Managing Eutrophication in Nigeria Inland Waters

doi:10.4236/jwarp.2013.57075

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Journal of Water Resource and Protection, 2013, 5, 743-746

http://dx.doi.org/10.4236/jwarp.2013.57075 Published Online July 2013 (http://www.scirp.org/journal/jwarp)

Managing Eutrophication in Nigeria Inland Waters

N. O. Erhunmwunse*, A. R. Dirisu, A. E. Ogbeibu

Department of Animal and Environmental Biology, Faculty of Life Sciences,

University of Benin, Benin City, Nigeria

Email: *[email protected], nosakha[email protected]

Received April 19, 2013; revised May 20, 2013; accepted June 15, 2013

cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Recently in Nigeria, cultural eutrophication is on the increase in water bodies. Observations from land use around riv-

erine areas are predominantly for farmland and explain the high level of phosphate from runoff during the rainy season.

Increased siltation, deforestation, flooding, lumbering activities and other land use perturbation are among the causes of

eutrophication. Aquatic animals usually suffer hypoxia and anoxia and the anesthetic quality of water for recreational

activities, like swimming, boating and picnic is reduced. The Federal Ministry of environment (FMENV) and River

Basin Authority of Nigeria should ensure that all those involved in effluent discharge into water bodies follow the es-

tablished frame work and existing guidelines. Point source an d non-point sources of pollutio n should be monitored and

the adoption of mathe matic model which describes the overall nutrient ru noff and the catchment model suitable fo r de-

scribing the overall transport of water and nutrient through the river basin should be encouraged as practiced in Poland.

Keywords: Eutrophication; Nigeria Waters; Pollution; Mathematical Model; Nutrient Management

1. Introduction

Eutrophication is a natural process whereby lakes, estu-

aries and slow-moving streams receive excess nutrients

as a consequence of weathery of rocks and soil from the

surrounding water shed [1]. The increased nutrient (ni-

trogen and phosphorus) leads to an increased growth of

aquatic plants and organic production of the water body.

[2] states that it takes thousands of years on the time

scale for a water body (Oligotrophic) to turn into eutro-

phic water body through a natural process based on the

nature of entrusted minerals and the rate of watershed

weathering [1]. Although there is no single definition of

eutrophication, certain parameters have been considered.

In defining such phenomenon, [3] used phosphorus con-

centration, while [4] used the relationship between min-

eralized and production. Eutrophication is a threat to the

water quality of rivers, lakes and reservoirs, hence their

classification into oligotrophic, mesotrophic and eutro-

phic based on level of eutrophication [5].

Recently in Nigeria eutrophication rates in water bodies

have increased dramatically as a result of alterations in

nutrient cycles related to land use (Anthropogenic activi-

ties). The increasing demand for food and food insecurity

which has the increased use of fertilizers on farmland has

been pointed out as contributing over 80% of eutrophica-

tion of water bodies’ worldwide.

Cases of observed eutrophication in waters are on the

increase as a result of domestic and industrial discharges

into surface water bodies which vary in nature and qual-

ity thereby contributing significantly to chemical, bio-

logical and physical pollution of these water bodies [6].

Eutrophication may result if sufficiently large amount of

nutrients through wastes are added over a long period to

surface waters [7]. At the same time, siltation resulting

from blockage or basal river flow with erection of a bar-

ricade to mimic water fall for improved water flow may

enhance nutrient accumulation in certain sections of the

river creating a eutrophic environment [8].

Domestic, agricultural and industrial effluence and

waste discharge into rivers is a reason for the high pollu-

tion of water in the state [9]. Murdoch et al. [10] argues

that high level of phosphate and nitrate can lead to eu-

trophication, which increases algae growth and ultimately

reduces dissolved oxygen levels in the water. Raw Sew-

age is the source of nitrogen and phosphate in rivers

[11,12]. [9] observes that land use around riverine areas

in Nigeria is predominantly for farmland and this could

be explanation for the high level of phosphate from run-

off during rainy season in Ibadan River. As a conse-

quence of unprecedented development human beings are

*Corresponding a uthor.

N. O. ERHUNMWUNSE ET AL.

744

responsible for choking several lakes to death [9].

