impact of municipal effluent on the water quality of pece stream...

International Journal of Social Science and Technology ISSN: 2415-6566 Vol. 1 No. 2; November 2016

59

Impact of municipal effluent on the water quality of Pece stream Gulu town,

Uganda

Ochieng Moses Otieno and Manyang Peter Mawut Atem

Faculty of Engineering, International University of East Africa, Uganda

[email protected]

ABSTRACT

Water quality monitoring in developing countries is inadequate, especially in stream water affected by urban

effluents and runoff. The purpose of this study was to investigate the effect of municipal effluents on the water

quality of Pece stream Gulu town. Water samples were collected along the stream and other samples from

Nakaseke River which served as a control site. Selected heavy metals (Zn, Cu, Pd and Cd) were determined

using Atomic Absorption Spectrophotometry. Sampling was done during the dry and the wet seasons of the

years 2011 and 2012, respectively. Physicochemical parameters were also determined for Electrical

conductivity, pH, hardness of water, Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD).

Results indicate that heavy metal concentrations in Pece stream water were significant.

Keywords: Municipal effluents, water quality, Pece Stream, Uganda

Corresponding author: [email protected]

1.0 INTRODUCTION

1.1 Background

Water covers about 75% of the earth’s surface. It is essential to all forms of life and makes up 50-97% of the

weight of all plants and animals and about 70% of the human body (Allan, 1995; Buchholz, 1998). Water is

also a vital resource for agriculture, manufacturing, transportation and many other human activities. Despite

its importance, water is the most poorly managed resource in the world (Chutter, 1998; Fakayode, 2005).

Water chemists study the impact of water on other elements in the systems and how other elements in these

systems affect the quality of water. Natural resources are the important wealth of our country, water is one of

them. Water is a wander of the nature. “No life without water “is a common saying depending upon the fact

that water is one of the naturally occurring essential requirements of all life supporting activities (Ayibatele,

1992). Since it is a dynamic system, it contains living as well as nonliving, organic, inorganic, soluble as well

as insoluble substances. So its quality is likely to change day by day and from source to source. Any change in

the natural quality may disturb the equilibrium system and would become unfit for designated uses. The

availability of water through surface and sound water resources has become critical day to day. Only 1% part


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is available on land for drinking, agriculture, domestic power generation, industrial consummation,

transportation and waste disposal (Gupta and Sharma, 2002; Mishra et al., 2002; Tahir et al., 2008).

Wastewater of the urban area is being used profitably to irrigate vegetable crops in the vicinity of cities from

the time unknown. Waste and sewerage water is still considered most rich in plant nutrients and organic

matter. In many cities and towns the sewerage water is sold and it is a good source of income to

municipalities. However, the situation is changed now (Saif et al., 2005). Urban systems may get their

freshwater requirements from a variety of sources, including ground water, surface water (lakes and rivers),

and the sea via expensive desalination procedures (Tian-xiang and Li-jun, 2009). The water is purified and

disinfected by chlorination. Large volumes of wastewater are subsequently generated after domestic and

industrial use, and this is typically discharged through sewer systems to treatment plants (Kwetegyeka et al.,

2010). These plants purify it for discharge back into rivers, lakes, seas (Metcalf and Eddy, 2003) and even

reuse for landscaping or irrigation.

1.2 Water Quality

“Water quality" is a technical term that is based upon the characteristics of water in relation to guideline

values of what is suitable for human consumption and for all usual domestic purposes, including personal

hygiene (Subrahmanyam and Yadaiah, 2001)). Components of water quality include microbial, biological,

chemical and physical aspects. In the view of Vinit K. et al., 2011, water quality is the physical, chemical and

biological characteristics of water. It is a measure of the condition of water relative to the requirements of one

or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of

standards against which compliance can be assessed. The most common standards used to assess water quality

relate to health of ecosystems, safety of human contact and drinking water.

In the setting of standards, agencies make political and technical/scientific decisions about how the water will

be used. In the case of natural water bodies, they also make some reasonable estimate of pristine conditions.

Different uses raise different concerns and therefore different standards are considered. Natural water bodies

will vary in response to environmental conditions. Environmental scientists work to understand how these

systems function, which in turn helps to identify the sources and fates of contaminants. Environmental lawyers

and policymakers work to define legislation with the intention that water is maintained at an appropriate

quality for its identified use.

The vast majority of surface water on the planet is neither potable nor toxic. This remains true even if seawater

in the oceans (which is too salty to drink) is not counted. Another general perception of water quality is that of

a simple property that tells whether water is polluted or not. In fact, water quality is a complex subject, in part

because water is a complex medium intrinsically tied to the ecology of the Earth. Industrial and commercial

activities (e.g. manufacturing, mining, construction, transport) are a major cause of water pollution as are

runoff from agricultural areas, urban runoff and discharge of treated and untreated sewage.


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1.3 Effluents

There are usually significant effects on water quality and on marine life arising from sewage disposal. Water

quality deterioration is one of the most important water resource issues of the 21 century. Therefore the quality

status of any water source is very important and would always be under public scrutiny because of the health

risk associated with sewage contamination (Monica, 2003). The potential deleterious effects of pollutants from

sewage effluents on the receiving river water quality are manifold and depend on volume of the discharge, the

chemical composition and concentrations in the effluent (Monica, 2003). It also depends on type of the

discharge for example whether it is the amount of suspended solids or organic matter or hazardous pollutants

like heavy metals and organochlorines, and the characteristics of the receiving waters (Nemerow and

Dasgupta, 1991; Canter, 1996). High levels of soluble organics may cause oxygen depletion (Woodbury,

1992) with a negative effect on aquatic biota and flora. Contamination of water streams may result in changes

in nutrient levels, abundance, biomass and diversity of organisms, bioaccumulation of organic and inorganic

compounds and alteration of tropic interaction among species. Receiving waters with high flushing capacity

are able to dilute or eliminate most of the conventional pollutants but persistent toxic compounds and long

lived pathogens will always be troublesome (Monica, 2003)

Water pollution is commonly defined as any physical, chemical or biological change in water quality which

adversely impacts on living organisms in the environment or which makes a water resource unsuitable for one

or more of its beneficial uses (World Health Organization, 2010). Water pollution due to discharge of

untreated industrial effluents into water bodies is a major problem in the global context (Mathuthu et al.,

1997). The problem of water pollution is being experienced by both developing and developed countries

Human activities give rise to water pollution by introducing various categories of substances or waste into a

water body. The more common types of polluting substances include pathogenic organisms, oxygen

demanding organic substances, plant nutrients that stimulate algal blooms, inorganic and organic toxic

substances (Cornish and Mensahh, 1999)

Waste water from industries and sewage spillages from burst pipes in urban centers in Uganda are released

into streams and wetlands which finally discharge into Lake Victoria. With the prevailing hard economic

situation in the country, most of the trade waste effluents are released into the environment untreated or

partially treated. Industrialists have adopted the use of substandard treatment methods that partially treat and

in some instances, forego the effluent treatment process (Walakira, 2011).Nevertheless, from the late 1980s

onwards; Uganda has been characterized by a high economic and industrial growth in the most parts of the

country. This has led to tremendous changes in the nutrient chemistry of the water resources, particularly of

the Lake Victoria (LVEMP/COWI, 2002). These tremendous changes in the nutrient concentrations may lead

to harmful effects to humans and aquatic life. For example most heavy metals in streams of water are

commonly associated with industrial discharges and almost all heavy metals common in industrial effluents

are cumulative toxins to aquatic life (Taylor and Crowder, 1983).

