ABSTRACT
Water samples from ground water and some rivers from Owerri Local Government
Area of Imo state Nigeria, were investigated for contaminants and heavy metals.
The results obtained showed that in the month of April 2009, the ground water
had mean maximum concentration 1.303 mg/dm3 of Pb, 1.048mgldm3
of Pb,1.488mgldm3 of Pb,for Otamiri and Oramiriukwa rivers
respectively.For the month of May 2009, the ground water results showed maximum
mean concentration 1.016mg/dm3 of Pb,1.069mg/dm3 of Pb,
1.7mg/dm3of Pb and 1.488mg/dm3 of Pb,for Otamiri and
Oramiriukwa rivers respectively.The underground waters had mean concentration
of 3.636mg/dm3 Cu,which exceeded WHO standard of 3.0mg/dm3
for drinking water.In the month of may Oramiriukwa river had Mn with a maximum
mean concentration of 3.334mg/dm3 which exceeded the WHO standard of
2.0mg/dm3. The results showed lead of values 2.852mg/dm3
for the ground waters, 0.255mg/dm3 of lead , 1.045mg/dm3
of Lead and 0.855mg/dm3 of Lead for Otamiri,Nworie and Oramiriukwa
rivers respectively. The correlation coefficient matrix for the element of 0.500
was taken to be significant. For the ground waters, Fe2+, Zn2+
were strongly correlated during April/June 2009 periods. The Otamiri river
results showed that the heavy element Cu2+, Fe2+, Mn2+
and Zn2+ were strongly correlated in the month of April/May 2009 .
The samples from Nworie River had strong correlation for the element Fe2+
Mn2+ and Zn2+ for the period of April/May 2009.Cu2+had
strong correlation in the period April/May 2009. Oramiriukwa River had strong
correlation for elements Cu2+, Fe2+, Pb2+ and
Zn2+ in the period April/May 2009. Pb+ had strong
significance in the April/May 2009 period. Mn24+ had very strong
correlation in April/May 2009. A histogram chart of the frequency distribution
of the heavy metal concentrations in the period,the pollution index of the
water bodies were determined using Horton’s rule. The above results indicate
that some of these water bodies should not be taken orally without
treatment.Nworie river was founded most polluted of all the water bodies,
followed by Oramiriukwa river,Otamiri river had mild pollutions, one of the
ground water site’s was reported as heavily polluted with the element copper
with a concentration of 3.636mg/dm3.It was discovered that none of
the water sources investigated met WHO standards for safe water.
CHAPTER ONE
1.0 INTRODUCTION
Water is an essential raw material for human life and a vital
factor to the establishment of industries. Without water no life [1].
Water in its natural environment is characterized by
impurities. Being a universal solvent, water contains dissolved solids, gases
and hosts a number of microorganisms.
Hence the quality of water is defined by the level of its
physical, chemical and biological impurities. [2]
Different sources of water include stream, lakes, ponds,
rain, springs and wells. Sources of water in Old Owerri LGA of Imo State
include rivers like Otamiri, Nworie and Oramiriukwa; and the underground waters
(Boreholes). These rivers and underground waters (boreholes) supply water for
the daily activities of the people living along the banks, tributaries and
environs. Well asFor example Nworie River discharges intoOtamiri river as a
tributary while Oramiriukwa River has a number of streams discharging into it
as crossed many communities on its course.
Pure, safe and clean water can only exist briefly in nature
but is polluted immediately by human activities and environmental factors.
Industrial effluents, fertilizers from farm lands, diesel from pleasure boats,
are possible pollutants of rivers and thier environ.[3]
The use of surface water by man is as old as the existence of
human beings. Water is a natural resource, and indispensable to life. Water
supplies for human consumption should be adequate and free from bacteria
harmful to humans. The quality of river water depends on the quality of the
feeding sources which include surface run off water, glaciers, swamp, rain and
underground water.
Underground water, like springs, boreholes are better quality
water than surface water, such as lakes,
rivers, streams, due to the purification of the former prior to distribution.
