sediments toxicity of the rivers draining ibadan metropolis southwestern, nigeria. 1 ajibade, o.m...
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Sediments Toxicity of the rivers draining Ibadan Metropolis Southwestern, Nigeria.
1Ajibade, O.M and 2Abimbola, A.F.
1 Department of Earth Sciences, Olabisi Onabanjo University
2The Department of Geology, University of Ibadan, Nigeria
INTRODUCTION
Ibadan is a mega-city and one of the
largest cities in Nigeria.
A densely populated city with
numerous distorted land use plan
STUDY AREAThe study area is drained by Rivers Omin, Ona, Ogunpa, Ogbere.
3 . 7 5 3 . 8 3 . 8 5 3 . 9 3 . 9 5 4
3 . 7 5 3 . 8 3 . 8 5 3 . 9 3 . 9 5 4
7 . 2 5
7 . 3
7 . 3 5
7 . 4
7 . 4 5
7 . 5
7 . 2 5
7 . 3
7 . 3 5
7 . 4
7 . 4 5
7 . 5
R i v e r O g b e r eR i v e r O g u n p a
R i v e r O m i n R i v e r O n a 2 K m
D a m
A
gric
ultu
ral
Indu
stria
l
Old
City
Cen
ter
New
City
Cen
ter
RIVER OMIN - AGRICULTURAL
FISHING
PLANTATION- Cocoa
RIVER ONA - INDUSTRIAL
INDUSTRIAL EFFLUENT
Fig. 1.1. An aerial view of part of unplanned urban setting of Ibadan metropolis http:/ /en.wikipedia.org/wiki/File:Ibadan_City.jpg
RIVER OGUNPA - OLD CITY CENTER
Unplanned urban settingHigh traffic DensityIndiscriminate solid/liquid waste
A
D
B
RIVER OGBERE - NEW CITY CENTER
OBJECTIVES OF THE STUDY• To determine the mineralogical and trace metal contents of the sediments.
• To evaluate the pollution status and identify the possible influence of Land use/human activities on metal concentration .
MATERIALS AND METHODS
• 233 bottom river sediment samples was collected along the stream and river channels
• Omin-29, Ona-53, Ogunpa-91, Ogbere-60.
• A sample was collected as control from a natural spring devoid of contamination.
MINERALOGICAL/GEOCHEMICAL
• XRD (NGSA Laboratory)
• ICP-MS (ACME Laboratory Canada)
• SEQUENTIAL LEACH (5-Methods)
Leach Methods
• Sulphides• Residuals• Reducibles• Organics• Exchangeables
kaolinite, illite, chlorite, mica, calcite, paragonite,
diaspore and quartz
Kaolinite, illite, were diminant in
Rivers Omin and Ogbere
Quartz is the dominant mineral in
Rivers Ona and Ogbere.
.
MINERALOGICAL DATA
SAND-CLAY CONTENT - (Si:Al) • Si/Al controls the sand-clay content of any given sediment.
• Mean Si/Al values in the sediment include: ≤14.09(Omin), ≤17.44(Ona), ≤18.73(Ogunpa), ≤15.0(Ogbere) indicating high degree of sand
• High sandy content was recorded for Ogunpa and Ona rivers, controlled by the lithology (Quartzite and quartz schist).
