Term Paper on "Environmental Toxicology Nitrogen Dioxide"

Term Paper 9 pages (2609 words) Sources: 4 Style: APA

[EXCERPT] . . . .

Nitrogen Dioxide

KILLING U.S. SOFTLY?

Chemical and Physical Data

Nitrogen Dioxide or NO2 is a red-brown or yellow liquid, which becomes a colorless solid at a specific temperature (EPA 2007). It is a non-combustible component of automotive exhaust fumes. It can be derived during the intermediate stage in the oxidation of ammonia to nitric acid. It is highly poisonous and even fatal when inhaled. Tolerance in the air is at 5 ppm. Nitrogen dioxide can react strongly with reducing materials. It occurs as environmental tobacco smoke and artificially as kerosene heaters, un-vented gas stoves and heaters. Among its effects on health are irritations on the eyes, nose and throat; pulmonary edema and diffused lung injury; chronic bronchitis; decreased lung function; and increased risk of respiratory infections, especially in young children (U.S. Environmental Protection Agency).

Occurrence/Sources in the Environment

Every living thing needs nitrogen to survive (Fields 2004). Plants and animals need nitrogen in a reactive fixed form, mostly as organic nitrogen compounds. Animals get the reactive fixed form from eating plants along the food chain. Plants get it from the soil or water. Most of it occurs in nature from nitrogen fixation by bacteria, like those in the genus Rhizobium. These bacteria are often present in plants like peas, beans and alfalfa. Bio-scientists generally agree that non-agricultural organisms put in 100 to 300 Tg or Teragrams of nitrogen a year on land surfaces (Fields).

Assistant Professor of ecology and evolutionary biology Alan Townsend of the University of Colorado and his colleagues, in a published report, said that there has been a huge explosion of humanly-produced reactive nitrogen in the environment (Fields 2004). The current amount produced was estimated at 170 Tg a year. The group added that the global use of nitrogen fertilizers has also been increasing to approximately 15 Tg every year. And the ratio between artificial or man-made and natural reactive nitrogen productions would also tend to increase as populations grew. Feeding more people would require more food and more food would require more fertilizers and other inputs to make more farmlands (Fields).

The largest contributor of man-made reactive nitrogen is nitrogen fertilizer (Fields 2004). Records say that, as of 2000, roughly 100 Tg of reactive nitrogen were released by nitrogen fertilizer spread out in farmlands throughout the world. More modern farming methods have been accompanied by more nitrogen being fixed. Widespread cultivation of nitrogen-fixing crops, like legumes, had added 40 more Tg of reactive nitrogen. Burning of biomass puts in another 40 Tg, more or less. Draining wetlands and clearing land for vegetation for crops likewise release nitrogen from soils and contribute an additional10 to 20 Tg Lightning contributes reactive nitrogen throughout the world each year at roughly 3-10 Tg the energy produced converts oxygen and nitrogen to nitric oxide. It oxidizes to NO and then to nitric acid. In days, it goes to the ground as rain, snow, hail or other types of atmospheric deposition. This type is valuable to the area where nitrogen-fixing plants are few (Fields).

Fossil fuel combustion further contributes reactive nitrogen (Fields 2004). Urbanization is at the base of it. Cars teem in cities and cars release nitrogen oxides or O, which goes up onto the air and comes down to make trouble. Fossil fuel combustion puts in about 20 Tg of reactive nitrogen year after year throughout the world. Some of NO is certainly beneficial. Nitrogen fertilizers are responsible for producing food and reducing starvation and malnutrition, especially in Asia in the last decade. At least a third of the most thickly populated countries use nitrogen fertilizers to stave off malnutrition and provide adequate diet. But the concern drifts to the net health effects of increased levels of nitrogen. A single atom can produce a host of troubles, including acid rain, particle formation in the atmosphere, reduced visibility, soil and stream acidification, coastal eutrophication, decreased biodiversity and human health problems as well as emissions, which wreak havoc on the greenhouse effect and the ozone layer (Fields).