The underground water is rarely polluted by both man and animals [4,5,6].
Industrial effluents like toxic chemicals and heavy metals
pollute several surface waters. Mercury is one of the heavy metals, in a group
that includes lead, cadmium, plutonium and others. A feature the heavy metals
have in common is that they tend to accumulate in the bodies of organisms that
ingest them, their concentrations increase up the food chain. Some marine algae
may contain heavy metals of concentrations of up to one hundred times that of
the water in which they are living, small fish eating the algae develop higher
concentrations of heavy metals in their flesh, larger fishes who eat the
smaller fishes concentrate the metal still further, and so on up to fish eating
birds or animals [7]
Some non-metallic elements commonly used in industries are
also potentially toxic to aquatic lives and to some extent to human beings.
Chloride is widely used to kill bacteria in municipal water, sewage treatment
plants and to destroy various microorganisms are found in plumbing lines in water works stations. Chlorine can also kill algae and harm
fish populations.[8]
Acids from industrial operations and acid mine drainages
especially in coal and sulphide areas remain serious source of surface and
ground water pollutions [9,10]
The run-off water from fertilized fields carries some of the
fertilizers to rivers. In rivers and lakes the fertilizer provides nutrients
that increase the growth of algae. The algae use up the oxygen dissolved in the
water, and the lack of oxygen causes the death of fish and other aquatic lives.
Phosphates in laundry detergents have the same effect. Hence the use of
fertilizers as well as detergents result in
entrophication of water. Pesticides used on crops get into rivers in this way
too [10,11] destroying aquatic lives.
Urbanization and industrialization develop countries
economically but lead to environmental pollution. The main effect of
urbanization is increased run-off, which causes increased erosion thereby
making the water muddy which is a type of pollution. In addition many new and
sometimes toxic chemicals are added to the environment, industrial activities
unbalance the natural cycles with harmful substances such as heavy metals
[10,12].
Many organic compounds occurring naturally and the synthetic
ones are widely used as herbicides and pesticides, as well as in a variety of
industrial processes. The negative effects in organisms vary with the
particular type of compound, some are carcinogenic, toxic directly to humans or
other organisms, and make water unpalatable, and some accumulate in organisms
as heavy metals. Oil spills are a kind of organic compounds pollution of
surface water. Vinyl chloride vapor used in the production of plastics is
carcinogenic and it is not known how harmful traces of vinyl chloride in water
may be. Laboratory tests conducted on animals revealed that polychlorinated
biphenyl’s (PCBs) cause impaired reproduction, stomach and lower alimentary
disorders and other problems [10,13].
Polluted water may contain pathogens and disease-producing
organisms such as fungi, bacteria, viruses, protozoa, parasites and worms which
are vectors that carry and spread disease like skin infections, dysentery,
diarrhea, typhoid fever, malaria and other related diseases [14, 15].
Most industrial effluents contain non-biodegradable, toxic
and hazardous wastes which bioaccumulate in living organism when consumed.
These wastes pose high health risks as well as threatening coastal and
estuarine fishes on which most rural populace especially in the riverine areas depend on for their livelihood.
[16,17].
The principal causes and sources of pollution in groundwater
have been grouped into four categories, namely municipal, industrial,
agricultural and miscellaneous [17].
Municipal sources – These include sewage leakages, liquid
wastes and soil wastes. Industrial sources-include liquid wastes and leakages
from tanks and pipelines as well as mining activities and oil field brines.
Agriculture produces pollution as a consequence of irrigation return flows,
animal wastes, pesticides etc. Under miscellaneous are listed spills and
surface discharges, septic tanks and cesspools, roadway deicing, interchange
through wells, etc [18].
Nitrates are important pollutants of groundwater and indeed
of the environment in general. All over the world an increasing input of
fertilizers aimed at increasing agricultural output is occurring and
concomitantly there is a general deterioration in the quality of both surface
water and ground water. Today, in most rivers there is an abnormal increase in
nitrogen and phosphorus concentrations. There is evidence of a link between
gastric cancer and high nitrate concentration in ingested water [11,19]
Such addition of nutritive elements induces entrophication
with problems concerning the use of water by human populations. The leaching of
nitrate from agricultural land is a great concern to the soil chemist. [5,19].
