What you’ll learn4 learning objectivesChoose one objective for a focused lesson, or study the complete topic.20.3.1Effects of untreated sewage and excess• Describe the effects of untreated sewage and excess fertiliser on aquatic ecosystemsSyllabus objective20.3.2Effects of non-biodegradable plastics• Describe the effects of non-biodegradable plastics, in both aquatic and terrestrial ecosystemsSyllabus objective20.3.3Sources and effects of pollution• Describe the sources and effects of pollution of the air by methane and carbon dioxide, limited to: the enhanced greenhouse effect and climate changeSyllabus objective20.3.4Process of eutrophication of water• 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 waterSyllabus objective