Nitrate Pollution: A Menace to Human, Soil, Water and Plant

Universal Journal of Environmental Research and Technology
Available Online at: www.environmentaljournal.org
(c) All Rights Reserved
2011 Vol 1 22-32

Open Access




Review Article

Nitrate Pollution: A Menace to Human, Soil, Water and Plant

1Subhash Chand, 2Malik Ashif, 3Zargar M.Y., 4Bhat M. Ayub

1, 4Assistant Professor, Division of Soil Science
2PhD Research Scholar, Division of Environmental Sciences.
3Professor cum Chief Scientist, Environmental Science
Sher-e-Kashmir university of Agriculture Sciences and Technology of Kashmir, Jammu and Kashmir
Corresponding author: subhashphd2002@yahoo.com; subhashchandm1@gmail.com

Abstract
Health of human, soil, water and plant are integral part of a sustainable ecosystem. Nitrogen is a major
constituent of the earth's atmosphere and occurs in different gaseous forms such as elemental nitrogen, nitrate
and ammonia. Natural reactions of atmospheric nitrogen with rainwater result in the formation of nitrate and
ammonium ions. While nitrate is a common nitrogenous compound due to natural processes of the nitrogen
cycle and nowadays anthropogenic sources have greatly increased the nitrate concentration, particularly in
groundwater. The largest anthropogenic sources are septic tanks, application of nitrogen-rich fertilizers to
turfgrass and agricultural processes. Levels of nitrates in groundwater in some instances are above the safe
levels proposed by the EPA and thus pose a threat to human health. Particularly in rural, private wells, incidence
of methemoglobinemia appears to be the result of high nitrate levels. Methemoglobinemia or blue baby
syndrome robs the blood cells of their ability to carry oxygen. Due to the detrimental biological effects,
treatment and prevention methods must be considered to protect groundwater aquifers from nitrate leaching
and high concentrations. Treatment through ion-exchange and other processes can rehabilitate already
contaminated water, while prevention, such as reduced dependence on nitrogen-rich fertilizers can lower the
influx of nitrates.

Keywords: Groundwater pollution, Human health, Methemoglobinemia, Nitrate nitrogen

1. Introduction
nitrate in the groundwater can be reduced over
Nitrate is a problem as a contaminant in drinking
time. Treatment processes, such as ion exchange can
water (primarily from groundwater and wells) due to
have an immediate effect on reducing levels in
its harmful biological effects. High concentrations
drinking water. These processes do not remove the
can cause methemoglobinemia, and have been cited
entire nitrate, but can help to bring the
as a risk factor in developing gastric an intestinal
concentration down to the suggested level of
cancer. Due to these heath risks, a great deal of
10mg/L.

emphasis has been placed on finding effective
2. Nitrogen Cycle (atmosphere-soil-water)
treatment
processes
to
reduce
nitrate
Nitrogen is the most abundant element in the
concentrations to safe levels. An even more
atmosphere; composing nearly 80% of the air we
important facet to reduce the problem is prevention
breathe (Berner and Berner, 1987). Gaseous
measures to stop the leaching of nitrate from the
nitrogen can be found in many forms, the major
soil. Some suggest that reducing the amount of
ones consisting of N
fertilizers used in agriculture will help alleviate the
2, N2O, NO, NO2, NH3 (Gaillard,
1995). Some of these gases readily react with rain
problem and may not hurt crop yields. Other new
water to produce nitrate and ammonium ions in
developments in leach pits and slurry stores help to
solution. These ions can become part of the soil
control the nitrate that comes from stored manure.
layer composition, or even enter into a groundwater
By installing these prevention methods and reducing
solution.
the amount of fertilizer used, the concentration of



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The two most important compounds that result from
the United States and other countries have reported
the reaction of these gases and rainwater are nitrate
significant contamination of groundwater from
(NO -
+
3 , an anion) and ammonium (NH4 ). In the
septic tanks. Ground water contamination is usually
atmosphere, major sources of nitrate include
related to the density of septic systems (Hallberg
reactions caused by lightning, photochemical
and Keeney, 1993). In densely populated areas,
oxidation in the stratosphere, chemical oxidation of
septic systems can represent a major local source of
ammonia, soil production of NO by microbial
nitrate to the groundwater. However in less
processes and fossil fuel combustion (Gaillard,
populated areas septic systems don't really pose
1995). Ammonia in the air comes from fertilizer
much of a threat to groundwater contamination.
manufacturing, anaerobic decay of organic matter,

bacterial decomposition of excreta and the burning
When
natural
sources
contribute
a
high
of coal (Gaillard, 1995). Anthropogenic activities
concentration of nitrate to the groundwater it is
have a major impact on the levels of these
usually as a result of anthropogenic disturbance.
compounds that are found in both rain water and
One example of this is the effect of forested areas on
the atmosphere. Many of the major sources of
the leaching of nitrate to the groundwater. Natural,
nitrate and ammonium come from the use and
mature forests conserve nitrogen but human
production of fertilizers and the burning of fuels, as
disturbances can lead to nitrate pollution of the
listed above.
groundwater. However, while this is a potential

