Abstract：
CH4 serves as an important greenhouse gas, yet limited knowledge is available in global and regional CH4 cycling, particularly in widely distributed karst terrain. In this study, we investigated an upland in Puding Karst Ecosystem Research Station, and explored CH4 concentration and/or flux in atmosphere, soil and cave using a closed static chamber method and an eddy covariance system. Meanwhile, we monitored atmospheric temperature, precipitation, temperature and wind velocity in the cave entrance. The results demonstrated that atmospheric CH4 and actual soil CH4 fluxes in the source area of eddy covariance system were -0.19 ± 8.64 nmols-1m-2 and -0.16 nmols-1m-2 respectively. The CH4 concentrations in Shawan Cave exhibited 10 ∼ 100-fold lower than that of the external atmosphere. CH4 oxidation rate dominated by methane-oxidizing bacteria was 1.98 nmols-1m-2 in Shawan Cave when it combined with temperature difference between cave and external atmosphere. Therefore, CH4 sink in global karst subterranean spaces was estimated at 106.2 Tg CH4 yr-1. We supplemented an understanding of CH4 cycling paths and fluxes in karst terrain, as well as CH4 sinks in karst subterranean space. Further works require to establish a karst ecosystem observation network to conduct long-term integrated studies on CH4 fluxes regarding atmosphere, soils, plants and caves.
摘要：
CH4是一种重要的温室气体,然而，在全球和区域CH4循环中可用的知识有限，特别是在广泛分布的喀斯特地形。在这项研究中,我们调查了普定喀斯特生态系统研究站的一个高地，并探索大气中的CH4浓度和/或通量，土壤和洞穴使用封闭的静态腔室方法和涡流协方差系统。同时,我们监测大气温度,降水,洞穴入口处的温度和风速。结果表明，涡流协方差系统源区的大气CH4和实际土壤CH4通量分别为-0.19±8.64nmol-1m-2和-0.16nmol-1m-2。沙湾洞穴的CH4浓度比外部大气低10~100倍。沙湾洞穴中甲烷氧化细菌占主导地位的CH4氧化速率为1.98nmol-1m-2，与洞穴和外部大气之间的温差相结合。因此,全球岩溶地下空间中的CH4汇估计为106.2TgCH4yr-1。我们补充了对喀斯特地区CH4循环路径和通量的了解，以及岩溶地下空间的CH4下沉。进一步的工作需要建立喀斯特生态系统观测网络，以对大气中的CH4通量进行长期综合研究。土壤,植物和洞穴
