Supplementary Information
Online Resource 1
Physicochemical properties and PTM concentration in sediments during the dry season.
Sample
no
Sampling
Month
Sampling
Points
pH
OM
%
CEC
(meq/
100g)
Cd
(mg/kg)
Cr
(mg/kg)
Cu
(mg/kg)
Pb
(mg/kg)
Zn
(mg/kg)
Odo-Iyaalaro
1D
January
1
3.8
6.2
4.0
42.1±1.8
31±2.4
94.5±5.4
108±3
805±25
2D
January
2
4.2
1.4
2.0
2.1±0.3
24.8±1.9
15.6±2.2
41.3±1.9
100±6
3D
January
3
3.8
4.3
5.8
3.6±0.2
31.5±2.1
32.9±1.3
43.5±3.2
110±6
4D
January
4
4.6
8.2
10.4
2.9±0.2
30.8±2.0
25.2±1.2
36±2.4
84.5±4.8
5D
January
5
4.2
11.6
7.4
1.9±0.1
<17.5
15.9±2.6
25.5±1.7
64.5±3.2
6D
January
6
3.9
16.4
7.5
8±0.5
29±1.5
62.2±2.3
54.8±3.7
266±8.4
7D
March
3
3.1
5.1
4.2
4.8±0.4
102±3.3
54.4±2.3
45.3±3.7
157±3
8D
March
4
2.8
7.8
11.2
1.9±0.3
<17.5
38.8±0.8
<15.8
75.2±3.4
9D
March
5
3.9
10.2
14.6
21.3±0.6
<17.5
139±2
119±8
777±16
10D
March
6
4.8
21
12.7
34.4±0.9
30.2±1.9
185±2
154±3
1040±5
11D
November
3
5.6
0.8
3.8
<0.9
<17.5
29.3±2.2
19.7±0.5
53.1±2.7
12D
13D
November
November
4
5
3.3
5.0
5.9
6.1
6.8
7.7
<0.9
6.9±0.4
<17.5
<17.5
44.1±0.8
67.4±3.4
28±3.7
60.6±3.6
82.6±3.7
298±4.2
14D
November
6
3.4
4.4
8.9
2.2±0.1
<17.5
48.6±1.1
43.1±3.7
165±3
Shasha River
15D
January
7
5.3
5.8
9.8
<0.9
43.1±2.6
48.6±3.7
189 ±7
433±7
16D
January
8
4.9
1.4
2.2
<0.9
24.2±3.2
42.7±1.9
24.5±2.4
87.6±3.2
17D
January
9
4.3
2.1
3.2
<0.9
<22
33.8±1.6
32.6±2.1
43.6±1.9
18D
January
10
5.2
0.8
2.2
<0.9
26.1±1.3
26.6±1.6
36.8±4.2
34.2±1.8
19D
January
11
4.3
8.2
6.4
<0.9
<17.5
44.8±4.7
19.4±1.8
65.9±2.8
20D
January
12
7.2
0.6
4.8
<0.9
<17.5
62.8±3.5
<15.8
40.2±2.5
21D
March
7
4.9
4.8
7.6
1.2±0.2
56.7±2.8
78.5±4.2
93.4±5.5
467±17
1
22D
March
8
5.2
0.9
2.4
<0.9
53.2±3.8
32.4±2.1
54.2±3.8
93.4±1.3
23D
March
9
4.3
3.2
3.4
<0.9
26.7±2.6
28.6±1.9
56.8±5.6
74.6±2.9
24D
March
10
4.6
0.9
1.8
<0.9
<17.5
15.9±1.9
<15.8
43.2±3.5
25D
March
11
6.7
7.6
3.2
<0.9
<17.5
78.2±1.7
34.2±2.2
129±4
26D
March
12
7.2
0.6
1.6
<0.9
<17.5
16.3±1.4
<15.8
20.1±1.2
27D
December
7
5.7
1.4
7.8
<0.9
25.1±1.5
11.9±0.8
