Table 1. Mössbauer Hyperfine Parameters at 77 K of Unreacted and Hg^II-Reacted Vivianite^a.

	type of sites	CS (mm s–1)	ΔE (mm s–1)	σ (ΔEQ)	R.A. (%)	χ2
unreacted vivianite	D1 (FeII)	1.34 ± 0.001	3.22 ± 0.004	0.08	56.4 ± 0.8	0.85
	D2 (FeII)	1.30 ± 0.002	2.62 ± 0.009	0.15	37.4 ± 0.8
	D3 (FeIII)	0.59 ± 0.027	0.76 ± 0.043	0.30	6.2 ± 0.4
HgII-reacted vivianite	D1 (FeII)	1.34 ± 0.002	3.23 ± 0.005	0.00	10.3 ± 0.1	0.59
	D2 (FeII)	1.31 ± 0.004	2.64 ± 0.012	0.14	16.8 ± 0.4
	D3 (FeIII)	0.50 ± 0.090	0.83 ± 0.120	0.48	72.9 ± 0.1

^aCS is the center shift with respect to α-Fe (mm s^–1), ΔE_Q the quadrupole splitting (mm s^–1), with σ(ΔE_Q) indicating sigma broadening of the quadrupole splitting, R.A. the relative abundance of each site (%), and χ² the goodness of fit. D refers to each doublet used during fitting.