Effects of temperature on the environmental concentrations of trace metals

40 4.2 Heavy metals in surface water and bottom sediment of Ovwian Mangrove .... 4.4 Spatial and monthly variation of water hardness - - 31 Fig.4.5 Spatial and monthly variation of Total

MINISTRY OF EDUCATION AND TRAINING

NHA TRANG UNIVERSITY

OLUOWO ELOHOR FREEMAN

EFFECTS OF TEMPERATURE ON THE ENVIRONMENTAL CONCENTRATIONS OF TRACE METALS: A CASE STUDY OF THE

OVWIAN MANGROVE, DELTA STATE, NIGERIA

NORWEGIAN HIGHER EDUCATION DEPARTMENT (NORHED)

MASTERS THESIS

KHANH HOA – 2018

MINISTRY OF EDUCATION AND TRAINING

NHA TRANG UNIVERSITY

OLUOWO ELOHOR FREEMAN

EFFECTS OF TEMPERATURE ON THE ENVIRONMENTAL CONCENTRATIONS OF TRACE METALS: A CASE STUDY OF THE

OVWIAN MANGROVE, DELTA STATE, NIGERIA

NORHED MASTERS THESIS

Major

Topic allocation Decision

Decision on establishing the Committees

UNDERTAKING

I undertake that the thesis entitled: “Effects of Temperature on the Environmental Concentrations of Trace Metals: A Case Study of the Ovwian Mangrove, Delta State, Nigeria” is my own work The work has not been presented

elsewhere for assessment until the time this thesis is submitted

… , Date …… month ……… year

Elohor Freeman OLUOWO

ACKNOWLEDGMENT

I would like to seize this opportunity to acknowledge first, God Almighty for the privilege of life and the overall success of the program, and those who made my stay in Vietnam worthwhile to mention The Norhed Management Board and Course Lecturers, Graduate Studies Department, Nha Trang University and the Rectorate Board My gratitude will be incomplete without mentioning the likes of Prof Kim Anh Nyugen, Prof Claire Armstrong, Dr Ngan Nyugen, Prof Nghia Ngo Dang, Dr Pham Thi Thanh Thuy, Dr Duy Nguyen Ngoc, Ms Le Anh Han, my father and friend, Prof Curtis Jolly for his words of encouragement and Prof Karin Pittman, my academic mentor, for providing me numerable academic materials and support which has helped me to develop great academic skills To my supervisor, Prof Augustine Arukwe, for his uncommon scientific knowledge, amidst his busy schedule provided timely feedbacks, materials, correction to my thesis, making it a useful library and reference material I appreciate you sir To my lovely wife, Onome Destiny Elohor and beautiful daughters Divine and Marvelous Elohor Freeman for their understanding and support throughout the study period My parents, Chief Isaac John Oluowo for laying the foundation for my life and finally to all my course mate in the program, I love you all

Thank you

………… , Date month year Elohor Freeman OLUOWO

TABLE OF CONTENT

UNDERTAKING iii

ACKNOWLEDGMENT iv

LIST OF ABBREVIATIONS vii

LIST OF SYMBOLS viii

LIST OF TABLES ix

LIST OF FIGURES x

ABSTRACT xii

CHAPTER ONE 1

1.0 Literature Review 1

1.1 Objective of Study 3

1.2 Heavy Metals in Aquatic Ecosystems 3

1.2.1 Toxicity of Heavy Metals 5

1.2.2 Some Heavy Metals and Their Sources 7

1.3.0 Description of Study Area and Sampling Stations 11

1.3.1 Geography 11

1.3.2 Geology 12

1.3.3 Climate 13

1.3.4 Vegetation and Land use 13

1.3.8 Human Activities 14

CHAPTER TWO 15

2.0 MATERIALS AND METHOD 15

2.1 Sampling Techniques 15

2.1.1Water and sediment 15

2.1.2 Water 15

2.1.3 Sediment 15

2.2.0 SAMPLING STATIONS 16

2.2.1 Sampling stations 16

2.3.0 WATER STUDIES 17

2.3.1 Rainfall 17

2.3.2 Temperature 17

2.3.3 Hydrogen Ion Concentration 17

2.3.4 Alkalinity 18

2.3.5 Total Hardness 18

2.3.6 Dissolved Oxygen 19

2.3.7 Conductivity 19

2.3.8 Total Solids 20

2.4.0 Pretreatment and digestion of water 20

2.4.1 For ICP scan 20

2.4.2 For AAS analysis 21

2.5.0 Bottom Sediment Studies 21

2.5.1 The Organic Matter 21

2.5.2 Pretreatment and digestion of sediment 21

2.5.3 For the AAS analysis 22

2.6.0 Instrumental Procedure 22

2.6.1 The Inductively Coupled Plasma Spectrometer (ICP) 22

2.6.2 The Atomic Absorption Spectrometer (AAS) 22

2.7 Data Analysis 23

CHAPTER THREE 24

3.1 RESULTS 24

3.1.1 Water Temperature 25

3.1.2 Hydrogen ion concentration (pH) 26

4.1.3 Total Alkalinity (mg/L) 27

3.1.4 Total Hardness of Water 27

3.1.5 Total Dissolved Solids (mg/L) 28

3.1.7 Biochemical Oxygen Demand (BOD) 29

3.2.0 HEAVY METAL CONCENTRATIONS 30

3.2.1 Copper (Cu) 30

CHAPTER FOUR 40

4.0 DISCUSSION 40

4.1 Physicochemical conditions of Ovwian Mangrove 40

4.2 Heavy metals in surface water and bottom sediment of Ovwian Mangrove 43

5.0 CONCLUSION 46

RECCOMMENDATION 47

References 48

LIST OF ABBREVIATIONS

FEPA :Federal Environmental Protection Agency

USEPA :United States Environmental Protection Agency DPR :Department of Petroleum Resources

NIS :Nigerian Industrial Standards

ATSDR :Agency for Toxic Substances and Disease Registry OSHA :Occupational Safety and Hazard Analysis

ALAD :Aminolevulinate dehydratase

HS :Heme Syntheses

APHA :American Public Health Association

NPA :National Population Commission

DSC :Delta Steel Company

GPS :Geographical Positioning System

BOD :Biochemical Oxygen Demand

TDS :Total Dissolved Solids

DO :Dissolved Oxygen

ASTM :American Society for Testing and Materials

ICPMS :Inductively Coupled Plasma Mass Spectrometer AAS :Atomic Absorption Spectrometer

SPSS :Statistical Package for the Social Sciences

LIST OF SYMBOLS

Mg/L: Milligram per litre

Ppt: Parts per millions

Ntu: Nephelometric Turbidity Units

LIST OF TABLES

Table 4.1 Summary of some physico-chemical parameters of

Table 4.2 Summary of some heavy metals in Surface water in

Ovwian Mangrove, Delta State, Nigeria - - - 27 Table 4.3 Summary of some heavy metals in bottom sediment in

