: 4. Plant nutrients

Plant nutrients: fertilizing water with mineralized nutrients including both phsophorous and nitrogen.

a. Eutrophication- primary problem with phosphorous fertilization: is an overly rapid growth of blue-green bacteria or in some cases larger plants, which out compete more friendly phytoplankton, and results in oxygen loads dropping as photosynthetic production is overshadowed by organismal need for oxygen for respiration & growth. Net result is all other non-photosynthetic organisms suffer or die out.

Some examples include......

 a.Scientists say nutrients are destroying Lake Victoria

Lake Victoria, the world's second-largest freshwater lake, is being slowly destroyed by nutrients carried in soil from deforested land, About 30 million people depend on the lake for their livelihoods.

Satellite remote sensing technology used by the Kenya-based International Center for Research in Agroforesty to study land soil types around the nearly 27,000-square-mile lake detected a flow of sediments whose water-dissolved nutrients stimulate the growth of aquatic plants.A dramatic plume of nitrogen-and-phosphorous-rich sediments feed the water hyacinth As the water hyacinths grow nourished with sediments from the shores of Uganda, Kenya and Tanzania, they starve more fish and plankton of oxygen and sunlight.

b. ALGAE LINKED TO ALLIGATOR DEATHS:

The growth of algae and associated toxins may be causing a wave of alligator deaths in Florida. Many species of blue-green algae release chemicals toxic to the nervous system and liver of animals. Some scientists believe algae may also be linked to non-cancerous tumors being found on sea turtles. The increase in algae has worsened in the past years and is caused by runoff of fertilizers, sewage, and other nutrients into the water system.

Nitrogen Pollution:

Every year, soil microorganisms "fix" 140 million tons of nitrogen, thereby enabling plants to grow and flourish. When plants die, some of that nitrogen is recycled back into the atmosphere. This process of moving nitrogen from one form to another is called the nitrogen cycle, and it's essential to all life.


People are part of this cycle too. We need nitrogen, and we get it from our food — both plants and animals. But we are also changing the cycle, it's causing tremendous amounts of pollution to our air and water.
The problem is that people are fixing vast quantities of nitrogen and releasing it into the environment. In fact, humans now release almost twice as much available nitrogen every year as do natural systems.

About one-quarter of this amount is released through burning fossil fuels, which creates nitrogen oxides, compounds that can cause smog, global warming, and acid rain. But the majority of humanity's excess nitrogen comes from synthetic nitrogen fertilizer used on farmers' fields.
Synthetic fertilizer was first developed in 1913, but its use really took off in the 1960s during the "green revolution," which doubled worldwide grain production. Synthetic fertilizer enhances plant production by boosting the amount of fixed nitrogen available in the soil.

Today we use so much of this fertilizer that excess nitrogen is leaching into groundwater, lakes, rivers, and coastal waters. This leaching removes important nutrients from the soil, reducing its fertility. It also pollutes groundwater and can cause an excessive growth of plant life in surface water, leading to oxygen depletion.
How big a problem is it? About 60 percent of streams sampled in the United States show some signs of excess nitrogen loading. The World Water Council, an independent association of water scientists and engineers, recently reported that more than half of the world's biggest fresh-water lakes are threatened by pollution or drainage schemes.

Coastal ecosystems are also affected. The Gulf of Mexico, for example, contains a notorious oxygen-depleted "dead zone" caused by agricultural runoff from the Mississippi River. In sum, ecologists at the recent nitrogen conference say that the negative impact of excess nitrogen in the environment ranks right up there with global warming.

But can we dump less nitrogen into the environment without hurting food and energy production? It certainly seems that way. Already, clean air laws in many countries have helped stabilize the production of nitrogen oxides from burning fossil fuels. Europe leads the way, with plans to reduce them by 40 percent in the next decade.
Reducing nitrogen leaking from farmer's fields has so far not been as successful. Fertilizer is cheap and farmers would rather apply too much, rather than too little, to ensure a bountiful crop. But studies show that precision application of fertilizers can reduce the amount of runoff and have little impact on crop yields. For example, a study on the Mississippi River basin published in the journal Nature found that reducing fertilizer use by just 12 percent would reduce nitrogen runoff by 33 percent.

.Nitrogen Pollution: An Assessment of Its Threat to Amphibian Survival

Modification of an abstract from a paper by Jeremy David Rouse,1 Christine A. Bishop,1 and John Struger

The potential for nitrate to affect amphibian survival was evaluated by examining the areas in North America where concentrations of nitrate in water occur above amphibian toxicity thresholds.

Environmental concentrations of nitrate in watersheds throughout North America range from < 1 to > 100 mg/L. Of the 8,545 water quality samples collected from states and provinces bordering the Great Lakes, 19.8% contained nitrate concentrations exceeding those which can cause sublethal effects in amphibians. In the laboratory lethal and sublethal effects in amphibians are detected at nitrate concentrations between 2.5 and 100 mg/L. Furthermore, amphibian prey such as insects and predators of amphibians such as fish are also sensitive to these elevated levels of nitrate. From this we conclude that nitrate concentrations in some watersheds in North America are high enough to cause death and developmental anomalies in amphibians and impact other animals in aquatic ecosystems. In some situations, the use of vegetated buffer strips adjacent to water courses can reduce nitrogen contamination of surface waters. Environ Health Perspect 107:799-803 (1999). [Online 31 August 1999]


b. Excess nitrites & nitrates (Gl bacteria convert nitrates to nitrites)

We know from numerous studies that excess amounts of nitrites/nitrates in our drinking water can have determental effects:

1. Nitrates educe the oxygen carrying capacity of our blood- Hemoglobin can pick up many molecules which contain oxygen. In your body they normally pick up oxygen and carbon dioxide. But we also recognize they can pick up carbon monoxide and nitrates. In agricultural areas where nitrogen loads may be especially high in well water suplies, baby formula made with well water may contain enough nitrate to cause the blue baby syndrome,,Inhibition of cell breathing because lack of blood cells /hemoglobin carrying oxygen to the cells; this induces cyanosis ( blue coloring of skin). at levels of 8-9 ppm .

2. Nitrates in the body have the capacity to cause dilation of capillary blood vessels resulting in stagnation of the circulating blood.

US Health service: 45ppm nitrates unsafe for infant feeding. Adult impact diarrhea as the body tries to rid itself of excess nitrogen.

.c.. In ground water bacteria convert nitrogen sources to N20-.....................a greenhouse gas


If you are really interested in the impacts of nitrogen on wildlife, this link will bring up the whole paper whose abstract was given above. Research paper on nitrogen impacts


Return to introduction 1. Go to sediments 2. Go to inorganics 3. Go to disease vectors 4. Go to plant nutrients

5. Got to organics 6. Go to Oxygen-demanding wastes 7. Go to radioactive & thermal wastes