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

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

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.

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.

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.

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

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.

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.

LITERATURE REVIEW

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.

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

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

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

Study area

METHODOLOGY

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

Pelletizing using hydraulic press SEDIMENTS Sampling at 30, 50 and 100 cm Dried and ground to 75μm 1.6 g sample + 0.4 g binder Pelletizing using hydraulic press Analysis in EDXRF Deconvolution

RESULTS AND DISCUSSIONS

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

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

WATER Element Concentration Mean concentrations WHO Guidelines Detection Limits Mn < 39 μgl-1 - 217 μgl-1 78 μgl-1 100 μgl-1 39 Fe 1574 μgl-1 - 12314 μgl-1 6144 μgl-1 2000 μgl-1 28 Cu <13 μgl-1 - 92.3 μgl-1 26.5 μgl-1 20 μgl-1 13 Zn 28.6 μgl-1 - 1399 μgl-1 161 μgl-1 15 Pb <10 μgl-1 - 24.25 μgl-1 11.2 μgl-1 10 Ni <13 μgl-1 - 21 μgl-1 13.7 μgl-1

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

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

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

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.

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.

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

QUESTIONS?????? AND COMMENTS!!!!!!