Fertilizers can cause eutrophication of water bodies. Eutrophication occurs when excess nutrients like nitrates and phosphates from fertilizers enter water, promoting algal bloom. As algae grow and then die, they are decomposed by bacteria which use up oxygen, potentially killing aquatic life. Pesticides include herbicides, insecticides, fungicides and bactericides and can persist in the environment if lipid soluble, allowing bioaccumulation in organisms over time. The key points are examined in more detail with examples of processes like eutrophication and concepts such as biochemical oxygen demand (BOD).

1. Aims of the session: Learn about fertilisers and their effects on the environment. Be able to answer exam questions on the effects. Learn about Pesticides and their effects Summarise the key points about pesticides

2. Fertilisers and Pesticides

3. Fertilisers

8. The process of Eutrophication fertilisers sewage (liquid domestic and industrial waste) minerals esp. nitrates minerals esp. phosphates eutrophication algal bloom competition for light consumers can't consume fast enough dead plants dead algae

10. The process of Eutrophication cont. dead plants dead algae detritus more decomposers use up oxygen by aerobic respiration (increased BOD) aerobes die (invertebrates, fish, etc) anaerobic bacteria thrive. Release NH4, CH4, HS2

11. Biochemical Oxygen Demand (BOD). This measures the rate of oxygen consumption by a sample of water, and therefore gives a good indication of eutrophication. A high BOD means lots of organic material and aerobic microbes, i.e. eutrophication

16. The nitrate concentration falls during spring and summer and rises during autumn and winter Less algal growth as autumn begins Possibly all plants have died

18. Pesticides

19. Pesticides Include: Herbicides Insecticides Fungicides Bactericides

22. Pesticides Persistence + Lipid solubility = Bioaccumulation

23. Bioaccumulation E.g DDT

26. http://www. abdn .ac. uk /~nhi904/ biocet /index. htm