ACUTE TOXICITY OF TEXTILE MILL EFFLUENTS AGAINST PELAGIC
ORGANISM (TILAPIA ZILLI) AND BENTHIC ORGANISM
(TYMPANOTONUS FUSCATUS)
OKWOK1, N. A.; *AKINOLA, M.O.2
*1
Ecotoxicoloy Laboratory, Department of Zoology,
University of Lagos, Lagos, Nigeria
2
Environmental Biology Laboratory, Department of Cell Biology & Genetics
University of Lagos, Lagos, Nigeria
*
Corresponding author
Akinola, M. O.
Environmental Biology Laboratory
Department of Cell Biology & Genetics.
University of Lagos
Akoka
Lagos Nigeria
Email tundeakin5@yahoo.com
ABSTRACT
Acute toxicity of a textile mill effluent a pelagic organism (Tilapia zilli) and a benthic
organism (Tympanotonus fuscatus) was investigated in this study using laboratory
bioassay method. The toxic effect of the effluent on the two organisms increased with
time and concentration from 24-96hrs as shown by the mortality. The 96hrs LC50 was
3.22ml/L against T. zilli and 78.98ml/L against T. fuscatus. T. zilli was 24.5 times
more susceptible to the effluent than T. fuscatus. T. zilli had its skin peeled at
concentration of 4ml and there was asphyxiation and eventually the skin colour
changed. Whilst T. fuscatus was affected at the concentration of over 80ml during
which it withdrew into its shell and eventually died. There is no doubt that the effluent
from this textile mill can be lethal to aquatic organisms if it is allowed to get into their
habitat.
INTRODUCTION
Industrial activities are an important component of modern life because they provide a
wide range of essential finished products for examples food, textile materials,
fertilizers, plastics, building materials, automobiles e.t.c. The textile industry is not
exempted from this fall out by the nature of its operation, it produces pollutants.
Pollution from the textile manufacturing process can be solids, liquids or gas in form
of organic and inorganic substances. Bhalared and Adeeko (1981) recorded that of all
the three forms of pollutants discharged by the textile mill, the liquid form effluent is
by far the most significant. The effluents from the textile industry find their way to
watercourse without being treated and become toxic to aquatic biota. The souring and
washing of cotton fabric, is a major source of organic pollution and waste loading
(McCaull and Crossland, 1975). Internationally, textile manufacturing is among the
first industries to be established in almost every developing nation. This industry
appears to rank high among the “problems” industry of every developed
or
developing nation.Ajao (1985), reported that sulphonated wash effluent from a textile
mill discharged into the water body was toxic to Clibanarius africanus after 24 hours
exposure. According to him, with an application factor of 0.1-0.05 for 48hrs LC50. It
showed hermit crab showed some tolerance, but the body of the water receiving the
textile effluents was devoid of fish. However, textile mill effluents discharged into
water bodies have been found to affect water quality because of high concentration of
caustic chemicals which increase pH, alkalinity (Ndaji, 1991). High concentration of
total dissolved solid, high turbidity, high biochemical oxygen demand and total
hardness, intense colouration, toxic organic chemical and heavy metals have been
reported for water bodies that received textile mill discharges (Ndaji, 1991).The
Lagos lagoon is the natural habitat of several benthic and pelagic species such as
Tympanotonus fuscatus, Clibanarius africanus, Seserma huzardi, Pachymelenia
aurita and Tilapia species. These organisms are useful in assessing water quality in
the field because they are ubiquitous, sedentary, and have long life cycles, hence they
act as continuous monitors of the water body they inhabit.The aim of this study is to
determine the acute toxicity of textile mill effluents from Nichemtex industries in
Ikorodu area of Lagos, Nigeria on a pelagic organism Tilapia zilli (Gerr) and
Tympanotonus fuscatus (L.) a benthic organism with a view to providing information
for regulatory agencies in setting up national standard for water quality
management/monitoring.
MATERIALS A ND METHODS
Test Animals, Collection and Acclimatization
Tympanotonus fuscatus otherwise known as “Periwinkles” were hand picked along
the sandy beaches of the Lagos Lagoon front of the University of Lagos. Tilapia zilli
fingerlings were collected from a fish pond located at Ayobo area of Lagos State.
Total size and length of the Tilapia zilli fingerlings ranged between 1.8cm-2.2cm
and 2.3-3.2cm for Tympanotonus fuscatus. T. fuscatus were collected by handpicking
into a bucket (12.6L) from the edge of the Lagos lagoon at low tide. They were
collected from the same place, in order to reduce variability in biotype. Sediment was
collected from the same site and placed in the holding tank as substrate. Tilipia zillii
fingerlings were transported in the morning between (8a.m.-9.30a.m.) from the fish
farm to the Ecotoxicology laboratory in air bags with pond water from the fish farms.