Ovwian Mangrove, Delta State, Nigeria - - - 27

LIST OF FIGURES

Fig 2.1 Map of the study area showing sampling stations - - - 14 Fig 4 1 Spatial and monthly variation of Temperature - - 28 Fig 4.2 Spatial and monthly variation of PH - - - 29 Fig 4.3 Spatial and monthly variation of alkalinity - - - 30 Fig 4.4 Spatial and monthly variation of water hardness - - 31 Fig.4.5 Spatial and monthly variation of Total Dissolved Solids (TDS) - 31 Fig 4.6 Spatial and monthly variation of Dissolved Oxygen (DO) - 32 Fig 4.7 Spatial and monthly variation of Biochemical Oxygen

Fig 4.8 Spatial and monthly variation of Salinity - - - - - - - - - - 33 Fig 4.9 Spatial and monthly variation of Copper (Cu) in surface water - 35 Fig 4.10 Spatial and monthly variation of Copper (Cu) in bottom sediment - 35 Fig 4.11 Spatial and monthly variation of Zinc (Zn) in surface water - 37 Fig 4.12 Spatial and monthly variation of Zinc (Zn) in bottom sediment - 37 Fig 4.13 Spatial and monthly variation of Iron (Fe) in surface water - - 39 Fig 4.14 Spatial and monthly variation of Iron (Fe) in bottom sediment - 39 Fig 4.15 Spatial and monthly variation of Cadmium (Cd) in surface water - 41 Fig 4.16 Spatial and monthly variation of Cadmium (Cd) in bottom sediment - 41 Fig 4.17 Spatial and monthly variation of Chromium (Cr) in surface water - 43 Fig 4.18 Spatial and monthly variation of Chromium (Cr) in bottom sediment -43 Fig 4.19 Spatial and monthly variation of Lead (Pb) in surface water - - 45 Fig 4.20 Spatial and monthly variation of Lead (Pb) in bottom sediment - 45 Fig 4 21 Spatial and monthly variation of Arsenic (As) in surface water - - 47

Fig 4.22 Spatial and monthly variation of Arsenic (As) in bottom sediment - 47 Fig 4.23 The distribution of metals in surface water - - - - 49 Fig 4.24 The distribution of metals in sediment - - - - 50 Fig 4.25 Comparative graph showing metals concentrations in surface water

and bottom sediment - - - 51

ABSTRACT

The variations in the concentrations of trace metals in surface water and bottom sediment of Ovwian River Mangrove have been reported There is limited data on the toxicological evidences, that is important in understanding the organismal stress responses and body burden, as well as how these are compromised by global climate change The present study was designed to investigate the physico-chemical characteristics of surface water and bottom sediment and occurrence of trace metals in the Ovwian river, and predict some of their health implications through consumption Samples of water and sediment were collected using scientifically recommended procedures from August to October 2017 at monthly interval The ICPMS was used to determine the concentrations of metals in both environmental matrices Seasonal changes in temperature followed a typical pattern of being higher in the dry season months, compared to the wet season, with notable increases from previous report from the Ovwian river The highest temperature values of 31ºC was recorded in October at stations 2 and 7 We observed acidic water with low pH values compared to previous reports, with respective highest and lowest pH values of 7.85 and 5.43 at station 5 and

7, in October Unlike biochemical dissolved oxygen (BOD), dissolved oxygen (DO) showed a decrease in the August – October sampling periods Although, the concentrations of heavy metals were considerably low, elevated concentrations above the NIS, FEPA and WHO regulatory limits were recorded at station 5 in August (0.004 mg/L) and September (0.003 mg/L) for cadmium, and station 1 in August (0.007 mg/L) and September (0.004 mg/L) for chromium in surface water Overall, trace metal showed a concentration pattern of Zn >Fe>Cu>Cr>Cd>Pb>As While in the bottom sediment of the Ovwian river, except the concentrations of arsenic in all the sampled stations and lead, however with worrisome concentration values of 0.010 mg/L at station

1 and 4 in September, and 0.008 mg/L at station 4 in August The concentrations of the other investigated metals were above the FEPA regulatory limit In summary, quantifiable measures of climate change such as temperature, acidity and salinity known

to influence aquatic systems was observed in the present study, showing that these variables were related to the low concentrations of some of the investigated metals in the surface water and increases in the bottom sediment of the Ovwian river, and in line with the report in Ekpan Mangrove Thus, there is need for a dynamic monitoring protocol of anthropogenic input of some these materials into the Ovwian river, with more in-depth studies on the effect of heavy metals physiological and general health conditions for both aquatic biota and humans, as well as the importance of mangroves

in regulating metals concentrations, and how these effects can be modified by changes

in global climate

Keywords: Heavy metals, Bioaccumulation, Ovwian river, Climate change,

Physico-chemical parameters

to biological material as non-essential heavy metals when found in high concentrations (Falusi & Olanipekun 2007; Ololade et al 2008 and Oluowo & Omoregie 2016)

Heavy metals, such as cadmium (Cd), lead (Pb), chromium (Cr), mercury (Hg) and metalliod of arsenic (As) have been implicated with high toxicity and carcinogenicity (Tchounwou et al 2012) Thus, these heavy metals are of severe environmental and public health significance These metals connote systemic toxicants that are known to induce multiple organ damage, even in small quantity and at low temperature The daily intake and exposure to these heavy metals has increased significantly due to their increased occurrence in the aquatic ecosystems, through anthropogenic activities such

as burning of fossil fuel, land run-off, oil spillage, gas leaks, blow outs, canalization and discharge from oil and gas operations into surface water, or release from industrial operations such as mining, canning and electroplating (Fufeyin 1994, Ayenimo et al 2005; 2006; Emoyan et al 2006 and Oluwa et al 2010)

The damages caused by these activities are enormous and includes - changes in water quality, loss of biodiversity particularly fauna and important icthyofauna of these water bodies, health and ecological risk with regard to their functions, as well as the ecosystems services they provide (Oluowo & Omoregie 2016)

The use of icthyofauna of water bodies, especially fish and shellfish species in pollution monitoring has received tremendous scientific attention in the last 10 years in Nigeria, representing useful contributions for monitoring anthropogenic pollution sources and

toxicity through ingestion However, there is still limited toxicological evidence of some

of these metals, especially for understanding their biological effects on organismal stress responses and body burden

Some of these metals belong to a family of cysteine-rich, low molecular weight (0.5 -

14 kDa) proteins These proteins are generally found on the Golgi apparatus membrane where they possess the capacity to bind to metals, particularly heavy metals such as Cd,

Hg, Ag, As through the thiol group of the cysteine residues (Vasak 2015)

