MARINE WATER POLLUTION MONITORING CASE STUDY OF MOMBASA COASTLINE KENYA

ABSTRACT

The increase in human population has resulted in natural resource depletion and the enormous production of wastes filling the dumpsites and landfills in high rates. There is a considerable harmful effect emanating from wastes which destroy the ecological set up of our ecosystems. Toxic substances are released into our natural systems; they can be consumed by organisms and may end up in the human food chain at higher concentrations. Pollution in the oceans is a major problem that is affecting the ocean and the rest of the world. When dealing with marine pollution, sewage is one of the problems that have become increasingly difficult to contend with. Poor management of sewage treatment and dumping of untreated sewage is threatening the very lives of thousands of poor people who ironically make a significant contribution to sewage discharge.

This study investigated the effects of sewage discharge on nutrient concentration. The study was carried out in the month of December in Makupa, Mtwapa and Tudor creeks in Mombasa to investigate the impact of sewage pollution on the marine ecosystem and Gazi creek used as the reference site. Samples collected were analyzed spectrophotometrically to determine the level of nitrates, ammonia and phosphates as a result of nutrients loading.

The results obtained show that nutrients concentration were found to be high in Tudor creek, mean were (see table 2). Concentrations were lowest Mtwapa among the sewage impacted sites. Makupa had intermediate mean concentrations. Gazi was used as a standard in this research since it is the least impacted creek.

CHAPTER 1

1.0 INTRODUCTION

The importance of marine is acknowledged worldwide. Coastal fisheries play a pivotal role in the livelihoods and culture of many coastal communities. More than one third of the world’s populations live in the coastal zones which is just a narrow strip constituting only 4% of the total land surface (UNEP, 2006). Rapid increase in population, food production, urbanization and coastal development in most of the world’s coastal regions are causing serious environmental concern such as marine pollution (Looser R Froescheis, 2002).

(Clark R B, Frid C and Attril M, 2001) , Identified oil, sewage, garbage, chemicals, radioactive waste and thermal pollution as some of the most common types of pollution in the marine ecosystems. Approximately 80% of pollution originates from land based sources that reach estuaries and coastal water via non point runoff, direct deposit of waste and atmospheric fallout (GESAMP, 2001). Despite this significant contribution of land based activities to coastal pollution, it has not been adequate attention (GESAMP, 1990).

Most eutrophication and organic loading problems in coastal regions in the world are linked to discharge of sewage effluent and dumping of sewage sludge (Subramanian B R, 1999). Coastal ecosystems serve as receptors for industrial and municipal effluents (Clark R B, Frid C and Attril M, 2001). Sewage can simply be defined as a cocktail of waste from food preparation, dishwashing, garbage grinding, toilets, baths, showers and sink. It contains a wide variety of dissolved and suspended materials as well as disease causing microorganisms. When small quantities of sewage are discharged into the ocean, a natural self-purification process occurs. However, densely populated communities generate such large quantities of sewage that dilution alone cannot avert pollution incidences.

Sewage pollution has been identified as one of the most serious of all land based threats to the marine environment and as an area where least progress has been achieved (Placeholder15; UNEP, 2006) . Between 80-90% of the sewage discharged into the coastal zone of many developing countries are untreated (UNEP, 2006). With the current population level, man has the potential to pollute every single waterway, ocean and drinking water supply with raw sewage if no urgent measures are put in place.

Sewage contaminated water introduces high levels of nutrients which cause eutrophication in the receiving water bodies. Nitrates, phosphates and organic matter found in human waste serve as food for algae and bacteria. This makes these organisms to rapidly increase in number to the point that they use up most of the dissolved oxygen that is naturally found in water, making it difficult for other organisms in such aquatic environments to live. It is a scenario of bacteria basically strangling the other organisms. Moreover, biotic communities in sewage impacted environments are commonly exposed to a multitude of contaminants (Michael J and Kennish T, 1998) and disease causing microorganisms. This situation puts human and wildlife health (Jensses B J, 2003) as well as livelihoods (from fisheries and tourism) at risk through reduction of biodiversity and productivity (Lopez-Gappa and Magaldi N H, 1990) and esthetic and intrinsic value of the marine environment especially when sewage discharge occurs into relatively shallow and sheltered coastal areas (as is the case in Kenya).

Sewage discharge is one of the main sources of coastal pollution in Kenya. Mombasa city has only one sewage treatment facility which had previously stalled for several years and is currently only working at 50% capacity after renovation works. This 50% capacity can barely serve even 12% of the Mombasa city population leading to volumes of sewage being discharged either untreated or slightly treated.