In the laboratory, the fingerlings were kept in glass tanks (100 fingerlings per tank)
measuring 70cmx29cmx30cm, half filled with dechlorinated tap water.
The test
organisms were acclimatized in the laboratory for a minimum of seven days at room
temperature (280C+10C) before use in experiments. The water in the stock tanks was
changed every two days to avoid accumulation of metabolic wastes and to remove
debris. The fingerlings were fed once a day with NIOMR formulated fish feed. They
were fed last a day prior to commencement of bioassay test. The acclimatization of
the fingerlings (T. zillii) was in accordance with guidelines for bioassay techniques
(APHA, 1980).
Source and Collection of Effluent
Industrial effluents used were collected in 10 litre plastic kegs from main discharge
point into the drainage system from a textile manufacturing company in Lagos State,
Nigeria. The effluent was however collected from Nichemtex textile mill located at
Abuja village in Ikorodu Local Government area of Lagos State. The discharge runs
through two villages Abuja and Offin before finally discharging into the Lagos
lagoon. The effluent used for the toxicity testing was collected on the day of the
experiment to avoid decay. When effluents were not in use, they were kept in a
refrigerator at 40 C to limit biodegradation before utilization.
Effluent Characterization
A two-litre volume of fresh effluents from the discharge point was taken to the
environmental Analytical Laboratory in the Department of Chemistry, University of
Lagos for analysis.
Procedures for physico-chemical analysis followed those
described by Ajao (1985), these includes colour, pH, conductivity, turbidity, total
suspended solids (TSS), total dissolved solids (TDS), Biochemical Oxygen Demand
(BOD), Chemical Oxygen Demand (COD), phosphate, nitrate and heavy metals. The
physico-chemical characters were determined to assess the quality of the water.
General Bioassay Procedures
Bioassay procedure followed methods described by Sprague (1971), ASTM (1988),
Rand and Petrocelli (1985) for fixed points discharge and static non-renewal bioassay.
A preliminary test was carried out to determine the range of concentrations to be used
for the actual bioassay before carrying out the final bioassay.
Test solutions
containing various concentrations of effluents were prepared using dechlorinated tap
water for T. zilli fingerlings and brackish lagoon water for T. fuscatus. A total of
twenty organisms was used with ten test organisms in each container (two replicates)
and a control.Plastic bowls and glass tanks served as bioassay containers for the T.
fuscatus and T.zilli respectively. The active specimens were selected and put into
bowls and glass tanks containing different concentrations of test effluents varying
from 2ml/L-12ml/L for T. zilli and 30ml/L-180ml-L for T. fuscatus and a control.
Observations were made on the behavioural response of the specimens in different
concentration and time taken for specimens to die was noted. Dead specimens were
removed from the medium.
Assessment of Quantal Response (Mortality)
Mortality assessment was made throughout the duration of the test over a period of
four days. Mortality was said to have occurred when the organism failed to respond
to stimulus when pricked by a sharp object. Lethal concentration studies were carried
out in which test organisms were exposed to different concentration and mortality was
monitored over 24hrs, 48hrs, 72hrs and 96hrs to time and expressed as LC50.
Test organism (T. zilli) was not fed for the duration of the experiment, there was no
mortality recorded in the control experiment.
Statistical Analysis
Toxicological dose-response data involving quantal response (mortality) were
analysed by probit analysis (Finney, 1971). The method of calculation of LC 50
minimizes the extremes of the result and maximizes the middle percentage survival or
mortality. The indices of toxicity measurement derived from this analysis were:
LC50- Median lethal concentration that causes 50% responses (mortality) of exposed
organisms.
LC95 - Lethal concentration that caused 95% responses (mortality) of exposed
organisms.
LC5-
Lethal concentration that causes 5% responses (mortality) of exposed
organisms.
RESULTS AND DISCUSSION
The physico-chemical characteristics of the effluents used in the experiment
compared with Federal Environmental Protection Agency (FEPA) limits are presented
in Table 1. The physico-chemical results of Nichemtex effluent were higher than
FEPA (1991) specification for maximum concentration of effluents allowed for
discharge into surface waters for all categories of industries.
Acute Toxicity Studies
Fig 1 is the probit-log dose graph showing the acute toxicity of Nichemtex effluent
against T.zilli and T. fuscatus. It is a straight line but parallel which indicates the
comparison of two different organisms (T. zilli (pelagic) which is more susceptible
and T. fuscatus (benthic) and less susceptible.
