“…Dashed lines represent fits with a slope of less than 0.01 V -1 . Numbers for datasets are (1) Bison Pool, Yellowstone National Park (unlike the other datasets, DNA was extracted from biofilm samples) (Swingley et al, 2012), (2) acidic and (3) circumneutral to alkaline New Zealand hot springs (Power et al, 2018), (4) Dallol Geothermal Area (hypersaline and moderate to extremely acidic water) (Belilla et al, 2019), (5) Copahue Volcano-Río Agrio (Lopez Bedogni et al, 2020;Massello et al, 2020), (6) Southwestern Yunnan (seven samples with pH > 7 and two moderately acidic samples) (Guo et al, 2021), (7) Eastern Tibetan Plateau (Guo et al, 2020), (8) Uzon Caldera (nine samples for acidic water and sediment and one high-pH sample) (Peltek et al, 2020), (9) Southern Tibetan Plateau (Ma et al, 2021), (10) Japan Hydrothermal Sediment (Omae et al, 2019). See Figure S1 for individual sample values.…”