Furthermore, temperature and pH variability have been noted to influence enzymatic reactions and processes While extremely high or low pH result in complete loss of activities in most enzymes and in determining their stability, increase in temperature will spontaneously increase the metabolic rate of enzymes and in aquatic lives, consequently on the cost of aquaculture through fish feeding, as well as the fate of metals

in aquatic systems

It has become imperative to understand the biological activities of metals, especially heavy metals effects on cellular organelles and components, membranes, mitochondria, lysosome, endoplasmic reticulum, nuclei and enzymes involved in metabolism, physiology, and overt toxicological damages For example, exposure to arsenic produced effects on all organs/systems including - hematological disorder, leading to cardiovascular disease, diabetes and hearing loss (Tchounwou et al 2012), Pb poisoning produced damages to the liver and kidney, while Cd caused kidney damage and other kidney diseases (OSHA 2009; Beers 2004)

The highest level of Cd in edible food materials was reported in shellfish, liver and kidney meats (James & Sampath 1996; OSHA 2009; USEPA 2009)

There is high abundance of shellfish (periwinkle and crab) in the Nigerian Niger Delta areas and they represent valuable food delicacies in these areas Further, quantifiable variables of climate change such as temperature, have been linked to heavy metals concentrations and known to increase metal bioaccumulation and bioconcentration in aquatic organisms (Olowoyo 2011) For example, Rajan et al (2012) reported the effects

of climate change on dissolved heavy metals concentrations in recreational tributaries

of Pahang, Malaysia Elsewhere, Ate et al (2009) reported the impact of climate change

on the leaching of a heavy metals, and subsequently in the contamination of small lowland catchment

The influence of temperature and salinity on heavy metals uptake by submerged plants has also been reported previously by Fritioff et al (2005), so also the effects of pH, temperature, dissolved oxygen and flow rate of overlying water on heavy metals release from storm sewer sediment by Haiyan et al (2013)

Elsewhere, Verweij et al (2010) further assessed the impacts of climate change on water quality in Netherlands, with striking reports on the direct impacts of climate change on water temperature and indirectly, on the physical and chemical processes related to changes in water columns The study concluded by substantiating exacerbating effects

of increasing temperature due to climate changes to cause eutrophication and temporarily reduce heavy metals concentration in water through uptake

1.1 Objective of Study

The present study is designed to:

a) Investigate the effect of temperature on heavy metal concentrations in surface water and sediment of the river

b) Evaluate the impact of climate change on the physicochemical characteristics, water quality and metal accumulation patterns in the bottom sediment of the river c) Highlight some of their toxicological responses and overt metals toxicity through consumption

1.2 Heavy Metals in Aquatic Ecosystems

Heavy metals are defined as metals having densities greater than 5 gcm-3 (Adekoya et

al 2006) and with atomic weight of 40 g and above They are inorganic elements required for plant growth in trace quantities and perform essential body functions, but which become toxic or poisonous in relatively higher concentration (Daffus 1980)

The emission of heavy metals into the biosphere has increased significantly over the natural level owing to human activities such as mining, smelting and fuel burning, with increasing report of their daily accumulation in the environment, particularly in coastal

waters (Fufeyin 1994, Ayenimo et al 2005; Emoyan et al 2006) The aquatic environment is considered as the most vulnerable ecosystem due to the high inputs of a diversified group of environmental pollutants (Nohynek et al 2013, Sheikh et al 2016 and Ibor et al 2017), with documented reports in different water bodies in Nigeria For example, Egborge (1994) reported heavy metals pollution and huge loss of biodiversity, and Ayenimo et al (2006) contamination of edible food in the study area, among other studies

Aquatic ecosystems in Nigeria have been reported for organic and inorganic contamination of severe biological consequences on resident biota and ecosystem health

by Adeogun et al 2016 a,b,c) However, there is still paucity in the use of biological responses for monitoring ecosystem health in Africa and most developing countries, including Nigeria, which was blamed in part on the poor scientific evidences in these countries to demonstrate their body burden and other ecosystem effects (Ibor et al 2017)

Nevertheless, some of these metals have been widely studied and reported to have different affinity for organs and tissues, as well as their occurrences in most environmental matrices (Murray et al 2010), their toxicity in terms of dose-response and exposure levels (Hodgson, 2004), deleterious effect on body organs (Falusi and Olanipekun, 2007; Oluowo and Omoregie 2016; Andem et al 2013; Ikejimba et al 2014) and their persistent nature in the environment (Ajao and Fagade 1987; Egborge 2003; Olomukoro 2006; Ayenimo et al 2006; Emoyan et al 2006; Puyate et al 2007; Oluwa et al 2010; Olowoyo 2011; Jimoh et al 2012) which is on the increase, especially

in the aquatic environment

The persistence of heavy metals in the environment have been attributed largely to their carrier particles with ability to camouflage toxic properties governing the spread of metal speciation in nature; a phenomenon of great concern because heavy metals constitute considerable hazards to human health due to their toxicity, accumulative tendencies, persistence, and made worse by their abilities to transform into more toxic

forms in the environment (Ayenimo et al 2005)

1.2.1 Toxicity of Heavy Metals

Heavy metals constitute varying degree of damage to the body, so also their fate in the environment Different empirical studies have attributed these effects on several other factors including the age of the organisms, time and route of exposure, body mass as well as the quantity released to the environment or consumed by the organisms This according to Hodgson (2004) has significantly increased the burden of some of these substances in the body, persistence in the environment and therefore, recommended investigation of their toxicological effects

While the accumulation of Pb and Cd, for instance in high concentrations have been reported to result into brain and kidney damage, Pb contamination resulted to metabolic interference, central nervous system toxicity, Cd caused skeletal illness, high blood pressure and sterility among male rats (Adekoya et al 2006; USEPA 2009)

Some of the documented evidences resulting from metal toxicity and their sources with notable contributions to the present study are, heavy metals concentrations in the water, sediment and fishes of Ikpoba reservoir, Benin City, Edo State-Nigeria (Fufeyin 1994), Heavy metals pollution in Warri river, Nigeria (a tributary river to the present study) (Ayenimo et al 2005), Evaluation of heavy metal loading of River Ijana in Ekpan river, Delta state (Emoyan et al 2006), Heavy metals determination and physicochemical quality of portable water supply in Warri river, Delta State, Nigeria (Nduka & Orisakwe 2007), Heavy metals and macroinvertebrates communities in bottom sediment of Ekpan Creek, Delta State, Nigeria (Olomukoro & Azubuike 2009), bioconcentration factors of

heavy metals in tropical crab (Carcimus Spp) from River Aponwe, Ado-Ekiti, Nigeria

