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重庆雪玉洞洞内CO_2浓度之高,在国内外皆罕见,但此洞穴系统碳循环特征及控制因素仍不清楚.利用土壤二氧化碳分压(P_(CO_2-soil))、洞内大气二氧化碳分压(P_(CO_2-cave))、地下河水二氧化碳分压(P_(CO_2-eq))、方解石饱和指数(SIc)、地下河水溶解无机碳同位素(δ~(13) CDIC)等指标来研究雪玉洞洞内CO_2浓度变化、控制因素以及地下河对洞内碳循环的影响.结果表明:雪玉洞上覆P_(CO_2-soil)雨季高,旱季低;降雨量是控制上覆P_(CO_2-soil)的重要因子.雪玉洞P_(CO_2-cave)变化规律明显,暖季高,冷季低;温度变化导致洞内外气流频繁交换是P_(CO_2-cave)突变的重要原因,地下河水CO_2脱气能够在短时间内让P_(CO_2-cave)上升到较高值.雨季由于土壤CO_2效应,地下河水具有低SIc、高P_(CO_2-eq)特性,矿化度较高,并且部分月份地下河水具有溶蚀性;旱季由于土壤CO_2效应及降雨较少,地下河水呈现高SIc、低P_(CO_2-eq)特性,矿化度较低,以沉积为主.
The CO 2 concentration in Xueyu caves in Chongqing is very high, which is rare at home and abroad, but the carbon cycle characteristics and controlling factors of this caves system are still not clear.Using the soil carbon dioxide partial pressure (P_ (CO_2-soil)), (P_ (CO_2-cave)), partial pressure of carbon dioxide in underground river (P_ (CO_2-eq)), calcite saturation index (SIc) and dissolved inorganic carbon isotope (δ ~ (13) CDIC) The change of CO_2 concentration in Yudong Cave and its controlling factors as well as the influence of underground river on the carbon cycle in the cave were analyzed.The results showed that the rainy season of Xueyu Cave overlying P_ (CO_2-soil) was high and the dry season was low.The rainfall was controlled by P_ (CO_2 -soil) .The P_ (CO_2-cave) of Xueyu-dong is obviously changed, the warm season is high and the cold season is low. The frequent exchange of air flow inside and outside the cave is the important reason of P_ (CO_2-cave) The CO_2-cave can be increased to a higher value in a short period of time by degassing with CO_2.In the rainy season, the groundwater has low SIc, high P_ (CO_2-eq) and high salinity due to soil CO_2 effects, and some In the month, the underground river water was erodible. Due to the CO_2 effect and rainfall in the dry season, the underground river water showed high SIc and low P_ (CO_2-eq) characteristics, the degree of salinity is low and sedimentary dominated.