Nitrates In World's Water Supply


Nitrates contamination of the world's underground water
supply poses as a potentially serious health hazard to the
human inhabitants on earth. High nitrate levels found in
well water has been proven to be the cause for numerous
health conditions across the globe. If we intend to provide
for the future survival of man, and life on planet earth,
we must take action now to assure the quality of one of our
most precious resources, our underground water supply.
Ground water can be defined as the water stored in the open
spaces within underground rocks and unconsolidated material
(Monroe and Wicander 420). Ground water is one of the
numerous parts that make up the hydrologic cycle. The
primary source of water in underground aquifers is
precipitation that infiltrates the ground and moves through
the soil and pore spaces of rocks (Monroe and Wicander
420). There are also other sources that add water to the
underground aquifer that include: water infiltrating from
lakes and streams, recharge ponds, and wastewater treatment
systems. As groundwater moves through the soil, sediment,
and rocks, many of its impurities are filtered out. Take
note, however, that some, not all, soils and rocks are good
filters. Some are better than others and in some cases,
serious pollutants are not removed from the water before it
reaches the underground supply.
Now that we have a good working definition of what
groundwater is, and where it comes from, just how important
is it? Groundwater makes up about 22% of the worlds supply
of fresh water. Right now, groundwater accounts for 20% of
all the water used annually in the United States. On a
national average, a little more than 65% of the groundwater
in the United States each year goes to irrigation, with
industrial use second, and third is domestic use (Monroe
and Wicander 420). Some states are more dependent on
groundwater for drinking than others. Nebraska and the corn
belt states rely on underground water for 85% of their
drinking needs, and in Florida 90% of all drinking water
comes from underground aquifers (Funk and Wagnall 2).
People on the average in the United States require more
than 50 gallons of water each day for personal and
household uses. These include drinking, washing, preparing
meals and removing waste. A bath in a bathtub uses
approximately 25 gallons of water and a shower uses about
l5 gallons per minute of water flow while the shower runs.
Just to sustain human tissue requires about 2.5 quarts of
water per day. Most people drink about a quart of water per
day, getting the rest of the water they need from food
content. Most of the foods we eat are comprised mostly of
water: for example, eggs, are about 74% water, watermelon
92%, and a piece of lean meat about 70%. Most of the
beverages we drink are also mostly comprised of water, like
milk, coffee, tea and soft drinks. And the single largest
consumer of water in the United States, is agriculture. In
dry areas, farmers must irrigate their lands to grow crops.
It is estimated that in the United States, more than 100
billion gallons of fresh water are used each day for the
irrigation of croplands (Funk and Wagnall 2). 

Since agriculture is the leading user of our groundwater,
perhaps it is fitting, that it is also the biggest
contributor of contaminating nitrates that work into our
water supply each year. Agriculture and livestock
production account for 80% of all nitrogen added to the
environment ( Terry, et al. 1996). Industrial fertilizers
make up 53%, animal manure 27%, atmosphere 14%, and point
source 6% (Puckett, 1994). Just how do these nitrates get
from the field into our water supply? There are two primary
reasons that nitrate contaminates reach our underground
water supply and make it unsafe. Number one reason is
farmer's bad habits of consistently over- fertilizing and
applying too much nitrogen to the soil. In 1995 America's
agricultural producers added 36 billion pounds of nitrogen
into the environment, 23 billion pounds of supplemental
industrial nitrogen, and 13 billion pounds of extra
nitrogen in the form of animal manure. Twenty percent of
this nitrogen was not used by the crops it was intended.
This accounts for about 7-8 billion pounds of excess
nitrogen remaining in the environment where much of it has
eventually entered the reservoirs, rivers, and groundwater
that supply us with our drinking water (NAS 1995). The
number two reason these contaminants reach our groundwater
supply runs parallel with the first. Over-irrigation causes
the leaching of these nitrates past the plants root zone
where they can be taken in by crops and used effectively.
Not all soils are the same and all have different drainage
characteristics. Soils with as higher amount of sand and
gravel are going to filter liquids down to the aquifer
faster than soils comprised of more silty finer sorted
particles. Today's farmers not only need to know when it is
time to irrigate, they also need to know how much and for
how long. When the two problems are added together,
over-fertilization, and over-irrigation, the potential for
harmful nitrate contamination runs terrifyingly high. 