problem for groundwater, forests represent a very
Nitrate that leaves the atmosphere can be converted
small source of nitrogen compared to agriculture
back into elemental nitrogen, through the process of
(Hallberg and Keeney, 1993).
denitrification. This often takes place in the soil

through the activity of bacteria that reduce the
3.1 Non-Agricultural Sources (NAS)
nitrate. Ammonium can undergo the process of
One potentially large source of nitrogen pollution of
nitrification, which is an oxidation reaction that
groundwater is the application of nitrogen-rich
converts it to nitrate. Through this mechanism, the
fertilizers to turfgrass. This occurs on golf courses
nitrogen in the ammonium ion is released back into
and in residential areas. There are five fates for this
the atmosphere (Berner and Berner, 1987). After the
nitrogen once it is applied to turfgrass. It may be:
conversion from elemental into nitrogenous ions in

solutions of rainwater, the nitrogen in these
1
Taken up by plants
compounds can be exhausted back to the
2
Stored in soil
atmosphere by the pathways previously described,
3
Lost to atmosphere
thus completing the cycle.
4
Lost to groundwater

5
Lost to runoff (Bocher, 1995)
3. Major Sources of Nitrate Pollution

Many studies have shown that most of the nitrogen,
Although there are many sources of nitrogen (both
about 30 to 50 percent is taken up by the plant.
natural and anthropogenic) that could potentially
According to United States Golfing Association study
lead to the pollution of the groundwater with
only one to two percent of the nitrogen is leached
nitrates, the anthropogenic sources are really the
beyond the root zone (Bocher, 1995). This finding
ones that most often cause the amount of nitrate to
may be slightly biased because this is the result that
rise to a dangerous level. Waste materials are one of
the USGA desires. Also, this result may occur only
the anthropogenic sources of nitrate contamination
when the nitrogen fertilizer is applied carefully and
of groundwater. Many local sources of potential
properly. Certain circumstances could lead to more
nitrate contamination of groundwater exist such as,
of the nitrogen leaching to the groundwater. Six
`sites used for disposal of human and animal sewage;
main factors affect nitrogen leaching:
industrial wastes related to food processing,

munitions, and some polyresin facilities (Vomocil,
1) Nitrogen rate - One study showed that at one
1987); and sites where handling and accidental spills
pound of nitrogen per 1,000 square feet, no
of nitrogenous materials may accumulate' (Hallberg
leaching occurred.
and Keeney, 1993). Septic tanks are another
2) Nitrogen source: Slow-release fertilizers are a
example
of
anthropogenic
source
nitrogen
nitrogen source that can reduce the chance of
contamination of the groundwater. Many areas of
leaching.
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3) Application timing: In late fall, plants take up less
nitrate. This problem is even worse in Europe where
nitrogen and there is a greater chance for leaching
grazing pastures are usually more intensively
to occur.
fertilized than in the U.S., therefore there is more
4) Irrigation practices: The more irrigation that takes
nitrate available to be leached to the groundwater
place the greater the chances for nitrate leaching.
(Hallberg and Keeney, 1993). Even small farms can
5) Soil texture: The sandier the soil the more chance
contribute to the problem of excess nitrates because
for nitrate leaching.
of the high concentrations of manure that they may
6) Age of site: Younger sites usually have less organic
have in the barnyard or feedlot areas (Hallberg and
matter and need to be fertilized more therefore
Keeney, 1993).
increasing the chance of leaching (Bocher, 1995).


One of the better ways to get rid of manure is to use
3.2 Agricultural: Fertilizers and Animal
it to fertilize cropland. Such organic material is often
Wastes
considered a desirable nitrogen source because the
nitrogen is in the mineralization-immobilization cycle
The main source of nitrate pollution in the
longer and thus is more slowly available (Hallberg
groundwater results from the actions of farmers.
and Keeney, 1993). For this reason, it is a safer
Farming alone pollutes more of our groundwater
fertilizer than chemical fertilizer. However manure
resources than anything else. Too many farmers are
use does have many drawbacks such as variable
caught up in an escalating cycle of pollution (Behm,
composition and quality and the extra time for
1989). The farmers first deplete the soil by
nitrogen to be mineralized may not coincide with the
"excessive, repeat planting" and then try to
high rate of nitrogen needed by the crop. The main
replenish the resulting less-productive soil by putting
problem is the fact that an accurate estimation of
more and more nitrogen-based fertilizer on the land
net nitrogen availability is very difficult to determine
in an attempt to keep crop yields constant.
(Hallberg and Keeney, 1993). Therefore farmers

usually apply an excess of manure to the crop to
One example of proof that farming is a major cause
insure that enough nitrogen will be available for the
of groundwater pollution is that nitrate problems are
growing process.
most common in the spring, which is the time that