30.4±2.5
53±2.2
28D
December
8
6.1
0.3
2.4
<0.9
<17.5
<2.8
<15.8
1.7±0.3
29D
December
9
6.4
0.4
3.6
<0.9
<17.5
3.4±0.5
<15.8
9.7±0.8
30D
December
10
5
1.6
2.4
<0.9
<17.5
16±1.6
<15.8
82.8±3.3
31D
December
11
5.4
2.2
4.2
<0.9
25.1±1.5
17.7±0.9
<15.8
139±8
32D
December
12
7.3
0.1
2.0
<0.9
<17.5
<2.8
<15.8
3.6±0.4
Ibeshe River
33D
February
13
6.2
4.1
2.0
<0.9
<17.5
4.2±0.3
<15.8
20.7±2.2
34D
February
14
5.8
6.1
3.2
<0.9
<17.5
332±11
<15.8
96.9±8.1
35D
February
15
5.2
1.8
2.2
<0.9
<17.5
264±10
<15.8
98.3±2.1
36D
February
16
3.7
0.4
2.0
<0.9
<17.5
4.2±0.2
<15.8
4.6±0.1
37D
February
17
4.8
0.4
1.8
<0.9
<17.5
3.4±0.9
<15.8
6±0.5
38D
February
18
6.5
0.3
1.8
<0.9
<17.5
3.6±0.2
<15.8
8.6±1.1
39D
March
13
6.3
3.8
2.6
<0.9
<17.5
<2.8
<15.8
11.3±1.7
40D
March
14
4.2
7.2
3.3
<0.9
32.1±1.3
246±4
<15.8
53.7±0.6
41D
March
15
4.6
2.1
3.2
<0.9
<17.5
84.6±3.1
<15.8
45.9±2.1
42D
March
16
3.9
1.0
2.2
<0.9
42.1±1.8
24.5±2.5
<15.8
10.3±1.2
43D
March
17
4.6
0.6
2.0
<0.9
48.3±2.4
7.2±1.3
<15.8
7.6±0.4
44D
March
18
4.8
0.4
1.6
<0.9
41.2±1.6
9.3±0.9
<15.8
7.6±0.2
45D
December
13
7.4
3.6
3.4
<0.9
<17.5
15.7±1.5
26.3±2.2
158±6
46D
December
14
5.7
4.1
4.2
<0.9
<17.5
13.7±1.1
18±3.3
43.3±1.1
47D
December
15
4.6
1.8
3.2
<0.9
<17.5
13.8±1.3
<15.8
19.7±1.4
48D
December
16
4.8
0.8
2.0
<0.9
34.4±1.2
14.2±0.7
<15.8
13.5±0.7
49D
December
17
3.6
0.8
2.0
<0.9
25.7±1.5
68.2±2.4
<15.8
27.5±1.5
50D
December
18
4.5
1.2
2.2
<0.9
<17.5
5.2±0.7
<15.8
13.1±1.2
2
Lagos Lagoon
51D
December
19
4.5
3.5
5.1
<0.9
34.4±2.1
33.7±2.1
33.2±0.7
164±8
52D
December
20
5.4
4.1
4.8
1.3±0.2
51.7±3.2
30±0.8
39±2.3
146±5
53D
December
21
4.3
12.6
11.2
2.1±0.2
51.7±4.8
33.7±1.5
39±3.4
190±4
54D
December
22
6.4
0.1
2.0
<0.9
42.5±1.3
<2.8
<15.8
1.3±0.1
55D
December 23
6.6
0.5
1.8
<0.9
43.0±3.2
<2.8
<15.8
Results are mean values ± standard deviation for n = 3; < indicates a value below the detection limit
3
14.8±1.9
Online Resource 2
Physicochemical properties and PTM concentration in sediments during the rainy season.