Effluents affect both the physical and chemical complies of any water body. Fount increases the boiling

temperature of water, decrease the amount of dissolved oxygen, increase the conductivity and cause the water

to have bad odor. All these effects put the life of the water consumers at risk. Due to increasing interest in

reusing waste water in water deficient regions, the environmental risk assessment (ERA) is suggested as a


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suitable tool to evaluate potential risks from trace pollutants in irrigation water (Munoz et al., 2009). The

urban aquatic ecosystems are strongly influenced by long term discharge of untreated domestic and industrial

wastewaters, storm water runoff, accidental spills and direct solid waste dumping (Sarika and Chandra

mohankumar, 2008). Generally speaking, water pollution is a state of deviation from pure condition, where by

its normal functioning and properties are affected.

Aggravated environmental problems often reflected the misuse or misunderstanding of technology (Prakasa

and Puttanna, 2000). Water quality degradation by various sources becomes an important issue around the

world. Usage of more land for agricultural purposes, soil Stalinization, an increase in the use of agricultural

fertilizers, common pesticide use, and erosion have become problems threatening natural water source (Zalids

et al., 2002). The increased demand of water as a consequence of population growth, agriculture and industrial

development has forced environmentalist to determine the chemical, physical and biological characteristics of

natural water resources (Regina and Nabi, 2003).

1.4 Heavy metals

Metals occur naturally in the earth's crust and their contents in the environment can vary between different

regions resulting in spatial variations of background concentrations. The distribution of metals in the

environment is governed by the properties of the metal and influences of environmental factors (Khlifi and

Hamza-Chaffai, 2010). Of the 92 naturally occurring elements, approximately 30 metals and metalloids are

potentially toxic to humans and these are; Be, B, Li, Al, Ti, V, Cr, Mn, Co, Ni, Cu, As, Se, Sr, Mo, Pd, Ag,

Cd, Sn, Sb, Te, Cs, Ba, W, Pt, Au, Hg, Pb, and Bi. Heavy metal is the generic term for metallic elements

having an atomic weight higher than 40.04g (the atomic mass of Ca) (Ming-Ho, 2005). Heavy metals enter the

environment by natural and anthropogenic means. Such sources include: natural weathering of the earth’s

crust, mining, soil erosion, industrial discharge, runoff, sewage effluents, pest or disease control agents applied

to plants, air pollution fallout, etc (Ming-Ho, 2005). Although some individuals are primarily exposed to these

contaminants in the workplace, for most people the main route of exposure to these toxic elements is through

the diet (food and water). The contamination chain of heavy metals almost always follows a cyclic order:

industry, atmosphere, soil, water, foods and human. Although toxicity and the resulting threat to human health

of any contaminant are of course, a function of concentration, it is well-known that chronic exposure to heavy

metals and metalloids at relatively low levels can cause adverse effects (Agency for Toxic Substance and

Disease Registry [ATSDR], 2003a, 2003b, 2007, 2008; (Castro-González and Méndez-Armenta, 2008).

Therefore, there has been increasing concern, mainly in the developed world; about exposures, intakes and

absorption of heavy metals by humans populations are increasingly demanding a cleaner environment in

general, and reductions in the amounts of contaminants reaching humans as a result of increasing

anthropogenic activities. A practical implication of this trend, in the developed countries, has been the

imposition of new and more restrictive regulations (European Commission, 2006; Figueroa, 2008).

Wood preservative chromated copper arsenate (CCA) can be used as an example to illustrate the effect of

some hazardous substances on human health and the environment. Lead (Pb), cadmium (Cd), mercury (Hg),

and arsenic (As) are widely dispersed in the environment. These elements have no beneficial effects in

humans, and there is no known homeostasis mechanism for them (Draghici et al., 2010; Vieira et al., 2011).

They are generally considered the most toxic elements to humans and animals; the adverse human health

effects associated with exposure to them, even at low concentrations, are diverse and include, but are not


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limited to, neurotoxic and carcinogenic actions (ATSDR, 2003a, 2003b, 2007, 2008; (Castro-González &

Méndez-Armenta, 2008; Jomova &Valko, 2011; Tokar et al., 2011).

1.4.1 Lead

Lead as a toxicologically relevant element has been brought into the environment by man in extreme amounts,

despite its low geochemical mobility and has been distributed worldwide (Oehlenschläger, 2002). Lead

amounts in deep ocean waters is about 0.01-0.02 µg/L, but in surface ocean waters is ca. 0.3 µg/L (Castro-

González and Méndez-Armenta, 2008). Lead still has a number of important uses in the present day; from

sheets for roofing to screens for X-rays and radioactive emissions. Like many other contaminants, lead is

ubiquitous and can be found occurring as metallic lead, inorganic ions and salts (Harrison, 2001). Food is one

of the major sources of lead exposure; the others are air (mainly lead dust originating from petrol) and

drinking water. Plant food may be contaminated with lead through its uptake from ambient air and soil;

animals may then ingest the lead contaminated vegetation. In humans, lead ingestion may arise from eating

lead contaminated vegetation or animal foods. Another source of ingestion is through the use of lead-

containing vessels or lead-based pottery glazes (Ming-Ho, 2005). In humans, about 20 to 50% of inhaled, and

5 to 15% of ingested inorganic lead is absorbed. In contrast, about 80% of inhaled organic lead is absorbed,

and ingested organic Pb is absorbed readily. Once in the blood stream, lead is primarily distributed among

blood, soft tissue, and mineralizing tissue (Ming-Ho, 2005). The bones and teeth of adults contain more than

95% of the total body burden of lead. Children are particularly sensitive to this metal because of their more

rapid growth rate and metabolism, with critical effects in the developing nervous system (ATSDR, 2007;

Castro-González and Méndez-Armenta, 2008).The Joint FAO/ World Health Organization Expert Committee

on Food Additives (JECFA) established a provisional tolerable weekly intake (PTWI) for lead as 0.025 mg/kg

bodyweight (bw) (JECFA, 2004). The WHO provisional guideline of 0.01 mg/L has been adopted as the

standard for drinking water (WHO, 2004).

1.4.2 Cadnium

The use of cadmium by man is relatively recent and it is only with its increasing technological use in the last

few decades that serious consideration has been given to cadmium as a possible contaminant. Cadmium is

naturally present in the environment: in air, soils, sediments and even in unpolluted seawater. Cadmium is

emitted to air by mines, metal smelters and industries using cadmium compounds for alloys, batteries,

pigments and in plastics, although many countries have stringent controls in place on such emissions

(Harrison, 2001). Tobacco smoke is one of the largest single sources of cadmium exposure in humans.

Tobacco in all of its forms contains appreciable amounts of the metal. Because the absorption of cadmium

from the lungs is much greater than from the gastrointestinal tract, smoking contributes significantly to the

total body burden (Figueroa, 2008; Ming-Ho, 2005). In general, for non-smokers and non-occupationally

exposed workers, food products account for most of the human exposure burden to cadmium (ExtoxNet,

2003). In food, only inorganic cadmium salts are present. Organic cadmium compounds are very unstable. In

contrast to lead and mercury ions, cadmium ions are readily absorbed by plants. They are equally distributed

over the plant. Cadmium is taken up through the roots of plants to edible leaves, fruits and seeds. During the

growth of grains such as wheat and rice, cadmium taken from the soil is concentrated in the core of the kernel.