farmers apply nitrogen fertilizer to their fields. Also,
Obviously the more nitrogen fertilizer a farmer uses
in a study done by Burkart and Kolpin (1993) it is
the greater the chance of nitrate pollution of
found that samples of water from wells surrounded
groundwater. Farmers still consider nitrogen
by more than 25% land in corn and soybean have a
fertilizer cheap insurance against crop failure
dramatically larger frequency of excess nitrate (30%)
(Looker, 1991). Approximately one dollar's worth of
than wells with approximately 25% of the
fertilizer could bring in ten dollars of corn if the soil
surrounding land in corn or soybean (11%). Also
has a lack of nitrogen. So the farmer would,
many of the same factors that affect nitrogen
financially speaking, much rather add too much
leaching in turfgrass affect it in crop fields. For
nitrogen than too little. To add to this problem, it is
example, the use of irrigation increases the chance
very difficult to determine exactly how much
of nitrate pollution. The frequency of excess nitrate
nitrogen a crop will need before harvest time due to
was also larger where irrigation was used within 3.2
yearly change in yields and weather conditions. Even
km of a well (41%) than where no irrigation was used
if farmers cut down on nitrogen fertilizer, there will
(24%) (Burkart and Kolpin, 1993). In areas where the
still be some nitrate leaching. As Dennis Keeney, the
soils over the aquifer are predominantly sand,
director of the Leopold Center for Sustainable
sorption of herbicides is limited and the rate of
Agriculture at Iowa State University, states, Even if
recharge is rapid, resulting in a relatively large
farmers add no fertilizer to fields, tilling the earth
potential for contamination of aquifers with nitrates
with machinery makes land more susceptible to
(Burkart and Kolpin, 1993).
leaking
nitrogen
(Looker,
1991).
Although

sustainable practices may not eliminate nitrates, it
One problem caused by farms results from the
might lower them to a safe level. Obviously, if there
grazed grasslands and feedlots. In grazing pastures
is a chance of nitrogen pollution when no fertilizer is
animal wastes are concentrated in small pastures,
applied, the chance of pollution is greatly increased
this leads to inefficient use of nitrogen and causes
when a large amount of fertilizer is applied. The
the potential for groundwater contamination by
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nitrate pollution may be overcome by judicious use
proposed MCLG (Vogt and Cotruvo, 1987). For many
of organic along with inorganic fertilisers. Several
contaminants,
carcinogenicity
is
the primary
production recommendations has been adopted and
characteristic which determines the MCL; however,
suggested for sustainable crop productivity and soil
because there are no conclusive epidemiological
health (Chand, 2008).
studies which link nitrate to cancer in humans,

carcinogenicity was not taken into account in the
3.3 Manure Storage
establishment of the MCL for nitrate (Kamrin, 1987).

Another potential source of nitrate leaching to the
The determining factor in the EPA's decision to set
groundwater that deals with farming is the storage
the MCL at 10 mg/L was the occurrence of
of the manure. Farmers commonly store manure in
methemoglobinemia in infants under of six months.
large holes in the ground. While this is convenient
The MCL reflects the levels at which this condition
and relatively inexpensive for the farmer in the short
may occur (Kamrin, 1987). Although the MCL for
term, it results in excessive leaching of nitrates. In an
nitrogen was set at 10 ppm nitrate-nitrogen, in 1976
attempt to prevent leaching some of these manure
the EPA suggested that water having concentrations
lagoons have been built with liners. However, as a
above 1 ppm should not be used for infant feeding
study at the University of Wisconsin at Madison
(Rail, 1989). This guideline is very conservative and
showed, there is a gradual but continuous
nitrate concentrations below 10 ppm are probably
breakdown of the liner and after some years the
harmless as well. However, because concentrations
liner no longer retains the ability to prevent leaching
this low are common, the EPA hopes this guideline
of contaminants from the manure to the soil below
will induce people in rural areas to have their wells
(Lagoon Reclamation, 1993). Problems also arise
tested so that severe nitrate contamination is
when these manure lagoons are left idle for a long
detected and serious health problems are avoided in
period of time without being properly broken down.
the future.
It has been found that an empty manure storage

facility can be more hazardous to groundwater than
a full one. The sides of an empty lagoon are directly
5. Problems Associated With High Nitrate
exposed to the sun and air. This results in the drying
Levels
and cracking of the soil material. Precipitation
When
nitrate-nitrogen
concentrations
reach
containing large amounts of dissolved oxygen will
excessive levels there can be harmful biological
then convert the ammonium in the contaminated
consequences for the organisms which depend on
soil and leftover manure to nitrates which can easily
groundwater. Of course, human interest is of
be leached out (Lagoon Reclamation, 1993).
primary concern when setting guidelines for

acceptable nitrate levels and proper agricultural
4. Environmental Protection Agency
practices.
The
United
States
Environmental
Regulations (EPARs)
Protection Agency established the current drinking
water standard and health advisory level of 10 mg/L
The United States Environmental Protection Agency
nitrate-nitrogen
(equivalent
to
10
ppm
is currently establishing National Primary Drinking
nitrate-nitrogen or 45 ppm nitrate) based on the
Water Regulations for over 80 contaminants under
human health risks due to nitrate consumption
the Safe Drinking Water Act (Vogt and Cotruvo,
(Kross, 1993). Although there have been studies
1987). The goal is to reduce the contaminant
performed attempting to link nitrate consumption to
concentrations of all drinking water to levels near
various illnesses, only methemoglobinemia, (also
those prescribed in the Maximum Contaminant Level
infant cyanosis or blue-baby syndrome) has been
Goals (MCLGs) previously established by the EPA
proven to result from ingestion of water containing
(Vogt and Cotruvo, 1987). MCLGs are non
high nitrate concentrations, above 10 ppm (Kross,
enforceable health goals at which no known or
1993).
anticipated adverse effects on health of persons
occur and which allow an adequate margin of safety