Sample
no
Sampling
Month
Sampling
Points
pH
OM
%
CEC
(meq/
100g)
Cd
(mg/kg)
Cr
(mg/kg)
Cu
(mg/kg)
Pb
(mg/kg)
Zn
(mg/kg)
1.4
11.3
12.3
15.7
5.1
7.2
10.9
15.3
2.9
4.5
8.1
7.5
5.2
8.6
12.8
12.6
4.2
10.2
11.2
12.4
4.6
7.8
14.2
11.8
<0.9
12.8±1.9
6.9±0.3
8.6±0.6
<0.9
<0.9
5.5±0.7
10.2±1.1
<0.9
<0.9
2.6±0.4
6.1±0.2
<17.5
<17.5
<17.5
<17.5
<17.5
<17.5
25.6±1.7
28.9±1.6
<17.5
<17.5
<17.5
<17.5
27.5±2.0
40.2±1.9
67.8±1.6
105±4
15.8±2.2
38.2±2.1
58.9±3.7
92.4±2.4
41.1±2.0
43.8±1.9
51.1±2.4
77.9±1.3
21.6±3.7
52.3±4.2
43.8±3.6
46.9±2.1
98.2±5.8
48.5±3.6
108± 3
89.7±4.8
59.5±2.7
48.5±3.6
58.2±3.2
86.7±4.5
18.7±2.8
68.3±4.5
105±10
224±22
134±11
64.3±3.6
264±8
197±13
64.8±5.9
59.9±2.9
190±7
377±5
6.6
1.6
2.6
1.0
1.2
0.4
7.4
0.9
3.8
0.8
3.1
0.5
1.4
0.2
0.3
8.2
3.4
4.4
2.3
3.8
2.2
10.2
2.4
4.8
2.2
2.8
2.0
6.4
3.2
3.6
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
1.4±0.2
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
140±3
112±8
34.2±3.3
<17.5
<17.5
26.1±3.8
47.2±3.8
35.5±3.2
29.8±2.8
45.5±3.3
25.9±2.2
<17.5
<17.5
40.7±2.4
25.6±2.1
106±2
33.8±2.6
15.4±2.1
28±0.4
15.9±1.1
23.8±1.3
98.6±4.3
<2.8
<2.8
26.8±2.0
54.4±4.1
44.2±4.1
27.9±1.9
<2.8
<2.8
202±5
44.2±1.9
67.8±3.5
39.2±1.1
<15.8
<15.8
75.2±3.8
18.6±1.4
43.2±1.5
19.9±0.8
35.6±3.2
<15.8
39±1.2
<15.8
<15.8
641±25
112±12
40.1±2.1
42.1±1.9
23.8±1.5
21.4±1.2
301±4
102±10
32.1±1.9
34.7±2.8
124±6
34.2±2.9
34.6±3.1
13±1.3
18.6±1.9
Odo-Iyaalaro
1R
2R
May
May
3
4
3R
4R
5R
6R
7R
8R
9R
10R
11R
12R
May
May
July
July
July
July
September
September
September
September
5
6
3
4
5
6
3
4
5
6
4.5
4.2
3.9
4.3
4.9
3.9
4.5
4.2
5.1
3.6
4.2
3.6
7
8
9
10
11
12
7
8
9
10
11
12
7
8
9
5.9
4.4
4.5
4.4
6.8
7.7
4.8
5.6
4.2
7.2
7.7
7.6
5.6
6.3
5.4
Shasha River
13R
14R
15R
16R
17R
18R
19R
20R
21R
22R
23R
24R
25R
26R
27R
May
May
May
May
May
May
July
July
July
July
July
July
October
October
October
4
28R
29R
30R
October
October
October
10
11
12
7.5
7.7
7.7
3.5
1.9
0.4
2.2
3.2
1.6
1.7±0.4
<0.9
<0.9
35.5±2.1
<17.5
<17.5
