A river water sample has a nitrate ion concentration of 55 mg per litre. The World Health Organisation (WHO) guideline limit for nitrate in drinking water is 50 mg per litre. Which human activity is most likely responsible for this elevated nitrate level?

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Question

A river water sample has a nitrate ion concentration of 55 mg per litre. The World Health Organisation (WHO) guideline limit for nitrate in drinking water is 50 mg per litre. Which human activity is most likely responsible for this elevated nitrate level?

Accepted Answer

Use of nitrogen-containing fertilisers on nearby farmland — Excess nitrogen-containing fertilisers applied to farmland are washed into rivers by rainfall (leaching), significantly raising nitrate concentrations — a process linked to eutrophication. Burning coal releases SO₂ and CO₂, not nitrate ions directly into water. Sulfur dioxide causes acid rain, not nitrate contamination. Chlorinated swimming pool water is not a significant source of nitrate pollution in rivers.

Answer

Burning of coal in power stations near the river

Answer

Use of nitrogen-containing fertilisers on nearby farmland

Answer

Evaporation of chlorinated water from swimming pools

Answer

Discharge of sulfur dioxide from industrial chimneys

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