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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.
3.75 3.8 3.85 3.9 3.95 4
3.75 3.8 3.85 3.9 3.95 4
7.25
7.3
7.35
7.4
7.45
7.5
7.25
7.3
7.35
7.4
7.45
7.5
River OgbereRiver Ogunpa
River Omin River Ona 2Km
Dam
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 metropolishttp://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 thedominant 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
Abaepo
Farinde
Odewunm
iPata
koAla
peO
min
-Adi
oO
nigbodo
giAak
eAak
e 2Bok
oBok
o 2Kuy
eFala
deAbato
mi
CtrlABR
K
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
Abanla 2
Nihor
tJer
icho
New gara
geO
na keker
eO
luyol
e
Idiis
inIy
aganku2
Ona E
lewe
Adeoy
oO
na Ele
we2
Moo
r Pla
ntatio
n CtrlABR
K
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
01000
20003000
40005000
6000
Yid
i
7th
Day
Iso
Par
t
Ash
i PS
Sec
reta
riat
Isal
e A
fa
Bod
e
Ogp
BC
Ogp
AC
Upstream Midstream Downstream
Cu-P
b-Z
n
05
1015
2025
30
Cd-A
s
Cu Pb Zn Cd As
A
250m
River Ogunpa
0
50
100
150
200
250
Gov House Ashi PS Ashi Hort. 1 Ashi Hort. 2 Secretariat
Low-Density High density
Cu-P
b-Z
n
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Cr-
Co-N
iCu Pb Zn Cd As
River Ogbere
0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
Abbat
toir
Agric
ultu
ral
Carwash
Conflu
ence Dye
Fish fa
rmin
gM
echa
nic
Refuse
Resident
ial
Sewage
Sourc
e
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
*Supplementary variable
Cu
Pb Zn
Cr
Co
Cd
Sb
*Ni
*Sn
*As
*Ag
-1.0 -0.5 0.0 0.5 1.0
Factor 1 : 61.63%
-1.0
-0.5
0.0
0.5
1.0
Fa
cto
r 2
: 1
6.7
8%
Cu
Pb Zn
Cr
Co
Ni
*Sn
*As
*Cd*Ag
*Sb
-1.0 -0.5 0.0 0.5 1.0
Factor 1 : 44.36%
-1.0
-0.5
0.0
0.5
1.0
Fa
cto
r 2
: 2
7.4
0%
Activ e
Supplementary
Cu
Pb
Zn
Cr Ni
As
Ag
*Co
*Sn
*Cd
*Sb
-1.0 -0.5 0.0 0.5 1.0
Factor 1 : 45.70%
-1.0
-0.5
0.0
0.5
1.0
Fa
cto
r 2
: 1
8.2
9%
Activ e
Supplementary
River Omin (PLI)
557
348
136
6126
0
100
200
300
400
500
600
Agricultural Residential Fishing Refuse Market/Abbattoir
Zones
Po
llu
tio
n L
oa
d I
nd
ex
(P
LI)
River Ona (PLI)
605
139
316
795814802
0
100
200
300
400
500
600
700
800
900
Agriculture Industrial Residential Refuse Mechanic Washing
Nihort - New garage - Ona Elewe2 - 1- Ago-Taylor Adeoyo
Po
llu
tio
n L
oa
d I
nd
ex
(P
LI)
PLI
River Ogbere PLI-1
300
74
474585
336
172
741
107
172
1050
100
200
300
400
500
600
700
800Abb
atto
irAgr
icul
tura
l
Carwash
DyeFish
farm
ing
Mec
hani
c
Refuse
Resident
ial
Sewage
Sourc
e
Zones
Po
llu
tio
n L
oa
d I
nd
ex
(P
LI-
1)
River Ogunpa (Old City Center)
886
349
440497
536
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 (
PL
I)
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
Me
an
Co
nc
en
tra
tio
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
Po
luti
on
Lo
ad
In
de
x A
ve
rag
e (
PL
I)
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
,Pb
,Zn
%
0.00
20.00
40.00
60.00
80.00
100.00C
d,A
s,M
n %
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
%0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
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
,Pb
,Zn
%
0.00
10.00
20.00
30.00
40.00
50.00
Cd
,As
,Mn
%
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
Co
ntr
ibu
tio
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 lithogenicmetal enrichment in sediment derived from the drainage channels.
CONCLUSION
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