus allotrope is formed when white
phosphorus is exposed to high temperatures or sunlight over
time. The rate of change depends on the quantity of heat or
sunlight applied. The physical properties of the phosphorus
change as it shifts from white to red phosphorus. The P4
molecules break down and form amorphous chains of red
phosphorus (Figure 2).
Red phosphorus is actually an intermediate phase between
white and violet phosphorus and is not its own distinct
allotrope. Therefore it has a wide range of properties. The
structure of red phosphorus is more stable than that of white
phosphorus. Red phosphorus does not self-ignite in air below
260 ºC, but it is still flammable.
Red phosphorus is used commercially in matches, strike
plates for matches, fertilizers, pesticides, rat poison, and
semiconductors.
Violet and Black Phosphorus
Violet and black phosphorus are thermodynamically stable
allotropes. They are rare forms of phosphorus due to the
specific conditions required for their creation.
Violet phosphorus is a crystalline solid that results from
exposing red phosphorus to temperatures above 500 ºC for
several days.
Black phosphorus is obtained by subjecting white phosphorus
to temperatures of around 500 ºC and extremely high
pressures (1200 atmospheres). It is flaky, resembling graphite
in texture, and is the least reactive form of phosphorus.
Figure 2.
Red Phosphorus Structure
Phosphorus | 6
THE PHOSPHORUS CYCLE
Phosphorus is the least abundant of the major nutrients
in water, behind carbon, nitrogen, hydrogen, oxygen, and
potassium. A low concentration of phosphorus in water
can limit biological productivity. The unique relationship
between phosphorus and aquatic ecosystems has made
it the subject of many ecological studies.
Inorganic Phosphorus
Phosphorus rarely exists in nature in its elemental
form. It is usually found in either inorganic or organic
phosphorus compounds in water, rock, soil, or living
organisms.
The phosphorus cycle begins with inorganic phosphorus,
which on average makes up less than 10% of the total
phosphorus found in freshwater systems. It is cycled
quickly in places where it is consumed by organisms.
Orthophosphate (PO 43-) is the most significant form of
inorganic phosphorus found in water. Polyphosphates,
more complex inorganic compounds, are also present
in water at lower concentrations.
Unlike other natural cycles, such as those of nitrogen
and carbon, the phosphorus cycle has no gaseous phase.
Phosphorus does not exist as a gas in the atmosphere.
Instead, phosphorus in the form of orthophosphate is
weathered from rocks and sediment, particularly apatite,
by rain and surface runoff. Over long periods of time,
phosphate rock is deposited at the bottom of water
bodies through sedimentation. It is also deposited into
the soil where it is used by crops and other
terrestrial plants.
Organic Phosphorus
Photosynthetic organisms synthesize ionized forms of
phosphates and other nutrients in the water or soil to
create various forms of organic phosphorus, which is
an essential component of life. Nucleotides, such as ADP
and ATP, drive the cellular transfer of chemical energy
used for metabolism. Nucleotides also make up part of
the structure of DNA and RNA.
Animals obtain organic phosphorus by eating plants and
other animals. Decomposing plants and animals release
organic phosphorus back into the soil or water. Organic
phosphorus is also released into the environment
through animal waste.
Organic phosphorus is found in various forms in water,
including soluble and suspended (sestonic) forms. Soluble
organic phosphorus also often includes phosphorus in
a colloidal state. Organic phosphorus makes up about
90% of the phosphorus in freshwater systems.
Phosphorus | 7
THE PHOSPHORUS CYCLE
Feeding by
heterotrophs
Cell respiration
Phosphate excreted
Fertilizer
Phosphate
taken up by
plants. Fixed
into organic
phosphate in
plant biomass.
Agriculture
Algae
phytoplankton
Leaching of
fertilizer
Phosphate in soil
Phosphate dissolved
in water
Millions
of years
Mining of
phosphate rock
Sedimentation
formation of
phosphate rock
The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike
many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorusbased compounds are usually solids at the typical ranges of temperature and pressure found on Earth.
