CLIMATE CHANGE: EFFECTS ON
CONCENTRATION OF HEAVY METAL
IN AQUATIC ENVIRONMENT
SADHU, H.
JOOMAN, U.
BRASSE, C.
LONG, P.B.G.
ABSTRACT
•
Heavy metals are metallic element that has a relatively high density. Common
examples are lead, copper and mercury. Heavy metals have biological, chemical
and industrial applications. They are of natural occurrence or present in everyday
commodities such as paint dust, batteries and cells; however, some have
detrimental toxicological effects on health and environment. In this study, the
effects of copper on aquatic environment were under investigation. Fish species of
Tilapia and water from Citron River were used to set up aquatic ecosystems in
laboratory. Copper sulphate pentahydrate (CuSO4. 5H2O) in the range of 0.05 to
0.22PPM were used as independent variable. Data logger (Data Harvester 2.7) was
taken to record change in parameters. Little significant effect on temperature
(28.2±1.3 oC), pH (5.6 ±0.3) and oxygen concentration (32.2 ±1.9%) on the aquatic
system was noted. Conductivity of the system and breathing rate of fish were
increased by 368.3% and 76.6% respectively. Minimum lethal dose of copper
sulphate on Tilapia was found to be 0.2PPM after 105min. Alarmingly, the survey
prior to investigation revealed that 10% of students do not know what are heavy
metals and 17% believed that heavy metals have no effect on environment.
Students should be met more aware of the danger of heavy metals.
Key words: Heavy metal copper, aquatic environment,
INTRODUCTION
• The term “heavy metals” refers to any metallic element that has a
relatively high density and is toxic or poisonous even at low
concentration (Lenntech, 2004). Heavy metals include lead (Pb),
cadmium (Cd), zinc (Zn), mercury (Hg), arsenic (As), silver (Ag)
chromium (Cr), copper (Cu) iron (Fe), and the platinum group
elements.
• Heavy metals occur as natural constituents or in common day
commodities such as batteries, cells, paints etc.
• They are toxic to health and the environment
• They have importance biological, chemical and industrial
applications.
• Veerappapillay (2000) , Chuckowree (2003) , Ramessur (2002) and
Petersson (2005) have studied different aspect of heavy metals in
Mauritius.
AIMS AND OBJECTIVES
• The aim of this study was to investigate the
effects of heavy metal copper on aquatic
environment.
• It was to be determined whether copper ions
affect the oxygen concentration, pH, conductivity
and temperature of aquatic ecosystem.
• The lethal dose of copper and the impact on the
breathing rate of Tilapia were to be determined.
• The perceptions of students on heavy metals
were to be examined also.
METHODOLOGY
• A survey was carried out in order to determine
the perceptions of students on aspect of heavy
metals on environment. A sample consisting of 30
students from upper six classes were selected.
Questionnaire was used to collect data. Analysis
was carried using Microsoft Excel
• Samples were collected in a Labourdonais river
located at Long Mountains, situated in the district
of Pamplemousses (fig 3.1) . The river receives
water from Citron River. Drift and fabric nets
were used to collect species of fish (Fig 3.2).
Figure 3.1: The sampling site
showing the bridge of River
Citron, Long Mountain. The
river is located in the region
of Long Mountains found in
the district of Pamplemousses
(Photo: Mr. Long)
Figure 3.2: Equipment used for samplings. Jeri Can, Drift Net and fabric net (Photo: Mr. LONG)
• Sensors (Data harvester 2.7) were used to
determine the oxygen concentration, pH,
conductivity and temperature of the water
collected (fig 3.3, 3.4). The presence of copper
ions in the water was also investigated using
NaOH precipitation method.
Figure 3.3: Sensors used (Photo: Mr. Long)
Figure 3.4: Home page of data harvester
• Six large glass beakers (2dm3) were chosen.
The beakers were labeled A, B, C, D, E and Z (
fig 3.5).
• 1000ml of river water collected was added in
each beaker.
• Different amount of Copper sulphate
pentahydrate (CuSO4. 5H2O) was then added.