64±3.1
13.6±1.1
11.5±1.0
104±7
22.4±1.2
30.4±2.9
190±4
70.8±4.1
38±3.8
13
14
15
16
17
18
13
14
15
16
17
18
13
14
15
16
17
18
6.0
4.0
3.4
4.8
4.7
3.8
7.3
4.1
4.3
3.8
4.3
4.5
6.9
3.6
3.2
3.6
4.8
4.5
0.7
7.6
1.4
5.3
0.2
0.5
3.0
5.2
1.5
1.0
4.7
0.3
2.8
6.2
1.3
1.0
0.4
0.3
2.4
4.8
3.2
2.0
2.2
2.4
4.6
4.8
3.2
2.0
2.2
1.8
4.0
5.2
2.2
2.6
2.4
2.8
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<0.9
<17.5
<17.5
<17.5
52.1±2.6
54.5±4.2
48.8±4.7
45.6±3.9
34.5±2.1
<17.5
37.2±4.2
35.9±2.1
33.3±1.6
<17.5
24.3±1.9
<17.5
<17.5
<17.5
<17.5
<2.8
115±2
42.2±1.6
10.2±0.4
5.7±1.1
8±0.4
15.2±0.4
13.6±0.4
6.8±1.2
13.5±1.3
74.7±3.7
56.7±2.7
3.6±0.5
12.4±1.7
12.2±1.7
12.7±0.8
6.2±0.9
7.8±0.4
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
21.8±2.4
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
<15.8
17.6±2.0
24.8±1.0
10.5±1.3
33.1±2.7
6±0.9
11.2±1.4
57.5±0.9
54.2±1.2
21.8±0.5
18.5±1.2
45.6±2.7
16.8±0.9
7.8±0.4
18.2±1.2
12.2±0.7
11.1±0.8
9.7±0.4
7.3±0.3
49R
July
19
4.6 3.7
5.4
<0.9
23.8±0.9 31±1.3
29.8±1.3
50R
July
20
5.9 4.3
6.2
<0.9
28.1±2.4 16.5±1.6 39.2±0.7
51R
July
21
4.4 10.8
11.0
<0.9
26.5±1.1 29.2±1.9 34.1±2.8
52R
July
22
6.7 0.2
2.2
<0.9
45.6±0.8 4.2±0.6
19.2±1.9
53R
July
23
6.5 0.1
2.0
<0.9
51.7±2.7 <2.8
<15.8
54R
October
19
4.1 3.3
4.2
<0.9
34.4±1.8 35.2±2.8 33.2±1.8
55R
October
20
7
4.4
4.4
<0.9
34.4±1.4 19.5±1.6 <15.8
56R
October
21
4.1 9.8
8.8
<0.9
25.7±0.9 43±3.4
39±3.1
57R
October
22
6.6 0.1
2.2
<0.9
51.7±1.9 <2.8
<15.8
58R
October
23
6.4 0.2
2.2
<0.9
36.2±1.3 4.2±0.6
<15.8
Results are mean values ± standard deviation for n = 3; < indicates a value below the detection limit
146±6
112±5
223±2
16.7±0.9
43.3±1.8
238±14
142±11
246±11
1.3±0.3
13.2±0.9
Ibeshe River
31R
32R
33R
34R
35R
36R
37R
38R
39R
40R
41R
42R
43R
44R
45R
46R
45R
48R
May
May
May
May
May
May
July
July
July
July
July
July
October
October
October
October
October
October
Lagos Lagoon
5
Online Resource 3
Grain size analysis of sediments collected during the dry season.