Cadmium also accumulates in animal milk and fatty tissues (Figueroa, 2008). Therefore, people are exposed to


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cadmium when consuming plant- and animal-based foods. Seafood, such as molluscs and crustaceans, can be

also a source of cadmium (Castro-González and Méndez-Armenta, 2008; WHO 2004; WHO 2006). Cadmium

accumulates in the human body affecting negatively several organs: liver, kidney, lung, bones, placenta, brain

and the central nervous system (Castro-González and Méndez- Armenta, 2008). Other damages that have been

observed include reproductive, and development toxicity, hepatic, haematological and immunological effects

(Apostoli and Catalani, 2011; ATSDR, 2008).The Joint FAO/WHO has recommended the PTWI as 0.007

mg/kg bw for cadmium (JEFCA, 2004). The EPA maximum contaminant level for cadmium in drinking water

is 0.005 mg/L whereas the WHO adopted the provisional guideline of 0.003 mg/L (WHO, 2004).

1.4.3 Zinc

In the periodic table of the elements, zinc can be found in group IIb, together with the two toxic metals

cadmium and mercury. Nevertheless, zinc is considered to be relatively non-toxic to humans (Nutr J., 2016).

This is reflected by a comparison of the LD50 of the sulfate salts in rats. According to the Toxnet database of

the U.S. National Library of Medicine, the oral LD50 for zinc is close to 3 g/kg body weight, more than 10-

fold higher than cadmium and 50-fold higher than mercury [http://toxnet.nlm.nih.gov (accessed January 21,

2010). An important factor seems to be zinc homeostasis, allowing the efficient handling of an excess of orally

ingested zinc, because after intraperitoneal injection into mice, the LD50 for zinc was only approximately

four-fold higher than for cadmium and mercury (Jones; Schoenheit; Weaver, 1979). In contrast to the other

two metals, for which no role in human physiology is known, zinc is an essential trace element not only for

humans, but for all organisms. It is a component of more than 300 enzymes and an even greater number of

other proteins, which emphasizes its indispensable role for human health. Optimal nucleic acid and protein

metabolism, as well as cell growth, division, and function, require sufficient availability of zinc (Vallee and

Falchuk, 1993).

1.4.4 Copper

Copper (Cu) is an essential trace element for humans and animals. In the human organism, copper exists in

two forms – the first and second oxidation form, as most of the copper in the human organism is in the second

form. The ability of copper to easily attach and accept electrons explain its importance in the metabolism, as

well as the interaction of copper with other micronutrients is not clearly specified (Magee, AC; Matrone, G.

1960). Changes in copper concentrations in body fluids and tissues are observed in different diseases and

conditions. There are indications of serious diseases, caused by disorders of the metabolism of copper in the

organism, but the role of copper in most of them is not completely clarified (Reiser, S; Powell, AS; Yang, C;

Canary, J. 1987). Investigation of copper functions in human bodies requires accurate, affordable, informative,

low-detection-limit methods for determination of trace copper in biological samples (Williams, DM., 1983).

Although a considerable number of methods for copper investigation exist, research continues in search of

more sophisticated analytical approaches, for its determination in serum and urine, applicable in clinical

laboratory diagnostics.

Heavy metal contamination of stream and river water ecosystem is a worldwide environmental problem.

Traces of some amounts of heavy metals are always present in fresh waters from the weathering of rocks and

soils (Muwanga, 1997; Anderson, 2003; Babel and Opiso, 2007; Samarghandi et al., 2007; Igwe et al., 2008;

Al-Juboury, 2009). Recently, water quality monitoring has become a matter of concern in stream and river


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water systems affected by careless disposal of urban effluents. Runoff, atmospheric deposition and domestic

and industrial effluent discharges are the major sources of aquatic pollution (Wasswa, 1997; Linnik and

Zubenko, 2000; Campbell, 2001; Lwanga et al., 2003; Lomniczi et al., 2007) and physico-chemical

characteristics such as dissolved oxygen and the pH of aquatic ecosystems may determine stream water

ecosystem integrity. Monitoring of stream water physico-chemical characteristics and heavy metal

concentration is necessary to establish the levels of contamination in wastewater. With increasing urbanization

and industrialization, there has been a rapid increase in industrial effluent discharge into the stream water,

leading to increased pollution load. In aquatic eco-systems, traces of elements may be immobilized within the

stream water and may involve complex formation and co-precipitation as oxides and hydroxides of Fe, Mn or

may occur in particulate form (Awofolu et al., 2005; Mwiganga and Kansiime et al, 2005; Srivastava et al.,

2008).

The stream is the major recipient of runoff and a surrogate end point for organic substances of industrial and

domestic effluents (Kansiime et al., 1995; Sentongo, 1998). The stream is increasingly being polluted with

direct discharge of raw industrial effluent, untreated sewage and wastewater from commercial, industrial and

domestic establishments. The streams are important because they are constructed primarily to minimize

flooding in the cities, but they can also be used for fishing, farming, washing and as a source of drinking water

(Sekabira et al., 2010). In the up streams, the flow rate is very low and water in the channel has a dark colour

characterized by bad odour of decaying organic matter during dry periods.

1.5 Legislations and standards on water quality

Historically, sewage has been discharged in raw or partially treated form, throughout falls into the receiving

waters, which could be sea, lake or river. Attempts have increasingly been made by several nations to regulate

or control the sewage discharges into the receiving waters in order to limit the negative effects. These attempts

and their implementations have, however, varied from nation to nation depending on both economic and

technological state of the country. The water quality standards and regulations do not vary between countries

and international organisations with interest in water quality and safety but all have common objective to

reduce or eliminate pollution (Monica, 2003). The water quality regulations can be considered from pollution

control and water- usage. Standards are usually made in reference to designated uses of the water such as

farming of fish, shellfish , wildlife , recreation , drinking and use in the food industry. Water quality standards

and guidelines should be regarded as tools for sound water resource management, rather than an automatic

assurance of good water quality.

Gulu is a fast growing town with many industrial units. However, waste disposal and management is still poor

as anything that looses value is dumped into the environment without sorting and separation. When it rains all

these wastes (industrial, domestic, and municipal) are washed away through the drains and find their way into

the Pece stream. This Stream is one of the easily accessed sources of water for the rural population of Gulu.

These effluents contain pollutants that can have deleterious consequences on the ecological balance and

functioning of the receiving environment as well as the public health of downstream end users of polluted

sites. There is need therefore to monitor these effluents for safety assessment of the environment and human


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health in particular. The purpose of this study was therefore to establish the full extent to which this stream

water may be contaminated with both heavy metals and other nutrients.

2.0 MATERIALS AND METHODS

2.1 Sampling and sample preparation

Gulu town is the biggest town in northern Uganda. It is the commercial and administrative centre of Gulu

District. The town is located at 2˚46'48N 32˚18'00E. The distance from Gulu to Kampala, Uganda's capital and

largest city, is approximately 200 miles (320 km) by road. The town is served by Gulu Airport and a railway

line. As you may know it has been through 23 years of war but now it is rebuilding and the population has

increased to about 150,000 people. Pece stream is located in the Eastern part of the Gulu Town, forming Pece

drainage (in Laroo and division) that link up Gulu town and Aswa River. Six sites were selected to represent

the water sampling sources. The research was done in between May 2011 to December 2012, for both dry and

wet season. Surface water samples were collected from six different points, 100m apart along the Pece stream.