The status of coastal water is important indicator of environmental quality in terms of pollution load and related issues. The information on these aspects is important in highlighting the need for urgent planning and action in these areas. The objective of this study was to assess the levels of sewage pollution and determines its effect and fate once it is discharged into the Kenyan coastal waters.

1.2 Mombasa City

Mombasa city is located in Kenya at Coast province. It covers an area of 295km2, that is land area 230km2 and water 65km2 with elevation of 50m. According to the census results received by the Ministry of Planning and National Development; the population of the Coast Province is 3,325,307. This is a 33.7% higher than the number 10 years ago. Mombasa remains to be most populated district at the coast with 523,183 inhabitants, (NATION, 2010)(Daily Nation, September 1^st, 2010), while population density is184km2 and the time zone of EAT (UTC+3).

Mombasa is the second largest city in Kenya lying next to the Indian Ocean. It has a major port and an international airport. The city also serves as a center of the coastal tourism industry.

Mombasa is characterized by a flat topography. The town of Mombasa is a central of Mombasa Island but extends to the mainland. The mainland is separated from the mainland by two creeks that is Portreiz in the south and Tudor creek in the north.

The coastal city of Mombasa is mainly occupied by the Muslims, Mijikenda, Swahili people and inhabitants from all over the world. Over the centuries there have been many immigrants and traders who settled in Mombasa, particularly form Persia, The Middle East, Somalia, and the Indian Sub-Continent, who came mainly as traders and skilled craftsmen. Even after four or five generations, their descendants continue to contribute to the economy of the present day.

1.2.1 Geography and climate

Being a coastal town, Mombasa is characterized by a flat topography. The town of Mombasa is centered on Mombasa Island, but extends to the mainland. The island is separated from the mainland by two creeks, Port Reitz in the south and Tudor Creek in the north.

Mombasa has a warm, tropical climate. The amount of rainfall depends essentially on season. The rainiest months are April and May, while in January to February the rainfall is minimal. The coastal climate of Kenya is influenced mainly by large-scale pressure system of the Western Indian Ocean and monsoon winds. The monsoon winds blow from the northeast (Northeast Monsoon wind) between December and March and from the Southeastern (South east monsoon wind) from May to October with the one to two month transition periods characterized by variable and weaker winds.

1.2.2 Economy

Mombasa is a major trade centre and home to Kenya's only large seaport, the Kilindini Harbor. Kilindini is an old Swahili term that means "deep". The port is so called because the channel is naturally very deep. Kilindini Harbor is an example of a natural geographic phenomenon called RIA, formed millions of years ago when the sea level rose and engulfed a river that was flowing from the mainland; Transport is by Air, Train, Road, Taxi, Matatu, Tuk-Tuk, and Boda-boda, (http://en.wikipedia.org/wiki/Mombasa).

1.2.3 Population growth

The coastal city of Mombasa and its environs has in recent times been seen to have considerable industrial and population development. The rapid expansion of the region is mainly because of the Kilindini harbor, several tourist’s hotels, Bamburi cement factory, meat and food processing factories, and grain millers and stores.

The anthropogenic influence associated with these developments may lead to both direct and indirect degradation of the marine environments which causes eutrophication in the receiving water bodies. Nitrates, ammonia and phosphates found in human wastes serve as a food for algae and bacteria. This makes organisms to rapidly increase in number to the point that they use up most of the dissolved oxygen that is naturally found in water making it difficult for other organism in such aquatic environments to live. The increase in concentration of nutrients leads to eutrophication

The study is developed to make assessment in order to evaluate the prevailing situations and provide accurate information on the ocean water quality in Mombasa using pollution indicators that would give basis for appropriate waste water management practices.

CHAPTER 2

2.0 LITERATURE RIVIEW

Pollution of marine ecosystems is a worldwide problem (Mwashote, 2003, pp. 25-34).runoff from coastal urban areas feeds directly into the marine environment via storm sewers which carry a mix of materials, including silt, hydrocarbons from oil, residues from industries, pesticides and fertilizers from residential areas and coli form bacteria from animal wastes. Chlorine added to drinking water and used to treat sewage effluents as a bactericide may form a complex with organic compounds in the water to produce chlorinated hydrocarbons that are toxic in the marine environments, (Arbrust, 2008, pp. 320-329).

Many toxicants reaching the coast do not remain in the water but become adsorbed onto the small particles of matter suspended in the water column, some of which have high organic content and form a food source for marine creatures. In this way, heavy metals and organic toxicants associated with the particles finds their way into the body tissues of organism, where they may accumulate and be passed on to predators (Arbrust, 2008).Pollution in the ocean indirectly affects human health and resources.

