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Fig. 1.
Site map with well locations and spatial distribution of THg concentrations in the Okochiri groundwater (basemap: Google Earth map). For color inter
pretation in this map, the reader is referred to the Web version of this article. (For interpretation of the references to color in this figure legend, the reader is referred
to the Web version of this article.)
Fig. 2.
Batch leaching experiment sample preparation.
Fig. 3.
Hydrochemical facies for groundwater in the Okochiri.
Fig. 4.
Profiles of THg and % C in sediment cores collected from the WDP in Okochiri.
Fig. 5.
Comparison between THg concentrations in the contaminated sediment
and non-contaminated sediment (reference) collected within the same geolog
ical unit in Okochiri.
Fig. 6.
(a) THg vs Hg
diss
concentrations,
(b)
THg vs. SO
4
2
−
, and
(c)
Hg
diss
vs. SO
4
2
−
for the wastewater-influenced groundwater in the Okochiri.
Fig. 7.
Hg species as a function of pH and Eh, using calculated activities for the
measured analytes and Miniteq thermodynamic data at 28
◦
C. The diagram was
generated using the Geochemist
’
s Workbench (version 17.0.3). The stability
diagram was constructed using chemical data from this study.
Fig. 8.
Concentration of mobilized Hg in the study sediments. Sediment cores
S3 B, S3 C, S3 D, S5 B, and S5 A were collected at
–
40 cm, 60 cm,
–
80 cm,
–
40
cm, and
–
20 cm depth, respectively
Fig. 9.
Schematic representation (not to scale) of Hg source, concentrations, speciation and behavior in the groundwater and sediment of the eastern Niger Delta,
Nigeria.
Notes: NOM: Natural organic matter, HC: Hydrocarbon.
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