(Vogt
and
Cotruvo,
1987).
The
Maximum
5.1 Blue-Baby Syndrome (BBS)
Contaminant Levels (MCLs) are to be set as close to
Cases of blue-baby syndrome usually occur in rural
the MCLGs as possible (Vogt and Cotruvo, 1987). In
areas which rely on wells as their primary source of
the case of nitrate concentrations, the MCL has been
drinking
water.
Often
these
wells
become
set at 10 mg/L (ppm) as nitrogen which is also the
contaminated when they are dug or bored and are
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located close to cultivated fields, feedlots, manure
that
infants
possess
much
less
oxidizable
lagoons or septic tanks (Comly, 1987; Johnson et al.,
hemoglobin than adults, so a greater percentage of
1987). The most contaminated wells are usually
their hemoglobin is converted to methemoglobin
those that were dug rather than drilled and have
which greatly decreases the blood's ability to carry
poor or damaged casings (Comly, 1987; Johnson et
oxygen. Other possible reasons are that nitrite ions
al., 1987). Until recent awareness of the dangers of
may be more strongly bound by infantile
nitrate contaminated groundwater prompted testing
hemoglobin due to immaturity of certain enzymes,
for nitrate concentrations, along with other
and that the kidneys of infants have inferior
contaminants, wells with dangerously high nitrate
excretory power which may favor retention of nitrite
concentrations usually went unnoticed until health
for longer periods of time (1987).
problems were brought to attention. A few isolated

cases of methemoglobinemia, primarily in the rural
Steps can be taken to prevent the child from
United States, have served as the catalyst for what
becoming a victim of methemoglobinemia. Residents
has grown into a broad awareness and concern for
of rural areas should have their wells tested,
nitrate contamination.
especially if pregnant women or infants are

consumers of the well water. If the well is
Methemoglobinemia is the condition in the blood
contaminated, other water source alternatives are
which causes infant cyanosis, or blue-baby
other safe wells, bottled water, a new, deeper well,
syndrome. Methemoglobin is probably formed in the
or a water purification system which is capable of
intestinal tract of an infant when bacteria converts
removing the nitrates (Johnson et al., 1987). Comly
the nitrate ion to nitrite ion (Comly, 1987). One
suggests that because cyanotic babies usually
nitrite molecule then reacts with two molecules of
contract methemoglobinemia from the water used
hemoglobin to form methemoglobin. In acid
to prepare their formulas, formulas which use
mediums, such as the stomach, the reaction occurs
diluted whole milk are less risky than those prepared
quite rapidly (Comly, 1987). This altered form of
from powdered or evaporated milk which require
blood protein prevents the blood cells from
large amounts of water in preparation (Lukens,
absorbing oxygen which leads to slow suffocation of
1987). Breast feeding or the use of bottled water in
the infant which may lead to death (Gustafson,
formula preparation offer the safest solution,
1993; Finley, 1990). Because of the oxygen
especially if the groundwater quality is unknown
deprivation, the infant will often take on a blue or
(Johnson et al., 1987).
purple tinge in the lips and extremities, hence the

name, blue baby syndrome (Comly, 1987). Other
Since 1945, there have been over 2000 cases of
signs
of
infant
methemoglobinemia
are
infant methemoglobinemia reported in Europe and
gastrointestinal disturbances, such as vomiting and
North America with 7 to 8 percent of the afflicted
diarrhea, relative absence of distress when severely
infants dying (Rail, 1989). However, problems can be
cyanotic but irritable when mildly cyanotic, and
severe as shown in a specific 1950 report; there
chocolate-brown colored blood (Johnson et al.,
were 144 cases of infant methemoglobinemia with
1987; Comly, 1987).
14 deaths in a 30 day period in Minnesota (Johnson

et al., 1987). This of course was an isolated case.
Treatment of infant cyanosis is simple once the
However, it shows that nitrate concentrations in well
condition has been recognized. If the patient is
water can increase to deadly levels rapidly and the
mildly affected, then he/she must simply refrain
issue of nitrate contamination should not be
from drinking from the contaminated well for a few
ignored.
days and the body will replenish the hemoglobin by

