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岩溶地貌(粵拼:ngaam4 jung4 dei6 maau6,Karst)係由溶得嘅岩石(例如石灰岩、白雲石同石膏)溶解而成嘅地形。佢嘅特點係帶有排水窿嘅地下排水系統。
雨水經過地球大氣層吸收咗二氧化碳(CO2)嗰陣,會形成導致岩溶特徵嘅碳酸。降雨到達地面之後,可能會穿過泥土,呢啲泥土因為泥土呼吸而產生咗額外嘅CO2。一啲溶咗嘅二氧化碳同水反應形成弱碳酸溶液,跟手溶解碳酸鈣。石灰岩溶解嘅主要反應順序如下:
H2O | + | CO2 | → | H2CO3 | ||
CaCO3 | + | H2CO3 | → | Ca2+ | + | 2 HCO3− |
喺某啲特別條件底下,可能會起到第啲機制。導致硫酸形成嘅硫化物嘅氧化亦有可能係岩溶形成嘅腐蝕因素之一。當有氧(O2)嘅地表水滲入深層嘅岩溶系統嗰陣,佢哋會帶埋氧氣入面,呢啲氧氣同硫化物(硫鐵礦、氫硫化物形成硫酸(H2SO4)。硫酸然後同碳酸鈣反應,導致石灰石地層入面嘅侵蝕增加:
H2S | + | 2 O2 | → | H2SO4 | (sulfide oxidation) | ||||
H2SO4 | + | 2 H2O | → | SO2−4 | + | 2 H3O+ | (sulfuric acid dissociation) | ||
CaCO3 | + | 2 H3O+ | → | Ca2+ | + | H2CO3 | + | 2 H2O | (calcium carbonate dissolution) |
Ca2+ | + | SO42- | → | CaSO4 | (formation of calcium sulfate) | ||||
CaSO4 | + | 2 H2O | → | CaSO4 · 2 H2O | (formation of gypsum) |
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