Table 3.

Mössbauer fitting and XANES fitting of As K-edge XAS data^a

Sample	Mossbauer fitting [% Fe(II)]	XANES fitting (% arsenic in form of:)
		Arsenate	Arsenite	As-S	FeAsS
Reference sedimentb	NAe	53	47	—f	—
Untreated	37	16	84	—	—
Nitrate	32	64	36	—	—
Nitratec	NA	28	72	—	—
Sulfate plus lactate	42	16	65	19	—
Sulfate plus lactated	NA	10	54	36	—

^aAll samples were taken from the microcosms on day 115. The fit index is S [(I_obs − I_calc)2]/n, where n is the number of points in each spectrum. Errors for proportions of standards are ca. ± 10.

^bSediment frozen at the start of the experiment and used as a reference for manipulated sediment.

^cSequentially extracted to remove nonspecifically sorbed As, exchangeable specifically sorbed As, and As bound to amorphous and poorly crystalline hydrous oxides of Fe and Al.

^dSequentially extracted to remove nonspecifically sorbed As, exchangeable specifically sorbed As, As bound to amorphous and poorly crystalline hydrous oxides of Fe and Al, and As bound to well-crystallized hydrous oxides of Fe and Al.

^eNA, data not collected.

^f−, not detected.