Phosphorus | 8
HOW PHOSPHORUS Enters the Environment
Phosphorus is naturally occurring and is conserved in
the environment in a multitude of substances. Along
with carbon dioxide, water, and sunlight, plants require
phosphorus to grow. Humans also need different forms
of phosphorus for various biological purposes, including
bone structure and retaining homeostasis.
Phosphate Mining
Natural sources of phosphorus include several minerals
found in rocks and soil. Exposure to rain or snowmelt
causes phosphate ions from these minerals to leach into
nearby water sources. Considering the low solubility of
phosphorus, this is generally a slow process.
Phosphorus is not always replenished in the soil by
natural means. Over-farming and aggressive agricultural
practices often deplete phosphorus in soil. For the
past century, the primary solution to this has been to
apply synthetic fertilizers liberally to agricultural land
in order to maximize crop production.
The use of phosphorus in fertilizer has revolutionized
the farming industry. In fact, the proliferation of modern
agricultural practices including fertilization after World
War II is often referred to as the “Green Revolution.”
Despite the environmentally friendly connotations
now associated with the descriptor “green,” the
impact of over-fertilization has been devastating to the
environment.
Despite the environmentally friendly
connotations now associated with the
descriptor “green,” the impact of overfertilization has been devastating to the
environment.
Phosphate mining on the island of Nauru
Inorganic phosphate is mined from large phosphate rock
deposits for industrial use. Of the phosphate mined, 84%
to 90% is used for fertilizer production. The remainder
is used in the chemical, light, and defense industries.
Phosphate mining has occurred for more than 100 years.
Phosphate rock deposits are found on the surface, so
phosphate is obtained primarily through surface mining.
The current method of mining uses diesel or electricpowered dragline excavators to mine the phosphate
rock from the Earth in large proportions. A single
dragline excavator can mine about 135,000 tons of
phosphate rock per month. In 2003, the phosphate
industry in Florida, the United States’ leading producer
of the chemical, mined 22.8 million metric tons of
phosphate rock.
Phosphorus | 9
Phosphate Processing
Phosphate rock is processed in beneficiation plants
near phosphate mines. It is turned into slurry by highpressure water guns on site then pumped into the
plants where it is processed and used in fertilizer and
other applications.
The phosphate rock slurry is first separated from sand
and clay. The remaining substance is calcium phosphate
(Ca 3(PO 4) 2). The calcium phosphate is then mixed with
sulfuric acid (H 2SO 4) to form phosphoric acid (H 3PO 4)
and calcium sulfate dihydrate (CaSO 4•2H 2O), according
to the following equation:
Fertilizer
NH3
CaSO4
• 2H2O
H3PO4
Ca3(PO4)2 + 3H2SO4 + 2H2O → 2H3PO4 + 3CaSO4 • 2H2O
Phosphoric acid is mixed with other substances to
produce the phosphate compounds used in industry.
Ammonium phosphate ((NH 4) 3PO 4), which is used as
an ingredient in fertilizer, is the most common of these
compounds.
Raw
Ore
Sulfur
Water
Slurry
SO2
Figure 3. Phosphorus Processing
Ammonium Phosphate Fertilizer
Ammonium phosphate is a synthetic fertilizer that is used
heavily in agriculture. Farmers apply it to their fields, where
it provides crops with the nutrients phosphorus and nitrogen.
Ammonium phosphate and other phosphorus-based fertilizers
help achieve optimal crop yield and ensure against crop
failure.
However, farmers often overuse fertilizer and apply many
times more than what is necessary, because fertilizer is cheap
compared to the price of losing crops. Leftover phosphorus
slowly leaches from the soil through surface runoff and rain.
This water flows into and contaminates ponds, streams, rivers,
lakes, and other surface waters. Phosphorus contamination
alters the natural properties of each aquatic ecosystem
through which it passes.
