Essay, Research Paper
Nitrate Contamination of Groundwater Poses a Serious Health Threat Nitrates contamination of the world’s underground water supply poses asa potentially serious health hazard to the human inhabitants on earth.High nitrate levels found in well water has been proven to be the cause fornumerous health conditions across the globe. If we intend to provide forthe future survival of man, and life on planet earth, we must take actionnow to assure the quality of one of our most precious resources, ourunderground water supply. Ground water can be defined as the water stored in the open spaceswithin underground rocks and unconsolidated material (Monroe and Wicander420). Ground water is one of the numerous parts that make up thehydrologic cycle. The primary source of water in underground aquifers isprecipitation that infiltrates the ground and moves through the soil andpore spaces of rocks (Monroe and Wicander 420). There are also othersources that add water to the underground aquifer that include: waterinfiltrating from lakes and streams, recharge ponds, and wastewatertreatment systems. As groundwater moves through the soil, sediment, androcks, many of its impurities are filtered out. Take note, however, thatsome, not all, soils and rocks are good filters. Some are better thanothers and in some cases, serious pollutants are not removed from the waterbefore it reaches the underground supply. Now that we have a good working definition of what groundwater is, andwhere it comes from, just how important is it? Groundwater makes up about22% of the worlds supply of fresh water. Right now, groundwater accountsfor 20% of all the water used annually in the United States. On a nationalaverage, a little more than 65% of the groundwater in the United Stateseach year goes to irrigation, with industrial use second, and third isdomestic use (Monroe and Wicander 420). Some states are more dependent ongroundwater for drinking than others. Nebraska and the corn belt statesrely on underground water for 85% of their drinking needs, and in Florida90% of all drinking water comes from underground aquifers (Funk and Wagnall2). People on the average in the United States require more than 50gallons of water each day for personal and household uses. These includedrinking, washing, preparing meals and removing waste. A bath in a bathtubuses approximately 25 gallons of water and a shower uses about l5 gallonsper minute of water flow while the shower runs. Just to sustain humantissue requires about 2.5 quarts of water per day. Most people drink abouta quart of water per day, getting the rest of the water they need from foodcontent. Most of the foods we eat are comprised mostly of water: forexample, eggs, are about 74% water, watermelon 92%, and a piece of leanmeat about 70%. Most of the beverages we drink are also mostly comprisedof water, like milk, coffee, tea and soft drinks. And the single largestconsumer of water in the United States, is agriculture. In dry areas,farmers must irrigate their lands to grow crops. It is estimated that inthe United States, more than 100 billion gallons of fresh water are usedeach day for the irrigation of croplands (Funk and Wagnall 2). Since agriculture is the leading user of our groundwater, perhaps itis fitting, that it is also the biggest contributor of contaminatingnitrates that work into our water supply each year. Agriculture andlivestock production account for 80% of all nitrogen added to theenvironment ( 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? Thereare two primary reasons that nitrate contaminates reach our undergroundwater supply and make it unsafe. Number one reason is farmer’s bad habitsof consistently over- fertilizing and applying too much nitrogen to thesoil. In 1995 America’s agricultural producers added 36 billion pounds ofnitrogen into the environment, 23 billion pounds of supplemental industrialnitrogen, and 13 billion pounds of extra nitrogen in the form of animalmanure. Twenty percent of this nitrogen was not used by the crops it wasintended. This accounts for about 7-8 billion pounds of excess nitrogenremaining in the environment where much of it has eventually entered thereservoirs, rivers, and groundwater that supply us with our drinking water(NAS 1995). The number two reason these contaminants reach our groundwatersupply runs parallel with the first. Over-irrigation causes the leaching ofthese 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 havedifferent drainage characteristics. Soils with as higher amount of sandand gravel are going to filter liquids down to the aquifer faster thansoils comprised of more silty finer sorted particles. Today’s farmers notonly need to know when it is time to irrigate, they also need to know howmuch and for how long. When the two problems are added together,over-fertilization, and over-irrigation, the potential for harmful nitratecontamination runs terrifyingly high. Just how harmful are nitrates in our drinking water? Nitrates levelsthat exceed the Federal standard level of 10 parts per million can cause acondition known as Methemoglobinemia, or Blue Baby Syndrome in infants.Symptoms of Methemoglobinemia include anoxic appearance, shortness ofbreath, nausea, vomiting, diarrhea, lethargy, and in more extreme cases,loss of consciousness and even death. Approximately seven to ten percentof Blue Baby Syndrome cases result in death of the infant (HAS 1977,Johnson et al. 1987). When nitrate is ingested it is converted intoanother chemical form, nitrate. Nitrate then reacts with hemoglobin, theproteins responsible for transporting oxygen in the body, converting themto methemoglobin, a form that is incapable of carrying oxygen. As aresult, the victim suffers from oxygen deprivation, or more commonlystated, the individual slowly suffocates (HAS 1977, Johnson et al. 1987).Although, Methemoglobinemia is the most immediate life-threatening effectof nitrate exposure, there are a number of equally serious longer-term,chronic impacts. In numerous studies, exposure to high levels of nitratein drinking water has been linked to a variety of effects ranging fromhypertrophy (enlargement of the thyroid) to 15 types of cancer, two kindsof birth defects, and even hypertension (Mirvish 1991). Since 1976 therehave been at least 8 different epidemeology studies conducted in 11different countries that show a definite relationship between increasingrates of stomach cancer and increasing nitrate intake (Hartmann, 1983;Mirvish 1983). The facts speak for themselves, increasing levels ofnitrates in our groundwater are slowly poisoning our society. We have only discussed contamination of our groundwater supply bynitrates through the misuse of resources involved in agriculture. Be awarethat there are hundreds of other substances and practices that add to thefurther contamination of our groundwater every day. Time does not allowfor 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 justbriefly. Storm water runoff. Streets and parking lots contain manypollutants including oils, greases, heavy metals and coliform, that canenter groundwater directly through sinkholes and drainage wells.Pesticides and herbicides can end up in the water supply much the same wayas do nitrates. Septic tanks that are improperly or poorly maintained, cancontaminate groundwater. Underground storage tanks, hazardous wastesites,landfills, abandoned wells, accidents and illegal dumping all threaten thequality of our drinking water. We must be aware of the potential hazardsand take measures to ensure the safety of our drinking water supply forgenerations to come. What can we do to prevent unnecessary contamination of ourgroundwater? Farmers will and must continue to use nitrogen fertilizer.They do not, however, need to overuse it. By following a few simpleguidelines, such as accounting for all sources of nitrogen in the system,refining estimates of crop nitrogen requirements, synchronizing applicationof nitrogen with crop needs, using nitrogen soil tests, and practicing goodwater management, farmers can not only help keep our aquifers safe fromcontamination, but can probably enjoy the same yields as before and spendless money on fertilizer, thus increasing their net profits, (Halberg etal. 1991, Iowa State University 1993). How about the rest of us? What canwe do to help drinking water safe? There are many hazardous substancesaround the house that frequently need disposal. Please don’t dump them onthe ground, pour them down the drain, and always use fertilizers andchemicals in moderation. Take proper care and maintenance of your septicsystem at all times. Finally, when in doubt, ask. Many areas have localAmnesty Days. For information or to request an Amnesty Day, call yourlocal 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 bea pleasant environment to live in. We must all act now to maintain a freshwater system that will be capable of sustaining us, and many generationsinto the future.