土壤CO2与喀斯特洞穴CO2季节变化响应分析

为了揭示土壤CO_2对洞穴内环境的意义,对大风洞和响水洞2016年洞内环境指标和上覆土壤的相关数据进行统计与回归分析。结果表明,洞内CO_2浓度、土壤CO_2浓度具有显著的季节性特征,土壤2#对应的洞内空气CO_2在夏冬两季差值达793~884mg/kg。土壤水PCO_2和滴水PCO_2在夏冬两季的差值最高可分别达1.12和0.41,因此洞内滴水PCO_2、土壤水PCO_2也表现出明显的季节性特征。土壤CO_2、洞内空气CO_2、洞内滴水PCO_2和土壤水PCO_2间均表现出一定的滞后现象,如4#土壤水PCO_2与滴水PCO_2的相关系数,由非滞后条件下的0.123上升至滞后条件下的0.596。同时在滞后条件下,土壤CO_2对洞内CO_2的贡献率的总和最高可达84.6%,高于非滞后条件下的值。

Seasonal Response Between Soil CO2 and Karst Cave CO2 Concentration

In order to reveal the significance of soil CO2 on cave environment,statistical and regression analysis were conducted on the related data of the cave environmental indexes and the overlying soil properties in 2016.The results showed that the cave air CO2 concentration and soil CO2 concentration presented the significant seasonal variation and obvious hysteresis phenomenon.The difference between summer and winter of cave air CO2concentration corresponded with soil 2 # was 793 ～884 mg/kg.The highest differences of soil water PCO2 and drip water PCO2 between summer and winter were 1.12 and 0.41 respectively.So the drip water PCO2 and soil water PCO2 also showed obviously seasonal variations.The lag phenomenon was shown among soil CO2,cave air CO2,drip water PCO2 and soil water PCO2,e.g.,the coefficients between soil water PCO2 and drip water PCO2were improved from 0.123 without hysteresis to 0.596 with hysteresis.Under the hysteresis,the highest total contribution of soil CO2 concentration to cave air CO2 concentration was 84.6 ％,higher than that without hysteresis.