itself in a few days (Johnson et al., 1987). However, if
5.2 Stomach and Gastrointestinal Cancer
the patient is severely cyanotic, methylene blue
Although many studies have been performed
must be administered intravenously in a dosage of
attempting to link stomach and gastrointestinal
1-2 mg/kg of body weight for a ten-minute period
cancer to nitrate intake, there is no conclusive
and improvement should be prompt (Johnson et al.,
evidence that there is a correlation. In fact, two
1987). Methemoglobinemia most often affects
particular studies in the United Kingdom have shown
infants of less than six months in age. Comly cites
an inverse relationship where instances of stomach
several factors that make infants more susceptible to
cancer are highest in areas where the groundwater
nitrate compounds that adults. The primary reason is
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concentration of nitrate is lowest and vice versa
6.1 Non-Treatment Sources (NTS)
(Payne, 1993; Forman et al., 1985). Scientists claim
The non-treatment sources are quite easy to
that nitrate represents a potential risk because of
understand in their logic; combine water with lower
nitrosation reactions which, with appropriate
levels of nitrate with waters of higher levels until a
substrates present, form N-nitroso compounds
safe quantity is reached, or if possible just avoid the
which are strongly carcinogenic in animals (Forman,
problem by utilizing another source. These methods
1985).
attempt to reach the suggested nitrate level of

10mg/L or less in potable water (Moore, 1991). In
In other areas of the world such as Columbia, Chile,
order to use any of these options the nitrate
Japan, Denmark, Hungary, and Italy, similar studies
problem must be localized to a very precise area.
have suggested a correlation, although there still
According to Guter (1981) four common alternatives
exists no concrete evidence to support this theory
are:
(Forman, 1985). At present, no other toxic effects

have been observed under conditions of high nitrate
1) Raw water source substitution: In this case an
levels. Even at exposure to levels of 111mg/L there
entirely new source of drinking water is used to
were no adverse conditions in infants except for
replace the heavily polluted water.
methemoglobinemia (Gustafson, 1993). Other claims
2) Blending with low nitrate waters: As a simple
that intake of nitrate contaminated groundwater is
example, if the current well water supply contains 15
linked to birth defects, and hypertension and high
mg/L of nitrates, then this could be combined with
blood pressure in adults are also unsubstantiated.
an equal amount of water with a concentration of 5
This inconsistency suggests that nitrate alone cannot
mg/L to achieve a safe concentration of 10 mg/L.
be the only cause of elevated regional gastric cancer
3) Connection to an existing regional system: This
mortality rates, but these could result from a
involves using a system that is already set up to
number of other factors, such as high pesticide
service the area, instead of drawing water from the
levels, presence of coliform bacteria, and/or other
contaminated well.
groundwater contaminants.
4) Organizing a regional system: This is similar to the

use of an existing regional system. One can form a

new regional utility by joining with other nearby
6. Clean-Up of Nitrate from Water
systems which may be having similar water quality
problems (Guter, 1981).
Nitrate causes problems as a contaminant in drinking

waters taken primarily from aquifers. In dealing with
The advantages of these methods, especially
the nitrate problem in subsurface waters, there are
combining existing resources, are the spread of the
two options for achieving safe nitrate levels. First of
costs of monitoring water quality amongst many
all there are non-treatment techniques that consist
different areas. This greatly reduces expenses and
of blending drinking waters, or changing water
helps to provide safe drinking water to larger
sources. The second alternative is the use of
numbers of people. However, these applications can
treatment processes, such as ion exchange, reverse
only be utilized if the contamination of nitrate is
osmosis, biological denitrification and chemical
confined to a specific area, otherwise tapping into
reduction to actually remove portions of the
other local or regional sources to dilute the water
pollutant. However, the most important thing to
would only result in perpetuating the problem.
note about these clean-up procedures is that neither

of these methods are completely effective in
Besides these methods of providing safer waters
removing all the nitrogen from the water. Treatment
with lower nitrate concentrations, there are
can remove some of the nitrate, but with varying
treatment methods. The most important idea to
efficiencies, much of which can depend on other
note about these processes, however, is that none of
substances found in the water. The non-treatment
them are completely effective in removing all nitrate
processes attempt to bring the nitrate concentration
from well water, or any other subsurface water.
down to a safer level, through blending with cleaner
Each one of these method's success rates depends
waters.
on the conditions of plant operation and the other

contaminants found in the water. The main sources

of research for nitrate removal consist of ion
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exchange, bio-chemical denitrification, and reverse
(Cl-) ion (Guter, 1981). This method of nitrate
osmosis. Today the primary system in use is ion
removal does not completely eliminate the
exchange.
contaminant from solution. However, `one such

facility [of ion exchange] in the San Joaquin Valley
6.2 Ion Exchange
resulted in a nitrate reduction from 16 to 2.6mg/L'
In the ion exchange process special resins are used
(Moore, 1991). The cost of the removal amounted to
to substitute chloride ions (C1-) for the nitrate
24.2 cents/1000 gal (Moore, 1991). So far this has
radical. This method of removal requires several
proven to be the most effective and efficient
steps for successful decontamination. Essentially,
treatment process.
the process relies on the fact that water solutions

must be electronically neutral, and therefore by
6.3 Bio-chemical Denitrification
inserting a negative ion, another negative ion can be
By using denitrifying bacteria and microbes, the
removed from the water. Besides the negative
nitrate ion can be reduced into its elemental state of
nitrate radical (NO3- ), common anions include
N2. These organisms are able to carry out this
sulfate
radical,
chloride
ion,
bisulfate
ion,
process through a reaction such as:
bicarbonate ion and carbonate ion. Some of the

