the water takes on a new, more erosive power. 水便有了一股新的、更强的侵蚀力

55. When the water reaches the more resistant bed of limestone
    当水流遇到更坚硬的石灰岩床时
56. its course is altered.
    就会改变路线
57. Once underground,
    一旦进入地下
58. the water takes on a new, more erosive power.
    水便有了一股新的、更强的侵蚀力
59. During its journey from the surface
    在地面上流淌时
60. the water absorbed carbon dioxide from the soil
    水从土壤中吸收了二氧化碳
61. making it mildly acidic.
    成为弱酸性

来自《行星地球 第一季 第四集 Planet Earth S01E04 洞穴》第 58 行