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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