common cations or positive ions are calcium,
6H+ 6

+

NO
5

+

-
CHO
H
3 N 5

+ CO 1

+

3H
O
3
3

2
2
2
magnesium and sodium (Guter, 1981).
By using a chemical such as ethanol, the removal of

nitrate is possible. Sometimes it is necessary to
The first part of the process is the selection of an
convert the nitrogen from the ammonium ion into
appropriate resin for the removal of the specific
nitrite with the use of nitrosomas (specialized
problematic ion, which in this case is nitrate.
bacteria) to facilitate the removal of all nitrogen
However, current resins are not completely nitrate
from the solution (Shuval, 1977). The nitrite
selective, and often remove other anions before
compound is then oxidized to nitrate, which can
removing the nitrogenous compound. Resin beds are
then be eliminated by the reaction shown above.
made up of millions of tiny spherical beads, which
Besides the use of special bacteria, photosynthetic
usually are about the size of medium sand grains
algae can remove nitrates from water. Using the
(Guter, 1981). As the solution passes through these
stoichiometric relationship of (Zajic, 329):
beds, the chloride anions are released into the
3-

+
water, removing first the sulfate ion, then the nitrate
aCO
c

+ NO
e

+

-
PO
(

+

c + 3e)H

+

2
3
4
radical. The entire process is composed of four major
1/2(b - c - 3e)H O-

C
aHbNcOdPe
+

steps to remove the selected ions from solution:
2
1) Resin recharge ( a +
b /
4 + c /
5 - d / 2 -
5
e/
4)
O
2

2) Anion exchange
Both of these processes can be somewhat effective
3) Resin becomes "exhausted" and
in removing nitrate, however, biological organism
4) Resin regeneration
are influenced by other toxic chemicals or

compounds that may be found in the water. These
In the first step of the process, the bed is recharged,
toxins can reduce greatly the effectiveness and
reaching its maximum exchange capacity. The resin
efficiency with which the organisms eliminate the
at this time has enough chloride ions to carry out the
nitrate
solution
(Organization
for
Economic
exchange as the solution passes through the
Co-Operation and Development, 1974). Another
complex. The ion exchange is the next part of the
important note about these processes is that the
process. The resin bed begins to remove the sulfate
practice of prechlorination greatly reduces the
radicals first, then when the majority of S0 2-
4 has
effectiveness of such techniques. Nitrates are, in
been removed from the water the exchange of
most cases, rapidly oxidized by chlorine (Moore,
nitrate and chloride begins. The completion of this
1991). However, the greatest benefit of the
phase is the third step as the resin becomes
bio-chemical denitrification is the fact that the
`exhausted' of the ion used for exchange. At this
nitrogen is completely removed in its gaseous
point no more anions leave the solution. Finally, in
elemental
form
(Organization
for
Economic
the fourth component of the process, the bed is
Co-Operation and Development, 1974). There is no
regenerated by passing a strong solution over the
residue or problems with disposal.
resin displacing the removed ions with the chloride

28
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Universal Journal of Environmental Research and Technology


7. Preventive Measures of Nitrate
back on nitrogen) was 127 pounds per acre (Looker,
Pollution
1991). However, the director of the Leopold Center
for Sustainable Agriculture at Iowa State University,
7.1 Non-Agricultural
Dennis Keeney, believes that farmers could
Based on the six factors affecting nitrate leaching in
eventually use only 75 pounds per acre and still have
turfgrass, seven practices can be adopted by
no drop off in yields. Mr. Dan Stadtmueller is an
turfgrass managers to help prevent the leaching of
example of an Iowan farmer who greatly reduced his
nitrates. One of the most important steps is to limit
fertilization practices. According to an article in the
the amount of nitrogen applied; "Use slow-release
Des Moines Register, Mr. Stadtmueller "is a miser
nitrogen sources, or low rates of soluble nitrogen
with nitrogen fertilizer". Some of Stadtmueller's
applied more often, where possible"(Bocher, 1995).
fields get as little as 60 pounds of fertilizer per acre,
Also the turfgrass manager should be very cautious
without displaying a decreasing yield (Looker, 1991).
about adding nitrogen during periods in which the

ground is not yet frozen but the grass is not growing.
There have been some steps taken to try and lessen
The manager should avoid over-irrigation, which
the amount of nitrogen fertilizer used by farmers.
increases the chance of nitrate leaching while doing
One such measure is a law written by then member
nothing for the plant. Effort should be made to
of the Iowa House of Representatives, Paul Johnson.
reduce the amount of nitrogen applied to older sites
This law taxed fertilizer-pesticides and used the
and collect drainage water instead of allowing it to
money raised from this tax to research and shows
drain into a river or stream. Finally, the turfgrass
farmers how to use fewer chemicals without losing
manager should use zeolite amendments. Zeolite is a
money (Looker, 1991). Also, Alfred Blacker, an Iowa
mineral with a high cation exchange capacity that
State University agronomist devised a test that
can hold on to things like potassium, calcium,
enables farmers to measure nitrogen already in the
phosphorous, magnesium or ammonium (Bocher,
soil more accurately. Dan Stadtmueller, the "miser"
1995). Most of these steps of prevention are even
of nitrogen fertilizer, switched to a method of
more important in areas of sandy soil. By following
farming called ridge tillage in 1975. This method
these steps the turfgrass manager will greatly reduce
enables him to put small amounts of fertilizer in
the chances of nitrate leaching into groundwater. If
permanent seedbeds instead of covering the entire
proper measures are taken, the fertilizing of golf
field. Stadtmueller switched to this method in 1975
courses, and athletic fields will not result in nitrogen
and insists that it is more profitable. However in
pollution of groundwater (Neal, 1995).
1991 only about two percent of farmers in Iowa used