The samples were collected using 1000 ml plastic containers. At each sampling site the containers were

cleaned and rinsed several times with the stream water before use. The water was filtered within a few hours

of sampling and stored at room temperature (25oC) until analysis.

Water samples (1L) from each site were evaporated to dryness. Concentrated nitric acid (10 ml), per-chloric

acid (2 ml) and hydrofluoric acid (4 ml) were consecutively added to the residue. The mixture was then heated

again to dryness; the final residue was reconstituted in hydrochloric acid (2 ml, 2M), transferred to a 25 ml

volumetric flask and made to the mark with deionized water. The solution was then analyzed for the heavy

metal concentration using an atomic absorption spectrophotometer (AAS)


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Figure. 1: Map of Uganda showing location of Gulu district


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Figure 2. Sampling sites in Pece Stream.

2.2. Analytical procedures

2.2.1. Determination of heavy metals and total suspended matter

Water samples (1L) from each site were evaporated to dryness. Concentrated nitric acid (10 ml), per-chloric

acid (2 ml) and hydrofluoric acid (4 ml) were consecutively added to the residue. The mixture was then heated

again to dryness; the final residue was reconstituted in hydrochloric acid (2 ml, 2M), transferred to a 25 ml

volumetric flask and made to the mark with deionized water. The solution was then analyzed for the heavy

metal concentration using an atomic absorption spectrophotometer (Perkin-Elmer, Model 2380)

2.2.2. Quality Control

To test the efficiency, or to obtain fortified sample recoveries of the techniques used, pure standard 1 × 10−4 M

aqueous solutions of each of Cu2+, Zn2+,Cd2+ and Pb2+ were prepared by dissolving requisite amounts of

soluble salts of the metals in de-ionized water. 500 ml of the solution was then subjected to a similar treatment

as described in section 3.2.1. Recoveries of 71–82% were obtained, which lent support to the reliability of the


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technique used. Consequently, no adjustment was made in the heavy metal data since the recoveries were

>70%. Further, analytical blanks were prepared by repeating the respective digestion procedures, minus the

samples, and subsequently used to determine the instrument detection limits. In each case a read-out from the

screen was taken as the concentration of the selected metals.

2.2.3. Determination of Electrical Conductivity

Electrical conductivity was determined by HANNA conductivity meter (model H1991000) following the

procedure of Richard (1954) (Richard, 1954; Amin et al., 2010; Olajumoke et al., 2010). The conductivity

meter electrode was dipped in each of the samples and the values were read out from the screen. Thorough

rinsing and drying was ensured.

2.2.4. Determination of pH

pH was measured by HANNA pH meter (model H1991000) which was calibrated first by standard buffer

solutions. The calibration graph was plotted as shown in Appendix B.

2.2.5. Determination of water hardness

Sample (50ml) was put into a 250 ml conical flask followed by ammonia buffer solution (1ml) of pH 10 and

Eriochrome black T indicator. The mixture was titrated with 0.01M EDTA solution until the colour changed

from red-wine to blue. Hardness was calculated using the following formation.

Hardness= Volume of EDTA x 1000

Volume of sample

2.2.6. Determination of total suspended solids

The total suspended solids in the water samples were determined by pouring carefully measured water

(typically l00 ml) through a pre-weighed Whatman No.40 filter paper. The filter paper and its contents were

then dried at 105 °C to constant weight. The gain in weight was taken to be the dry weight measure of the

particulates present in the water sample. Total suspended matter was then determined by the following

formula (Anon, 1992).

TSS mg /1=(final weight — initial weight)/volume of sample x 1000.

2.2.7. Determination of the Chemical Oxygen Demand (COD)

The COD was determined using potassium dichromate in the presence of concentrated sulphuric acid, mercury

(II) Sulphate and Silver Sulphate Catalysts. The mixture was digested in a Hach COD reactor. The amount of

Cr3+ determined after complete oxidation was used as an indirect measure of the organic content of the water

sample. To 15m1 COD digestion tubes (prewashed with dilute sulphuric acid), was added 1.00 ml of the waste

water sample. 2.5m1 of 0.0167M standard potassium dichromate was added followed by 3.5m1 of

concentrated sulphuric acid reagent (containing silver sulphate and mercury sulphate). The tubes were capped

and the contents were mixed. The tubes were transferred to the preheated COD digester at 150°C and digested

for 2 hours. The contents of the COD digestion tubes, each were transferred into a beaker followed by 50 ml


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of distilled water. 2 drops of ferroin indicator were added and the mixture was titrated against 0.05M ferrous

ammonium sulphate solution.

Three blanks were run by substituting distilled water for the sample. COD as mg O2/1 was calculated using the

formula (A-B) x M x 8000 where:

Volume of the sample

A is the volume of ferrous ammonium sulphate used for the blank.

B is the volume of ferrous ammonium sulphate used for the sample.

M is the molarity of ferrous ammonium sulphate.

3.0 RESULTS AND DISCUSSION

The levels of pollution downstream (when the stream is traversing through the town) are higher than those

upstream (before the stream approaches the town). This clearly indicates that the Gulu town effluent affects

the water quality of Pece stream. Results show that the river gets polluted most during the rainy season

probably because the rate of runoff is high. Meanwhile the results from the control site (Nakaseke) in Table

14, is very low compared to the one from the study site (Pece stream), indicating that there was much

pollution in urban streams compared to rural streams.

3.1 Heavy metals

The results were obtained for the metals; zinc, lead, copper and cadmium in both the dry and rainy seasons for

the two years 2011 and 2012. All the tolerances in the observed metal levels were computed and quoted as

standard deviations (*SD). The results indicated that the total heavy metal content in the river was significant

and is likely to increase. This was probably due to a number of factors, notable among which were the

increasing population density and the associated waste-water output in the Gulu town. In general the heavy

metal content in the untreated effluent was on a gradual increase. Distribution of the metals in the water varies

widely according to the nature of the metal (Mbabazi et al., 2010).

3.1.1 Zinc

Table 1: Concentration of zinc in river Pece water during wet and dry seasons of 2011 and 2012

Average of metals(mg /L)

Metal Season P1 P2 P3 P4 P5 P6

Zn May ,2011(Rainy)

Dec, 2011(Dry)

May ,2012 (Rainy)

Dec, 2012(Dry)

0.87

0.62

0.78

0.69

0.68

0.54

0.73

0.61

0.85

0.77

0.79

0.72

0.73

0.55

0.87

0.66

0.84

0.56

0.84

0.69

0.86

0.62

0.93

0.71

Mean

(*SD)

0.74 ±

0.0060

0.64±

0.0040

0.78±

0.0039

0.70±

0.0120

0.73±

0.0118

0.78±

0.0095


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Table 2: Anova table for comparing the concentration in zinc in Pece

Source of Variation SS df MS F P-value

Seasons 0.187413 3 0.062471 20.72574 1.36274E-05

Collection points 0.056871 5 0.011374 3.773569 0.020619729

Error 0.045213 15 0.003014

Total 0.289496 23

Result in table 2 indicates that there exists a difference in the concentration of Zinc across collection points (P

< 0.05). This relationship is significant since it is associated with a small P-value as shown in the table above.

