Study On The Characteristics Of Air Elements Variety In Karst Cave And Its Impact On The Cave Environment

China's cave tourism resources are abundant.With the development of cave tourism resources,various levels of environmental problems have appeared in the karst tourist cave environment in various parts of China.Therefore,it is of great significance to carry out cave environment research in the typical karst region to protect karst caves.Through the study of the laws and trends of changes in the air environment of tourism caves and the influence of tourism activities on the natural environment of caves,it can provide decision support and theoretical basis for tourism cave environment restoration.In this study,Zhijin Cave in Guizhou Province was used as a research object to conduct long-term,systematic monitoring of cave air environment,water environment,ecological environment,precipitation outside the cave,atmospheric environment outside the cave,and soil environment over the cave,using correlation analysis,and scale and system analysis methods,combined with SPSS,Origin,and Phreeqc analysis software,analyze the spatial and temporal migration characteristics and influencing factors of air environment elements in tourist caves from seasonal scales,diurnal scales,and spatial scales,and further study the change of cave air environmental factors impact to Micro-climate environment,water environment,deposition environment and ecological environment of cave.Through the analysis of long-term monitoring data,the following conclusions are mainly drawn:?1?Seasonal variation shows that the CO₂ concentration in Zhijin cave is the seasonal variation trend of summer high and low in winter.It is mainly affected by soil CO₂,air exchange inside and outside the cave,tourism activities and its special"U"shaped tunnel structure.The temperature and relative humidity have a certain seasonal change near the entrance,and the change is gradually stable in the depths of the cave.On day and night changes,CO₂ concentration and temperature are characterized by high during the day and low during the night,which is mainly controlled by the number of visitors and cave ventilation effects.Relative humidity shows the opposite trend with CO₂,and tourism activities also have an impact on it.Due to the cave ventilation effect and the closedness of the tunnel structure,the CO₂ of Zhijin cave has a significant distribution trend of“low at both ends and high in the middle”,and the temperature and relative humidity in different part in the cave are also have different characteristics,and the extent of their changes gradually decreased from the opening section to the transition section to the depth of the cave.?2?Tourism activities have an important influence on the water environment of the cave.When the air CO₂ in the cave is higher or exceeds the partial pressure of CO₂ in the water,the CO₂ entering the drip will increase,causing the PCO₂?water?to rise,and the corresponding HCO₃^-increases and the pH decreases,which makes the water erosive.As a result,the concentration of Ca²⁺increases and the TDS increases.This is mainly due to the conversion mechanism between water and gas.?3?Tourism activities also have an impact on the sedimentary environment of caves.The increase of CO₂ concentration in cave air results in a decrease in the partial pressure difference between water and gas,which makes the deposition and degassing of drip water inhibited,which is not conducive to the growth of cave deposits.In Zhijin Cave,PCO_2?water?is affected by PCO_2?air?,and its contribution to SI is obviously weaker,because?P is vulnerable to tourism activities,especially during the tourist season,PCO_2?air?has a significant effect on?P.Therefore,the balance between them was broken,and the correlation between?P and SI was weak.There was no significant negative correlation between?P and SIc and SId,and there was no obvious axis of symmetry,This shows that tourism activities have caused the original environmental balance of natural caves to be broken,which affects the growth rate of sediments in caves.?4?Tourism activities have a certain impact on the ecological environment of caves.Due to the use of cave lighting equipment for tourism,a large number of light plants in the cave are breeding,breaking the original biological balance of the cave.According to field observations,generally 30-50cm away from the light,the temperature,relative humidity,and ambient CO₂ were approximately 19.07°C,76.34%,and 1337.3 ppm,respectively,and the light plants grew most vigorously.