33. Rio Tinto, Portugal, and Spain
The head of Rio Tinto, or Tinto River, has been a fossil excavation site for over 3,000 years. This river is truly saturated with iron, copper, and heavy metals. Thus, the water’s acidity levels are sky-high. Despite the rising acidity of this river, the water’s ecosystem remains in operation. It now includes specific bacteria that actually oxidize metals and turns the color of the water to bright red.
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