Result in table 2 further indicates that there exists a difference in the concentration of Zinc across seasons (P

<0.05). This relationship is significant since it is associated with a small P-value also as shown in the table

above.

Table 3: Concentration of Zinc in the control site (Nakaseke) during wet and Dry Seasons


Metal Season P1 P2 P3 P4

Zn May, 2011(Rainy)

Dec, 2011(Dry)

May, 2012 (Rainy)

Dec, 2012(Dry)

0.13

0.07

0.16

0.08

0.18

0.11

0.11

0.13

0.22

0.12

0.25

0.13

0.25

0.22

0.27

0.20

0.110±0.006 0.133±0.044 0.180±0.0086 0.235±0.0015

Table 4: ANOVA table for comparing the concentration in Zinc in Nakaseke

Source of Variation SS Df MS F P-value

Seasons 0.016319 3 0.00544 6.231504 0.014085

Collection points 0.036819 3 0.012273 14.05967 0.00096

Error 0.007856 9 0.000873

Total 0.060994 15


72

Result in table 4 indicates that there exists a difference in the concentration of Zinc across collection points

(P<0.05). This relationship is significant since it is associated with a small P-value as shown in the table

above. The results further indicate that there exists a difference in the concentration of Zinc across seasons

(P<0.05). This relationship is significant since it is associated with a small P-value as shown in the table

above.

Sampling PoP1 P2 P3 P4 P5 P6

Mean conce 0.74 0.64 0.78 0.7 0.73 0.78

mean conce 0.11 0.133 0.18 0.235

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

P1 P2 P3 P4 P5 P6

Me

an C

on

cen

trat

ion

of

Zn M

eta

l

Sampling Sites

Mean concentration of study

sites

mean concentration of

control sites

Figure 1: A line graph showing the mean concentration of Zn against the sampling points for both study site

(Pece stream) and control site (Nakaseke).

From the results obtained, there appears to be significant pollution of the river waters by zinc within the two

years of the research, despite being in the range of the permissible limits (WHO, 2008). From the graph above

it is clear that there is much pollution of Zinc metal on the stream water in the study site compared to the

control site. The high mean concentration at P1 (0.74 ± 0.0060) may be due to activities such as car washing-

bay which is next to the steam and also the availability of the metal work on the upper side of the road. At

point P3 there is a small path crossing the stream and the community around tend to collect and do wash their

Utensils and clothes there, that could have been the reason on the high mean concentration (0.78 ± 0.0039). It

is also observed that Zinc metals pollutes the stream water more during the wet season compared to dry

season, (Table 1). The mean concentration of Zinc during the two years of study ranges between 0.64 ± 0.0040

and 0.78 ± 0.0095, it was observed that Zinc metal pollution was moderately higher during the rainy seasons

compared to the dry seasons; this is probably due to the runoff during rainy seasons. Meanwhile on the other

hand the concentration of Zinc in the control site (Table 3) is much lower compared to the ones found in the

study site; this is clearly showing the difference in population and the kind of activities taking place in control


73

site. The population on control site is parse and no major activities taking place there, compared to the

research site.

Whereas zinc is a naturally occurring metal and was expected to be present in low levels in river water, its

presence in the river water is most probably due to several factors. Currently, the building construction

industry has increased tremendously in the town, with an extraordinary demand for wall and roof paints, most

of which are zinc-based. The result is an increased release of zinc into the urban environment, which finds its

way into the municipality’s major drainage system and on to the stream. Zinc-coated corrugated iron sheets,

the commonest roofing material in the country, on corrosion release considerable amounts of zinc as its oxide

or sulphide into the soil, the leaching of which concentrates the metal in the water body via surface ‘run-off

and other processes. This is perhaps not too surprising considering that for over a century the major roofing

material in Uganda has been and continues to be galvanized iron. It is possible that the oxides and sulphides of

zinc presumably subsequently dissolve in the various corrodents in urban effluent and release the heavy metal

mainly in its cationic form. There is a growing shift, however, to the use of fired clay roofing tiles particularly

for suburban residential housing. This has precipitated an excessive demand and availability for wall and roof

paints, most of which are zinc-based (Mbabazi, et al., 2010). According to (Mwamburi, 2015), Zn is

geochemically associated in most occurrences and its mobility may be reduced in alkaline conditions and

precipitated in conditions of high abundance of carbonate and phosphates in water.

Zinc is also extensively used in the manufacture of dry cells that are commonly used as chemical sources of

electrical energy to operate radio sets, electric searchlights, remote controls, calculators, microphones,

loudspeakers, etc. When they are spent, these dry cells are simply discarded into the environment (Mbabazi, et

al., 2010). In a crowded town of over 150,000 people such throw-away cells could easily number in their

thousands each day and that is a considerable amount of zinc concentrated on a land area of only a few km2.

All this eventually drains into the nearby river. It is recommended that a policy on collection of used dry cell

batteries would be a great improvement.

3.1.2 Copper.

Table 5: Concentration of Copper in River Pace Water during Rainy and Dry



Cu May ,2011(Rainy)

Dec, 2011(Dry)

May ,2012 (Rainy)

Dec, 2012(Dry)

0.08

0.05

0.14

0.08

0.09

0.07

0.11

0.07

0.09

0.05

0.09

0.07

0.05

0.03

0.03

0.03

0.04

0.05

0.04

0.04

0.03

0.04

0.06

0.05

Mean 0.088±

0.0054

0.085±

0.0016

0.075±

0.0018

0.035±

0.0011

0.042±

0.0072

0.048±

0.0016


74

Table 6: Concentration of Copper in the controlled site (Nakaseke) during Rainy and Dry Seasons of 2011 and

2012

Average of metals (mg /L)


Cu May ,2011(Rainy)

Dec, 2011(Dry)

May ,2012 (Rainy)

Dec, 2012(Dry)

0.07

0.05

0.06

0.05

0.06

0.04

0.03

0.04

0.03

0.05

0.05

0.07

0.05

0.03

0.04

0.04

0.058±

0.0001

0.043±

0.0001

0.050±

0.0019

0.040±

0.0001

Sampling SitP1 P2 P3 P4 P5 P6

Mean Conce 0.088 0.085 0.075 0.035 0.042 0.048

Mean Conce 0.058 0.043 0.05 0.04

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

P1 P2 P3 P4 P5 P6

Me

an

co

nce

ntr

ati

on

Cu

Me

tal.

Sampling Sites

Mean Concentration of

the Study Site

Mean Concentration of

the Control site

Figure 2: A line graph showing the Mean Concentration of Cu against the Sampling Points for both Study site

(Pece Stream) and Control Site (Nakaseke).

