1. DISTRIBUTION OF HEAVY METALS IN WATER AND SEDIMENTS OF LOWER RIVER NZOIA  
PRESENTED BY
OMONDI CAVIN
S56/61784/2013
SUPERVISORS:
MR. DAVID MAINA
PROF. JOHN ONYARI

2. TABLE OF CONTENTS INTRODUCTION PROBLEM STATEMENT JUSTIFICATION
OBJECTIVES
LITERATURE REVIEW
METHODOLOGY
RESULTS AND DISCUSSION
CONCLUSIONS
ACKNOWLEDGEMENTS

3. INTRODUCTION
Sediments are particles produced by land disturbing activities and are transported by water and deposited in water bodies.
Importance of sediments include; addition of nutrients, provision of spawning areas as well as transporting nutrients.
Sediment analysis helps in determining contaminants in them, knowing impact of pollution from sediments and knowing patterns of pollution of aquatic systems.

4. INTRODUCTION C’NTD
Pollution by heavy metals is by; natural and anthropogenic sources.
Natural sources include weathering, windblown dust and volcanic eruptions.
Anthropogenic sources include extraction of minerals and metals, electroplating and discharge of pollutants such as industrial, municipal and domestic waste to the aquatic system.
River Nzoia is mainly polluted by urban and household discharge to the river, agricultural runoff and effluents from industries.

5. PROBLEM STATEMENT
River Nzoia transverses several municipalities, industrial, informal sector zones and agricultural zones that rely heavily on agrochemicals.
The river collects pollutants including heavy metals as it passes through these points.
Concerns have been raised over the quality of products obtained from the river hence the need for regular studies and determination of heavy metal concentration levels.
The concerns are mainly due to the re-mobilization of the heavy metals in the water and sediments.

6. RIVER NZOIA POLLUTION
Serves several functions some of which introduce pollutants into the river

7. JUSTIFICATION
Intensive agricultural activities characterize the Lower section of River Nzoia which involve use of farm inputs and agrochemicals some of which are enriched with heavy metals which coupled with waste from industrial establishments, municipalities and residential areas introduce heavy metals to the river system.
The heavy metals then get to human beings mainly through the food chain via eating aquatic plants and drinking contaminated water.
There is however inadequate information on heavy metals concentration in both surface water and sediment samples on the lower section of River Nzoia.
Concentration levels of heavy metals in sediments determined by depth profiling.

8. OBJECTIVES Main Objective
To investigate the extent of pollution of the water and sediments from the lower section of River Nzoia with heavy metals.
Specific Objectives
To determine levels of concentration of selected heavy metals in water samples from the Lower Nzoia River.
To determine the concentrations levels of selected heavy metals in sediments along the Lower Nzoia River.
To assess the spatial and vertical distribution patterns of selected heavy metals in sediments along the Lower Nzoia River.

9. LITERATURE REVIEW

10. LITERATURE REVIEW
Study of heavy metals is essential since they are toxic and non-biodegradable at certain concentrations and once consumed, they are incorporated, stored and accumulated by the body.
Rapid industrial development and increased food production has led to introduction of contaminants such as heavy metals to aquatic ecosystems.
Pollutants are introduced to surface waters through urban and industrial waste discharge, agro based chemicals and discharge as well as deposition of domestic effluents and solid waste.

11. SEDIMENTS
Sediments help in replenishing of nutrients and provision of spawning areas.
However, they also act as sinks and reservoirs for contaminants and thus re- introduce contaminants into the aquatic system through remobilization.
Analysis of sediments helps to determine the concentrations that might be absent in the water column

12. EFFECTS OF HEAVY METALS
Effects of Heavy Metals on Plants
Some are essential e.g. Zn, Cu and Fe while others like Pb, Hg aren't.
Effects include;
Decreased growth yield
Reduced growth and development
Leaf chlorosis
Inhibition of seed germination
Reduction of photosynthetic rate
Effects of Heavy Metals on Human Beings and Animals
Contact occurs mainly via food chain and consuming contaminated water.
Essential and non essential
Effects include;
Skeletal damage
Destruction of internal body organs
Elevated blood pressure
Renal failure
Death in some cases
Peripheral nerve damage

13. NZOIA RIVER POLLUTION
Source is at Cherengani Hills with its water used mainly for agricultural, industrial and domestic household purposes with its major pollutants being urban and agricultural runoff and effluent from residential and industrial sectors
Research on heavy metal pollution of Nzoia River have shown minimal levels of some heavy metals at selected points within the lower section of Nzoia with concentrations in sediments generally being higher than those in water