The concentrations added are shown in table
3.2.
Beaker
Concentration of CuSO4. 5H2O/ppm*
Z
0.00
A
0.05
B
0.10
C
0.15
D
0.20
E
0.25
*1 ppm= 1mg of CuSO4. 5H2O in 1000ml of river water
Table 3.2: Concentration of copper sulphate used
• Sensors were used to determine the temperature, the oxygen
concentration, the pH and the conductivity of the water before fish
was added. This was denoted t=0
• One fish was added to each beaker.
• At 30 minutes interval for 2 hours sensors were used to determine
the temperature, the oxygen concentration, the pH and the
conductivity of the water against (See fig 3.6).
• Six digital stop watches were used to record time; one for each
beaker.
• The breathing rate was determined by counting the number of gill
beat produced per minutes.
• Care and precaution were strictly considered. Manipulation of
copper ions was carried as per MSDS of copper (MSDS, 2010)
Figure 3.5: The beakers with Tilapia (Photo: Mr.
LON G)
Figure 3.6: Students measuring time and other
parameters (Photo: Mr. LONG)
RESULTS OF SURVEY
• 17 % do not know what is heavy metals (fig. 4.1)
• 27% only know that copper is a heavy metal (fig. 4.2)
• 11.90% seem not to know the effect of heavy metals at
all (fig. 4.3)
• 31.9 % stated that heavy metals are present in rivers
(fig. 4.4)
• 10% stated that heavy metals are not dangerous (fig.
4.5)
• 63% stated that heavy metals are dangerous to the
environment (fig 4.6)
Fig. 4.1. Do you know what is a heavy
metal?
Yes
Fig 4.2. Which one of the following is a heavy
metal?
No
I donot
know Magnessium
23%
20%
17%
Copper
27%
Calcium
30%
83%
Fig 4.3. Which of the following is/are likely
effect(s) of heavy metals?
I do not know
11.90%
38.10%
Bad for the environment
Good for environment
Cause diseases to humans
Fig. 4.4. Where can we have heavy metals?
25.50%
23.40%
31.90%
19.10%
23.80%
26.20%
Motor
vehicle
smokes
In air
In rivers
I donot
know
Fig. 4.5. Can heavy metals kill organisms?
No
10%
Yes
90%
Fig 4.6. Can heavy metals damage the
environment?
No
37%
Yes
63%
RESULTS OF PRE TESTING OF SAMPLES
Figure 4.7: Tilapia
• .The fish as an average
mean length of 5.7 cm
(fig. 4.7)
• The pre test of the sample of water collected
revealed the absence of copper ions in the water.
All three sites (R1, R2 and R3) show the absence
of copper ions. The result is represented in figure
4.8. The blue precipitate indicates the presence
of copper ion.
• The temperature, the oxygen concentration,
conductivity and pH of the water sample R1, R2
and R3 were also analysed. The result is
represented in table 4.1
Figure 4.8: Pre test for copper ions in sample
of river water. R1, R2 and R3 are samples
collected at 3 different sites along the bank of
the river. +C is the positive control and –C the
negative control
Sample
Temperature/
Oxygen
Conductivity/
oC
concentration/
μS
pH
Table 4.1: Parameters
analysis of water sample R1,
R2 and R3
%
R1
27.6
32.3
12
5.9
R2
27.8
33.2
12
6.1
R3
28.0
33.2
12
5.7
RESULTS OF CHANGES IN PARAMETERS OF
THE AQUATIC ENVIRONMENT.
• There was a 76.6% decrease in the breathing rate
of the fish as time goes by and concentration of
copper sulphate increases. The standard
deviation was 26.6. (fig 4.9)
• During the experiment, the oxygen concentration
shows a slight decrease with both increasing
concentration of copper sulphate and with time
(fig 4.10).