the method (Looker, 1993). Stadtmueller figures that
7.2 Agricultural
this is because the majority of the farmers are afraid
The restricted and precise use of nitrate fertilisers
of change (Looker, 1993). This also represents the
coupled with use of organic sources and slow release
problem with the tests and laws that have recently
fertilisers reduce overall nitrate pollution. Many of
been formed; it might take some time to convince
these same steps can be implemented by farmers as
farmers that they can switch to new techniques
well to prevent nitrate leaching. The most important
without losing money in the process.
step for farmers is to reduce the amount of nitrogen

applied to the crops. This is easier said than done
7.3 Manure Storage Sites (MSS)
because most farmers consider nitrogen fertilizer to
Another method of prevention in the area of farming
be `cheap insurance' against a crop failure (Looker,
deals with manure lagoons. This is an easier problem
1991). As previously mentioned, nitrogen is a
to solve because there are proven solutions which
definite limiting factor in crop yields. "If soil lacks
are also better for the farmer in the long run. One
nitrogen, a dollar spent on the fertilizer can bring
technique of manure storage that is better than the
$10 in extra corn" (Looker, 1991). Therefore, from a
aforementioned manure lagoons is storing the
financial standpoint, a farmer would obviously
manure in concrete pits. Another possible solution is
rather add too much nitrogen to his crop than too
the installation of a storage facility termed a
little.
Slurrystore. These facilities are proven to store

manure without leaking and are actually more
In 1990, according to the U.S. Department of
convenient for the farmer once they are installed.
Agriculture, the rate of nitrogen fertilizer use in Iowa

(a state whose farmers lead the nation in cutting
29
Subhash Chand et al.

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Universal Journal of Environmental Research and Technology


7.4 Flood Plain Management (FPM)
While the study was limited to Iowa, the Iowa
One method of prevention of nitrate pollution of
Department of Natural Resources claims that the
groundwater that is unrelated to farming is actually
results can be extrapolated to other rural areas with
a method not of new technology but of going back
intensive agricultural production. The natural
to old ideas. Traditionally, flood plains in Britain
background concentration of nitrate-nitrogen in
were not vigorously farmed, but land drainage now
Iowa is less than 2 mg/L. Higher concentrations
allows these zones to be plowed up or managed
indicate a loading from anthropogenic sources (Kross
more intensively as grassland (Haycock, 1990). They
et al. 1993).
point out that this action results in the rapid

conduction of nitrate contaminated groundwater
The study revealed that many private wells suffer
across the flood plain whereas this water was once
from nitrate contamination; approximately 18.3% of
allowed to drain slowly across the flood plain. After
Iowa's private, rural wells have NO-N concentrations
work in the upper Thames Basin in England, Haycock
exceeding the EPA health advisory level. Results also
and Burt discovered that a grass-covered flood plain
show that the contamination of shallow wells (less
can greatly reduce the nitrate concentration of
than 15m in depth) is much more prevalent than
groundwater throughout the winter. One example
contamination of deep wells. Thirty-five percent of
they use to prove this point is that as a result of a
wells less than 15m deep exceed the 10 mg/L
major runoff incident in 1990, the nitrate
threshold. The mean concentration for these shallow
concentration of groundwater increased by about
wells was even over the health advisory limit (Kross
400% while the grass covered flood plain maintained
et al., 1993). However, in Iowa contamination of
a nitrate-buffering capacity near its mean level
deep wells has grown more common in recent years,
(Haycock, 1990). Haycock and Burt conclude that,
indicating a more pervasive problem.
"flood plains need to be preserved in (or returned

to) their undrained state as these areas sustain a
Doctors at the State University of Iowa Medical
potential to reduce nitrate concentrations in ground
Center have encountered many babies suffering
water throughout the year" (Haycock, 1990).
from diarrhea and other symptoms consistent with

methemoglobinemia. After a battery of tests to
8. Case Study: Iowa
determine the cause, it was found that all of these
infants were being fed water from private wells in
Given the health risks associated with nitrate
Iowa. The NO-N level of the water from these wells
contamination
of
groundwater,
government
was found to range from 64 to 140ppm and the
agencies are concerned with the nitrate levels in
severity of the symptoms appears to roughly
public drinking water supplies. The United States
correspond to the nitrate levels in the water.
Environmental Protection Agency has set the health
Doctors from Cedar Rapids, Fort Dodge and hospitals
advisory level at 10ppm NO -N or 45ppm NO for
across the state have documented many additional
drinking water supplies. Although certain studies
cases
of
apparent
nitrate-induced
indicate that nitrates in drinking water have a
methemoglobinemia (Comly, 1945).
carcinogenic effect, the EPA standard is based only