The results of the toxic effect of Nichemtex effluent on T. zilli and T. fuscatus
increased with time and concentration from 24hr-96hr as indicated by observed
increased in percent mortality values (Figs. 2 and 3). The 96hrs LC50 values was
3.22ml/L against T. zilli and 78.98ml/L against T. fuscatus. Comparative analysis of
the toxicity of Nichemtex effluent on the test organisms on the basis of 96hrs LC 50
value showed that T. zilli is 24.5 times more susceptible to effluent than T. fuscatus
(Fig. 4 and Table 2)
Behavioural response of test organisms to toxic effluents
The fish fingerlings exposed to concentration above 4ml had their skin peeled off.
There was asphyxiation and colour of skin changed. These are indication that the
textile effluent was toxic to fish (T. zilli). When T. fuscatus was exposed to
concentrations above 80ml/L of the textile toxic effluent the animal withdrew into its
shell, but eventually died when no movement was noticed after being pricked with a
sharp object.
In this study, T. zilli was more susceptible to the textile mill effluents, than T.
fuscatus, and the susceptibility increased with time of exposure from 24hrs to 96hrs.
The susceptibility of the fish fingerling and periwinkles exposed to the textile
effluents could be attributed to its high BOD5, pH, TSS, low dissolved oxygen content
and the presence of different organic and inorganic compounds in varying
concentrations (Table 1). According to Boyd (1979), industrial wastes are poisonous
to fishes if the effluent reduces the pH value of receiving water below 4.0 or increases
it above 11. Aquatic fauna such as fish and shellfish die according to the BOD load
of the water, the higher it exceeds the stipulated standard limits the higher the
mortality (Odiete, 1993). Total suspended solids affect feeding habits of organisms
and also block the respiratory organs and surfaces of aquatic organisms (Alasbaster
and Lloyd, 1982). According to Herbert and Merkens. (1961), many substances
become more toxic as the dissolved oxygen content of the water decreases. The rate
of oxygen consumption of fish is altered by the presence of toxins (Jones, 1964) and
their resistance to low oxygen tensions may be impaired.
Many authors in different parts of the world including Nigeria (Mance, 1987),
Edwards (1981), Klein (1975), Mason (1992), Ajao (1985) and Chukwu (2001), have
observed and reported industrial effluent toxicity against aquatic life by means of
short term bioassay test. Results from Chukwu and Ogbeva (2003), indicated that the
96hours
LC50
value
of
a
textile
mill
effluent
(Afprint
effluent)
against T. zilli was 2.88mg/L and 26.69mg.L for Clibanarius africanus and (Texlon
effluent) was 4.46 mg/L against T. zilli and 53.75mg/L against C. africanus. This is
in agreement with result obtained from this study where the 96hr LC50 values of the
effluent against T. zilli was 3.22ml/L and 78.8ml/L against T. fuscatus. The
differential responses of test organisms to industrial chemicals can be attributed to
factors such as permeability of body membrane, metabolism, excretory capacity, sex,
age, body size, site of action and behaviour (Don-Pedro, 1996).
Although, the
specific underlying reasons for the observed differential responses of the test animals
were not evaluated in this study, explanations based on available literature and
observations on their ecology and morphology suggest that the tolerance of T.
fuscatus may be due to the behavioural mechanisms in which the animal withdraws
into its shell and seals of the shell aperture with its operculum upon its detection of
noxious compounds in its surrounding. They also have good adaptation to common
environmental factors such as dissolved oxygen and pH. Their ability to live out of
water for long periods of time makes it less toxic to chemical. Otitoloju (2001)
demonstrated that animals with high tolerance level to toxic substance, usually
bioaccumulate such substances in their body. This implies that tolerance in some
organisms may not only be related to exposure to toxicants but may include other
metabolic and physiological processes such as sequestration of the toxicants.The
findings of this study established that some physico-chemical characteristics of the
textile effluent were higher than the FEPA’s limit for industrial effluent discharge
thus the effluent from the textile was untreated before discharge into the nearest river.
It is suggested that further work be carried out on the effects of sublethal dosages of
these effluents on more sensitive pelagic organisms such as Daphinia sp. and
Palaemonestes) and benthic (Clibanarius africanus). This is necessary to ensure that
the safety limits prescribed would indeed be able to protect all organisms in the
aquatic ecosystem. We would therefore recommend that the Federal Environmental
Protection Agency (FEPA) should ensure proper enforcement of their set limits for
effluent discharges so as to prevent the discharge of partially or untreated effluents
into water bodies, thus reducing biodiversity of the water bodies, devaluation of
aesthetic and recreational purpose of the water bodies and causing bioaccumulation of
metals by some benthic and pelagic organisms which when eaten by man may be very
harmful.
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