Rivers Parameter Others (>2mm)
Sand (<2mm)
Silt (75µm) Clay (63µm)
Min 1.6 31.6 0.0 0.0
Omin Max 64.8 97.4 5.4 4.2
Ave 30.6 66.2 1.4 0.9
Min 0.0 81.6 0.1 0.0
Ona Max 2.6 99.8 17.3 5.1
Ave 0.5 95.2 3.0 1.0
Min 0.0 50.2 0.1 0.0
Ogunpa Max 47.6 99.8 17.3 5.1
Ave 9.3 87.1 2.3 1.1
Min 0.2 17.1 0.0 0.0
Ogbere Max 82.7 97.9 21.1 2.8
Ave 28.3 69.5 1.6 0.3
Omin Omin Si/Al Ti/Al Fe/Al min 8.01 0.06 0.39 Max 26.22 0.32 1.74 Mean 14.09 0.12 0.95
Ona min 11.08 0.05 0.23
Max 25.59 0.21 2.53 Mean 17.44 0.09 0.96
Ogunpa min 8.55 0.04 0.61 Max 36.05 0.28 5.96 Mean 18.73 0.12 1.38
Ogbere min 8.5 0.05 0.36 Max 32.83 0.26 2.65 Mean 15 0.1 1.58
Shale Ratio 2.59 0.05 0.51
River Omin
0
100
200
300
400
500
Upstream Midstream Downstream Controls
Cu-
Pb-
Zn
00.511.522.533.54
Cd-
As
Cu Pb Zn Cd As
River Omin
Idiishin
New garage
Oluyole
River Ona
0
100
200
300
400
500
600
Agriculture Industrial Mechanic Refuse Residential Controls
Cu-
Pb-
Zn
00.511.522.533.544.55
Cd-
As
Cu Pb Zn Cd As
River Ona
Market Residential Market/Residential
0100020003000400050006000
Upstream Midstream Downstream
Cu
-Pb
-Zn
051015202530
Cd
-As
Cu Pb Zn Cd As
A250m
River Ogunpa
0
50
100
150
200
250
Gov House Ashi PS Ashi Hort. 1 Ashi Hort. 2 Secretariat
Low-Density High density
Cu
-Pb
-Zn
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Cr-
Co
-Ni
Cu Pb Zn Cd As
River Ogbere
0.00100.00
200.00300.00
400.00500.00
600.00700.00
Cu-
Pb-
Zn
0.00
1.00
2.00
3.00
4.00
5.00
6.00
Cd-
As
Cu Pb Zn Cd As
RIVER OGBERE
GEOCHEMICAL MAP
GEOCHEMICAL MAP
*S u p p le m e n ta ry va ri a b le
Cu
P b Zn
Cr
Co
Cd
S b
*Ni*S n
*A s
*A g
-1 .0 -0 .5 0 .0 0 .5 1 .0
Fa cto r 1 : 6 1 .6 3 %
-1 .0
-0 .5
0 .0
0 .5
1 .0
Fa
cto
r 2
: 1
6.7
8%
Cu
P b Zn
Cr
Co
Ni
*S n
*A s
*Cd*A g*S b
-1 .0 -0 .5 0 .0 0 .5 1 .0
Fa cto r 1 : 4 4 .3 6 %
-1 .0
-0 .5
0 .0
0 .5
1 .0
Fa
cto
r 2
: 2
7.4
0%
Ac t iv e Supplem entary
Cu
P b
Zn
Cr Ni
A s
A g
*Co
*S n
*Cd
*S b
-1 .0 -0 .5 0 .0 0 .5 1 .0
Fa cto r 1 : 4 5 .7 0 %
-1 .0
-0 .5
0 .0
0 .5
1 .0
Fa
cto
r 2
: 1
8.2
9%
A c t iv e S upp lem entary
River Omin (PLI)
557
348
136
6126
0
100
200
300
400
500
600
Agricultural Residential Fishing Refuse Market/Abbattoir
Zones
Pol
lutio
n Lo
ad In
dex
(PLI
)
River Ona (PLI)
605
139
316
795814802
0100200300400500600700800900
Agriculture Industrial Residential Refuse Mechanic Washing
Nihort - New garage - Ona Elewe2 - 1- Ago-Taylor Adeoyo
Pol
lutio
n Lo
ad In
dex
(PLI
)
PLI
River Ogbere PLI-1
300
74
474585
336
172
741
107
172
1050
100200300400500600700800
Zones
Po
llu
tio
n L
oad
In
dex
(P
LI-
1)
River Ogunpa (Old City Center)
886
349440
497536
0
100
200
300
400
500
600
700
800
900
1000
Old city Refuse Market LDR Hospital
Po
llu
tio
n L
oad
In
dex
(P
LI)
Comparison between the Pollution Load Index (PLI)
PLI COMPARISON
Comparison between the mean concentration and PLI values of trace metals in the four Rivers.