(Falusi & Olanipekun 2007), Investigation of heavy metals contamination of edible marine seafood in Ondo coastal region, Nigeria (Ololode et al 2008), Determination of heavy metals in crab and prawn in Ojo Rivers Lagos, Nigeria (Olowu et al 2010), bioaccumulation of some heavy metals and total hydrocarbon (THC) in the tissues of

periwinkle (Tympanotomus fuscatus var radula) in the intertidal regions of Qua Iboe

river basin, Ibeno, Akwa Ibom State, Nigeria (Andem et al 2012), Evaluation of some

heavy metals and Total Petroleum in Water and Palaemond Shrimps (Macrochium

vollenhovenii) of Egboko River, Delta State, Nigeria (Omoregie & Oluowo 2016), and

Heavy metals in the farming environment and in some selected Aquaculture Species in

the Van Phong bay and Nha Trang Bay of the Khanh Hoa Province in Vietnam (Ngo et

al 2008)

According to these authors, the lack of natural elimination processes of metals has aggravated the situation, having metals shifting from one compartment within the aquatic environment to another including the biota, with worse effect through bioaccumulation Food chain transfer also increases toxicological risk in humans (James

& Alagurathinam 1996) Due to adsorption and accumulative tendencies of these metals, their concentrations in bottom sediment is expected to be higher than those in the surface water (Adekoya et al 2006), especially as bottom sediments are repository to heavy metals pollution in aquatic systems (Fufeyin 1994; Puyate et al 2007; Olomukoro 1996)

Whereas essential metals are generally considered to be less toxic than non-essential metals, non-essential metals often exert their actions through their chemical similarity

to essential elements, for example Cd with copper or zinc (Emoyan et al 2006; Adekoya

et al 2006)

Various environmental factors such as temperature, pH, water hardness, dissolved oxygen, photoperiod, salinity and organic matter can influence the toxicity of metals in solutions (Dojlido & Best, 1993; DWAF 1996; Puyate et al 2007) Particularly, temperature have been widely reported to increase bio-concentration and bio-accumulation, as well as bioavailability of metals in organisms (Egborge, 1994; Fufeyin, 1994; James & Sampath, 1996; Ayenimo et al 2005; Adekoya et al 2006 and Olomukoro & Azubuike 2009)

Accumulation of metals by some of these organisms, for example periwinkle and crab have become useful indicators in biomonitoring aquatic pollution (Ayenimo et al 2005), and as bioaccumulation in organisms is noted to increase with increasing temperature (Fritioff et al 2005; Verweij et al 2010)

The impact of climate change through temperature increase is a growing knowledge in metals bio-accumulation and bio-concentration in organism, thus their affinity for organs, is a key consideration in toxicology and pollution management as well as, in the present study

1.2.2 Some Heavy Metals and Their Sources

Different heavy metals have been reported to constitute different health hazards Cheremisinoff (2016) prioritize substances such as lead, mercury, cadmium, hexavalent chromium and nickel as toxic metals with a high frequency of occurrence in the environment Some of the commonest metals and their sources are discussed below;

Cadmium (Cd)

Cadmium is the seventh most toxic heavy metals as per ATSDR ranking It is a product of zinc production which humans or animals may get exposed to, at work or in the environment (Jaishankar et al 2014) It is also a natural element in the earth’s crust, usually found as a mineral combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulfur (cadmium sulfate, cadmium sulfide) It does not have a definite taste or odor All soils and rocks, including coal and mineral fertilizers have some cadmium in them

by-The industrial cadmium is usually extracted during the production of other metals such

as zinc, lead, and copper (Fufeyin 1994) and do not corrode easily and has many uses in industry and consumer products, for example used for rechargeable batteries and special alloy production (Ni-Cd batteries of mobile phones), pigments, metal coatings and plastics (OSHA 2009) A constituent of easily fusible alloys, soft solder and solder for aluminum used in electroplating, and as deoxidizer in nickel plating used in process engraving in electrodes for cadmium vapor lamps, photoelectric cells, photometry of ultraviolet sun-rays; filaments for incandescent lights (CDC 2004; OSHA 2009) Cadmium may enter water as a result of industrial discharges or deterioration of galvanized pipes, cadmium containing products such as plastics, tires, and some batteries, phosphate fertilizers, metallurgy, paints and dyes, and the discharge of wastes from industrial plants also contribute to the concentration of cadmium in the environment It binds strongly to soil particles, dissolves in water (Ferner 2001; USEPA 2009), and does not break down, however changes form The naturally occurring concentration of cadmium in freshwater is less than 0.001 mg/L

Fish, plants, and animals take up cadmium directly from the environment (James et al

1997), while human gets exposed to this metals by inhalation and ingestion leading to

acute and chronic toxicity Once absorbed by humans, it accommodates the body through-out life time and can build up from low to high exposure (Hodgson 2004; Monisha et al 2014)

The US Environmental Protection Agency (USEPA) drinking water limit for Cd is 0.01 mg/L, while the Nigeria Industrial Standards (NIS) is 0.003 mg/L Whereas, the US Food and Drug Administration (FDA) limit in food is 15 ppm, the Occupational Safety and Health Administration (OSHA) workplace air limit is 100 microgrammes/m3 as cadmium fumes and 200 microgrammes/m3 as cadmium dust The highest level of

cadmium contamination was found in shellfish, liver, and kidney meats (James et al 1997; Olomukoro et al 2009; OSHA 2009; USEPA 2009) Long term exposure to low

levels of cadmium in air, food, or water leads to a buildup of cadmium in the kidney and possible kidney disease (CDC 2004) Other potential long-term effects are lung damage

and fragile bones, abdominal pain, choking and tenesmus (Beers et al 2004) Cadmium

salts are more toxic than those of zinc (US medical Association, 2010)

The US Department of Health and Human Services (DHHS) has determined that cadmium and cadmium compounds may reasonably be anticipated to be carcinogens

in diets, is required in very small amounts Other forms of chromium are not needed by the body, but resides in the organic matter of soil and aquatic environment in the forms

of oxides, hydroxides and sulphates (Cervantes et al 2001), and as a natural elements in rocks, plants, animals, and in volcanic dust and gases (Fufeyin 1994; Ferner 2001; USEPA 2009)

Chromium is used in the manufacturing of chrome-steel or chrome-nickel-steel alloys (stainless steel) and other alloys, bricks in furnaces, dyes and pigments, and to increase resistance, durability and electroplating of metals, leather tanning, and wood preserving, chemical manufacturing of pulp and paper, disposal of products or chemicals containing chromium, or fossil fuel burning together release chromium to the air, soil, and water (Fufeyin 1994; Prasad 2004; Jaishankar et al 2014), with resultant effect in increasing chromium pollution with adverse effect on biological species (Ghani 2011)

All forms of chromium can be toxic at high levels, but chromium (VI) is more toxic than chromium (III) Acute toxicity result when breathing very high levels of chromium (VI)

in air causing damage and or, irritation to the nostrils, lungs, stomach and the intestines, while long term exposure to high or moderate levels of chromium (VI) leads to bleeding, itching, sore in and around the nose, and can increase risk of non-cancer lung diseases Ingesting very large amounts of chromium can as well cause stomach upsets and ulcers, convulsions, kidney and liver damage, and even death (Prasad 2004; US Medical Association 2010)

