Fig. 5

Schematic diagram of the HIM station sampling layout at the Old Well fumarole, Sulfur Banks solfatara field, Kilauea. See Fig. 2c for large area view. Small arrows in the HIM station box indicate direction of pumped gas flow through the thick-walled, flexible silicone tubing, denoted by blue lines. The two main areas designated for ground-truth sampling are at the VGPS pump exhaust and the sampling Tee. TOP INSERT: photo of manual sampling at VGPS exhaust hose. An evacuated Giggenbach sampler is in place. A copper tube and manual cold welder (Team product) is nearby. BOTTOM INSERT: photo of the sampling Tee established near the Old Well fumarole. The borehole is the top of the original well, now buried under rocks. Directional flow gas samples were obtained by changing the position of the hose clamp from the short 90° tube to the longer tubing connected to the HIM station. Those samples were obtained by manual hand pumping, following standard field protocols (e.g., Hunt et al., 2015)