Interaction in the Environment

Nitrogen is found in the air, in water and in the soil. There are more automobiles than agriculture, thus nitrogen is more present in the air (Fields 2004). It forms from nitrogen fertilizers, burning of biomass and combustion of fossil fuels. As smog and ground-level ozone, it is the most important part of air pollution. NO is found in high concentrations in urban areas on account of their high car populations. These produce low-lying ozone, which in turn, produces or worsens asthma, cough, reactive airways disease, respiratory tract inflammation and chronic respiratory disease. This pollutant can also make viral infections worse. At mid-altitude, it acts as a greenhouse gas, it can absorb roughly 200 times outgoing radiation as carbon dioxide. At low altitudes, it increases ozone. And it actually destroys ozone at very high altitudes. Destroying ozone in the stratosphere would allow more ultraviolet light to enter the earth's surface and afflict human beings with skin cancers. Reductions in the ozone layer could explain the 20-40% increase in skin cancers since the 70s. Nitrogen gases in the air can also produce tiny particulates, which can enter deep into the lungs and contribute to cardiovascular diseases, respiratory diseases, asthma, weakened lung function and overall mortality (Fields).

Nitrogen is highly soluble in water and quickly seeps down the root zone of an agricultural field, forest and groundwater (Fields 2004). At that level, it would be difficult to control. In bays and coastal zones, it becomes a steady source of food to algae. When these algae die, they sink and decay. The process draws oxygen from the water. When too much is taken out, the body turns into a "dead zone," an area which cannot sustain aquatic life. Reactive nitrogen can also reach and infect drinking water from nitrogen fertilizers and runoff from livestock. High concentrations of nitrates can bring on the "blue baby disease," which weakens the blood capacity to carry oxygen. Nitrates have also been blamed for reproductive ailments and cancers of the bladder and ovaries.

And nitrogen is found in the soil. The soil, however, takes it up only up to a limit (Fields 2006). Beyond that limit, the soil will shed it off and become saturated. But shed off nitrogen leaves the soil with other nutrients. The soil acidifies and the whole system thrown out of balance (Fields).

The United States Environmental Agency reported that transportations operating on ultra-low sulfur diesel could hit the 2007 limit on heavy-duty emission standards (Peckham 2000). The new report said a trap system technology would be needed but did not say that it was already commercially ready. Even the slightest fuel sulfur would ultimately impact nitrogen trap performance, according to the EPA. The agency believed that a reliable trap desulfurization scheme should be added to the trap system. Residual sulfur masking would reduce NO trapping strength. More frequent desorption or conversion would avoid NO slipping from a "full" trap (Peckham).

Swedish-based International Geosphere-Biosphere Program and the French-based Scientific Committee on Problems Program merged to support the International Nitrogen Initiative or INI to address the problems on nitrogen cycle changes (Fields 2004). Their project would assess the status of knowledge on nitrogen flows and problems. It would come up with region-specific strategies and set these strategies in the proper places. Regional centers would be established to implement the goals. The INI, in turn, co-sponsored the Third International Nitrogen Conference in October 2004 in Nanjing, China. The participating scientists focused on problems germane to Asia and reviewed its options for increasing food and energy production while reducing nitrogen use and pollution. The INI Scientific Advisory Committee met to plan on setting up regional centers for Asia. In the end, the participants confronted the same objective and need to regulate reactive nitrogen the same way as other pollutants has been or has to be regulated. Europe has installed regulations that have shown to help reduce nitrogen pollution, according to reports. In comparison, the United States and developing nations still have to adequately understand the dynamics of the nitrogen cycle before they can come up with regulations and implement them (Fields).

Effects on the Human Body

According to a 2007 United Nations report, the combination of agricultural activities and fossil fuel combustion presently releases 125 million metric tons of nitrogen a year (Bohan 2007). In comparison, natural sources release 113 million metric tons at the same frequency. The same report said that there was virtually no such nitrogen release from human activity in 1860. This overdose has disrupted ecosystems, polluted waters and injured human health. Most importantly, it has been changing the earth's climate in cooperation with another harmful element, carbon dioxide or CO2.. There have been serious efforts at reducing CO2 but these would be futile unless nitrogen release was also reduced. A single nitrogen compound cast into the atmosphere can bring a lot of trouble. It stays there for a century and has shown to be more capable of trapping heat than CO2. Head of Climate… READ MORE

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