Geochemical Fingerprinting of Rising Deep Endogenous Gases in an Active Hypogenic Karst System

Table 2

Mean measurements (and ±sd: standard deviation) for the concentrations of CO₂ and CH₄, and their stable isotopic compositions (δ¹³C_CO2 and δ¹³C_CH4) in the cave environment, and in vertically adjacent soils and the local outdoor atmosphere.

	CO2 (ppm)		δ ^13cc02 (%)		CH4 (ppm)		δ ^13ccH4 (%)
	avgr	± sd	avgr	± sd	avgr	± sd	avgr	± sd
Sep. ‘15
Soil	527	6	−9.83	0.15	1.80	0.00	−46.89	0.80	4
Cave	8257	1795	−5.77	0.56	1.09	0.16	−42.57	3.31	8
Ext.	411	2.06	−8.26	0.16	1.91	0.01	−47.55	0.39	4
Mar. ‘16
Soil	810	218	−11.80	0.53	1.86	0.12	−46.36	0.57	4
Cave	9040	2575	−6.29	0.83	2.62	0.49	−49.17	1.95	9
Ext.	—	—	—	—	2.06	0.02	−48.10	0.45	4
Nov. ‘16
Soil	1907	929	−15.60	2.33	0.52	0.55	−44.07	5.30	5
Cave	11.964	1535	−5.83	0.32	0.87	0.06	−44.43	16.42	9
Ext.	503	153	−7.84	0.58	2.03	0.01	—	4.28	4
Apr. ‘17
Soil	1472	1430	−15.87	0.56	0.71	0.61	−42.66	6.34	3
Cave	7507	2036	−6.35	0.43	1.08	0.14	−45.95	1.64	10
Ext.	465	20	−10.71	0.51	2.01	0.01	−51.93	0.64	3
Jun. ‘17
Soil	1035	702	−12.46	1.60	1.76	0.37	−45.33	0.20	3
Cave	7775	979	−5.56	0.12	0.95	0.06	−35.29	2.22	5
Ext.	434	271	−9.25	1.29	2.16	0.08	—	5.49	4
Jul. ‘17
Soil	639	87	−12.79	0.57	1.88	0.18	−47.20	1.72	3
Cave	8998	1718	−5.72	0.08	0.94	0.22	−41.40	16.31	3
Ext.	433	193	−8.08	1.10	2.04	0.04	—	0.83	3
Aug. ‘17
Soil	649	329	−11.07	0.18	1.94	0.12	−47.68	3.39	4
Cave	10.441	1230	−5.35	0.16	0.89	0.12	−38.66	5.31	6
Ext.	434	16	−9.07	0.65	2.00	0.00	−53.08	0.46	3
Sep. ‘17
Soil	2034	646	−13.45	1.89	0.50	0.06	−62.89	4.02	3
Cave	12.251	3251	−5.60	0.50	1.07	0.09	−39.41	7.09	8
Ext.	417	9	−8.65	0.09	1.99	0.00	—	1.23	3
Average
Soil	1134	543	−12.86	0.98	1.37	0.25	−47.88	2.79	29
Cave	9529	1890	−5.81	0.38	1.19	0.17	−42.11	6.78	58
Ext.	442	95	−8.84	0.63	2.02	0.02	−50.17	1.72	28