Copper in the samples (Table 5) gave mean total concentrations between 0.0880±0.0054mg1-1 and

0.0420±0.0072mg/l during the two consecutive years of the study. The concentration mean decreases as the

stream moves downward, this may be because of accumulation of metal ions along the river bed. There was

also an observable increase of mean concentration of copper between the two seasons in on both the two years


75

of study, with rainy seasons having a higher mean concentration than the dry seasons. Copper was more or

less evenly distributed among all the sites, with the total metal concentrations lying in the range 0.0—0.14

mg/l over the entire study period. On the other hand the concentration of copper on the controlled site

(Nakaseke) is very minimal compared to the one found in the study site, this is possibly because of the low

population in the area and the activities carried out there. For all the samples, the values obtained were within

the maximum permissible limit of NEMA (2006) drinking water standards (Appendix A). The presence of

elevated copper concentrations in the water along the Pece stream in Gulu town may at first sight not be easily

understood. For, unlike Jinja town, located at the source of the Nile on Lake Victoria, where the presence of a

copper-smelting plant for the copper ore from the Kilembe mines in western Uganda in the 1960s is usually

blamed for the relativity significant levels of copper in the surrounding lake waters (Mbabazi et al., 2010),

there does not seem to be any immediate sources of copper in Gulu. However increased usage of imported

electrical copper wire and cables in the town leaves on a daily basis a considerable amount of waste metal in

the form of bits, chippings and cut-offs. Metallic copper washed down in the run-offs subsequently dissolves

in the fluctuating acidities and alkalinities of the effluent.

Together these factors were presumed to be partly, if not wholly, responsible for maintaining the levels of

copper in the stream water at fairly steady, but not declining, values over the study period. Besides, the use of

copper pipes for running water in the town and surrounding areas should not be underestimated.

3.1.3 Lead

Table 7: Concentration of Lead in River Pace Water during Rainy and Dry Seasons of 2011 and 2012



Pb May ,2011(Rainy)

Dec, 2011(Dry)

May ,2012 (Rainy)

Dec, 2012(Dry)

0.03

0.02

0.01

0.02

0.04

0.03

0.03

0.01

0.03

0.02

0.04

0.03

0.05

0.03

0.03

0.03

0.04

0.05

0.04

0.04

0.03

0.04

0.06

0.05

Mean 0.020±

0.0012

0.028±

0.0016

0.030±

0.0082

0.035±

0.0011

0.043±

0.0003

0.045±

0.0014


76

Table 8: ANOVA table for comparing the concentration of Lead in Pece

Source of

Variation SS df MS F P-value

Rows 0.000167 3 5.56E-05 0.526316 0.670886

Columns 0.001783 5 0.000357 3.378947 0.030452

Error 0.001583 15 0.000106

Total 0.003533 23

Result in table 8 indicates that there exists a difference in the concentration of lead across collection points (P

> 0.05). However, this relationship is not significant since it is associated with a very large P-value as shown

in the table above. Result in table 2 indicates that there exists a difference in the concentration of lead across

seasons (P < 0.05). This relationship is significant since it is associated with a very large P-value as shown in

the table above.

Table 9: Concentration of Lead in the controlled site (Nakaseke) during Rainy and Dry Seasons of 2011 and

2012



Pb May ,2011(Rainy)

Dec, 2011(Dry)

May ,2012 (Rainy)

Dec, 2012(Dry)

0.01

0.00

0.00

0.00

0.00

0.01

0.02

0.00

0.00

0.00

0.00

0.01

0.01

0.00

0.01

0.00

0.003±

0.0002

0.008±

0.0003

0.003±

0.0002

0.005±

0.0021

Figure 1: A line graph showing the Mean Concentration of Pb against the Sampling Points for both Study site

(Pece Stream) and Control Site (Nakaseke).


77

Sampling SiP1 P2 P3 P4 P5 P6

Mean Conce 0.02 0.028 0.03 0.035 0.043 0.045

Mean Conce 0.003 0.008 0.003 0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

P1 P2 P3 P4 P5 P6

Me

an C

on

cen

trat

ion

Of

Pb

Me

tal

Sampling Sites

Mean Concentration

of the Study Site

Mean Concentration

of Study Site

The total lead concentrations in the samples (Table 7) were <0.003 mg/l. In fact, the findings from the study

showed that lead was detected at very lower concentrations from most of the samples both in the dry and the

rainy seasons and even in the controlled site as well, even though the mean concentration increases from P1 to

P6. However, for some samples the maximum concentration was 0.06 mg/l which is within the WHO (2008)

permissible limits (Appendix A). The presence of this lead in the river waters either as free cations or as

associations with organic matter could be attributed to several factors, which include the continued use of

lead-based paints for face-lifting buildings in the town and their inappropriate disposal. In addition, there is

poor management of industrial and municipal waste. Car washing and emptying of dead lead- acid

accumulators regularly takes place directly along the streams and channels leading to the river (Mbabazin et

al., 2010) and even along the river itself especially on a bridge which is along Kitgum- Juba road, 200 meters

from the town center. The untreated lead laden effluent discharges directly into the river waters. From the turn

of the century, the volume of motor vehicles on Gulu roads has greatly increased on the busy streets. Although

unleaded petrol is available at fuel pump stations in the country, a number of operators and drivers do not

insist on it. As a result, most car engines and numerous small electric generators still run on leaded fuel for

hours in the end, emitting exhaust fumes and as they do so, these emissions often result in the usual associated

respiratory problems, more so in the dry windy season of January- March. The slow aerial deposition of lead,

coupled with the run-off incorporating, particulates from the internal combustion of the leaded fuel is another

part of the problem. The gradual shift to the use of unleaded petrol should lead to a reduction or elimination of

the release of lead into the urban atmosphere.

3.1.4 Cadmium

The results were obtained for cadmium metal for both the dry and rainy seasons for the two years of study,

2011 and 2012 as shown in table 10. All the tolerances in the observed metal levels were computed and quoted

as standard deviations. The results indicated that the cadmium metal content in the river was low but is likely

to increase. This was probably due to a number of factors, notable among which were the increasing

population density and the associated waste-water output in the Gulu town. In general the cadmium metal

content in the untreated effluent was on a gradual increase.


78

Table 10: concentration of cadmium in Pece stream water during rainy and dry seasons



Cd May,2011(Rainy)

Dec, 2011(Dry)

May ,2012 (Rainy)

Dec, 2012(Dry)

0.00

0.00

0.01

0.00

0.00

0.00

0.001

0.00

0.01

0.00

0.00

0.00

0.00

0.00

0.00

0.01

0.00

0.01

0.01

0.00

0.01

0.00

0.00

0.01

Mean

(*SD).

0.0025±

0.0002

0.0003±

0.0001

0.0025±

0.0002

0.0025±

0.0002

0.005±

0.0021

0.005±

0.0021

Table 11: ANOVA table for comparing the concentration in cadmium Pece channelized stream

Source of

Variation SS Df MS F P-value

Rows 1.25E-05 3 4.17E-06 0.151515 0.927096

Columns 7.08E-05 5 1.42E-05 0.515152 0.760879

Error 0.000413 15 2.75E-05

Total 0.000496 23

Result in table 11 indicates that there exists a difference in the concentration of Cadmium across collection

points (P > 0.05). However, this relationship is not significant since it is associated with a very large P-value

as shown in the table above. The result in table 11 indicates also that there exists a difference in the

concentration of Cadmium across seasons (P> 0.05). This relationship is also not significant since it is

associated with a very large P-value as shown in the table above.


79

Table 12: Concentration of Cadmium in the control site (Nakaseke) during rainy and dry seasons

Season P1 P2 P3 P4

May

,2011(Rainy) 0.000223 0.000233 0.00021 0.00021

Dec, 2011(Dry) 0.0000123 0.0000113 0.0000112 0.000012

May ,2012

(Rainy) 0.000013 0.000015 0.00001125 0.000013

Dec, 2012(Dry) 0.000004 0.0000011 0.00001111 0.0000112

Mean and

(*SD).

