Pollution is the introduction of contaminants into the environment. The contaminants may be spewed into the air, water or soil. They contaminate our natural resources. In this activity, we are concerned with distinguishing between various sources of pollution.
Point source pollution results when the contaminants come from a single location. Examples of point source pollution in the air, water and soil are given below.
Air. A certain factory is producing chemicals. As part of the manufacturing process, certain poisonous chemicals and toxic gases result, such as benzene. The chemical company permits these toxins to be released from the stack at the factory without treating them. The untreated, toxic chemicals are released directly into the air.
Water. A company has a new tank. This tank is being treated with a special chemical. After the tank is treated, the treatment chemicals are drained into a stream that runs hear the building where the company is. The chemicals are released directly into the stream water without being treated or decontaminated to make them safe.
Soil. A garage does mechanical work on cars. As a result they have accumulated waste oil. The waste oil is supposed to be sent to a treatment company for recycling but, instead, they dump the oil into the ground where it enters the underground water supply and contaminates it.
Each of these examples illustrates point source pollution. In each of the examples, the contaminant is introduced directly into the environment at a single location. There are laws to prevent this type of abuse but people do it any because they do not want to spend money, or they do not want to take the time necessary, or both. Environmental authorities are concerned with locating and punishing violations of environmental protection regulations. And, even if laws are followed now, these types of practices occurred in the past before the laws were enacted and the pollutants are still around.
Non-point-source pollution results when contaminants are introduced into the environment over a large, widespread area. Some examples follow.
Air. People drive cars. When a car is running, the engine produces a variety of chemical products including oxides of nitrogen (some of which are toxic) and molecules of unburned hydrocarbons from gasoline.
Similar pollutants and soot result from burning and other combustion processes. Combustion of fuel is used for heating homes and buildings. Large trucks and buses with diesel engines contribute to smoke and hydrocarbons. New federal standards approved in late 2000 call for changes in these vehicles over a five-year period. Once the changes are in place, it is expected that emissions from these vehicles will decrease.
Burning of fuels with a high sulfur content also produces sulfur dioxide which enters the air. Sulfur dioxide reacts with water in the air to produce sulfurous acid which is a major component of acid rain.
Water. Acid rain from the air can enter the water cycle. The result is that it enters the environment. The acid is harmful to fish and other creatures in fresh-water lakes and streams.
Whenever there is snow or ice on the roads in winter, the salt trucks come out and spread salt. The salt dissolves the snow and ice and makes the roads safe. But it also washes off the roads into lakes and streams and makes them salty. The salt is also carried down into the ground water where it enters the ground water supply.
Soil. Harmful pollutants can enter the soil either from the air or from the water. Sometimes these pollutants are absorbed by plants so then the plants become toxic as well.
In the middle part of the 20th century they used to add lead to gasoline so that cars would run better. The lead passed out from the cars through the tailpipe and was deposited in the soil along roads and highways. The lead was absorbed by plants making the plants poisonous to any animals that ate them. By this means, the lead entered the food chain.
Summary. All of these examples illustrate sources of pollution and contamination in the environment. If the origin of the pollution can be traced to a single point, it is called point source pollution. If the pollutants are entering the environment in a widespread fashion, or the pollution is of a general nature and cannot be traced to a single source, it is said to be non-point-source pollution.
1. Students brainstorm the different pollutants and different types of pollution that they can think of.
2. Students investigate measures taken to prevent or remediate pollution effects. They write about these measures in their Science Journals.
1. Students will have prepared a list of different types of pollution and pollutants and have sorted them according to their nature as point source pollutants and non-point-source pollutants.
2. As a class or individually, students return to this list from time to time to do further investigations or to add new pollutants and sources to the lists. For example, there might be a news item about pollution in New Jersey or in the community. The pollutant can be added to the list.
1. Students investigate the efforts of governmental agencies such as the US Environmental Protection Agency and the New Jersey Department of Environmental Protection. They study what activities these agencies engage in as they attempt to regulate pollution and abate its effects.
2. Students investigate the superfund and the importance of cleaning up superfund sites.
3. Students investigate sources of hazardous materials in the community, county, state or country.
4. Students monitor the activities of the government in their recently announced project where the Hudson River will be dredged in order to remove PCBs (poly-chlorinated biphenyls). PCBs are toxins that have been put into the environment. The students investigate what will happen to the material removed from the bottom of the Hudson River and what will happen to the PCBs.