Essay/Term paper: Nitrate contamination of groundwater

Essay, term paper, research paper:  Science

Nitrate Contamination of Groundwater Poses a Serious Health Threat

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, 1983;
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.