Fig. 1: Fraction of Ni adsorbed vs Δ60Nimineral-aqueous (‰) for synthetic samples and natural sediments from this study, and synthetic samples from the literature (Sorensen et al.24 and Wasylenki et al.29).
Fraction of Ni adsorbed was determined for our synthetic samples and natural sediments by this study using wet chemical treatment, and for the synthetic samples from the literature by those studies using EXAFS spectroscopy. Isotope ratios were determined for our synthetic samples by this study, and for natural sediments (Pacific Ocean sediments, MANOP Site H and M, and USGS NOD A1 and NOD P1) by previous work4,13. Isotopic fractionation for natural sediments is calculated relative to the mean value of seawater at 1.33 ± 0.13‰32. Isotopic ratio data for the synthetic samples from the literature were determined by those studies. x-Axis error bars for our synthetic samples represent the standard deviation from three repeated wet chemical treatments, where the fraction of Ni that is adsorbed agrees well between our treatment and EXAFS spectroscopy. x-Axis error bars for natural sediments represent a ±0.2 discrepancy between the fraction of Ni adsorbed as determined by wet chemical treatment vs that determined by EXAFS spectroscopy of the USGS nodules. y-Axis error bars are the long-term reproducibility of the isotope ratio analyses (±0.08‰) combined with the variation of isotope ratios in seawater (±0.13‰)31. The grey bar represents a York linear regression fit to our equilibrium-dominated synthetic samples and natural sediments (r = 0.64, p < 0.01). Circled data in black highlights the kinetic-dominated synthetic samples from the literature, and in blue highlights the MANOP Site M samples.
