Understanding water quality
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# Introduction

Please note, this course was written in 2003/2004 therefore some of the information is now outdated.

In this free course, Understanding water quality, you will look at the main properties of natural water and how these may be altered by pollutants of various types. Natural water is not just H2O: all natural waters contain dissolved and suspended substances - seawater is an obvious example of water containing dissolved salts, but freshwater does also, although at a far lower concentration. Water pollution is defined as a change in the quality of the water due to human activity that makes the water less suitable for use than it was originally (Figure 1). It is difficult to set absolute standards of purity that apply for all uses of water however, because water that is considered clean enough for one purpose may be too polluted for another.

Figure 1 Faulty oil tanks leak oil into a river in New Orleans, USA. Because oil floats on water without dissolving, a small amount can quickly spread out to cover a large area. Some types of oil contain toxic compounds that can enter the food chain.

This OpenLearn course provides a sample of level 2 study in Environment & Development .

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OpenLearn - Understanding water quality
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