H2SO4
Ca3(PO4)2
Catalyst
(V2O5)
SO3
Phosphorus | 10
EFFECT OF PHOSPHORUS on the Environment and Human Health
Phosphogypsum
Eutrophication
Calcium sulfate dihydrate is called gypsum, a soft mineral
that is abundant in nature. The gypsum that is the byproduct
of producing phosphoric acid is known as phosphogypsum.
Phosphogypsum is more radioactive than naturally occurring
gypsum because radium found in mined phosphate rock
associates with the calcium sulfate after the production of
phosphoric acid.
Excessive levels of phosphorus are detrimental to aquatic
ecosystems. Surface runoff leaches phosphorus from
agricultural land and into streams, rivers, and other water
systems. This land tends to be over-fertilized with either
synthetic fertilizers like ammonium phosphate or natural
fertilizers like hog manure that are high in phosphorus. When
phosphorus concentrations rise significantly above natural
levels in the water, a phenomenon called eutrophication
occurs. It is estimated 48% of lakes in North America are
eutrophic.
For every ton of phosphoric acid produced, five tons of
phosphogypsum are produced. The use of phosphogypsum
in industry is prohibited by the EPA unless it has an average
concentration of less than 10 picocuries per gram (pCi/g)
radium. Because most of Florida’s phosphogypsum exceeds
this limit, the state’s phosphate industry generally cannot use its
phosphogypsum in consumer products.The phosphogypsum is
instead piled in massive stacks (Figure 4). There are currently
over one billion tons of phosphogypsum in twenty-five stacks
in Florida, and approximately 30 million tons are added every
year. The phosphogypsum stacks pose the threat of becoming
permanent fixtures of the land, taking up more space every
year.
Eutrophication occurs in water with abnormally large
concentrations of nutrients, especially phosphorus and
nitrogen. The presence of excessive nutrients causes a rapid
increase in primary production, meaning phytoplankton and
bacteria grow in large proportions.
Algal blooms are common in eutrophic waters. When
phosphorus levels are too high, algae grow quickly. Slow
moving, green-water lakes and ponds are especially susceptible
to algal blooms.
Some varieties of algae can even produce toxins that are
dangerous to aquatic organisms, wildlife, and humans. Bluegreen algae, which are actually bacteria called cyanobacteria,
are notorious for releasing harmful toxins in aquatic
environments.
Figure 4. Phosphogypsum Stack in Fort
Meade, Florida
Symptoms of a eutrophic water system include:
•Increased amount of algae/phytoplankton
•Toxic varieties of algae/phytoplankton
•Decrease in dissolved oxygen
•Increased number of fish kills
•Decrease in edibility of fish and shellfish
•Decrease in aesthetic value of water
•Undesirable color and smell
•Difficulty in water treatment
Phosphorus | 11
Dead Zones
Phosphorus and Human Health
In addition to releasing toxins, algal blooms are
responsible for large fluctuations in the dissolved oxygen
content of water. During the day, algae photosynthesize,
consuming carbon dioxide and releasing oxygen into
the water. However, during the night, algae respire,
consuming oxygen and releasing carbon dioxide. In
this way, algal blooms can create hypoxic conditions
at night. Additionally, when algae decay, bacteria uses
dissolved oxygen in the water as part of the bacterial
decomposition process.
Organophosphates are frequently used in pesticides.
Organophosphates such as these are powerful nerve
agents that disrupt the action of the acetylcholinesterase
enzymes that allow neurotransmitters to function.
Exposure to organophosphate nerve agents causes
pupil contraction, salivation, lacrimation, involuntary
urination and defecation, vomiting, convulsions, and
eventually death by asphyxiation as control is lost over
respiratory muscles.
Fish and other aquatic species cannot live in an aquatic
environment with low concentrations of dissolved
oxygen. When conditions are hypoxic — less than 30%
dissolved oxygen saturation — aquatic species can
suffocate and die en masse. Areas that cannot sustain life
because they are hypoxic are known as “dead zones.”