Just how harmful are nitrates in our drinking water?
Nitrates levels that exceed the Federal standard level of
10 parts per million can cause a condition known as
Methemoglobinemia, or Blue Baby Syndrome in infants.
Symptoms of Methemoglobinemia include anoxic appearance,
shortness of breath, nausea, vomiting, diarrhea, lethargy,
and in more extreme cases, loss of consciousness and even
death. Approximately seven to ten percent of Blue Baby
Syndrome cases result in death of the infant (HAS 1977,
Johnson et al. 1987). When nitrate is ingested it is
converted into another chemical form, nitrate. Nitrate then
reacts with hemoglobin, the proteins responsible for
transporting oxygen in the body, converting them to
methemoglobin, a form that is incapable of carrying oxygen.
As a result, the victim suffers from oxygen deprivation, or
more commonly stated, the individual slowly suffocates (HAS
1977, Johnson et al. 1987). Although, Methemoglobinemia is
the most immediate life-threatening effect of nitrate
exposure, there are a number of equally serious
longer-term, chronic impacts. In numerous studies, exposure
to high levels of nitrate in drinking water has been linked
to a variety of effects ranging from hypertrophy
(enlargement of the thyroid) to 15 types of cancer, two
kinds of birth defects, and even hypertension (Mirvish
1991). Since 1976 there have been at least 8 different
epidemeology studies conducted in 11 different countries
that show a definite relationship between increasing rates
of stomach cancer and increasing nitrate intake (Hartmann,
Mirvish 1983). The facts speak for themselves, increasing
levels of nitrates in our groundwater are slowly poisoning
our society.
We have only discussed contamination of our groundwater
supply by nitrates through the misuse of resources involved
in agriculture. Be aware that there are hundreds of other
substances and practices that add to the further
contamination of our groundwater every day. Time does not
allow for an in-depth analysis of all aquifer contaminates
in this paper, however, I would like to mention a few that
are at the top of the list just briefly. Storm water
runoff. Streets and parking lots contain many pollutants
including oils, greases, heavy metals and coliform, that
can enter groundwater directly through sinkholes and
drainage wells. Pesticides and herbicides can end up in the
water supply much the same way as do nitrates. Septic tanks
that are improperly or poorly maintained, can contaminate
groundwater. Underground storage tanks, hazardous
wastesites, landfills, abandoned wells, accidents and
illegal dumping all threaten the quality of our drinking
water. We must be aware of the potential hazards and take
measures to ensure the safety of our drinking water supply
for generations to come. 

What can we do to prevent unnecessary contamination of our
groundwater? Farmers will and must continue to use nitrogen
fertilizer. They do not, however, need to overuse it. By
following a few simple guidelines, such as accounting for
all sources of nitrogen in the system, refining estimates
of crop nitrogen requirements, synchronizing application of
nitrogen with crop needs, using nitrogen soil tests, and
practicing good water management, farmers can not only help
keep our aquifers safe from contamination, but can probably
enjoy the same yields as before and spend less money on
fertilizer, thus increasing their net profits, (Halberg et
al. 1991, Iowa State University 1993). How about the rest
of us? What can we do to help drinking water safe? There
are many hazardous substances around the house that
frequently need disposal. Please don't dump them on the
ground, pour them down the drain, and always use
fertilizers and chemicals in moderation. Take proper care
and maintenance of your septic system at all times.
Finally, when in doubt, ask. Many areas have local Amnesty
Days. For information or to request an Amnesty Day, call
your local public works department.
Nitrate contamination poses a serious health threat to all
of us. 

Each of us uses a little more than 50 gallons of fresh
water every day. When all our fresh water is contaminated
beyond use, our world will not be a pleasant environment to
live in. We must all act now to maintain a fresh water
system that will be capable of sustaining us, and many
generations into the future. 


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