Fig. 5: N2-fixation rates as a function of salinity in soda lakes worldwide.
From: Biogeochemical explanations for the world’s most phosphate-rich lake, an origin-of-life analog
Data are from Goodenough and Last Chance lakes (this study) as well as from Mono Lake41,42 and the Kulunda Steppe (Russia) lakes Bitter-144,45, Cock Soda Lake, Bitter−3, Tanatar VI, Picturesque Lake, and Crooked Lake44. Except for the present study and the Mono Lake water column rates41, plotted rates are based on the acetylene assay, which measures nitrogenase activity via acetylene reduction to ethylene. The conversion factor relating acetylene reduction to actual N2-fixation rates is typically (including in this figure) assumed to be 4 on theoretical grounds100, but in reality can vary by at least one order of magnitude64,101. None of the cited studies determined the locally applicable acetylene-N2 conversion factors, so the plotted rates should be taken with caution, especially when comparing rates from different studies.