Phosphorus was a significant contributor to dead zones
in Lake Erie and the Gulf of Mexico. In the 1970s, Lake
Erie was completely anoxic (without oxygen) and was
declared a “dead lake.” Because of this, controls were
enacted on the nutrient loading that was contributing
to algal blooms in the lake. The EPA also monitored
the dissolved oxygen content of the lake to measure
any changes. In the 1980s, the lake’s dissolved oxygen
concentration was on the rise, and the dead zones were
disappearing. In recent years, however, the status of the
lake’s dead zones worsen, and dissolved oxygen levels
are down.
A similar situation is occurring in the Gulf of Mexico,
where nutrient loading from the Mississippi River has
caused eutrophic conditions and the creation of dead
zones. First noticed in the 1970s, the dead zones in the
Gulf of Mexico now make up about 10,000 square miles,
and they continue to increase in size.
Despite the alarming and potentially deadly effects of
organophosphate, these pesticides have little effect
on humans when used properly. However, prolonged
exposure can cause organophosphate poisoning.
Organophosphate pesticides are widely used as poisons
and as a method for suicide. Production of chemical
weapons that include organophosphates was outlawed
in the Chemical Weapons Convention of 1993.
Phosphorus necrosis of the jaw, also known as
“phossy jaw,” is a disease caused by exposure to white
phosphorus and its vapors. It most commonly occurs in
people who regularly work around white phosphorus.
Sufferers of this condition have phosphorus deposited
in their jaws that can cause painful toothaches and
swelling of the gums.
Inorganic phosphate, on the other hand, is not
considered harmful for human consumption. In fact, it
is added to drinking water in some places to lower its
pH and prevent corrosion in pipelines.
Phosphorus necrosis of the jaw, also known as
“phossy jaw,” is a disease caused by exposure to
white phosphorus and its vapors.
Phosphorus | 12
HOW PHOSPHORUS CONCENTRATION is Measured
There are several processes for testing phosphorus
concentration in water. The type of phosphorus
compound being measured dictates what method is
appropriate. Phosphorus in a water sample is broken
into three components for analytical purposes: soluble
reactive phosphorus (SRP), soluble unreactive (or
soluble organic) phosphorus (SUP), and particulate
phosphorus (PP). Together, these three make up total
phosphorus (TP) concentration.
The analysis of a phosphorus sample involves two
steps: the conversion of the phosphorus compound
into dissolved orthophosphate (sample preparation),
and the colorimetric determination of the dissolved
orthophosphate in the sample (measurement). The
concentrations of the different types of phosphorus
compounds mentioned above can be found using the
procedure shown:
Whole Water Sample
Filter
Digest
Soluble
Reactive P
Soluble
Unreactive P
Digest
Total
P
Figure 5. Phosphorus Sample Preparation
Filtration
Soluble forms of phosphorus are separated from suspended
forms through filtration in the first step of sample preparation.
A 0.45μm pore diameter membrane is the established standard
for making a thorough separation. However, it is recognized
that this method of filtration does not necessarily produce
complete separation. Some colloidal forms of phosphorus can
pass through this filter size.
Glass fiber filters can replace or supplement membrane
filters. Glass filters transmit more suspended phosphorus than
membrane filters, which can cause the soluble phosphorus
measurement to be inflated. The benefit of glass filters is their
low cost compared to membrane filters. Glass fiber filters
are also convenient due to their frequent use in other water
quality tests for suspended solids.
The concentration of soluble reactive phosphorus can be
determined using filtration alone. Soluble reactive phosphorus
is measured as the orthophosphate concentration in the
filtered sample. In order to find the concentration of all soluble
phosphorus, and subsequently soluble unreactive phosphorus,
the filtered sample must be digested.
Digestion
Digestion is the second step in sample preparation. It is a
technique used to oxidize all present forms of phosphorus
to release measureable orthophosphate. Various acids have
been used as oxidizers for digestion, but none of them are
completely effective.
Popular methods for digestion include perchloric acid, sulfuric
acid-nitric acid, and persulfate digestion. The perchloric acid
method is the most difficult and time consuming and is
therefore only recommended for difficult samples. The nitric
acid-sulfuric acid method is viable for most samples. The
persulfate oxidation method is the simplest, but it is also the
most suspect to error.