The presence of chromium in excess above allowable limits is destructive to plants since

it severely affects the biological factors of the plants and enters food chain on consumption Another effect is chromium phytotoxicity which leds to reduction in root growth, leaf chlorosis, seed germination inhibition and depressed biomass (Jaishankar

et al 2014), especially on maize, wheat, barley, cauliflower, citrullus and in vegetables, and plant necrosis (Ghani 2011), as well as enzymes such as catalase, peroxidase and cytochrome oxidase with iron as their component are affected by chromium toxicity (Jaishankar et al 2014), including photosynthetic processes and pigmentation, nitrate reductase activity, protein content in algae which have been reported by Nath et al 2008

Chromium (IV) can pass through the cell membrane easily, while chromium (III) requires a simple diffusion into the cell and does not depend on any specific membrane carrier (Chandra & Kulshreshtha 2004), which has serious health implication through consumption

The USEPA and NIS maximum level for chromium (III and VI) in drinking water is 0.05 mg/L, while the Occupational Safety and Health Administration (OSHA) limit is

8-hour workday, 40-hour work week exposure And 500 micrograms/m³ for soluble chromic of chromium (III) or chromous of chromium (II) salts and 1,000 micrograms/m³ for metallic chromium (0), and insoluble salts

water-Lead (Pb) are toxic metal widespread in use and have been reported to cause severe

environmental damages and health problems in most part of the world It is bright silvery metals, slightly bluish in a dry atmosphere (Sharma & Dubey 2005) Lead is an extremely toxic heavy metal that obstructs plant physiological processes (Jaishankar et

al 2014), unlike other metals, it does not play any biological functions in plant, however fastens the production of reactive oxygen species (ROS) in high concentrations, causing lipid membrane damage that ultimately lead to damage of chlorophyll growth of plants (Najeeb et al 2014) Because of the long-term wide spread use of lead, it is one of the ubiquitous toxic metals (Hodgson, 2004) In animals, the main target of lead toxicity are the hematopoietic systems and nervous systems, with documented evidences of several enzymes involvement in the synthesis of heme which are sensitive to lead inhibition, especially the aminolevulinate dehydratase (ALAD) and heme synthetase (HS) (Hodgson, 2004) Inorganic lead for example, can be absorbed through the gastrointestinal (GI) tract, the respiratory systems and the skin, with far worse deleterious report in young children by contaminating placenta as well as the blood brain barrier Hodgson (2004) also reported the effects of lead toxicity on nervous system even in small amount causing hyperactivity, decreased attention span, mental deficiencies and impaired vision and encephalopathy, ataxia, stupor, coma and convulsion in high amount in both children and adult

The main sources of lead exposure are industrial processes, food, smoking, drinking water and domestic sources, in products such as paints, gasoline, pipes The industrial limits for lead in drinking water is 0.05 for USEPA and 0.01mg/L for the NIS Other heavy metals of considerable health implications are arsenic, selenium, iron, copper, cobalt, nickel, aluminum are also known to have deleterious effects when introduced in

undesirable amount to the environment (James et al 1997; Adekoya et al 2006)

Copper gets into the aquatic systems from the corrosion of copper pipes and fittings as

well as from copper salts used to control algal growths in reservoirs They may occur in most natural waters but generally at low levels between 2 to 50µg/L (Fufeyin 1994)

Iron ranks next to aluminum in abundance in the earth’s crust (APHA, 2009) Iron is relatively soluble in natural waters where it is available as a result of flaking of rust from pipes The presence of iron in natural water is mainly as a result of leaching The ferric forms of iron are sparingly soluble in water but solubility increases at low PH The reduced ferrous form can become very high under anaerobic condition through bacterial reduction (Fufeyin 1994; USEPA 2009)

Aluminum is absorbed from aluminum cookware, aluminum foil, antacids,

antiperspirants, baking powder, buffered aspirin, canned acidic foods, food additives, lipstick, medications and drugs (anti-diarrheal agents, hemorrhoid medications, vaginal

douches), processed cheese, “softened” water, and tap water (Ayenimo et al 2005; Puyate et al 2007; US, Medical Association 2010)

The adverse effects of heavy metals in aquatic environment have been widely documented Strictly speaking, virtually all metals are harmful if the exposure level is exceeded (USEPA 2009) Heavy metals have been found to endanger public health when incorporated in the food or being released into water layers which serves as drinking water supply or habitat to some organisms

1.3.0 Description of Study Area and Sampling Stations

According to Egborge (1994), the mangrove is one of the wettest regions of Nigeria characterized by two seasons (dry and wet), with a population size of 280,000 in 1981, which grew rapidly to over 500,000 in 1991 (National Population Commission 1991)

resulting from urbanization, shipping activities, oil exploration and petroleum refining activity within the area It is believed that the population must have tripled by now, around 1.2 million and would have been more if Delta Steel Company and other companies located in the area is operating at full capacity

Elementary schools Public market places

generally porous, permeable and unconsolidated The landforms result from the seemingly uncomplicated geological structure that belongs to the Pliocene-Miocene periods The sedimentary rocks of these periods are classified as the Sombreiro-Warri deltaic deposits Below the Sombreiro-Warri Deltaic plain sands are the three stratigraphic units that constitute the Nigeria Niger Delta.; these include the Benin, Agbada and Akata formations in the order of increasing age

1.3.3 Climate

The climate characteristic of the environment is similar to what is obtained in other humid tropical environment Primarily rainfall, temperature, wind (speed and direction), relative humidity and sunshine were found to constitute the major climatic elements of the area Furthermore, the relatively short distant from the sea, prevailing wind over the season, latitudinal location, apparent movement of the sun across the tropics over the area are major factors that determines their climatic formations The area is characterized by high relative humidity (80-92%) and annual average rainfall exceeding 2800mm Although, there are two distinct seasons (wet and dry), measurable precipitation occurs in all the months of the year, which signals climate change

Notwithstanding, the period of April to October is often regarded as raining season, while November to March is regarded as the dry season Atmospheric temperature ranged between 27 - 290C (Ohimain et al 2008) As such, temperature is relatively stable for most months of the year

1.3.4 Vegetation and Land use

As a result of the fresh-saltwater mixture, a brackish environment is created at the banks of the river and associated creeks; which is typical for tropical mangrove forest ecosystems Consequently, vegetation along the bank is made up of mangrove plants of different species, dominated by Rhizophora species, marginal vegetation which include

Elaeis guineesis, aquatic plants dominated by water hyacinths (Eicchornia crasspies)

including water lily, Nympea spp, crytosperm spp and ceratophyllum submersum The

area is dominated once by fish farms, spaced farm lands, and the crops cultivated include cassava, yam, maize, sweet potatoes etc, is fast losing its potentials