on the non-cancer health effects such as infantile
methemoglobinemia. While the EPA regulations
9. Conclusions
safeguard public water supplies, private, rural
The main concern with high levels of nitrate in
well-water supplies are unregulated. Since farming
groundwater
is
the
increased
incidence
of
runoff is a significant source of nitrates in
methemoglobinemia. Also known as blue-baby
groundwater, these private, rural wells are
disease, it causes the child to develop a bluish or
potentially unsafe.
grayish tint around the extremities. If left untreated

the baby will not receive enough oxygen through the
To determine the safety of private wells, state
blood and could die. This problem arises primarily in
environmental agencies have surveyed and tested
rural areas where nitrate levels are not well
wells. In Iowa, where anthropogenic inputs of
monitored. With regard to the nitrate problem in
nitrates due to intensive agriculture are high, a
groundwaters the best suggestion to avoid health
state-wide rural well-water survey was conducted.
risks is to have wells checked frequently and to
The survey was performed between April 1988 and
reduce the fertilization of fields. The overload of
June 1989, taking 686 samples from across the state.
nitrogenous fertilizers to the soils actually kills the
30
Subhash Chand et al.

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Universal Journal of Environmental Research and Technology


biota that helps to provide nitrogen to the soil,
Hydrologic and Land-Use Factors Associated
which the crop plants can use. By using much lower
with Herbicides and Nitrate in Near-Surface
amounts of fertilizers these crops may still be as
Aquifers, Journal of Environmental Quality, 22:
productive as those produced under heavily
646-656.
fertilized soils, due to the healthier environment for
6. Chand,
S.
(2008):
Integrated
Nutrient
the microbes. If the farmer adds large amounts of
Management for Sustaining Crop Productivity
fertilizer in the beginning then he is forced to use
and Soil Health. Published by International Book
more and more each year. Using only moderate to
Distributing Company.pp112
low amounts at the outset allows the farmer to
7. Chnad, S. (2010): Challenges of Soil Quality of
avoid the entrapment into this vicious cycle.
Indian Soils vis-a-vis Food Security. Current
Furthermore,
many
of
the
aforementioned
Science. 99:3:278-280.
prevention methods can be incorporated to help
8. Chand, S. (2010): Tackling Salinity in Indian
reduce nitrate leaching from the soil into the
Vertisols
for
Food
Security,
Current
groundwater. Slurrystores and concrete lagoon pits
Scence.99:6;716.
can greatly reduce the concentration of nitrate. By
9. Comly, H. H. (1987): Cyanosis in Infants Caused
avoiding over-irrigation of a field both turfgrass
by Nitrates in Well Water. Journal of the
managers and farmers can help to control the
American Medical Association, 257: 2788-2792.
leaching of nitrate to the groundwater.
10. Environment Directorate (1974): Waste Water

Treatment Processes for Phosphorus and
The clean-up of nitrate from the contaminated
Nitrogen Removal. Organization for Economic
waters is not an easy job. So far, the most effective
Co Operation and Development, Paris, 109.
and widely used technique for removal is ion
11. Finley, B. (1990): Well-water Nitrates Endanger
exchange model FGA-60N 30,000 grain whole house
N. Colorado, Denver (Colorado) Post (16
nitrate unit. Other processes are either in an
Nov,1990).
experimental stage or not as universally employed.
12. Forman, D., Al-Dabbagh, S., and Doll, R. (1985):
The nitrate can most effectively be removed in a
Nitrates, Nitrites and Gastric Cancer in Great
plant and is not treated while still in the aquifer.
Britain. Nature, 313: 620-625.
While nitrate cannot be completely removed from
13. Gaillard, J.F. (1995): Lecture on Nitrogen Cycle.
groundwater, the use of treatment methods such as
(www..cousrse hero.com/file/2049520 ecess on
ion exchange and the adoption of preventative
11-05-2011)
measures will help to reduce nitrates to biologically
14. Gustafson, D. I. (1993): Pesticides in Drinking
safe levels. Challenges of soil quality of Indian soils
Water, Van Hostrand Reinhold, New York, 241.
vis-a-vis food security is a major issue in advanced
15. Guter, G. A. (1981): Removal of Nitrate from
agriculture (Chand 2010).Nitrate pollution coupled
Contaminated Water Supplies for Public Use.
with salinity in Indian soils has also been noticed
Environmental Protection Agency, Cincinnati.
(Chand 2010). Restricted and precise use of
16. Hallberg, G.R. and Keeney, D.R. (1993): Nitrate.
nitrogenous fertilisers and slow release, ammonical
Alley, William A., ed., Regional Ground-water
fertilisers is an important activity to reduce overall
Quality, Van Nostrand Reinhold, New York,
pollution in soil, water and plant.
297-322.

17. Haycock, Nicholas, (1990) : Handling Excess
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