Table I. Arsenic concentrations and related groundwater chemical conditions from sampling points in the anoxic zone of the sewage plume.
Altitude (meters to sea level)	Turbidity (NTU)a	pH	Fe (µM)	P (µM)	AsT (µM)	As(III) (µM)	As(V)b (µM)
F625 sampled June 4, 2003
3.1	0.6	6.34	69	18.3	0.038	0.018	0.020
2.2	0.7	6.66	244	61	0.203	0.143	0.060
1.4	0.7	6.66	234	84	0.196	0.131	0.065
0.6	0.7	6.71	207	91	0.189	0.062	0.127
–0.2	2.8	6.70	175	64	0.166	0.114	0.052
–1.0	1.4	6.73	102	34.9	0.158	0.100	0.058
–1.5	5.4	6.75	148	44.0	0.157	0.111	0.046
–1.9	1.2	6.78	141	51	0.159	0.111	0.048
–2.7	0.9	6.63	236	93	0.192	0.135	0.057
F343 sampled June 18, 2002
2.9	0.3	6.48	250	24.3	0.174	0.101	0.073
2.0	0.3	6.54	330	90	0.197
1.1	0.8	6.56	280	77	0.165
0.2	0.3	6.50	255	49.2	0.143	0.073	0.070
–0.7	1.0	6.58	214	41.2	0.152
a Nephelometric turbidity units.
b By difference between AsT and As(III).

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Table II. Selected water chemical data from the injection port, sampled after completing the injection.
Hours after injection	SpC (µS/cm)a	pH	P (µM)	AsT (µM)	As(III) (µM)	As(V)b (µM)
1.4	447	6.23	640	0.0215	0	0.0215
14.4	ndc	6.17	530	0.0593	0	0.0593
a Specific conductance, microSiemens per centimeter.
b By difference between AsT and As(III).
c Not determined.

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Table III. Extractable arsenic content of sediments.
Core number	Altitude (m)a	Mineral fraction	Arsenic (nmol/g)
			Oxidativeb	Reductivec
<2 mm size fraction
R23AWC02d	13.4±0.2	whole	4.0±0.2	1.08±0.03
R23AWC02e	12.9±0.2	whole	2.3±0.7	1.11±0.01
R23AWC03f	13.4±0.2	whole	3.2±1.1	0.98±0.04
R23AWC03g	12.9±0.2	whole	2.0±0.6	0.97±0.02
94UZComposite		wholeh	5.18±0.02	0.91±0.02
>2 mm size fraction
R23AWC03	13.4±0.2	whole except quartz	1.54	0.90
R23AWC03i	13.4±0.2	quartz grains	nd	0.66
R23AWC02	13.4±0.2	whole except quartz	0.33	1.49
R23AWC02j	13.4±0.2	quartz grains	nd	1.77 nd = not determined.
a Altitude (meters to sea level) of middle of 0.4-m-long cored interval.
b Hot, concentrated nitric acid and hydrogen peroxide.
c Hydroxylamine hydrochloride at 50 °C for 96 h.
d <2 mm size fraction comprised 97% by weight of sample.
e <2 mm size fraction comprised 90% by weight of sample.
f <2 mm size fraction comprised 98% by weight of sample.
g <2 mm size fraction comprised 91% by weight of sample.
h <1 mm size fraction.
i Quartz grains comprised 36% by weight of >2 mm size fraction.
j Quartz grains comprised 22% by weight of >2 mm size fraction.

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