By digesting a filtered sample, one can determine total soluble
phosphorus concentration, while digesting an unfiltered
sample reveals total phosphorus concentration.The difference
between total soluble phosphorus concentration and soluble
reactive phosphorus concentration is soluble organic
phosphorus concentration, and the difference between total
phosphorus concentration and total soluble phosphorus
concentration is particulate phosphorus concentration.
Phosphorus | 13
Colorimetry
Orthophosphate concentration in a sample is
determined by colorimetry. There are a few colorimetric
methods, depending on the range in concentration
being measured. The vanadomolybdophosphoric acid
method is suitable for the range of 1 to 20 mg P/L. The
stannous chloride and ascorbic acid methods are more
appropriate for the range of 0.01 to 6 mg P/L, at which
greater sensitivity is needed for precision.
The vanadomolybdophosphoric acid method is
based on the reaction of ammonium molybdate
and orthophosphate in an acid medium to form
molybdophosphoric acid. When vanadium is introduced
to the sample, vanadomolybdophosphoric acid forms.
Vanadomolybdophosphoric acid is yellow in color.
The intensity of the yellow is proportional to the
concentration of orthophosphate in the sample.
The stannous chloride method is also based on the
formation of molybdophosphoric acid. Once formed,
the molybdophosphoric acid is reduced by stannous
chloride to form molybdenum blue. The intensity
of the blue is proportional to the concentration of
orthophosphate in the sample.
The ascorbic acid method is based on the reaction
of ammonium molybdate and potassium antimonyl
tartrate with orthophosphate in an acid medium
to form phosphomolybdic acid. Once formed, the
phosphomolybdic acid is reduced by ascorbic acid to
form molybdenum blue. The intensity of the blue is
proportional to the concentration of orthophosphate
in the sample.
By testing the colored samples in a spectrophotometer
at a specific wavelength, a quantitative value for the
absorbance of the sample is measured. The absorbance
is then compared to a standard calibration to determine
the concentration of orthophosphate in the sample.
Orthophosphate concentration can be
measured by colorimetry, such as with a
Hach Pocket Colorimeter.
Phosphorus | 14
APPLICATIONS for Monitoring Phosphorus
Agricultural Runoff
Fields utilized for agricultural purposes are typical
sources of phosphorus contamination. These are
identified as nonpoint sources because phosphorus
is not added directly to the water; rather, it leaches
through the soil.
Nonpoint sources can be difficult to monitor directly.
Alternatively, freshwater systems in the vicinity of
farmland are often monitored in order to test the impact
agriculture has on local surface water. Phosphorus
monitoring is important in order to gauge the success
of efforts to control nonpoint pollution levels in the
surrounding watershed.
Ecosystem Preservation and Reclamation
Various projects for the preservation and reclamation
of freshwater systems use phosphorus monitoring
extensively. A prime example of an ecosystem
reclamation project that requires phosphorus monitoring
is the Comprehensive Everglades Restoration Plan. The
CERP involves monitoring several Florida water bodies
including Lake Okeechobee, the Caloosahatchee River,
and St. Lucie Estuary, and other sources of phosphorus
contamination to the Everglades. The CERP also
involves the construction of more than 36,000 acres of
stormwater treatment areas that filter thousands of tons
of phosphorus out of Everglades waters. Phosphorus
monitoring is important in order to measure the
progress being made in reclamation efforts.
Load Monitoring and Wastewater
Effluent Standards
The EPA enforces water quality standards regarding
phosphorus contamination in a number of ways. The
agency commonly implements Total Maximum Daily
Loads on affected freshwater systems. In order for these
systems to meet the TMDL, the water is monitored at
a number of sites within the system to help identify
the source or sources of the contaminant. When the
source is discovered and work begins to alleviate the
contaminant load, monitoring efforts continue in order
to measure progress.