0.000107±6.31E-4

0.000112±6.51E-4

9.94E-05±6.41E-4

9.9E-05±6.12E-4

Table 13: Comparison of Cd concentration in study and control sites using ANOVA

Source of

Variation SS df MS F P-value

Rows 1.3E-07 3 4.35E-08 935.8268 1.52E-11

Columns 4.2E-11 3 1.4E-11 0.301024 0.823999

Error 4.18E-10 9 4.65E-11

Total 1.31E-07 15

Result in table 13 indicates that there exists a difference in the concentration of Cadmium across collection

points, (P < 0.05). This relationship is significant since it is associated with a small P-value as shown in the

table above. Result in table 13 also indicates that there exists a difference in the concentration of Cadmium

across seasons, (P> 0.05). This relationship is not significant since it is associated with a very large P-value as

shown in the table above.


80

Figure 1: mean concentration of cd at sampling points for both study and control site

Cadmium was detected at very low levels in all the samples with the highest mean concentration being 0.005 ±

0.0021 at P5 and P6 and the lowest 0.0003±0.0001 which is below the water quality standards(Amanatidou et

al., 2007) for all seasons, while on the control site (Nakaseke) there was a very low detection in almost all the

samples which may be attributed by the low population in the area. The lower concentration on the study site

probably can be attributed to the fact that the small-scale metal work activities could still be at a stage where

the amount of cadmium is still below the detectable limits(Sekabira, Origa, Basamba, Mutumba, & Kakudidi,

2010). The continued use of artificial fertilizers in the agricultural river basin enhances the presence of Cd in

the waters as a result of drainage, arising from heavy equatorial rainfall, into the stream. According to (Mead,

2010) cadmium is widely used in plastics and paints.

Uganda relies heavily on scrap metal from old cars, rusty steel doors, windows, corroded roofing iron and,

occasionally, rail steel girders(Mbabazi et al., 2010). Traces of cadmium embedded in the scrap iron and steel

are released to the environment in the effluent and run-off. If this continues, soon cadmium levels will soon be

detected. Further, cadmium is widely used in paints, and, owing to the booming construction in the town, there

is a considerable release of the metal into the environment via the associated painting and face-lifting of

buildings. According to (Alessandria et al., 2012; Hutton, 1987; Monteiro, et al., 2011), cadmium has been

blamed for large-scale poisoning incidents in industrial workplaces, particularly where any ore is being

processed or smelted and among welders who have unsuspectingly welded on cadmium-containing alloys or

working with silver.

The total cadmium concentration levels at various sites along the Pece Channelized stream during the rainy

May seasons and the December dry seasons of 2011 and 20012 respectively are shown in table 1, which

includes the mean total concentrations (±SD) in the effluent water. This time was chosen primarily due to

frequent torrential runoffs from the municipality and increased total volumes of effluent and leachates.


81

Under Ugandan law in section No. 153-4 (National Environment Management Authority, 2004) requires that;

(1) ‘Every industry or establishment shall install at its premises anti-pollution equipment for the treatment of

effluent chemical discharge emanating from the industry or establishment’, and that (2) ‘Antipollution

equipment installed, under Regulation 1 shall be based on the best practicable means, environmentally sound

practice or other guidelines as the Executive Director may determine.’ Under S.I.153-6 (National

Environmental Management Authority, 2004)of the same law, ‘any person who contravenes these regulations

commits an offence and is liable, on conviction, to imprisonment for a term not exceeding eighteen months or

to a fine not less than one hundred and eighty thousand shillings and not more than eighteen million shillings

or both. In spite of this, however, only the Nile Breweries Industry at Jinja seems to be taking serious steps

towards pre-treatment of effluent before discharge into a water body (Mbabazi, et al., 2010).

3.2 Physicochemical Parameters (pH, Conductivity, Hardness of water, TSS and COD)

3.2.1 pH

pH is a term used universally to express the intensity of the acid or alkaline condition of a solution (Murhekar,

2011). pH is a function of dissolved materials in water and should be less than 8.50 (USEPA, 2002). The

average pH of the filtered water samples (Table 14) at 25°C was ranging from 7.04 ± 0.0011 to 7.24 ± 0.0008

for the two years of the study. In spite of the direct seepage of the untreated municipal effluent, into the stream

waters, these ranges are in line with the WHO (2008), US — EPA (2005) and NEMA (2004) (Appendix A).

There was a generally decrease in average pH in the dry season compared to the rainy season (Table 14). The

relatively lower values of pH in the rainy season could be due to a combined effect of the effluent and

incoming fertilizers such as calcium ammonium nitrate and urea from the farming areas due to run off (Phiri

et al., 2005).

3.2.2 Electrical Conductivity (ec)

Electrical conductivity is a measure of water capacity to convey an electric current. It signifies amount of total

dissolved salts (Sudhir and Amarjeet, 1999). Electrolytic conductivities (Table 5.1) were comparatively high,

with the mean values ranging between 226.3± 0.0352 and 232.5± 0.0048 in both the rainy seasons and dry

seasons of the two years of study, more than 200-fold that of pure distilled deionized water. This suggested a

presence of more soluble ionic substances, among them metallic hydroxides, carbonates and hydrogen

carbonates that would in tend to buffer the waters against excessive intrusive acidities and alkalinities.

Although the figures shows small deviations in the two seasons, solubilisation of heavy metals in the water

may occur as cationic, anionic, non-ionic (dialyzable) and non-ionic (non-dialysable) modifications. The

existence of the metals in non-ionic and non-dialysable forms is attributable to metal associations with high

relative molecular mass (RMM) organic matters (Mbabazi et al., 2010). There was dilution of the salts arising

from the increased water volumes in the river (Phiri et al., 2005).Values obtained for the samples were within

the permissible limits of USEPA(2005) 400 µScm-1), WHO(2008)300µS/cm and NEMA(2004) 400µScm-

1(Appendix A),(Rahman, 1997).


82

Table: 14: Changes in pH, conductance, hardness, TSS and COD of surface water of the Pece Stream.

Parameters Season P1 P2 P3 P4 P5 P6

pH

May,2011(rainy)

Dec,2011 (dry )

May,2012(rainy)

Dec, 2012(dry)

6.72

7.33

6.79

7.40

6.88

7.42

6.65

7.19

6.93

7.27

6.92

7.20

6.80

7.39

6.97

7.29

6.94

7.44

6.85

7.42

6.98

7.45

7.00

7.51

Mean 7.06±

0.0067

7.04±

0.0011

7.08±

0.0017

7.09±

0.0265

7.16±

0.0076

7.24±

0.0008

Electrical

Conductivity

(µS/cm)

May,2011(rainy)

Dec, 2011 (dry)

May,2012(rainy)

Dec 2012 (dry)

230

223

236

220

223

227

230

225

228

228

231

238

225

234

226

232

231

232

232

235

227

229

226

233

Mean 227.3±

0.0351

226.3±

0.0352

231.3±

0.0139

229.3±

0.0180

232.5±

0.0048

228.8±

0.0343

Hardness

(mg/L as

CaCO3)

May,2011(rainy)

Dec, 2011 (dry)

May,2012(rainy)

Dec, 2012 (dry)