There are several decaying trunks along the river edges Its upstream is fresh water with dense forest vegetation, surprisingly behaving as lentic instead of lotic water source which is expected of a river, the downstream is however brackish and consist of Mangrove with free flowing water The study area house Steelways, Subsea 7, N.D.N, Delta Whysky, N.B.T.C, Globestar, Willis, Westminster, Steel ways, Delta Steel Company, Udu market, Pesu and main market, however it was noticed during field sampling that most of these companies operate scantly or closed operation due to the country’s economy situation

1.3.8 Human Activities

The activities along the river course include wood logging and milling, auto-mechanic workshops, shipping services, petroleum product and services, farming, fishing, bathing, boat and ship building, transportation, etc

CHAPTER TWO

2.0 MATERIALS AND METHOD

2.1 Sampling Techniques

2.1.1 Water and sediment

Samples for water quality analyses and bottom sediment was collected once monthly for physiochemical and heavy metals analyses from August to October, 2017 Sampling was conducted between 7 - 11am on each sampling day, this time was chosen because human activities in the study area were still be very low, except in few occasions Water samples of both rivers, hand dug well and sediment was collected for three (3) months

2.1.2 Water

Water samples (1 litre) were collected into an appropriately labeled bottles for chemical analysis Dissolved oxygen (DO) was determined by the azide modification of Winkler’s methods as described and adopted by Mackereth 1963; Schwoerbel 1973; Egborge & Ezemonye 2003; Olomukoro & Azubuike 2009; Oluowo & Omoregie 2006, respectively for HACH standard equipment While, biochemical oxygen demand (BOD) was collected into a 250ml colored glass-stopped BOD bottles filled to over flowing directly from source; just below the water surface using the direct sampling method (USEPA 2009; USEPA/ERT 2011) Other parameters such as pH, TDS, EC and few metals were determined in-situ to avoid changes during transportation using mercury in glass thermometer, Hanna probe and HACH metal analyzers

2.1.3 Sediment

Sediment samples were collected using an Ekman grab in adherence to scientific method previously described by Paul & Anita 2014; Fufeyin 1994; Olomukoro 1996; Adekoya et al 2006 The content trapped by the grab was forced into the substratum placed in a well-labeled polythene bags, preserved in 10% formaldehyde and transported immediately to the laboratory for processing and analysis using standard methods

2.2.0 SAMPLING STATIONS

2.2.1 Sampling stations

A total of eight sampling stations (with component described below) have been carefully identified for their proximity to facilities, structure or human activities that could have potential effect on water and/or aggravate pollution; five on the water stretch, one creek and two hand dug well, to cover activities upstream, midstream and downstream of the study area

Station 1 was situated mid-downstream of the water stretch around Aladja Town The

water is murky, behind Delta Steel Company (DSC) facility, with a boat building yard and anchorage and shipping activities Others are bathing and drinking with spoilt batches, boats, jetty and diesel loading jetty The dominant vegetation were coconut, plantain GPS reading (N05.48833, E005.76444, elevation of -7m GPS reading taking

at 3m)

Station 2 is downstream adjoining Pesu Market and Main market It is a brackish water

source, the dominant activities in the area are boat Jetty, fishing, spoilt batches and residential GPS reading (N05.49670, E005.75267, elevation of 1m, GPS reading taking

at 3m)

Station 3 was situated in the Aladja Creek, which was dominated by water hyacinth

indicating very high nutrient activities and also implicated to climate change through temperature increase, it is a slow flowing brackish water populated by raffia palm, shrubs and short mangrove plants GPS reading (N05.49431, E005.76596, elevation of 2m GPS reading taking at 3m)

Station 4 is Mid-stream between Ovwian and Meiogun communities housing

Westminister, NDN, Steel ways, Willis Group of Companies and other shipping and oil carrying vessels / platforms with over eighteen (18) ships and platforms The water is slow flowing with mangrove vegetation (N05.52114, E00.77367, elevation of 2m GPS reading taking at 3m) and covered with oil film

Station 5 is the mid-upstream station, with brackish water and nearly pristine fresh

water mangrove vegetation, with brackish water, this station is situated nearly under the

Udu bridge housing over 30 wood processing, log preparation factories and burning activities, and Judesco Company limited GPS reading (N05.51568, E005.78589, elevation of 2m taking at 3m)

Station 6 was upstream near Udu village with clear mangrove forest, the water is

expected to be lotic but at some point lentic and may have resulted from the high human activities such as wood processing activities noticed in the area may have negatively impacted on the water flow rate GPS reading (N05.51703, E005.79921, elevation of 3m taking at 3m)

Station 7 (Hand dug-well) GPS reading (N05.49495, E005.78324, elevation 7m taking

at 4m), one of the sampled hand dug well for the study, constructed on a populated residential and business area The inhabitants completely depend on it for drinking,

cooking, laundry and bathing So also, Station 8 (Hand dug-well) (N05.59967,

E00.78453, elevation of 4m taking at 3m)

2.3.0 WATER STUDIES

2.3.1 Rainfall

The rainfall data for Warri during the sampling period was collected from the Warri

Meteorological station, Airport Road Warri Delta State

2.3.2 Temperature

Water samples of Ovwian Mangrove were recorded using a mercury-in-glass centigrade thermometer The water was collected in plastic containers, prewashed and rinsed with distilled water The thermometer was held in the water for 2-4 minutes and the readings taken while the thermometer was still inside the water

2.3.3 Hydrogen Ion Concentration

Accurate determination of PH of the water samples was carried out in the laboratory using a PH meter ORION MODEL 290A; type ASTM D1293B standardized with appropriate buffer solution and the readings made to the nearest 0.1pH unit (Olomukoro

et al 2009)

2.3.4 Alkalinity

Alkalinity was determined by titration using the method of Golterman et al

(1978) Phenolphthalein alkalinity was first determined by titration using 100ml of each sample against 0.02N Sulphuric acid with two drops of phenolphthalein indicator In all samples, phenolphthalein alkalinity (P.A) was zero (i.e samples remained colourless) Two (2) drops of methyl orange indicator was then added to the colourless solution and was titrated against the acid until the appearance of a faint pink colourless

The total alkalinity was calculated from the equation:

T.A (meq/L) = Vol of titrant * N of acid* 1000/Vol of samples used

A correction factor of 0.02 was subtracted from the value obtained as suggested by

Sutcliffe et al (1982) and then converted to mg/L with a multiplication factor of 50

2.3.5 Total Hardness

A 150ml conical flask was washed with the water samples and filled to the 50ml mark 2ml of the buffer solution was then added with 2-drops of the indicator solution (Eriochromes Black T) and mixture swirled An end point colour change from wine to blue colour was observed when titrated with 0.01N EDTA

