Where Are All the Nitrates Coming From? (page 2)
The Nitrogen Cycle
Nitrogen is a component of all proteins and nucleic acids. In the nitrogen cycle, nitrogen moves in a large atmospheric cycle. Our atmosphere is about 80% nitrogen gases. Nitrogen (N2) has a very strong covalent bond which can only be broken by certain bacteria, volcanic action, and lightning. After the bond breaks, it enters the food webs.
During nitrogen fixation, nitrogen-fixing bacteria convert nitrogen to ammonia (NH3). The ammonia will then dissolve and become ammonium. Next the nitrogen becomes fixed in the water by cyanobacteria. Nitrogen becomes fixed on land by specific animals. Then plants use the fixed nitrogen in the biosynthesis of amino acids, proteins, and nucleic acid. Plant tissues are the only source of nitrogen to animals.
During decomposition and ammonification, fungi and bacteria will break down wastes containing nitrogen and the remains of organisms. The decomposers use some of the released proteins and amino acids for their metabolism. Plants absorb the rest of the nitrogen left over from the decay. Nitrifying bacteria and plants absorb the leftover ammonia or ammonium. During nitrification, they will strip the ammonium or ammonia of their electrons. As a result, nitrite develops.
Nitrates are a type of nutrient that is necessary for the growth and reproduction of all living organisms. They are located naturally in air, soil, water; they are also present in chemical fertilizers and animal waste. Other nitrate sources include septic systems, organic materials, industry, sewage treatment plants, and in the atmosphere.
This wide range of nutrient inputs is commonly classified into two categories; "point" sources, and "non-point" sources. Point sources are those that empty nitrate-bearing materials directly into a waterway. This would include sewage treatment plants, and industrial plants. Point sources of nitrates are considered to be of less environmental damage because the amounts of them being discharged are regulated. However, non-point sources of nitrates, like organic material, agricultural fields, etc., can pose greater environmental risks. Non-point sources of nitrates are either carried overland by rain to waterways as runoff, or are carried by ground water into streams or other bodies of water. Both ways are very hard to regulate.
Nitrates though essential for life may have severe consequences if too large of quantities are exposed to the environment. For example, massive algae blooms can occur which causes eutrophication. Eutrophication results in sunlight depletion and dissolved oxygen depletion in surrounding water. Due to sunlight depletion, SAV (Submerged Aquatic Vegetation) dies and consequently so do the organisms that depend on SAV. Then, when the algae dies, the decomposition processes lowers the dissolved oxygen levels, and the deaths of many organisms are results of this also. However, currently nitrate removal treatment plants, as well as forest buffers, manure pits, and farmers are using reduced fertilizer applications.
The Hydrologic cycle
First surface water is evaporated from the earth by the energy from the sun. Then, the water vapors form clouds in the sky. Depending on the weather and temperature conditions, the water vapor condenses and falls to the ground as different forms of precipitation. Some of that precipitation runs from high areas to low areas on the earth's surface, which is basically known as surface runoff. Other precipitation seeps in to the ground and becomes ground water.
Groundwater is a layer of soil where each soil particle is surrounded by water. Groundwater may be found at various depths beneath the earth's surface in formations called "aquifers". Most surface water supplies are simply continuations of groundwater supplies, such as the stream Gravel Run. To humans, groundwater is important, it contributed 95% of our water used for consumption. Therefore, the prevention of groundwater contamination is vital to the health of society. Groundwater can become contaminated in rural areas by percolation and in both rural and urban areas by runoff. Groundwater pollution is a very intensely researched topic because, in most cases, once the water is contaminated it is nearly impossible for it to be cleansed and returned to its once normal state.
Located at various points on the schools property, and the high schools property, there are four ground water wells. There are two (#3 high #4 low) wells located on or near an agricultural field, and two (#1 high #2 low) located on Centreville Middle School's property.
Agricultural effects on Nutrients (various tidbits of information):
- "Watersheds with greater proportions of agricultural land have been found to discharge greater amounts of Nutrients." - Effects of Agriculture on Discharges of Nutrients from Coastal Plain Watersheds of Chesapeake Bay
- "We found dramatic differences in watershed discharges related to both land use and location within the Coastal Plain. Several other studies have found that discharges of Nitrogen and Phosphorus increase as the proportion of agricultural land increases, but some studies have found no apparent effect of agricultural use on Nitrogen and Phosphorus discharge." - Effects of Agriculture on Discharges of Nutrients from Coastal Plain Watersheds of Chesapeake Bay
- "Most of the variability in the concentrations of forms of nitrogen could be explained by the proportion of cropland in our watersheds." - Effects of Agriculture on Discharges of Nutrients from Coastal Plain Watersheds of Chesapeake Bay