Table IV.

μEXAFS and μXRD results

Grain	Proportion of Zn Species (%) Determined by Linear Combination Fitting the μEXAFS Spectra				Sum	NSSb	Elements Detected by SEM-EDX and/or μXRFa	Minerals Identified by μXRD
	Zn-Substituted Calcite	Zn-Organic Acids	Zn-Sorbed Silica	Zn-Sorbed Phosphate
						%
Grains from the Ca treatmentc
Ca1							Ca, Mn (elements lighter than Ca not analyzed)	Subst. calcite (Ca(0.84 − 0.09X)Mg[0.16(1 − X)]Mn(0.25X)CO3), whewellite (CaC2O4, H2O)
Ca2							Ca, Mn (elements lighter than Ca not analyzed)	Subst. calcite (Ca(0.91 − 0.05X)Mg[0.09(1 − X)]Mn(0.14X)CO3), whewellite (CaC2O4, H2O), weddellite (CaC2O4, 2 H2O), vaterite (CaCO3)
Grains from the Ca + Zn treatmentc
ZnCa1	53	–	–		53	23.6d	Zn, Ca (elements lighter than Ca not analyzed)	Subst. calcite (Ca0.84(Mg,Zn)0.16CO3), whewellite (CaC2O4, H2O)
	40	50	–	–	90	8.9d
	44	–	–	49	93	9.5
ZnCa2	59	–	–	–	59	18.9	Zn, Ca (elements lighter than Ca not analyzed)	Subst. calcite (Ca0.92(Mg,Zn)0.08CO3)
	50	39	–	–	89	11.3d
	53	–	–	38	91	11.7
ZnCa3	22	78	–	–	100	7.2d	Zn, Ca, Si, O	Subst. calcite (Ca0.93Zn0.07CO3), aragonite (CaCO3)
ZnCa4	23	57	–	–	80	7.9d	Zn, Ca, Si, O	Subst. calcite (Ca0.87Zn0.13CO3)
Grains from the Zn treatmentc
Zn1	15	73	–	–	88	4.8d	Zn, Ca, K, Cl, Si, Mg, O	Subst. calcite (Ca0.92(Mg,Zn)0.08CO3)
Zn2	–	37	79	–	115	2.7d	Zn, Ca, K, Cl, Si, Mg, O

^aCarbon could not be analyzed because the grains were coated with this element.

^bResidual between fit and experimental data: NSS = Σ [k³ χ(k) − k³ χ(k)_fit]²/Σ [k³ χ(k)]² × 100.

^cCa and Zn concentrations given in Table I.

^dSimulations shown in Figure 9.