1) The titration pipette was used to drop the reagent solution slowly to the prepared water sample The appearance of a blue colour from wine is an indication of the end point The total hardness of water was read off in 0d from a table and converted to ppm

of CaCo3 The evaluation was read off from the scale

CALCULATION:

Total Hardness as CaCO3 mg/l = ml of (EDTA) (0.01) 50 x 1000

Vol of sample (ml)

Fufeyin (1994)

2.3.6 Dissolved Oxygen

A 250-ml brown bottle was filled with the sample, and in ensuring that bubbles are not trapped in, 2ml of MnSO4 5H2O was added well below the surface of the sample simultaneously with 2ml of alkaline-iodide solution at the surface of the sample Stopper was carefully placed so as to avoid inclusion of air bubbles and mix thoroughly by rotating and inverting the bottle several times The precipitate was allowed to settle down completely and with aid of a pipette, 4ml of diluted Sulphuric acid or alternatively 85-90% ortho-phosphoric acid The stopper was replaced and mix thoroughly with the contents by rotating it 100ml of the solution was measured into a conical flask and was titrated immediately with 0.0125N NaS2O2.5H2O using as indicator, a 2ml of starch solution was added towards the end of the titration and presented a straw yellow to blue colour indicate the reaction end-point

Calculate the DO with the following equation DO = V1 N (8) x 1000

of measurement

The specific conductance of the water was measured in µS using an electronic conductivity meter by Oakton Model 35607; APHA 2520B/ASTM D1125

2.3.8 Total Solids

An evaporating dish was properly washed and rinsed with distilled water, oven dried, put in a desicator to cool and then weighed (W1) 100ml of unfiltered water sample was put in the evaporating dish and evaporated to complete dryness at 150-

1800c The dish was then transferred to the desicator to cool and reweighed, until a constant was obtained (W2)

Weight of the dried sample= (W1-W2)g The total solids in 1L of water was extrapolated using the formular (W1-W2)* 1000* 10 mg/L (Fufeyin 1994)

2.3.8.1 Total dissolved solids

This was done similar to the total solids except that the water used was filtered through Whatman filter paper No 41 prior to analysis

2.3.8.2 Total suspended solids

The total suspended solids were got by subtracting the total dissolved solids from the total solids i.e Total suspended solids=Total dissolved solids (mg/L)

2.4.0 Pretreatment and digestion of water

2.4.1 For ICP scan

The method used was the wet oxidation method described by Martin et al (1992),

having all glass wares cleaned as recommended

1) 100ml of the water sample was placed in 150ml beaker 5.0ml of conc nitric acid was added The solution was mixed and left to evaporate to near dryness on a hot plate to ensure that the sample does not boil, low to medium heat was applied The beaker and the contents were allowed to cool Another 5.0ml of conc HNO3 was added to the beaker and covered immediately with a watch glass The beaker was returned to the hot plate, to set

a gentle reflux action of the solution by increasing the temperature of the hot plate from medium to high It was heated continuously while HNO3 was been added until a light-colour residue was formed (then digestion is completed) 1-2ml of conc HNO3 was added

to the residue and washed with distilled water It was then filtered into a100-ml volumetric

flask to remove silicate and other insoluble materials Filled with distilled water to make

up to the mark and stored in a 125-ml polypropylene bottle (Fufeyin 1994)

2.4.2 For AAS analysis

The water samples that had already been fixed in nitric acid were filtered through Whatman filtered paper no 1 and aspirated directly into the AAS for metal such as Cd,

Cu, Pb, Mn, Ni and Zn The blanks were prepared accordingly with corresponding

quantity of nitric acid (Emoyan et al 2006; Olomukoro et al 2009)

2.5.0 Bottom Sediment Studies

2.5.1 The Organic Matter

The total organic matter (TOM) contents of the sediments were estimated from the percentage loss on Ignition (LOI) described by Allen (1989) Ig of Oven dried soil was put into a pre-weighed crucible The crucible and contents were placed in a muffle furnace The temperature was allowed to rise slowly to 550C and left for 2 hours When cool, the crucible and contents were transferred to a desicator to cool to room temperature and reweighed

The % loss on Ignition was calculated from the weight loss during combustion using the formula

% loss on Ignition= wt loss (g)* 100/oven dry wt (g)

2.5.2 Pretreatment and digestion of sediment

The air-dried samples were mixed thoroughly 1g of each sample was weighed into a 250ml beaker 4ml of conc nitric acid and 10ml of Hydrochloric acid were added and covered with a watch glass The content was heated on a hot plate and gently refluxed for 30minutes To ensure the solution does not boil low; a temperature of 85ºC was maintained The sample was allowed to cool and then transferred to 100ml volumetric flask It was diluted to volume with ASTM type 1 water and mixed thoroughly This samples were allowed to stand overnight (in place of centrifuging) to separate insoluble

materials and filtered through 0.45µm Millipore type filter (APHA 1997; Olomukoro et

al 2009)

2.5.3 For the AAS analysis

The method described by Fufeyin (1994) was used 1g of sediment was weighed into a beaker 10ml nitric and 5ml perchloric acids added The mixture was heated for two hours and was allowed to cool as well as stand overnight for about 20 hours The supernatant was then transferred to a clean beaker The sediment was washed with 10ml

of distilled water and added to the supernatant This was filtered through a Whatman no

42 filter paper into a 25ml volumetric flask and made up to the mark

2.6.0 Instrumental Procedure

2.6.1 The Inductively Coupled Plasma Spectrometer (ICP)

The ICP was used to scan for the presence of possible heavy metals in a few samples of water and sediment

The ICP procedure describes a technique for simultaneous or sequential multielement determination of metals and trace elements in solution The basis of the method is a measurement of atomic emission by an optical spectrometric technique

Samples are nebulized to produce aerosols which is transported to the plasma torch where desolvation and excitation occurs While, the characteristics atomic-line emission spectra were produced by a radio-frequency inductively coupled plasma (ICP), the spectra are dispersed by a grating spectrometer and line intensities monitored by a photosensitive device (e.g a photomultiplier tube or a diode array) A photocurrent from

a photosensitive device are processed and controlled by a computer system A background correction technique was required to compensate for variable background contribution to the determination of the analytes Background was measured adjacent to the analyte line on sample during analysis The position selected for measurement of background intensity was free of spectral interference on both sides of the analytical line (Dojlido and Taboryska 1991)

2.6.2 The Atomic Absorption Spectrometer (AAS)

The use of AAS was first proposed and developed by Walsh in 1955 according to Allen, 1989 Basically, as a spectrophotometer that consists of a radiation source, a burner with sample compartment, monochromotor, a detection and measuring device

The Varian Techron Spectr AA – 10 Atomic Absorption Spectrometer (ser no 902 1318) with a printer attached was used for the quantitative determination of all heavy metals The principle is based on the formation of atomic absorption spectra by the absorption

of radiation of certain wavelengths by atoms, whose electrons are in the ground state

