Many other forms of pollution mentioned previously could be considered as biological pollutants, e.g. algal blooms and the growth of sewage fungus. Examples that are more clearly of this type of pollution are the many species of blue-green algae, which produce substances that are toxic to terrestrial organisms and can impart tastes and odours to water.
Identify which of the following statements are true. If a statement is false, give the reason why.
Statement (e) is true. Statement (c) is also true, though concern has also arisen because fish farm effluents contain antibiotics (see Section 2).
Statement (a) is false: heavy organic loads on a watercourse can cause long-term damage to the water in the vicinity of the effluent outfall. However, recovery is more likely if pollution ceases than would be the case for toxic chemicals.
Statement (b) is false: the BOD will increase, as the metabolic rates of the microorganisms will be higher at a higher temperature.
Statement (d) is false: householders use a large quantity of pesticides in the form of herbicides and insecticides, and these can also contribute to water pollution.
Identify which of the following statements are true. If a statement is false, give the reason why.
Statements (b) and (e) are true.
Statement (a) is false: there may be synergistic effects between the individual chemicals in the mixture.
Statement (c) is false: fish spawning and the ecology of invertebrates are also disrupted.
Statement (d) is false: certain strains of E. coli (e.g. E. coli O157:H7) are pathogens and can cause fatalities.
Statement (f) is false: the discharge of oestrogens, often at high levels, due to the use of contraceptive pills will still contribute to the problem.
Indicate the causative agent (virus, bacterium, protozoan or helminth) of each of the following diseases:
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