A sugar cane factory in Trinidad discharges untreated wastewater containing organic matter into a nearby river. Which of the following is the MOST likely immediate effect on the river ecosystem?

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Question

A sugar cane factory in Trinidad discharges untreated wastewater containing organic matter into a nearby river. Which of the following is the MOST likely immediate effect on the river ecosystem?

Accepted Answer

Decrease in dissolved oxygen levels — Award 1 mark for identifying that organic matter decomposition by bacteria uses up oxygen (biochemical oxygen demand). A is incorrect — oxygen levels decrease, not increase, as bacteria decompose organic waste. C is incorrect — fish populations would decline due to oxygen depletion. D is incorrect — decomposition is an exothermic process that may slightly increase temperature.

Answer

Decrease in dissolved oxygen levels

Answer

Increase in dissolved oxygen levels

Answer

Decrease in water temperature

Answer

Increase in fish population

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