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Answer:
because harmful substances often chemicals or microorganisms contaminate a stream, river, lake, ocean, aquifer, or other body of water, degrading water quality and rendering it toxic to humans or the environment.
Explanation:
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-Mountains provide us with freshwater, energy, food, biodiversity, and medicinal products – resources that may become very rare in the coming decades. They are also very prone to climate changes, land degradation, deforestation and natural disasters.
A Landslide is a type of mass movement that occurs when a thin block of soil, rock, and debris separates from the underlying bedrock.
Actually, this thin block of soil and rocks were held by Tree's roots so it do not separated from the bedrock. Now days, more and more trees were cutted down for modern development, and more landslides happen because of this.