The EPA also limits phosphorus contamination by
enforcing federal regulations on wastewater from
industrial facilities. This is similar to a TMDL, except
it regulates point source rather than nonpoint source
pollution. For example, the EPA Code of Federal
Regulations sets the maximum output of phosphorus
in phosphate manufacturing effluent at 105 mg/L on any
day and an average of 35 mg/L for a thirty day period.
Manufacturers are obligated to monitor their effluent to
determine whether they are within these regulations.
Research
Research on the effects of phosphorus in lakes and other
freshwater systems is an ongoing process that requires
constant monitoring of phosphorus levels. Studies on
the relationship of phosphorus and the ecology of
freshwater systems is of practical importance. Data and
models produced from this research can help predict
the changes in water quality of a system based on the
concentration of phosphorus. It also provides useful
information for current and future water reclamation
and preservation projects.
Phosphorus | 15
BIBLIOGRAPHY
Averbuch-Pouchot, M.T., A. Durif. 1996. Topics in Phosphate Chemistry. World Scientific.
Carlson, R.E., and J. Simpson. 1996. A Coordinator’s Guide to Volunteer Lake Monitoring Methods.
North American Lake Management Society.
Gain, W. Scott. 1997. An Optimized Network for Phosphorus Load Monitoring for Lake Okeechobee, Florida.
U.S. Geological Survey.
Greenberg, Arnold, Lenore Clesceri, and Andrew Eaton. 1992. Standard Methods for the Examination of Water and
Wastewater, 18th Edition. American Public Health Association.
Wetzel, Robert. 2001. Limnology: Lake and River Ecosystems, 3rd Edition. Academic Press, San Diego, CA.
Zhang, Patrick. Mining and Beneficiation. Florida Institute of Phosphate Research. n.d. Web.
<http://www.fipr.state.fl.us/>
IMAGE CREDITS
Phosphate mining in Nauru photo (page 8) by Jacky Ghossein.
Phosphogypsum stack photo (page 10) by Harvey Henkelmann.
Phosphorus | 16
GLOSSARY
Absorbance: The measureable quantity of light absorbed
by a substance.
Allotrope: One of multiple existing structural forms
of an element. Different allotropes of an element have
distinct properties.
Apatite: A type of mineral that contains phosphate and
is often referred to as phosphate rock or phosphate
ore. It is mined in large quantities for phosphate that is
used in industry and agriculture.
Beneficiation: The process by which mined ore is
separated into a desired product and waste material.
Cyanobacteria: Photosynthetic bacteria commonly
known as blue-green algae. It is found in both aquatic
environments and in soil.
Digestion: The process by which organic material is
broken down into inorganic compounds.
Dissolved Oxygen: The concentration of oxygen gas
dissolved in water. Commonly abbreviated as DO.
Eutrophication: The rapid growth of algae and other
ecologically damaging effects that result from large
concentrations of dissolved nutrients entering an
aquatic ecosystem.
Green Revolution: The development and spread of
agricultural technology throughout the globe beginning
in the 1940s. These technologies include mechanization,
irrigation, crop rotation, and the application of synthetic
fertilizers and pesticides.
Homeostasis: The property of a living organism
maintaining constant stable internal conditions, such as
body temperature and blood constitution.
Hypoxia: The quality of an aquatic system with a
depleted concentration of dissolved oxygen, causing
the asphyxiation of many aquatic organisms.
Nucleotide: A molecule that includes a nitrogenous
base and one or more phosphate groups. Nucleotides
make up DNA and RNA, as well as the ATP and ADP
that are responsible metabolism
Organophosphate: An ester of phosphate that is often
used in herbicides and insecticides. It is also a powerful
nerve agent.
Orthophosphate: The most basic form of inorganic
phosphate, PO 43-.
Polyphosphate: Phosphate polymer. It is used in
laundry detergents and water softeners, among other
applications.
Phosphogypsum: A substantial byproduct of phosphoric
acid production in phosphate manufacturing. It tends to
be more radioactive than naturally occurring gypsum.
Pyrophoric:The quality of a substance that spontaneously
ignites when exposed to air.
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