Rivers in Nigeria are important ecosystem as they

serve as a main nutrient source for aquatic organisms,

source of water to neighbouring communities for domes-

tic and industrial purposes. Therefore the water quality is

important in drinking water supply, irrigation, fish pro-

duction, recreation and other purposes. Current practices

of Nigeria living in the southern part of the country ob-

served by concerned environment are regular dumping of

dirt and waste material in large quantities into water

bodies and flood which even tually carry them into rivers.

Water quality deterioration in water bodies in the

country resulting from excessive nutrient inputs (Eutro-

phication) needs to be checked as a result of the effect of

such phenomenon on the social economic function asso-

ciated with water bodies.

2. Causes of Eutrophication in Nigeria

Gromec [13] states that the causes of eutrophication are

related to meteorological and climatic status anthropo-

genic activities. The aq uatic environment, where fish and

other aquatic organisms live, is subjected to different

types of pollutants which enter water bodies through in-

dustrial, domestic and agricultural discharge systems

thereby introducing stress to living creatures. The dis-

charge of industrial effluents into receiving water bodies

in Nigeria invariably results in the presence of high con-

centrations of pollutant in the water and sediment [14].

The constant flow of agricultural effluent discharge into

water bodies often leads to a variety of pollutant accu-

mulation, which becomes apparent when considering to-

xic pollution [15].

Nwaze et al. [16] indicated that indiscriminate use of

fertilizers around Nike lake in Enugu, Nigeria is the ma-

jor source of pollution causing Cyanophycean blooms

and ecological disaster. Stirin [17] pointed out that the

time frame for natural eutrophication to occur is about

1000 - 10,000 years as against cultural eutrophication of

less than 10 years caused by human activities. Since the

population boom in Nigeria in the 80’s the use of N.P.K

fertilizer has increased and led to the treat observed in

water bodies located close to these farmland. When

washed as a result of erosion, flooding increased the nu-

trient load of these water bodies. Other anthropogenic

activities that can cause eutrophication in water bodies

include increased silt, deforestation, lumbering activities

and other land use perturbation.

Ekhaise and Anyansi [18], reported high counts of

bacterial population in Ikpoba River in Benin City Nige-

ria receive brewery industrial effluent. Similar results

were reported by [14] of the effect of brewery discharge

into Eziama River, Aba, Nigeria. Val AL, Paula da.,

Silva MN and Almeida-Val V MF [1], pointed out re-

gardless of the origin of eutrophication, its end result

usually led to change within the aquatic communities.

3. Effect of Eutrophication

Lundberg, [19] stated that eutrophication will cause hy-

poxia and anoxia in aquatic life as a result of sedimenta-

tion associated with primary production. Eutrophication

is related to physical, chemical and biological distur-

bances, increased production of algae biomass, the de-

creasing amount of silica and increased turbidity of the

water bodies [14], foul smell and will eventually lead to

the death of the water bodies. Nitrogen and phosphorus

are the major causes of eutrophication. Eutrophication

affects aesthetics on lak es, rivers an d results in odour and

appearance problems [15]. It reduces the anesthetic qual-

ity of water for recreational activities, like swimming,

boating, and picnic.

The presence of high algal biomass occurring from eu-

trophication of the shallow tropical African reservoirs

will jeopardize the effective functions of the reservoir in

providing domestic and industrial wa ter supply, fish pro-

duction, irrigation, recreation as well as loss of biodiver-

sity and other socio-economic functions of the reservoir

[20]. Loss of biodiversity and socio-economic functions

of the reservoir, poor water quality, anoxia, low trans-

parency and disruption in food web interactions is some

of the effects of cultural eutrophication in these lakes.

3.1. Managing Nutrient and Water Quality

Although in Nigeria, the Federal Ministry of Environ-

mental is saddled with the responsibility of providing

guide line for managing effluent discharge into the envi-

ronment. This body provides the frame work for every

industry involved in the utilization of water resources

and hence ensures the protection of water bodies across

the country. The main objective is to ensure all those

involved in discharging effluent into water meet the re-

quirement in order to protect water use.

It is therefore of paramount interest for FMENV

(NESERA) to work with the River Basin Authorities in

order to combine effort in controlling pollution and the

self guideline to be followed strictly. Following the water

quality standard set by [21] (NESERA) it is of interest

that company’s effluent must be checked regularly to see

if they conform to the existing standard and to check the

effect of population growth on their production which in

turn, increases the waste discharge into the environment.