2.1 Sources of Pollution

Main sources of pollution includes: oil spills, discharge of untreated sewage into the ocean, toxic waste and dumping of harmful materials are major sources of pollution in the ocean.

Toxic wastes are poisonous materials that are being dumped into the ocean. They harm many plants and animals in the oceans and have a huge impact on our health. Other source of pollution includes boating pollution that is pollution which more comes from the boat engine. The engine gives off excess gasoline which pollutes water and ends up killing plants and animals in the sea.

Garbage dumping which is the dumping of harmful materials into the ocean, like human waste from bathing and plastic materials. This waste enters the sea through sewage pipes. Storm water mixes with sewage, rain water makes sewage to overflow, and this mixture ends up in the ocean as runoff. This pollutes the ocean water causing death on plants and animals

Waste water needs to be treated before being released into the ocean. Human sewage consist of toilet flushing, waste water form bathing, laundry and dishwashing, animal and vegetation matter from food operation that is disposed through an in-sink garbage disposal. Because coasts are densely populated, the amount of sewage reaching sea and ocean are of particular concern because some substances it contains can harm ecosystem and pose a significant public health threat. In addition to the nutrients which can cause over enrichment of receiving water bodies, sewage carries an array of potentially disease causing microbes called pathogens

The problem associated with sewage disposal has become a major problem of the urban world due to increase in human population and urbanization. The commonality of sewage related problems throughout the coastal areas of the world is significant since these areas are inhabited by over 60% of human population. Consequently domestic waste water discharges are considered one of the most significant threats of the coastal environment worldwide (UNEP, 2006)

2.2 Impacts of Marine Pollution

Environmental effects related with domestic waste water discharges are generally local with transboundary implications in some areas.

Coastal water are facing a variety of pressure affecting both the ecosystem and human health through sewage waste water discharges and disposal practices that may lead to introduction of high nutrient loads, hazardous chemicals and pathogens causing diseases. The adverse public health, environmental, socio-economic, food quality and security and aesthetic impact from sewage contamination in coastal areas are well documented (WHO, 2003)

Pollution of the coastal water usually interferes with various water uses. Cultured bivalves are generally reared in areas that are often densely populated and are sensitive to heavy pollution from human activities.

Pathogens transmitted by human faeces are most commonly involved and the discharge of sewage polluted by human and animal pathogens into the sea represents the main source of bacterial pollution.

Every pathogen present in the water may be trapped and concentrated in the tissues of the bivalves and so represents a potential health hazard.

Legislation, directives and water quality standards for various coastal users like shell fish harvesting, recreation, drinking and aquaculture have been developed in many countries to limit problem associated with sewage. These standards are usually not realized due to poor sewerage management. Usually arises from the fact that waste water management decisions take place in complex situations governed hypothetical, bureaucratic and financial forces often interfere with the implementation of existing regulations and standards

In most cases, waste disposal decisions encounter resistance and inefficiency in the eventual administrative implementation and financial difficulties that affect the disposers’ ability to comply with the original decision.

The fact that majority of urban population depends on coastal surfaces water which are usually used for sewage disposal, in one way or another make water pollution the principle problem that requires solid waste management practices to contain impacts.

2.3 Main Sources of marine pollution

a) Solid waste dumping

Using the sea as a dump for trash and garbage was and is still a common practice around the world. Probably more than 25% of the mass of all materials dumped at the sea is dredged material from ports and waterways and one of the industrial waste disposals is dumping at the sea. Once the pollutants enter the environment they can be transported anywhere in the ocean,. Kibarani dumpsite next to Makupa creek is an example of sources of intrusion of solid waste into the marine waters.

b) Sewage effluent

The Changamwe Sewerage Treatment Plant discharges their treated sewage water directly into the ocean, the storm water runoff, tourist hotels discharges their wastes into the ocean. Other sources of pollution include discharges from municipal wastewaters facilities, power generating stations and industrial effluents.

c) Toxicants

Surface runoff from coastal urban areas feeds directly into the marine environment via storm sewers. Storm sewers carry a mix of materials including silt, hydrocarbons from oil, residues from industry, pesticides and fertilizers from residential areas and coliform bacteria from animal wastes. From rural and agricultural land, runoff finds its way through rivers and stream to the coast. These runoffs supplies pesticides and nutrients which can over fertilize the water, (Sverdrup, 2008).

d) Plastic trash

Plastics from residential places and commercial places always fill the beaches. Thousands of marine organisms are crippled or killed each year by these materials.

e) Oil spills

Human activities in the 21^stcentury depend heavily on oil and this dependence requires the bulk transport of crude oil by sea to the land based refineries and centres of use. This transport crates the potential for accidents that releases large volumes of oil and expose the world’s coasts and estuaries to spills associated with vessel casualties and transfer procedures. Because industry, agriculture and private and commercial transportation requires petroleum products, oil is constantly being released into the environment to find its way directly or indirectly to the sea, (Sverdrup, 2008).

