55-5-2

原文︰
Throught out the hydrologic cycle, many natural pro-
cesses purify water. Evaporation and subsequent pre-
cipitation act as a natural dissolved in water. Water flowing
above ground through streams and lakes and below
ground in aquifers is naturally filtered and partially pu-
rified by chemical and biological processes, mostly by
the actions of decomposer bacteria, as long as these nat-
ural processes are not overloaded. Thus, the hydrologic cy-
cle can be viewed as a cycle of natural renewal of water quality.

翻譯︰
　　在水文循環方面，許多天然的作用淨化了水。蒸發散
作用以及接著發生的降雨過程被視為一種天然的淨化處理
，分離並移除了水中的雜質。水透過溪流跟湖泊流動在地
表上以及在地表下的地下蓄水層也可視為天然的過濾方式
，還有部分的淨化是經由化學上跟生物學的處理，大多數
是由分解者細菌來完成，只要這些天然的作用沒有超出負
荷量。因此，水文循環可以被看成是一種復原更新水品質
的循環。