为探究岩溶关键带碳循环机制,揭示洞穴通风对洞穴环境变化的响应机制,在2018年国庆期间对贵州绥阳大风洞洞内空气环境指标(温度、湿度、CO2浓度)和滴水水化学指标(温度,pH值,EC,Ca2+,HCO-3)进行为期7 d的连续自动监测,并运用系统分析方法对各要素进行了综合分析。结果 表明:(1)受游客数量、洞道结构的影响,洞穴空气CO2浓度表现出明显的昼夜变化特征; 与2#(神泉玉露)点相比,1#(夜明珠)点位于大风洞主洞道,洞腔体积较大,洞道较宽,洞穴空气CO2浓度增加幅度及变化幅度表现为2#>1#。(2)洞穴通风效应与洞穴滴水水化学相关性显著。洞穴通风与lgPCO2(w)呈反相关,与pH值,SIc和SId为正相关; 受监测点洞道结构、通风效应和滴水水量的影响,洞穴通风与1#点的Ca2+和HCO-3浓度变化呈反相关关系,与2#点的相关性不显著。(3)不同通风模式下,不同监测点的水气CO2分压差及沉积环境存在差异。当ΔTv>0时,洞穴属于积极通风状态,洞穴空气CO2浓度降低,ΔPCO2>0,有利于洞穴景观的沉积; 反之,洞穴沉积物趋向于产生溶蚀作用。
To explore the carbon cycle mechanism in the Karst Key Zone and reveal the response mechanism of the cave ventilation to the charge of environment. During the vacation of National Day of 2018, the 7-day continuous automatic monitoring on air environment index in tunnel(Temperature, Humidity, CO2 concentration)and chemical index of dripping water(Temperature, pH value, EC, Ca2+, HCO-3)had been carried out in Dafeng Cave of Suiyang in Guizhou Province. The systemic analysis method was used to do a comprehensive analysis on the factors. The results showed that:(1)affected by the quantity of tourists and tunnel structures, there were obvious diurnal variation characteristics in air CO2 concentrations of caves; compared with 2#, 1# located at the main tunnel of Dafeng Cave, has a large cavity and wide tunnel; the increasing range and changing range of CO2 concentration in the air of caves decreased in the order: 2#(shenquanyulu)>1#(yemingzhu);(2)correlation between the effect of cave ventilation and the chemistry of cave dripping water was significant; the cave ventilation effect was negatively related to lgPCO2(w), positively correlated with pH value, SIc and SId; influenced by the tunnel structures of monitoring point, cave ventilation effect and dripping water volume, cave ventilation were positively related to the concentration changes of Ca2+ and HCO-3 at 1#, but the correlation in 2# was not significant;(3)under different ventilation modes, there were differences in water vapor CO2 partial pressure difference and deposition environment at different monitoring points; when ΔTv>0, the cave will be positively ventilated and the CO2 concentration in the air of caves will decline, ΔPCO2>0, it will be conducive to the deposition of cave landscape. On the contrary, cave sediments tend to produce dissolution.
