Environmental Engineering Reference
In-Depth Information
Table 3
Descriptive statistics of physicochemical properties and PTM concentration in sediments of dry and rainy seasons
Parameter
Dry
Rainy
Minimum
Maximum
Mean
Minimum
Maximum
Mean
Odo-Iyaalaro
pH
2.8
5.6
4.0
3.6
5.1
4.2
OM (%)
0.8
21
7.8
1.4
15.7
8.5
CEC
2.0
14.6
7.6
4.2
14.2
9.6
Cd (mg kg
-1
)
\0.9
42.1
9.6
\0.9
12.8
4.8
Cr (mg kg
-1
)
\17.5
102
31.0
\17.5
28.9
22.9
Cu (mg kg
-1
)
15.6
185
60.9
15.8
105
55
Pb (mg kg
-1
)
\15.8
154
56.7
21.6
108
63.5
Zn (mg kg
-1
)
53.1
1,040
292
18.7
377
147
Shasha River
pH
4.3
7.3
5.6
4.2
7.7
6.2
OM (%)
0.1
8.2
2.4
0.2
7.4
2.1
CEC
1.6
9.8
3.9
1.6
10.2
3.8
Cd (mg kg
-1
)
\ 0.9
1.2
0.9
\0.9
1.7
1.0
Cr (mg kg
-1
)
\17.5
56.7
27.8
\17.5
140
40.6
Cu (mg kg
-1
)
\ 2.8
78.5
31.3
\2.8
106
32.0
Pb (mg kg
-1
)
\ 15.8
189
38.6
\15.8
202
45.5
Zn (mg kg
-1
)
1.7
467
101
13
641
104
Ibeshe River
pH
3.6
7
5.1
3.2
7.3
4.5
OM (%)
0.3
7.2
2.3
0.2
7.6
2.4
CEC
1.6
4.2
2.5
1.8
5.2
3.0
Cd (mg kg
-1
)
\0.9
\0.9
0.9
\0.9
\0.9
0.9
Cr (mg kg
-1
)
\17.5
48.3
27.1
\17.5
54.5
31.3
Cu (mg kg
-1
)
\2.8
332
62.0
\2.8
115
23.3
Pb (mg kg
-1
)
\15.8
26.3
16.2
\15.8
21.8
15.8
Zn (mg kg
-1
)
4.6
158
35.9
6.0
57.5
21.3
Lagos Lagoon
pH
4.3
6.6
5.4
4.1
7.0
5.6
OM (%)
0.1
12.6
4.2
0.1
10.8
3.7
CEC
1.8
11.2
5.0
2
11.0
4.9
Cd (mg kg
-1
)
\0.9
2.1
1.2
\0.9
\0.9
\0.9
Cr (mg kg
-1
)
34.4
51.7
44.7
23.8
51.7
35.8
Cu (mg kg
-1
)
\2.8
33.7
20.6
\2.8
43.0
18.8
Pb (mg kg
-1
)
\15.8
39
28.4
\15.8
39.2
25.6
Zn (mg kg
-1
)
1.3
190
103
1.3
246
118
Dixon
1997
) were used. Of the 103 sediments studied, 11
exceed the PEC for Cd (all in the Odo-Iyaalaro); two exceed
the PEC for Cr; four exceed the PEC for Cu (one from Odo-
Iyaalaro and three from Ibeshe River); three exceed the PEC
for Pb and four exceed the PEC for Zn. Forty of the sedi-
ments were above the Dutch sediment guideline for Cu and
four (three from Odo-Iyaalaro during the dry season) exceed
the guideline for Zn.
In order to determine the mobility and bioavailability of
the metals studied, BCR sequential extraction technique
was used. In the Odo-Iyaalaro, cadmium and zinc showed a
similarity in their fractionation pattern. They were mostly
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