14. Study area

15. METHODOLOGY

16. Mixing + addition of HCl
WATER SAMPLES
sampling
Mixing + addition of HCl
20 ml sample + 10μl Ga
10 μl mixture on carrier
Analysis in TXRF for 1000s

17. Pelletizing using hydraulic press
SEDIMENTS
Sampling at 30, 50 and 100 cm
Dried and ground to 75μm
1.6 g sample g binder
Pelletizing using hydraulic press
Analysis in EDXRF
Deconvolution

18. RESULTS AND DISCUSSIONS

19. Quality Assurance- Water
Element
Experimental Value (µg/l)
TXRF Standard Values (µg/gl V
9.1 ± 0.91
10.0 ± 0.03 Cr
9.5 ± 0.69 Mn
9.9 ± 0.76 Fe
9.3 ± 0.88 Ni
11.0 ± 0.93 Cu
10.0 ± 0.00 Zn
10.3 ± 0.48

20. Quality Assurance- Sediments
Element
Experimental Value (mg/kg)
TXRF Standard Values (mg/kg) Mn
1065 ± 80
940 – 1060 Fe
29750 ± 1550
28700 – 30700 Ni
30.6 ± 9.7
35.5 – 40.3 Cu
32.3 ± 7.8
18.1 – 22.2 Zn
76 ± 12.4
88.4 – 103.8

21. WATER Element Concentration Mean concentrations WHO Guidelines
Detection Limits Mn
< 39 μgl μgl-1
78 μgl-1
100 μgl-1 39 Fe
1574 μgl μgl-1
6144 μgl-1
2000 μgl-1 28 Cu
<13 μgl μgl-1
26.5 μgl-1
20 μgl-1 13 Zn
28.6 μgl μgl-1
161 μgl-1 15 Pb
<10 μgl μgl-1
11.2 μgl-1 10 Ni
<13 μgl μgl-1
13.7 μgl-1

22. SEDIMENTS Element Concentration (mg kg-1) Mean Concentration (mg kg-1)
Guidelines
Detection Limit Mn
519 – 2064
1163
30 μg/g (USEPA) 75 Fe
27,000 – 83,000
46,197 50 Cu
251 – 392
331
25 μg/g 20 Ni
262 – 509
389
20 μg/g V
<150 – 384
176
150 Cr
85 – 322
122 Zn
43 – 100
69.0
123 μg/g 15 Pb
7 – 26
13.5
40 μg/g (USEPA) 5 As
<10 – 15
10.5 10

23. SEDIMENTS CNT’D River and Location Mn Fe Cu Zn Pb As Cr V Ni
Nzoia (Present)
1163
46,190
331
69.2
13.6
10.4
122
176
389
Nzoia (Lalah)
(2008)
838 -
17.5
76.0
15.6
3.9
Nzoia (Mwamburi) (2003)
680
20,100
110
3.1
1.9 17
Buriganga (Bangladesh) (2010)
184
502
79.8
101
Ganga
(India) (2015)
372
31,989
29.8
67.8
26.7
69.9
Euphrates
(Iraq) (2012)
228
2250
18.9
48.0
22.6
58.4
67.1
World Average
975
57,406
123
303
231
126
102

24. Mean concentrations of heavy metals in water (μg l-1)Mn Fe Ni Cu Zn Pb
Current study 78
6144
13.7
26.53
161
11.2
Lalah et al. (2008) 50 13
20.0 40 15
River Kisat (2008)
693
52.5
157.5
135 60

25. CONCLUSIONS
Concentration of metals increased downstream with a significant variation between sampling points.
Levels for most metals in water except Cu were within acceptable limits.
Evidence for local pollution mainly from effluent discharge.
The Nzoia sediments were determined to be contaminated with Mn, Fe, Cu, Cr and Ni with Pb and Zn being below the guidelines set by USEPA.

26. RECOMMENDATIONS
Need for greater public awareness to educate the communities that use the water for domestic purposes as concentrations exceeded those set by regulatory bodies.
Pollution mitigation measures need to be enhanced to reduce the concentration levels of metals.
Analyze soils adjacent to the river bed to have a quantitative knowledge of their effect on the concentrations reported in sediments.
Crops grown in the area such as sugarcane should be analyzed for heavy metal content to determine their uptake.
The analysis should be done both for the dry and wet season to show the effects of water evaporation on concentration of heavy metals.

27. ACKNOWEDGEMENTS Almighty God Supervisors – D. Maina J. Onyari
Staff at INST
MSc. Class 2013
KNEB

28. QUESTIONS?????? AND
COMMENTS!!!!!!