Research Of Microclimatic Mathematical Modelling On Migration Changes Mechanism Of Cave CO₂

The aim of this project is to find out the mechanism of CO₂ change in cave environmental system and quantitative analysis of its factors controlling the mechanism in the cycle of carbon, water and calcium in karst kinetic system which combine together varies of processes in karst region, and use the more accurately mathematical models, this is important because it’s a key to couple research between the interior and exterior of cave environmental parameters. And this follows from earlier research on this topic in that the material source of cave CO₂, the spatiotemporal variations and its mechanisms and controlling factors, and finally use the spatiotemporal migration change mechanisms of CO₂ in cave tourism management and others.Zhijin Cave World Geo-park（ZCWGP） in central and western Guizhou province has been studied for 30 years but yet little is known about the quantitative analysis of Carbon Dioxide within the cave system. In order to explain these CO₂ change through a mathematical model several other factors（cavity indices, atmospheric parameters, hydrochemical data, soil properties, and tourist data） were examined. The research was carried out by field/ lab/ documentary methods, in which took upon a hydro-year study during January 2015 to March 2016 on the microclimatic environment in Zhijin Cave, A temperature, humidity, barometric pressure, wind speed, and CO₂ concentration in cave atmosphere, altitude of cave entrance and monitoring sites in cave, dripwater hydrochemistry, physical properties of soil above the cave and soil water and CO₂ and temperature study was undertaken in Zhijin. Both surface and cave temperatures etc. were collected, as were precipitation, cave drip water and drip rates. All data were collected on a monthly basis to investigate the relationships between precipitation and drip waters, and then between cave CO₂ and the water inside and outside the cave.It was observed that there was a consistent pattern of temporal change of CO₂ in the system of soil-water-cave, and there was a certain degree of spatial and temporal variation and coupling response to each other. Specific performance as the CO₂ concentration in Summer-Autumn was higher than that in Winter-Spring, and the highest one was in August whilst lowest in February, and in diurnal scale there was a cycle of 24 hours or 12 hours, usually the Peak valley values appear at 11 and 5（both a.m. and p.m.）.And found that CO₂ in cave was increased from entrance to inner part, and arrived at a relative stability in a distance as 180 m and 900 m in entrance and exit, respectively, and the CO₂ concentration was a bit of difference between higher and lower height, which shows a season degeneration with two models of “high-lower and low-higher” and “high-higher and low-lower”; what’s more, there was a lag on a certain time scale in the system of soil-water-cave.This suggests that the interaction of carbon cycle, water cycle and calcium circulation in the cave environment is unified, which occupies an important position in the karst dynamic system. And it is necessary to carry out extensive and profound research, which study is feasible.It is therefore concluded that, 1) the source of CO₂ in Zhijin Cave is mainly from the overlying soil carbon pool by drip degassing process and the release and exchange of natural factors such as atmospheric convection, and tourist activities etc. human factors, Natural factors and human factors take on their dominant position in different seasons and day and night time and spatial scale; 2) Changes of CO₂ in Zhijin Cave shows regularity and differences in time and space, it is necessary to divide the entrance zone, transition zone, and the stable zone into six sections to study space respectively, to achieve the whole research be unity of the whole and the local, and the coupling of time response and lag effect, and effectively guide the relevant scientific practices and management activities; 3) The stable zone in cave is the key of research, there was a seasonal variation of CO₂ between the high and low altitude passages in Zhijin Cave, the main two performance was "high-lower and low-higher"（i.e., the CO₂ concentration in high altitude in Summer and Autumn was lower than that in low altitude） and “high-higher and low-lower”（i.e., the concentration of CO₂ in high altitude passages in Winter and Spring was higher than that in low altitude）; 4) The mathematical model is established by analyzing the change of the environmental factors in different spatiotemporal scale in the Zhijin cave, which can apply to the study of geomorphology and caves in a wider area of Karst, and have an important theoretical significance and reference value on the further expansion of the two unified structures of the ground-floor, and finally, it can also provide scientific basis for the sustainable protection and management development of Zhijin Cave World Geological Park.