Routes of administration to humans include:

a) Percutaneous- This is the exposure to toxicants with the skin

b) Oral-This is the exposure through the gastrointestinal tract. Toxicants within the gastrointestinal tract do not produce injury until they pass through the wall of the gastrointestinal tract and are absorbed into the blood stream, (GIRARD, 2005)

2.4 Impacts of sewage effluents

Sewage effluents have historically been discharged throughout all in-shallow coastal waters and are one of the major stresses impacting coastal ecosystem. These 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 resources issues of the 21^st century, therefore the quality status of coastal surface water is very important and would always be under public scrutiny because of health risk associated with sewage contamination.

The potential deleterious effects of pollutants from sewage effluents on the receiving water quality of the coastal environment are manifold and depend on volume of the discharge, the chemical composition and concentration in the effluents.

Example; whether it is amount of suspended solids / organic matter or hazardous pollutant like heavy metals and organochlorides and the characteristic of the receiving waters Higher levels of soluble organics may cause oxygen depletion (Peter and Robin, 2002) with negative effects on aquatic biota. Contamination of the coastal water may result in changes in nutrients levels abundance, biomass and diversity of organism, 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.

2.5 Nutrients in the Sea

Large quantities of nutrients released into the coastal water through the sewage waste water result into nutrient enrichment stimulating algal growth that in turn affects the photic zone depth, cause dissolved oxygen depletion, bioaccumulation of organic and inorganic compounds and alteration of tropic interaction among both aquatic flora and fauna Elevated nutrient levels may also result in excessive growth of algal bloom, some of which may result in production of algal toxins. The algal toxins are risks for water and sea food quality and safety (GIRARD, 2005)

2.6 Effects associated with bacterial pollution

Effects arising from bacterial pollution are many and they involve public health as well as social and economic implications. The survival of enteric bacteria in the aquatic environment has attracted interest in view of its public heath significance (Gareth Rees 1993, Nelson et al 1996).

It has been shown that filter feeding bivalves example mussels and oysters accumulate pathogens bacteria in the tissue making the shellfish unsafe for human consumption. In fact contamination from sewage discharge have resulted in close or prohibition of many shellfish areas worldwide and on the basis of this contamination some of these areas have been designated as approved, conditionally approved or unapproved areas depending on the situation.

Data are available linking waste water contaminated bathing water to swimming associated illness (Cabell 1979). Epidemiological studies have shown that there is a linear relation between microbial water quality and gastro-intestinal illnesses (Baron et al 1982, Cabell et al 1982). The damages caused by increased illness or mortality due to ingestion or skin contact with contaminated water gives rise to direct health care cost and indirect opportunity costs. (Narayana, P. 2009)

The joint Group of Experts on Scientific Aspects of Marine Protection (GESAMP, 2001) estimated the impact of bathing in and eating shellfish from polluted sea at a cost of approximately US$ 12-24 billion per year.

In Peru 1999, when the cholera outbreak was severe is an example of negative consequence that can result from poor sewage management, the abrupt halt in tourism and agricultural export cost Peruvians economy US$ 1000 million just in ten weeks. The total economic loss was more than three times the total national investment in water supply and sanitation improvement in the 1980s. Other possible effects include loss of income for fishermen, fish processing plants and loss of amenity value where the environment deteriorates.

CHAPTER 3

3.0 METHODOLOGY

3.1 Preliminary survey

A survey of the three creeks was conducted to identify the sampling sites, accessibility, activities such as the Kibarani municipal dumpsite, tourist hotels, sewage effluent points and the Kenya Meat Commission Processing plant are some of the considerations made.

3.2 The study site

The study sites sampled are Makupa, Mtwapa and Tudor creeks in Mombasa as impacted areas, whereas Gazi (located more than 55km from Mombasa city) chosen as reference or a relatively pristine area to provide or act as reference area.

