Finding out about water pollution 1.3

Finding out about water pollution

Ways to identify water pollution

First, before we start today's topic, let's have some focus questions on the subtitle-

1. How do we know when water is polluted?
2. How do scientists measure the quality of the water?
3. What are the indicators being known as reliable ways of measurment?

Having a glance at the picture:



Can we tell the water being captured in the picture is polluted? Why?
By instinction? By common sense? Or ....?

Well, here's the answer

How do we know when water is polluted?

Some forms of water pollution are very obvious: everyone has seen TV news footage of oil slicks filmed from helicopters flying overhead. Water pollution is usually less obvious and much harder to detect than this. But how can we measure water pollution when we cannot see it? How do we even know it's there?

There are two main ways of measuring the quality of water. One is to take samples of the water and measure the concentrations of different chemicals that it contains. If the chemicals are dangerous or the concentrations are too great, we can regard the water as polluted. Measurements like this are known as chemical indicators of water quality. Another way to measure water quality involves examining the fish, insects, and other invertebrates that the water will support. If many different types of creatures can live in a river, the quality is likely to be very good; if the river supports no fish life at all, the quality is obviously much poorer. Measurements like this are called biological indicators of water quality.