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How water pollution is measured and observed

Water pollution occurs in a wide range of forms as discussed in the previous unit. Some of these are invisible, some are visible and some have visible effects.

The type of pollution that is suspected, and the type of environment that it is occurring in, will affect how the water quality is monitored.

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The most basic form of water quality monitoring is through using our senses – intuitively, most people know if a waterbody doesn’t look or smell right. For example, observing a very dark river indicates high levels of turbidity (sediment).

Other observations could be the results of the pollution, such as dead fish, which may then require further investigation to identify the root cause of this effect.

Technological advances in mobile phones, with their cameras and GPS, and communication methods in social media, are starting to revolutionise this form of monitoring where data can be crowd-sourced through teams of volunteers providing large-scale observations of watercourses.

For example, see ZSL Let's Work for Wildlife - London's Rivers

For a more quantitative approach, specialist equipment can be used to record specific parameters. In general, these are hand-held rather than installed, and so the data that is collected only records a specific observation at a specific point in time and space. Patterns can be built up through repetition over time, but there is still considerable uncertainty around what might occur between the points. In addition, it is difficult to capture key flood events which may have water quality implications because of the unlikeliness of taking an observation at that exact time, as well as health and safety implications of being in or near the watercourse during high flows.

Water quality probes can be supplied by companies such as Hanna Instruments.

In addition, in some cases, for some pollutants, laboratory analysis may be required. Samples can be collected from site in specially designed containers and then couriered (within 24 hours, and sometimes in chilled conditions) to the laboratory for further analysis.

Activity: Designing a water quality monitoring programme

You have been given a budget of £2,500 to undertake a comprehensive water quality study in an urban area. The scope of the study is to provide wide-ranging information about the surface water network, about which little is known, with more detailed information on key pollution hotspots.

Speculate as to what might be the key pollutants and how you would get information on their concentrations over time and space.

Outline how you would design the study and how you would apportion the budget to achieve the objectives as described above.

Sketch out your thoughts.