The three creeks lie within 4⁰00’ and 4⁰ 04’S and 39⁰ 36’ and 39⁰42’E. Makupa creek forms part of a larger creek system in which the port of Mombasa is located to the eastern side of Mombasa Island. Tudor creek is on the eastern side of Mombasa Island and is separated from Makupa creek by a narrow strip of landfill, The Makupa causeway, (Mwashote, 2003)

The sampling sites considered include;

· Tudor creek-

Fort Jesus (FOJE)

Madubini (MBD)

Nyali Bridge (NY)

Coast general hospital (CGH)

Kenya meat commission slaughter (KMC),

Mikindani (MKD).

· Makupa creek-

Makupa mangroves (MKMA)

Makupa causeway (MKCW)

Makupa Bridge (MKBR)

Makupa channel (MKCH)

Makupa dumpsite (MKDS)

· Mtwapa creek-

Mtwapa ferry (MTFE)

Mtwapa Bridge (MTBR)

Mtwapa prison (MTPR)

· Gazi

Samples are to be collected from new and old fish laundry beaches.

FIGURE 1: map of the study area showing sampling site.

3.3 Research objectives

The objective of the study is to investigate the impact of sewage pollution on nutrient levels at Makupa, Mtwapa and Tudor Creeks.

3.3.1 Specific Objectives

· To find out are the main sources of marine pollution in the studied sites

· To find out the impact of the waste water on nutrients level

· To find out the influence of waste water pollution on primary productivity.

· To evaluate to what extend does the sewage discharges/disposal impact on the marine water quality.

· To find out if the existing water quality criteria or standards for various water uses like aquaculture, shellfish, bathing and recreation met.

· To interpret the water quality results assembled during the study.

· To determine the remediation and control measures.

· To find out the socio-economic impact of marine pollution.

· To find out management options to control marine pollution.

3.3.2 Research Questions

What are the sources of marine pollutants in Mtwapa, Makupa and Tudor creeks?
What are impacts of the waste water on nutrients level?
What are the impacts of sewage pollution on primary productivity?
To what extend does the sewage discharges/disposal impact on the marine water quality?
Are the existing water quality criteria or standards for various water uses like aquaculture, shellfish, bathing and recreation met?
What is the implication water quality results collected during the study?
What are the remediation and control measures?

· What are the socio-economic impacts of marine pollution?

· What are the management options to control marine pollution?

3.3.3. Justification of the Study

The unprecedented anthropogenic activities and the resultant environmental degradation, the ever increasing human population which increases the pressure on the natural resources which in turn increases the volume of wastes produced. The municipal solid waste contains a variety of substances which may be toxic or carcinogenic. When the leachates from the dumpsite find their way through the intrusion of the ground water into marine waters, they cause severe degradation of marine ecosystems. For instance, the domestic waste water when they enter the oceans can cause to increase in nutrient loads, that is eutrophication due to high level of phosphates in the waters and there are also heavy metals from industrial wastes, this heavy metals can be incorporated by filter feeders which may in turn be consumed by other organisms. This results into the biomagnifications of these toxic metals in the tissues of organisms higher in the tropic levels. This may cause vulnerable species become endangered or even extinct.

This study is trying to investigate the impact of introduction of waste water into the ocean on the nutrient level at Makupa, Mtwapa and Tudor creeks in Mombasa. The expected results are that the introduction of this waste leads to increase in the nutrient level and thirds in turn causes eutrophication which alters primary productivity. The study findings will assist different government ministries, research institutions, local communities and non-governmental organizations which are increasingly attempting to control the growing problems of waste water disposal and trying come up with measures to control ocean water pollution, thus measures such as policy formulation, capacity building and environmental education, and therefore the study is worth undertaking.

3.4 Parameters to be measured

Nutrients

Nutrients in the sea water (Ammonia, Nitrates and Phosphates) sample and analyzed using a double beam spectrophotometer.

3.5 Collection of samples

The samples were collected randomly at the identified sites with the help of the local fishermen and the Kenya Marine and Research Institution. A total of 16 samples 4 from each sampling point will be used. The sample points (4) were strategically positioned in the three creeks to represent important features that show sewage discharge in the creeks.

3.6 Methods used

Standard Operating Procedures (SOPs) adopted at KMFRI were used in determining nutrients levels. The absorbance of nitrates, phosphates and ammonia were measured spectrophotometrically and the concentration determined.

Physical observation and verbal communication was also used to gather some information.

3.6.1 Determination of Nitrates

Nitrates in sea water are reduced almost quantitatively to nitrates when a sample is run through a column containing cadmium fillings coated with metallic copper.

