Insights on Climate-Driven Fluctuations of Cave ²²²Rn and CO₂ Concentrations Using Statistical and Wavelet Analyses

Table 1

Results of variable grouping from PCA considering the different stages that Rull Cave undergoes.

Cave atmosphere stage	Variables	Component 1	Component 2	Component 3
1 (gaseous recharge)	Rainfall	-0.149	-0.953	-0.163
	Visitors	0.253	-0.353	0.850
	CO2	-0.269	0.453	0.806
	^222Rn	0.757	0.162	0.077
		-0.122	0.922	-0.285
		0.857	-0.042	0.080
		0.653	0.451	-0.555
	RHind	-0.883	0.238	0.190
% explained variance	86.26	33.60	29.70	22.96
2 (cave recharged)	Rainfall	-0.756	0.065	-0.080
	Visitors	0.079	0.852	-0.080
	CO2	0.291	0.543	-0.318
	^222Rn	0.743	0.434	0.118
		-0.112	0.904	0.066
		0.763	-0.364	-0.323
		0.882	0.234	0.090
	RHind	0.122	-0.091	0.940
% explained variance	74.46	32.53	27.82	14.11
3 (gaseous discharge)	Rainfall	0.057	-0.002	0.998
	Visitors	-0.948	0.053	-0.281
	CO2	0.916	-0.222	-0.333
	^222Rn	0.843	0.418	0.106
		-0.938	-0.199	0.049
		-0.260	0.913	0.311
		0.264	0.910	-0.317
	RHind	0.976	-0.160	-0.036
% explained variance	97.21	55.29	24.43	17.48
4 (cave discharged)	Rainfall	0.770	0.308	(only two components in stage 4)
	Visitors	-0.893	0.091
	CO2	-0.467	0.827
	^222Rn	0.592	0.745
		0.437	0.748
		0.969	0.214
		0.899	-0.137
	RHind	-0.031	0.975
% explained variance	85.16	48.70	36.45	—