On absorption this energy, the atoms become excited The extent is dependent on the number of atoms in the ground state, the path of the radiation beam at a time and thus, used in the quantitative determination of their numbers

Atomization was achieved by use of the air-acetylene flame for all the metals determined The sample was introduced by means of a nebulizer spray chamber system Radiation of a characteristic wavelength from the hollow cathode discharge lamp was passed through the flame, while the decrease of intensity was measured using a monochromotor and detector system The decrease was related to the concentration of

the element in solution (Dojlido & Taboryska 1991; Ayenimo et al 2005; Emoyan et

al 2006)

2.7 Data Analysis

Data obtained from the laboratory were subjected to different statistical methods such as mean, test of significance, standard error, etc using Excel and SPSS computer packages While the analysis of variance was carried out to show significant differences

in the monthly metal concentrations in the water and sediment using computer Excel and SPSS package

CHAPTER THREE 3.1 RESULTS

Table 3.1: Summary of some physico-chemical parameters of Ovwian Mangrove

(August to October 2017)

P-Values

Regulatory limits

Table 3.2: Summary of some heavy metals in surface water in Ovwian Mangrove

(August to October 2017)

P-Values

Regulatory limits

0.001

0.001±0.000 0.00±0.001 0.001±0.000

0.00-0.001 0.00

* X connote mean values for the stations, while S.E is the standard error of standard deviation; P values less than 0.05 or equal to 0.05 shows significance differences, while greater than 0.05 show no significance difference NIS connotes Nigerian Industrial Standards, DPR – Department of Petroleum Resources, FEPA (Federal Environmental Protection Agency)

Table 3.3: Summary of some heavy metals in Bottom Sediment in Ovwian Mangrove

(August to October 2017)

P-Values Regulatory limits

Parameters Unit

(s)

(2003) Copper Mg/L 0.561±0.196 0.210-

1.320

0.284±0.042 0.135-0.413 0.609±0.190 0.119-1.083 0.28 1 Zinc Mg/L 6.704±0.795 4.082-

9.508

7.364±0.843 4.154-9.432 5.507±0.549 3.863-7.102 0.07 3 Iron Mg/L 271.516±23.394 206.1-

0.014

0.014±0.004 0.006-0.032 0.005±0.001 0.001±0.011 0.14 0.003 Chromium Mg/L 1.439±0.237 0.850-

2.034

1.599±0.267 0.832-2.546 1.322±0.237 0.781-2.201 0.64 2 Lead Mg/L 0.002±0.001 0.001-

0.008

0.004±0.001 0.010-0.003 0.002±0.000 0.001-0.006 0.01 0.01 Arsenic Mg/L 0.001±0.000 0.00-

1986

(Egborge, 1991)

2008

(Wogu and Okaka, 2011)

2017 Present study

Copper (mg/L) 0.009 0.1870 0.0290 0.019 0.019 0.0068** Zinc (mg/L) 0.025 0.5050 0.0300 ND ND 0.0312** Iron (mg/L) 0.1610 1.9000 0.1551 2.770 2.770 0.0198 Cadmium (mg/L) 0.0008 0.2290 0.0031 0.275 0.275 0.0036* Chromium (mg/L) - 0.5930 ND 0.059 0.059 0.0043 Lead (mg/L) 0.0020 1.0810 0.0073 0.086 0.086 0.0030

The October temperature range in all the studied Stations, except Station 3 and 8 was the highest temperature value in the study, followed by September except at Station

5, thus showing a seasonal trend of being higher in the drier months with a steady temperature decrease from October to August

Figure 3.1: Spatial and monthly variation of air temperature

3.1.2 Hydrogen ion concentration (pH)

The monthly variations in the pH values of the water (Figure 4.2) shows that, the waters are becoming very acidic, with values obtained along the Stations ranging from 5.43 to 7.83 on the pH scale Both the highest and lowest pH values was obtained in October, while the highest pH value of 7.83 was obtained at station 8, the lowest of 5.43

at Station 5 Although, a significant difference in pH values was observed along the studied Stations (P = 0.03), there was however no significance differences in the months

of study (i.e July to August) with a P > 0.05 Generally, the month of August was more acidic with the lowest mean value of 6.115, while October was the highest with a mean

of 6.385 in the study period

Figure 3.2: Spatial and monthly variation of pH

0 1 2 3 4 5 6 7 8 9

4.1.3 Total Alkalinity (mg/L)

Although, there were no observable significance differences (P>0.05) in total alkalinity

in the study period for both the Stations and months (Figure 4.3) The range of values was between 64.0 and 150.0 mg/L in the study, with the highest value of 150.0 mg/L at Station 8; which is one of the drinking water sources has some health implication on aquatic lives and humans through consumption, followed by Station 1 in the August (143.5 mg/L) and the lowest value of 64 mg/L at Station 4 in September While September had the lowest mean value of 92.62 mg/L, October was the highest in the study with a mean value of 103.37 mg/L

Figure 3.3 Spatial and monthly variation of alkalinity 3.1.4 Total Hardness of Water

Variations in the hardness of water during the period of investigation (Figure 4.4) The highest value of 80 mg/L was obtained at Station 8 in October along the studied stations and the highest in the study period, followed by 70 mg/L in September in the same station The very high values recorded in the study was from the drinking water sources at Stations 7 and 8 in all the stations While on the water stretch is Station 1 in October (12 mg/L) and the lowest of 5 mg/L at Stations 4 and 6 in September, and station 6 in August respectively However, the water was generally soft with values ranging between 5.0 and 80.0 mg/L

0 20 40 60 80 100 120 140 160

Figure 3.4: Spatial and monthly variation of water hardness

3.1.5 Total Dissolved Solids (mg/L)

The pattern of distribution of total solids (Figure 4.5), showed values above the NIS regulatory at Station 8 (510 mg/L) in August and elevated concentration in September (499 mg/L) and October (486 mg/L) respectively, are drinking waters source in the study The values obtained ranged from 12.7 to 510 mg/L with the lowest value of 12.7 mg/L at Station 6 in October along the water stretch Generally, the month of August had the highest values, followed by September in the study

Figure 3.5: Spatial and monthly variation of total dissolved solid (TDS)

3.1.6 Dissolved Oxygen (mg/L)

The spatial and monthly distribution of DO is presented in Figure 4.6 with a unique pattern in values that ranges between 4.7 and 8.5 mg/L Both the highest and lowest values recorded along the studied Stations were recorded in October at Station 8 (8.5 mg/L) and 1 (8.5 mg/L), and the lowest of 4.7 mg/L at Station 3 and 6 respectively The study observed a decreasing monthly pattern in DO from August to October, however there was no significance

0 100 200 300 400 500 600