The nitrite produced is determined by diazotizing with sulfanilamide and coupling with N-(1-naphthyl)-ethylenediamine to form a highly colored azo dye which can be measured spectrophotometrically.

Apparatus

· 50ml graduated cylinder

· 100ml Erlenmeyer flask

· Micropipette

· A reduction column Reagents

· Concentrated ammonium chloride

· Dilute ammonium chloride solution

Sampling and storage

100ml sampling bottle were rinsed with sea water, and then filled with water to the brim. Mercury chloride should was added for preservation. (This applies also in phosphates and ammonia sampling)

Sample analysis

25ml of water sample was measured using the cylinder and put in the Erlenmeyer flask.1.0ml of concentrated ammonium chloride was added and mixed. The solution was then poured in the reduction column and allowed to run for some time, then 25ml of the solution was collected .0.5ml of naphthylene-diamine solution added and mixed. The absorbance was measured after 1 hour by use of UV/V spectrophotometer at a wavelength of 543nm.

3.6.2 Determination of Phosphates

The sea water that was collected as sample was allowed to react with composite reagents containing sulphuric acid, ascorbic acid, and ammoniummolybdate and potassium antimony-tatrate. The resulting complex was reduced to give a blue solution which was measured spectrophotometrically.

Apparatus

· 50ml graduated cylinder

· 100ml Erlenmeyer flask

· Micro pipette

Reagents

· Sulfuric acid solution

· Ascorbic acid

· Ammonium molybdate reagent

· Potassium antimony-tatrate solution

· Mixed reagent (the 4 solution are mixed in the ratio 2:5:2:1)

Sample analysis

20ml of the water was measured using the cylinder and put in the Erlenmeyer flask.2ml of a mixed reagent was added using a micro pipette. The mixture was allowed to stand for 5 minutes and then absorbance read at 885nm wavelength using a UV/V spectrophotometer.

3.6.5 Determination of ammonia

Sea water was treated in an alkaline citrate medium with sodium hypochlorite and phenol in the presence of sodium nitroprusside which acts as a catalyzer. A blue indophenol color was formed and measured spectrophotometrically.

Apparatus

· 50ml graduated cylinder

· 100ml Erlenmeyer flask

· Automatic pipette

Reagents

· Reagent 1(phenol and sodium nitroprusside solution)

· Reagent 2 (alkaline citrate, sodium hypochlorite)

Sampling and storage

35ml of the water sample was measured into a flask.1ml of reagent 1 was added followed by 1ml of reagent 2 and shaken well. The mixture was allowed to settle for 6 hours. Absorbance was read using a UV/V spectrophotometer at 630nm.

3.7 Assumption

Assumptions made during the study includes:-

· All sewage discharge on the ocean is distributed and mixed uniformly by currents and tides.

· Only mean concentration was determined in this study, holding other parameters constant.

· The results reflect the whole regions marine status.

· Instrumentation is in perfect conditions and gives reliable information.

3.8 Limitations

1. The study period is too short (3 weeks) which might be challenging in the collection and analysis of data.

2. Lack of funds to buy materials and specimens and hiring assistants to help in the data collection.

3. The study will only cover a portion of Mombasa Island; the information obtained may not represent the whole area.

4. Some areas are inaccessible require equipments like boats which are expensive to hire.

3.9 Analytical Frame Work

Oceans

Untreated/Partially Treated Sewage

Eutrophication

Reduced Productivity

Increased Productivity

Poor Health, Aesthetic

Improved Livelihood

Poor Livelihoods poor housing

Poor Sewage Disposal

CHAPTER 4

4.0 DATA ANALYSIS AND DISCUSSION

This study investigated the impact of waste water disposal on marine nutrient level. The first main objective of this study was to find main sources of marine pollution in the studied area. Results obtained indicated that waste water disposed in the ocean contained high concentration of phosphates which from waste water from municipal sewage, residential areas especially at Madubini and Mtwapa prison which directly deposits its waste water in the ocean (table 2 and 3).

The second objective of the study was to find out the impact of waste water disposal in the ocean on nutrient level, this study confirmed the deposit of untreated waste water directly into the ocean has a direct impact on the nutrients level (table 1, 2, 3).

