Gurbacewar iska da ruwa sun kasance daga cikin batutuwan da suka fi daukar hankali a duniya, suna jefa muhimman halittu, sarkar abinci, da muhallin da suka dace don rayuwar dan adam cikin hadari. Gurbacewar ruwa takan samo asali ne daga ions ƙarfe masu nauyi, gurɓatattun ƙwayoyin cuta, da ƙwayoyin cuta-mai guba, ...
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