(1)3-6(個人翻譯)55-2-2

原文:
Throughout the hydrologic cycle,many natural processes purify water.Evaporation and subsequent precipitation act as a natural distillation process that removes impurities dissolved in water.Water flowing above ground through streams and lakes and below ground in aquifers is naturally filtered and partially purified by chemical and biological processes,mostly by the actions of decomposer bacteria,as long as these natural processes are not overloaded.Thus,the hydrologic cycle can be viewed as a cycle of natural renewal of water quality.
翻譯:
在水文循環圖中，有許多自然淨化水的過程。蒸散和下雨是一個自然的淨化過程，可以除去溶於水中的雜質。只要沒有超過自然淨化過程的負荷，流動在地上的水就可以通過河與湖以及地下含水層自然的過濾和部分的淨化，藉由化學的作用以及生物學的作用，主要的淨化是分解細菌的作用結果。因此，水文循環圖可以被看成是水質的自然更新循環。
此段重點:
透過水文循環圖可以看出水的淨化過程，只要不超過自然的負荷，水文循環圖就可以被看成是水質的自然更新週期。