The results are summarized in the table below:

4.1 Mean concentrations of nutrients in µg/L water

Table 1: Makupa creek

Sites	Ammonia	Nitrates	Phosphates
Makupa channel (mach)	15.77	0.275	0.564
Makupa bridge (mabr)	22.4	0.742	0.744
Makupa mangroves (mama)	25	0.727	1.164
Makupa causeway (maca)	32.21	0.608	1.266
Makupa dumpsite (madu)	38.28	0.665	1.917
Mean	26.732	0.6034	1.131

Makupa dumpsite was found to have the highest concentration of phosphate and ammonia while Makupa Bridge was found to have highest concentration of nitrates in Makupa creek. The ammonia level was the highest in Makupa creek compared all the other creeks. This could be attributed high garbage at Makupa dumpsite which is washed down as runoff into the ocean.

Table 2: Tudor creek

Sites	Ammonia	Nitrate	phosphate
Fort Jesus (FJ)	0.94	0.32	0.12
Mikindani (mkd)	8.9	0.88	0.56
Nyali bridge (nb)	9.52	2.53	0.58
Kenya meat comm.(KMC)	17.32	0.23	3.07
coast gen hospital(CGH)	24.04	0.31	1.11
Madubini(mad)	41.06	13.26	6.42
Mean	16.96333	2.921667	1.976667

Madubini was found to have the highest levels of ammonia, nitrates and phosphates. This is attributed by direct discharge of sewage affluent into the ocean leading to enormous nutrient loading. Coast general hospital and Kenya meat commission had high levels of nutrients and this is attributed by waste they dump into the ocean.

Table 3: Mtwapa creek

Sites	Ammonia	Nitrate	Phosphate
Mtwapa bridge (mtbr)	1.41	0.69	0.5
Mtwapa mouth (mtmo)	1.88	0.31	0.26
Mtwapa prison (mtpr)	2.37	0.88	0.49
Mtwapa ferry (mtfe)	1.56	0.71	0.46
Mean	1.805	0.6475	0.4275

Mtwapa prison was found to have the highest nutrients concentration of the sites studied at Mtwapa creek. The reason for this is the lack of sewage treating facilities in the prison causing a direct disposal of wastes into the ocean.

Table 4: Gazi creek

Sites	Ammonia	Nitrate	Phosphate
Old fish laundry 1	5.48	0.2	0.24
Old fish laundry 2	4.38	0.43	0.23
New fish laundry 1	17.88	0.44	0.22
New fish laundry 2	12.17	0.01	0.14
Mean	9.9775	0.27	0.2075

Gazi compared to the other 3 creeks studied was found to have the lowest level of levels of nutrients.

4.2 Graphical presentation of results

This study confirmed that locations and sites with more intensive development and associated effluent discharge points are a major source of sewage pollution expressed as increase in level of nutrients and bod5. This confirmed to the previous study by (E . Okuku, 2002), which had attributed severe aquatic deterioration to the indiscriminate release of municipal sewage.

The different levels of nutrients observed at different sampling stations in the 3 sewage impacted creeks could be attributed to such factors as difference in sewage discharge volumes, distances from point source and prevailing current and tidal directions.

Nitrates enriched water column in comparison to ammonium concentration observed in this study could be attributed to the preference of ammonia by phytoplankton, this lowering the level in the water column.

The preference of ammonia in comparison to other form of nitrogen is driven by the fact that phytoplankton can incorporate ammonium directly into amino acids where as other nitrogen forms such an nitrates and nitrites have to be converted enzymetically into ammonia in order to be utilized, a process that require energy expenditure (Emmeis K C and Struck U, 2000).

This general preference of ammonia over nitrate usually keeps ammonia concentration lower than nitrate in the water. Coastal water is generally regarded as P limited. The relatively high N: P ratio could be indicative of sewage impacted creeks in comparison to Gazi creek could have resulted from sewage discharge .as reported by (Emmeis K C and Struck U, 2000) such an increase in N: P ratio could be indicative of increased anthropogenic input of nitrogen and phosphorus.

Naturally, phosphorus is driven form composed organic matter and leaching of phosphorus rich bed rocks. The levels of phosphate in the coastal water are slowly are rising due to increase loading of human waste, animal waste, industrial waste. Worth mention are the increasing phosphate observed in the samples from the sites adjacent to Madubini and Mtwapa prison.

This increase levels could be attributed to the kind and quantities of soaps used in Mombasa old town and Mtwapa prison that are densely populated (Goldman G C and Home J A, 1988). It’s observed that phosphate containing detergents were the major source of soluble phosphate contributing to approximately half of the phosphate contained in domestic sewage.

This study identified sewage as the source of nutrient increase concentration by reporting elevated mean concentration of dissolved nutrients in water from sewage impacted sites in comparison to Gazi. Such increase in level has been reported elsewhere to cause multiple and detrimental effects on exposed organisms (Schlacher, T.A.,Stark,J.FischerA.B.P, 2007) and can alter key structural and functional attributes of the marine ecosystem that are affected by waste water loads such as sewage could already be affecting or there is a possible threat to the ecosystem health.