96

94

93

100

102

100

98

96

106

101

95

98

104

97

101

99

108

98

99

99

111

105

102

95

Mean 95.8±

0.0125

99.0±

0.0252

100.0±

0.0825

100.3±

0.0167

101.0±

0.0817

103.3±

0.1106

Total

Suspended

Solids(TSS)

(mg/)

May,2011(rainy)

Dec, 2011 (dry)

May,2012(rainy)

Dec 2012 (dry)

0.099

0.051

0.102

0.047

0.103

0.046

0.100

0.048

0.101

0.051

0.099

0.048

0.102

0.053

0.102

0.049

0.101

0.052

0.099

0.049

0.100

0.046

0.102

0.050

Mean 0.075±

0.0041

0.074±

0.0051

0.075±

0.0039

0.077±

0.0037

0.075±

0.0042

0.075±

0.0041

Chemical

Oxygen

Demand

May,2011(rainy)

Dec, 2011 (dry)

May,2012(rainy)

120.00

90.00

120.00

140.00

100.00

140.00

135.00

101.00

160.00

169.00

97.00

171.00

130.00

98.00

150.00

131.00

102.00

152.00


83

3.2.3 Hard Water

Hardness is the property of water which prevents lather formation with soap and increases the points (Trivedy

and Goel, 1984). Hardness mainly depends upon the amount of calcium or magnesium salts or both

(Murhekar, 2011). The levels of average hardness (Table 14) were between 95.8 ± 0.0125 and 103.3± 0.1106

mgl-1of CaCO3 respectively in both the rainy seasons and dry seasons of 2011 and 2012 respectively, as

compared with the WHO(2008) l00 mgl-1 and USEPA(2005) l00 mgl-1 permissible limits (Appendix A).

People with kidney and bladder stones should avoid high content of calcium and magnesium in water

(Olajumoke et al., 2010), Water has been classified on the basis of hardness as follows: water having (0 — 75)

mgl-1 ‘of CaCO3 as totally hard as soft, for (75— 150) mgl-1 of CaCO3 as hard and for 300 mgl-1 of CaCO3 as

totally hard (Adeyeye and Abulude, 2004). Therefore basing on this, water in Pece stream varies between

moderately soft and hard for almost all the water samples. Activities such as farming, bathing and washing of

clothes by villagers along and around the stream could also account for the relatively high levels of hardness.

3.2.4 Total suspended Solids (TSS)

water must be free from disease causing organisms, poisonous substances and amount of minerals and organic

matter, and certain levels of minerals and dissolved are allowed(WHO, 2008). The levels of the Total

suspended solids (TSS) (Table 14) were in the range of 0.074 ± 0.0051to 0.077± 0.0037 mg1-1 in the both the

wet and dry seasons. It was observed that there was a general increase in the average levels of the total

suspended solids (TSS) during rainy seasons compared to dry seasons (Table 4.8). The values obtained for all

the samples were within WHO/USEPA, 2005 (0 -5 mgl-1) permissible limits (Appendix A).In the dry season

the levels of the total suspended solids were lower and this can be attributed to the fact that the water was free

from materials that could be brought into the river through runoff (Phiri et al., 2005). In the rainy season, the

degree of runoff is high and this is the reason for the increased levels of total suspended solids (TSS).

3.2.5 Chemical Oxygen Demand (COD)

Chemical oxygen demand (COD) or Biochemical oxygen demand (BOD) is used for estimating the

concentration of organic matter in waste water (Aremu et al., 2011). COD is an oxygen demand to decompose

the biodegradable as well as non-biodegradable organic waste (Vinit et al., 2011). Polluted water contains low

levels of dissolve oxygen (DO) as a result of heavy biological oxygen demand (BOD) and chemical oxygen

demand (COD) placed by effluents waste materials discharged into surface water. The values of COD (Table

14) ranged from 107.5 ± 0.7820 to 134.3 ± 4.634 mg (O2)l-1 in both the dry seasons and rainy seasons for the

two years of the study. For all the water samples the values of COD obtained were above the maximum

(mgO2l-1) Dec 2012 (dry) 100.00 96.00 99.00 100.00 95.00 91.00

Mean 107.5±

0.7820

119.0±

1.847

123.8±

2.520

134.3±

4.634

118.3±

2.146

119.0±

2.398


84

permissible limits according to WHO (2008) 10 - 20 mg l-1and USEPA (2005)10 mg l-1 (Appendix A).

However some samples from the sampling points gave values which were within the maximum permissible

limits of NEMA (2004) 100 mgl-1 drinking water standards (Appendix A). High values of COD make the

water to have objectionable odour, render the water unfit for domestic purpose and reduce oxygen available

for organisms. The values of COD show a very high concentration of organic material.

4.0 CONCLUSION AND RECOMMENDATIONS

4.1 Conclusions

Heavy metal element concentrations in Pece stream water in Gulu Municipality were mainly within the

permissible limits according to e.g. WHO, USEPA and NEMA limits and criteria (Appendix A). However,

there was significant water pollution on the stream and this might have been due to the increasing swept-out

effluents along different drains into the Pece Stream and extensive water use like washing of the vehicles’

along the stream , the quality of the stream water is exposed to deterioration. It was also found that pollution

were moderately high during the rainy seasons compared to the dry seasons. The values of the total suspended

solids (TSS) obtained for all the samples were within WHO/USEPA (2008) maximum permissible limits

meanwhile in all the water samples the values of COD obtained were above the maximum permissible limits

according to WHO (2008) and USEPA (2005).

The heavy metal concentrations in the stream sediments were significant, but varied among sampling points.

Even though the heavy metal pollution were in a small extend within the maximum permissible limits of

NEMA (2006), WHO (2008) and USEPA (2005) there are signs that, the concentration will go up due to

increase population and construction site taking place in the town. I would suggest that special attention must

be given to the issue of element re-mobilization, because a large portion of elements in sediments are likely to

release back into the water column. Special attention should also be paid to mitigate pollution from these

sources as their effects may become significant during seasons and years of low water flow in the stream.

Therefore, constant monitoring of the Pece stream water quality is needed to record any alteration in the

quality and mitigate outbreak of health disorders and the detrimental impacts on the aquatic ecosystem.

4.2 Recommendations

• Dumping of wastes and municipal effluents into Pece stream should be regulated to limit pollution.

Solid wastes from the town should be taken and buried at landfills far away from the stream.

• Studies should be done to determine heavy metals in sediments, plants and animals growing in this

stream.

• There is need if possible, to install a treatment plant for all the municipal wastes so that they are treated

before they are dumped into the river.


85

ACKNOWLEDGEMENT

The authors wish to thank Kampala International University for financial support during his MSC – Chemistry

studies.

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APPENDIX A

WHO, USEPA AND NEMA, WATER QUALITY STANDARDS

Parameters WHO(2008) USEPA(2005) NEMA(2004)

EC (µS/cm 300 400 400

pH 6.5 – 9.2 6.0 – 8.5 6.0 – 8.0

TSS (mgl-1) 5 0 - 5 5

COD (mg(O2)l-1 10 - 20 10 100

Zinc (mg/l) 5 5 5

Copper (mg/l) 1.0 1.3 1.0

Cadmium (mg/l) 0.01 0.05 0.1

Lead (mg/l) 0.05 0.05 0.1

impact of municipal effluent on the water quality of pece stream...

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