The environmental chemist in this photo is “fishing” for a sample of river water. He works for the US Environmental Protection Agency. He is looking for evidence of pollution in the water.
Doing Science in the Field
Although experiments are the “gold standard” for scientific investigations, sometimes it’s not possible or desirable to do experiments. Often it’s important to investigate a problem in the real world instead of in a lab. An investigation that gathers evidence in the real world—as the environmental chemist above is doing—is called a
Why are field studies important for environmental scientists?
To learn about the environment, scientists need to take measurements and make observations in the real world. This means gathering evidence in field studies; collecting samples of water from a river is one example of this method.
Case Study: River Water Pollution
The environmental scientist above will gather samples of river water in several different locations. Then he will take the samples back to a lab to analyze them. He will do tests to identify any pollutants in the samples. Taking samples from different locations may help him identify the source of any pollution he finds. Pollution can enter a river from a single source, such as a waste water pipe from a factory. This is called point-source pollution. Or pollution can enter a river in runoff rainwater that picks up pollutants as it runs over the ground. This type of pollution enters the river everywhere. This is called nonpoint-source pollution.
Assume that the river is polluted only by nonpoint-source pollution. Describe how the samples of river water would compare in terms of the pollutants they contain.
All of the samples would contain about the same amount and types of pollutants.
How might point-source pollution be identified?
Just one sample might be polluted. This would be the sample taken at, or just downstream from, the single source of pollution.
In a field study, a scientist gathers evidence in the real world instead of in a lab.
Field studies are needed to investigate the environment. An example of a field study is collecting samples of river water to test for evidence of pollution.
The mileage sticker pictured below states how many miles this car can go on 1 gallon of gas. The sticker shows the mileage for city driving and for highway driving. Unless you read the fine print at the bottom of the sticker, you would expect to get these mileages if you buy the car. However, these mileages were measured under ideal conditions in a lab, not as cars are actually driven in the real world. Gathering evidence to estimate average mileages in the real world would require a field study.
How do you think a scientist could gather evidence on the gas mileage of a car as it is actually driven in the real world?
Do you think drivers should expect to get lower or higher mileages than the values given on the sticker? Why?
What is a field study?
When is a field study more appropriate than a laboratory experiment? Give an example of a problem that might be investigated with a field study.