Topic 4: Water and aquatic food production systems and societies Topic 4.4: Water Pollution Starter: 1) List as many sources of water pollution as you can think off. 2) Suggest how we could reduce each of these.

I took water samples from 4 different sites, however, I forgot to label my samples and now have no idea which site each came from. You are going to do a series of pollution tests to correctly identify which water came from which site.

The four sites

What you’re doing: Around the room are various “stations”, each with a different pollution test. The method is at each station. You are to record the results for water A, B, C and D. Then using the pollution information table I have given you, you should decide the location of each water.

Biodegradation of organic material utilizes oxygen. There is a finite source of oxygen, and once it is used the water becomes anoxic. This leads to anaerobic decomposition which leads to the formation of methane, hydrogen sulphide and ammonia (toxic).

A measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity. BOD is used to indirectly measure the amount of organic matter within a sample. More organic matter = less dissolved oxygen Biochemical oxygen demand (BOD)

Eutrophication Sort the steps into the correct order

Red tides Algal bloom Phytoplankton Red species Produce toxins that kill fish and accumulate in shell fish – can make humans seriously ill

Indicator species and biotic index Indicator species indicate whether there is pollution present or not. Biotic index is an indirect measure of pollution. Assessing the relative abundance of different organisms.

Dealing with pollution There are three main ways to reduce all types of pollution: 1)Reduce production of pollution 2)Regulate and reduce release of pollution (treatment) 3)Clean up and restoration Using the iPads research methods aimed at mitigating the effects of eutrophication and place them in one of the above categories. Then evaluate 3 of your methods. E.g. Ban or limit detergents with phosphate (phosphate are only needed in hard water areas). This could be difficult as you would have to get companies to agree to making two products, and would people accept their washing powder being not as effective.