Nutrient management is important to assess the impact of

human activities from known sources (Point Sources)

and from diffuse sources and other human activities [13].

The established water quality Criteria by [21] after the

illegal dumping of toxins in Koko Port in the then Bendel

State: Nitrate (No3) 20 mg/l for surface water, Phospho-

rus (3



) 5 mg/l for surface water and 10 mg/l for land

N. O. ERHUNMWUNSE ET AL. 745

use. The standards were adopted for monitoring water

quality based on the method for water and waste water

analysis by United States Environmental Protection

Agency (USEPA) Department of Environment (DOE)

UK, American Public Health Association (APHA).

If the above criteria and requirement must be meant,

the state of the art equipment must be acquired by the

industries involved. Effluent must be properly treated to

meet these standards as point source of population.

Controlling non-point source has always been difficult

as the cause and effect cannot be directly documented. In

recent past, non point sources of nutrient from agricul-

tural practices have been analyzed with the aid of mathe-

matical models, based on the presentation of reliable and

correct data. In Poland, such model has been developed

and can be used in the Nigeria context [22]. In line with

the above statement, the total nitrogen and phosphorus

were calculated using data collected from point source

and subtracting it from the total, the applied mathemati-

cal model method an agricultural field model which de-

scribed the over-all nutrient runoff from the root zone

and agriculture practice. Again a catchments model is

suitable for describing the overall transport of water and

nutrients through the river basin including different nu-

trient and concentration in different water compartment

and lastly a full hydrodynamic and water quality model

system as developed for rivers, lakes and wetland areas,

describs water flow, transport and transformation of or-

ganic material and nutrient.

3.2. Mathematical Model for Measuring

Pollution/Pollution Index

Value of Nitrogen/Phosphorus of a water body from

non-point source = Mean Total value (MT) of Nitro-

gen/Phosphorus of the water body-Value of Nitrogen/

Phosphorus from point sour ce of the same water body.

3.3. Recommendation

A comprehensive systematic survey of the eutrophication

status of Nigerian waters should be undertaken and na-

tional framework for managing eutrophication should be

defined with the key elements of which are:

 A two-pronged appro ach whereby measures to reduce

nutrient inputs to the water environment nationally are

complemented by more comprehensive, catchment-based

management action, within the context of a national

framework, for waters most at risk from or affected by

eutrophication;

 The promotion of a partnership approach, at both lo-

cal and national level, since solutions are generally be-

yond the re mit of any one regulatory body or other party;

 The adoption of a range of mechanisms (regulatory,

voluntary, collaborative, educational and economic) by

the Agency and others, as appropriate, in order to reduce

nutrient inputs to environmental waters and manage local

problems;

 The development and adoption of consistent method-

ologies for assessing eutrophication in a water body;

 A review of the arrangements for measuring the ex-

tent of eutrophication in the different types of environ-

mental waters and the impacts of discharges and land use

on water quality;

 The prioritization of waters for management action:

initial priorities will be waters where there are statutory

requirements, or where water uses are adversely affected,

or where wildlife conservation interest is at risk, where

benefits can be delivered or deterioration prevented, with

adequate confidence, at reasonable cost;

 The adoption of interim targets for eutrophication

control in freshwaters and the continuing application of

specific statutory and/or international commitments in

relation to saline wat ers by reg ulatory bodies;

 Trials of the proposed tools, techniques and proce-

dures through pilot catchment-based action plans, to re-

fine the approach and its potential wider adoption within

the country;

 The promotion of a wider understanding of the nature

and significance of aqu atic eutrophication;

 A programme of research and development to im-

prove understanding of the eutrophication process within

Nigeria should be set up.

4. Conclusion

For the effective management of Nutrient load of water

bodies in Nigeria, both point and non-point sources of

pollution must be taken into recognition and controlled.

Strict compliance to the combined guidelines by NESE-

RE and River Basin Authority must be met without

compromises. The Federal Government and the Ministry

of Environment must set huge amount from the ecologi-

cal funds for proper evaluating by hydrobiologist and

toxicologist in the nation. Land use coupled with other

anthropogenic activities near this water must be moni-

tored and in some cases relocated always from these wa-

ter bodies. The threat of water pollution to man’s exis-

tence has informed the adaptation strategies aimed at its

control and one of such strategies according to Imhoff

[23] is the provision of information on the quality and

quantities of contaminant in a water body.

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