Omin Ona Ogunpa Ogbere
0
100
200
300
400
500
600
700
Omin-N=24 Ona-N=37 Ogunpa-N=51 Ogbere-N=42
Rivers
Mea
n Co
ncen
tratio
nCu Pb Zn As Cd
4.094.14
2.392.53
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Omin Ona Ogunpa Ogbere
River Channels
Polu
tion
Load
Inde
x Av
erag
e (P
LI)
Comparison of Geo-accumulation Indices of the four rivers
Sediment fractions for Cu, Pb, Zn, Cd, As, Mn
River Ogunpa (Old City Center)
0.00
10.00
20.00
30.00
40.00
50.00
60.00
Sulphides Residuals Reducibles Organics Exchangeable
Sediment Fractions
Cu,P
b,Zn
%
0.00
20.00
40.00
60.00
80.00
100.00Cd
,As,
Mn
%
Cu Pb Zn Cd As Mn
M
River Ogbere (New City Center)
0.00
10.00
20.00
30.00
40.00
50.00
60.00
Sulphides Residuals Reducibles Organics Exchangeable
Sediment Fractions
Cu,
Pb,
Zn %
0.0010.0020.0030.0040.0050.0060.0070.0080.00
Cd,
As,
Mn
%
Cu Pb Zn Cd As Mn
M
River Ona (Industrial)
0.00
10.00
20.00
30.00
40.00
50.00
Sulphides Residuals Reducibles Organics Exchangeable
Sediment Fractions
Cu,
Pb,
Zn %
0.00
20.00
40.00
60.00
80.00
100.00
Cd,
As,
Mn
%
Cu Pb Zn Cd As Mn
M
River Omin (Agricultural)
0.00
10.00
20.00
30.00
40.00
50.00
60.00
Sulphides Residuals Reducibles Organics Exchangeable
Sediment Fractions
Cu,P
b,Zn
%
0.00
10.00
20.00
30.00
40.00
50.00
Cd,A
s,M
n %
Cu Pb Zn Cd As Mn
M
Table 3: Sediment Guidelines
RIVERS Guidelines/Toxicity Levels
Metals Omin Ona Ogunpa Ogbere CBSQG TEC PEC
Cu 109.9 84.44 138.6 118.2 32 31.6 149
Pb 93.4 94.8 228.9 202.2 36 35.8 128
Zn 142.5 177.1 520 304.2 120 121 459
Cd 0.24 0.4 0.71 0.37 0.99 0.99 4.98
As 1.65 1.73 4.15 3.93 9.8 - -
TEC-Threshold Effect Concentration; PEC-Probable Effect Concentration CBSQG-Canadian Sediment Quality Guideline
Lithogenic and anthropogenic contributions
0%10%20%30%40%50%60%70%80%90%
100%
Rock Soil Omin Ona Ogunpa Ogbere
Sediments
Con
trib
utio
ns in
%
As
Sr
Ni
Co
Cr
Zn
Pb
Cu
Table 4: Lithogenic and anthropogenic contributions of
metals in the River sediments of Ibadan metropolis
Lithogenic and anthropogenic contributions
(ppm) Elements Cu Pb Zn Cr Co Ni Sr As
Rock Rock 19.79 35.36 60.92 82.8 7.74 11.83 250.51 0.8
Soil(Fadina 2008) Soil 28 43 93 94 36 25 14 -
Omin 110 93 142 107 50 36 111 1.7
Sediment Ona 85 95 177 96 29 26 117 1.7
Ogunpa 139 229 520 156 22 34 84 4.1
Ogbere 132 226 322 248 37 35 73 4.2
River
Are the concentration of these metals in the sediments truly
anthropogenic?
•Enrichment of Pb, Zn, Cr, Co, Ni, As in the sediments, attributed to anthropogenic sources(Table 3; Fig. 16).
High concentration of Cu, Pb and Zn is in agreement with earlier findings of Odewande and Abimbola (2008); Fadina, (2008);Olatunji, et al., (2011) on road dust, outdoor and indoor particulate matter and soils of the urban city.
Weathering & Land-use; Urbanization: Population density; Human activities;
Cu, Pb, Zn, Cd and As: dominates the Bio-available sediment fractions
Efforts should be made to reduce pollution level: through mitigation
Toxicity of sediment has occured in River Ogunpa (Old City Center) drainage channel
Anthropogenic metal enrichment is greater than the lithogenic metal enrichment in sediment derived from the drainage channels.
CONCLUSION
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