In general, phosphate enrichment was evident to be high in Tudor and Mtwapa creeks exceeding 0.022µg/l as compared to Gazi creek which had a mean concentration of 0.007µg/l. following the argument of (Girija T R,Mahanta C and V.Chandramouli, 2007), the water course with phosphate concentration exceeding 0.02µg/l could be termed eutrophic and thus the study can confidently classify Tudor, Makupa as being eutrophic systems.

This is further supported by trophic classification scheme based on nutrients; the 3 creeks can be classified as eutrophic while Gazi creek could be classified as lower limits of higher mesotrophy.

In the fight against water pollution, sewage seems to be 1 of the easiest pollutant to control in theory, but the hardest to deal with in practice. It is absurd that human beings that pollute water are the very people that are affected by that pollution.

If the current trends of sewage discharge are allowed to continue, then the swimmers will continue being at risk of contracting illness due to bacteria’s and viruses present in the sewage effluent (gastrointestinal disorder, giardiasis, amoebic dysentery etc) and sea foods will continue to be contaminated thus increasing consumers risk of adverse health effects. Sewage contamination also leads to high income losses associated with the closing of fishing grounds and beaches which has an impact on tourism and fishing industries thus negatively resulting into heavy economic losses for Kenya, a country depends on tourism as the source of foreign exchange.

Even though the government understands the importance of treating raw sewage through a combination of physical, biological and chemical process to remove pollutants before discharge into the receiving body, the local authority that is mandated to carry out such activity are heavily in capacitated by lacking of necessary human, technical and financial capabilities to address the rising levels of sewage volumes. The role of controlling sewage pollution should therefore not be left to the local government alone for simple reason that construction of sewage treatment facilities may not be able to catch up with the increasing human activities. It is vital that everyone recognizes raw sewage as one of the nastiest but solvable water pollution issues. The cooperation of hotel owners, institutional and factory managers, local inhabitants and waste water treatment managers could help reduce the threat of sewage pollution.

CONCLUSIONS

The main objective of this study was to find the impact of waste water disposal on nutrient levels in impacted creeks compared to the Gazi creek is less impacted. In t he results obtained Nutrients concentration were found to be high in Tudor creek, mean were 16.96µg/L, 2.92µg/L and 2µg/L for ammonia, nitrates and phosphate respectively (see table 2). Concentrations were lowest Mtwapa among the sewage impacted sites with means of 1.80µg/L, 0.65µg/L, and 0.43µg/L for ammonia, nitrates and phosphate respectively (see table 1). Makupa had intermediate mean concentrations.

In Tudor creek, Madubini and coast general hospital had the highest concentrations of all study sites, where as in Makupa creek, Makupa causeway Makupa dumpsite and Makupa mangroves had the highest nutrient concentration. In Mtwapa creek only Mtwapa prison had the highest concentrations. Gazi creek which was included in the study as a reference site had very low mean concentrations of 9.98µg/L, 0.27µg/L and 0.21µg/L for ammonia, nitrates and phosphate respectively.

From the study, it is evident that Tudor creek is eutrophic Makupa and Mtwapa are at upper limits of eutrophic and higher mesotrophy, a condition that is caused by a continuous discharge of sewage. Additional inflows of sewage to these systems compounded by occasional re-suspension of nutrient enriched sediments will continue to reduce water quality significantly.

Effective sewage management and long term water quality monitoring should be adopted to ensure that coastal systems continue to support the marine life and livelihood of the riparian coastal vegetation and communities. In this regard there are immediate needs to:

Fully repair and continuously maintain the sewage treatment facility at Kipevu.

Encourage a national campaign that will encourage bagging of waste instead of flushing them to the water ways. The more efforts put into public education the closer the move to solving the problem water pollution.

The long term approach to controlling sewage pollution would be install new sewage treatment plants alongside the repair of the existing ones, Adoption of the whole community approach to reduce waste and recycling waste (ecosan) and exploration of new technology to minimize the use of marine ecosystems waste discharge basin.

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MARINE WATER POLLUTION MONITORING CASE STUDY OF MOMBASA COASTLINE KENYA

ABSTRACT

2.4 Impacts of sewage effluents

2.5 Nutrients in the Sea

2.6 Effects associated with bacterial pollution

3.3.2 Research Questions

3.3.3. Justification of the Study

3.6 Methods used

3.6.5 Determination of ammonia

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