Arsenic Transfer from As-Rich Sediments to River Water in the Presence of Biofilms

Table 2

Arsenic speciation in the overlying water for systems C (control) and B (biofilm).

System	Time (day)	As (µg L^−1)	As (µg L^−1)	MMA (µg L^−1)	DMA (µg L^−1)	AsB (µg L^−1)	As sp. (µg L^−1)	Total As (µg L^−1)	% recovery
B	0	1.73	n.d.	0.47	n.d.	n.d.	2.19	2.50	87.94
	1	4.28	n.d.	0.52	n.d.	n.d.	4.79	7.19	66.64
	4	9.92	n.d.	n.d.	0.03	0.04	9.98	9.92	100.70
	11	13.28	0.03	n.d.	0.02	0.01	13.34	11.90	112.86
	18	12.69	n.d.	n.d.	n.d.	0.02	12.71	12.75	99.36
	24	10.67	n.d.	n.d.	0.12	0.10	10.89	11.21	96.90
	33	7.58	n.d.	n.d.	0.19	n.d.	7.77	9.69	80.04
	39	7.30	0.13	n.d.	0.41	0.07	7.91	9.17	86.34
C	0	5.52	0.47	0.29	n.d.	0.12	6.40	6.88	92.64
	1	20.52	2.47	0.12	0.08	0.39	23.58	26.14	89.80
	4	24.80	1.54	n.d.	0.59	0.61	27.54	30.30	91.09
	11	24.62	0.47	n.d.	0.43	0.89	26.42	25.51	103.35
	18	22.66	0.47	n.d.	0.59	0.92	24.63	23.73	103.98
	24	22.07	0.08	n.d.	0.60	0.94	23.69	23.34	101.50
	33	17.56	0.29	0.09	0.61	0.73	19.29	22.20	86.83
	39	16.74	0.34	0.18	0.67	0.68	18.62	21.67	85.64

n.d.: not detectable.