Research On CO₂ Migration And Its Synergistic Response Between Soil And Cave In Karst Area

Soil cave environment as an important part of the karst environment is an important place to study changes in carbon migration.In this study,we study the soil environmental indicators on the basis of the previous study on the environment of Zhijin Cave.Through the monitoring data and GIS spatial technology,the temporal and spatial migration patterns and synergistic of soil-cave CO₂ were analyzed,and the change of CO₂ and its influencing factors were analyzed from soil environment and cave environment.The results are:1)Soil aspects.The CO₂ content in the study area showed that the CO₂ content in the spring increased slowly until the end of summer or early autumn reached the highest value.The the end of autumn began to decline until the lowest in the year.This reflects the migration of soil CO₂ migration with seasonal variation.In the space,the CO₂ content of the monitoring sites is different in the vertical or horizontal direction,but the whole shows a certain regularity.The change of CO₂ in the depth of each monitoring site shows that the maximum CO₂ content appears between summer and autumn.The right deviation distance of the high CO₂ content is higher than that in the 1 # point,the 2 # point and the 3 # point,and the right deviation distance of the CO₂ content in the 4 # point is larger than that in the 1 # point,2 # Point distance,5 # point CO₂ content in the high value of the right shift distance to reach the maximum.High value area appears in the autumn.2)Cave side.From January 2015 to May 2016,the high CO₂ content of the Zhijin Cave moved from the middle-rear of the cave to the middle of the cave,from the middle of the cave to the middle-front of the cave,from the middle-front of the cave to the front of cave.After September,the high CO₂ content moved from the front of the cave to the front-middle of the cave,from the front-middle of the cave to the middle-rear of the cave.From February 2015 to February 2016,it goes back to the origin and the new round of migration started by.This shows that the cycle is strong.In the space,with the further away from the mouth of the cave,the CO₂ content is rising.When it reached the maximum,the CO₂ content shows the distribution trend of low middle high on both ends.3)Soil-cave CO₂ synergy.In the whole study area,the CO₂ content of soil CO₂ at 20 cm,40cm,60 cm and 80 cm was stronger than that of cave CO₂,and R2 was 0.742,0.751,0.803,0.814.This indicates that the migration of soil-cave CO₂ in the study area is synergistic.Performance: Spring soil-cave CO₂ rises slowly.It reached the highest value in the summer and autumn.With the climate change and the migration of the season,soil cave CO₂ began to decline-a larger decline in the late autumn.When arriving in winter,soil-cave CO₂ reaches the minimum of the year.In general,the soil cave CO₂ in the study area showed a strong regularity.This is mainly due to the existence of the underground world cave is a certain area rather than a point-like,cave CO₂ source does not have a point of nature.Therefore,the single soil point on the cave can't control the migration of CO₂ in the cave,but the synergistic effect of the whole cavern covering area,and finally it plays a certain influence to the soil-cave CO₂ migration.Based on the analysis of CO₂ migration process,the main factors leading to the co-migration of soil-cave CO₂ in the study area are as follows:?1?Soil air CO₂ continuous sinking;it through the bedrock fissure,dissolved tube directly into the cave,the change in the CO₂ play a role in the cave.?2?Precipitation is caused by the precipitation of CO₂ in the soil.Then it enters into the bedrock to fully dissipate and erode the bedrock so that the water reaches a saturated state.Finally it enters into the cave and contacts the cave air and moves.This facilitates the deposition of CO₂ at the same time.?3?Seasonal changes contribute to changes in soil organisms and microbiological activities,soil physical and chemical properties,and precipitation.Eventually it leads to significant synergistic changes in soil-cave CO₂ content in different seasons.4)In the process of monitoring,the study area has the guidance and practical significance for the ordinary year.But for the unusual year,such as drought,rain and hail and other year data there is a certain lack.I would like to continue to follow up on this research in order to achieve an in-depth analysis of a regional cave to make up for its deficiencies.At the same time,I also expect continuous monitoring to be more persuasive and more detailed.