Mining operations produce many ground water pollution
problems. The nature of the pollutant depends on the material actually being
mined and also on the mining processes. Very important contributors are the
coal, phosphate, uranium mines and bodies producing iron, copper, zinc and
lead, etc. Since surface and subterranean mines usually extend below the water
tables, expansion of mining activities necessitates de-watering. The water so
removed is highly mineralized and referred to as acid mine drainage. Acid mine drainage is characterized by low
pH, high iron, aluminum and sulphate contents. Coal accumulations are usually
associated with pyrite, which is stable for sub-water table conditions, but
oxidizes if the water table is lowered. Oxidation succeeded by contact with
water produces iron [III]sulphate and tetraoxosulphate (VI) acid in solution,
and of course, if they reach ground water its pH will be reduced and its iron
and sulphate contents will increase [2,5].
Drainage from waste heaps produced by mining and run-offs
contain agricultural and industrial wastes, water flowing through municipal and
industrial wastes leaches soluble materials and these become contaminated.
Leachate contains poisonous substances and if disposal sites are not carefully
managed in other to collect and treat leachate effectively, it can enter the
ground water system [19].
Other sources of ground water contamination include widely
used substances such as highway salt, fertilizers that are spread across the
land surface and pesticides. In addition, array of chemicals and industrial
materials leak from pipelines, storage tanks, and holding ponds. Among these
pollutants are classified as hazardous meaning they are either inflammable,
corrosive, explosive or toxic. As rain water percolates through the soil, it
carries pollutants to the water table. Here they mix with the ground water and
contaminate the supply. Because groundwater movements are usually slow,
polluted water may go undetected for a long time [20].
Another common source of groundwater pollution is sewage,
which emanates from an ever-increasing number of septic tanks. Others are
inadequate or broken sewer systems and farm wastes [21,22]
Sewage water, which is contaminated with bacteria, enters the
groundwater system and gets it polluted. Sewage and manure contain both ammonia
and acid, organic forms of nitrogen. Organic nitrogen may be converted into ammonia in the soil.
Nitrate is a problem as a contaminant in drinking water due to its harmful
biological effects. High concentration of nitrates causes methamoglobinemia
which causes gastric and intestinal cancer [19,23]. Several human activities
have indirect or devastating effects on water quality and aquatic environment.
Such activities include accidental or unauthorized release of chemical substances,
discharge of untreated water or leaching of noxious liquids from solid waste
disposal [24-26].
A recent work by Yahaya in
2006[27] revealed that the cat fish has been isolated as net accumulators or
bio accumulators of pollutants such as zinc, Mn, Cr, Co, Ni, Rb, C, Cd etc.
Zinc, an indispensable trace element, is essential for human and fish
existence, and is as well regarded as a pollutant in several areas. Compared to
the other bio-available metals, it was the second most abundant in the Shell
fish . Industries producing pesticides, plastics, chlorine, caustic soda, pulp
and paper introduce into the environment (soil, water) heavy metals such as
mercury [28,29]. Acid rain breaks rocks, releasing heavy metals into streams,
lakes and ground water, by this aquatic environments are heavily contaminated
by these heavy metals. Heavy metals can not be degraded bio-chemically in
nature. The stability of these metals therefore allows them to be transported
to considerable distances by water. As a result of this process, the level of
heavy metals in the upper member of the food chain can reach values
significantly high to cause health hazards, when such organisms are used as
food by man [26]. Some of these heavy metals are clearly in organic form at the
time of discharge and do undergo further bio-transformation inside the fish,
which render them extremely dangerous. For example mercury exists in zero, [O],
plus one,[+], and plus two,[+2], oxidation states.Methyl mercury CH3Hg+ is an
important feature of this cycle, particularly with regard to its uptake by fish
and humans. Methyl mercury CH3Hg+ is the major mercury species found in fish
and about....
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