Sample no
% sand
Odo-Iyaalaro
1D
31.48
2D
40.64
3D
54.44
4D
49.96
5D
42.26
6D
43.25
7D
73.31
Shasha River
15D
64.57
16D
95.81
17D
44.88
18D
77.67
19D
32.17
20D
77.08
21D
54.58
22D
79.42
23D
41.64
Ibeshe River
% silt
% clay
Sample no
% sand
% silt
% clay
29.89
24.52
12.85
16.06
27.37
28.81
10.68
38.63
34.84
32.71
33.98
30.37
27.94
16.01
8D
9D
10D
11D
12D
13D
14D
61.61
59.7
67.21
47.32
48.23
45.82
38.14
13.37
18.41
13.44
16.46
14.96
22.93
18.21
25.02
21.89
19.35
36.22
36.81
31.25
43.65
10.67
1.92
16.09
13.47
17.79
11.94
17.77
13.73
17.1
24.76
2.27
39.03
8.86
50.04
13.98
27.65
6.85
41.26
24D
25D
26D
27D
28D
29D
30D
31D
32D
77.67
32.17
74.08
58.83
95.20
91.02
67.15
79.29
97.66
13.47
17.79
11.94
17.84
2.40
2.78
17.94
13.37
0.35
8.86
50.04
13.98
23.33
2.40
6.20
14.91
7.34
1.99
33D
35.27
34D
46.44
35D
64.78
36D
75.67
37D
87.28
38D
96.71
39D
42.28
40D
54.20
41D
64.28
Lagos Lagoon
19.76
20.17
15.28
14.21
9.28
3.12
18.4
18.23
19.27
44.97
33.39
19.94
10.12
3.44
0.17
39.32
27.61
16.45
42D
43D
44D
45D
46D
47D
48D
49D
50D
93.35
82.81
95.08
29.7
19.78
93.88
54.03
68.21
46.98
6.47
12.36
4.92
17.53
13.92
3.32
34.71
19.92
32.17
0.18
4.83
0.00
52.77
66.30
2.80
11.26
11.87
20.85
51D
52D
53D
18.95
8.87
13.53
19.97
11.37
17.63
54D
55D
100.00
91.12
0.00
8.83
0.00
0.05
61.08
79.76
68.84
6
Online Resource 4
Grain size analysis of sediments collected during the rainy season.
Sample no
% sand
Odo-Iyaalaro
1R
86.43
2R
57.85
3R
60.18
4R
63.62
5R
74.86
6R
59.76
Shasha River
13R
55.92
14R
50.79
15R
82.76
16R
76.68
17R
89.99
18R
96.04
19R
56.42
20R
77.72
21R
90.81
Ibeshe River
% silt
% clay
Sample no
% sand
% silt
% clay
5.18
14.95
15.31
11.37
7.28
18.21
8.39
27.20
24.51
25.01
17.86
22.03
7R
8R
9R
10R
11R
12R
55.23
57.18
80.36
59.14
54.03
57.90
25.15
27.21
7.88
11.58
20.35
13.13
19.62
15.61
11.76
29.28
25.62
28.97
17.05
17.61
8.56
13.61
8.87
0.70
19.20
16.54
7.26
27.02
31.6
8.68
9.71
1.14
3.26
24.38
5.74
1.93
22R
23R
24R
25R
26R
27R
28R
29R
30R
79.03
90.24
91.28
52.18
81.19
79.92
92.37
94.28
91.76
11.28
3.71
2.73
20.17
10.12
10.71
3.76
3.10
2.78
9.69
6.04
5.99
27.65
8.69
9.37
3.87
2.62
5.46
31R
1.09
32R
16.07
33R
98.95
34R
62.25
35R
98.59
36R
85.52
37R
30.21
38R
31.27
39R
82.61
Lagos Lagoon
6.71
20.70
1.05
16.82
1.34
11.02
18.24
46.01
7.52
92.20
63.23
0.00
20.93
0.07
3.46
51.55
22.72
9.87
40R
41R
42R
43R
44R
45R
46R
45R
48R
80.51
76.47
68.27
33.29
84.96
80.49
54.36
60.21
47.23
18.21
11.22
16.15
12.69
7.20
7.23
29.23
16.74
21.00
1.28
12.31
15.58
54.02
7.84
12.28
16.41
23.05
31.77
49R
50R
51R
52R
53R
18.21
19.27
20.12
1.12
4.18
10.54
5.41
18.26
1.24
0.06
54R
55R
56R
57R
58R
68.01
77.21
62.67
95.27
96.72
17.26
9.86
17.21
4.61
3.28
14.73
12.93
20.12
0.12
0.00
71.25
75.32
61.62
97.64
95.76
7