Pollution

1 Describe the effects of untreated sewage and excess fertiliser on aquatic ecosystems

4 Explain the process of eutrophication of water, limited to: • increased availability of nitrate and other ions • increased growth of producers • increased decomposition after death of producers • increased aerobic respiration by decomposers • reduction in dissolved oxygen • death of organisms requiring dissolved oxygen in water

2 Describe the effects of non-biodegradable plastics, in both aquatic and terrestrial ecosystems

3 Describe the sources and effects of pollution of the air by methane and carbon dioxide, limited to: the enhanced greenhouse effect and climate change