• The conductivity of the aquatic environment
showed a net increased of 368.3%. (fig 4.11)
• Little change was noted on pH over time and over
increase in concentration of Cu2+. The standard
deviation was only 0.3. (Fig. 4.12)
• Little change was noted in the temperature of the
aquatic system. The mean temperature was
28.1oC (fig. 4.13)
• It was noted that a concentration of copper
sulphate in order of 0.25ppm cause the fish to die
within 80minutes. The mortality was less obvious
in the other concentration; fish also died at
105min at 0.2ppm.
Oxygen conc. (%)
40
30
20
10
0
t=0min
0 ppm
t=30min
0.05 ppm
t=60 min
0.1 ppm
t=90 min
0.15 ppm
t=120 min
0.2 ppm
0.25 ppm
Figure 4.9: Decrease (-76.6%) in the breathing
rate of fish as concentration of Cu2+ increases.
Figure 4.10: Showing
a decrease in
concentration of
oxygen in the aquatic
environment as
concentration of Cu2+
and time increases.
The SD was 1.9.
Conductivity
120
0 ppm
100
80
0.05 ppm
60
0.1 ppm
40
0.15 ppm
20
0.2 ppm
0
t=0min t=30min
t=60
min
t=90
min
t=120
min
0.25 ppm
Figure 4.11: Increase in conductivity with increase in copper concentration. SD 16.7.
pH
7
6
5
4
3
2
1
0
0 ppm
0.05 ppm
0.1 ppm
0.15 ppm
0.2 ppm
0.25 ppm
Figure 4.12: Change in pH
when time and
concentration of copper
sulphate increased.
Temperature/oC
Temperature
30
29
28
27
26
0 ppm
0.05 ppm
0.1 ppm
0.15 ppm
0.2 ppm
Figure 4.13: Change in temperature with increase
in Cu 2+ concentration
DISCUSSION
•
•
•
•
Copper sulphate pentahydride was used because it is highly soluble and is not a
toxic heavy metal to man (Damgaard, 2003; OSHA, 2004). It is easily available also.
The aquatic system set up consisted of glass beakers with same volume of water
and approximately same sized and number of fish. So the variable volumes,
number and sized were controlled. Water sample from river was used in order to
have same starting level. A control with no copper added was used to facilitate
comparison of results.
During the experiment, the oxygen concentration shows a slight decrease with
both increasing concentration of copper sulphate and with time. With a standard
deviation of 1.9 this demonstrates that all the results were near to the mean.
Therefore, copper ions of different concentrations and time seem not to affect
concentration of oxygen in the water.
Breathing rate is an important parameter to determine the condition of the fish. It
has been noted that the breathing rate was slower at higher concentrations of
copper than at lower concentrations. There was a net decrease of 76.6% in
breathing rate. This confirms the view of (Duruibe et al, 2007) that heavy metals
are toxic to fish. Copper ions are strong non competitive inhibitor of enzymes and
they can easily denatured protein by destruction of ionic bonds (Duruibe et al,
2007)
• The data obtained during study period concurred with observations
elsewhere. It was noted that a concentration of copper sulphate in
the order of 0.25ppm cause the fish to die within 80mins. The
mortality was less obvious in the other concentration; fish dies at
105min at 0.2ppm. PAN (2006) approximately, similar results were
obtained. Gholami et al, 2010 revealed that white fry were killed at
a copper concentration of 0.4 mg per liter.
• pH is the concentration of proton in a solution. Change in pH can
affect enzymatic activities and protein structures (Duruibe et al,
2007). Little change (pH5.6 ±0.3) was noted on pH over time and
over increase in concentration of Cu2+. The conductivity shows an
increase of about more than 300%. This is normal because as
concentration of copper was increased more copper ions would be
present in the water. Little change in temperature was noted. The
mean temperature was 28.1.
LIMITATIONS OF THE STUDY
• No replications were carried. Replication would have given more
accurate results
• The data logger is not very portable. It would have been suitable if
the pre testing of samples was done in situ
• The sensors used have their own limitations. For instance due to
charged particles distribution, the pH and conductivity sensor could
not be used at the same time. In addition only 3 sensors could be
used at any moment because only 3 slots are present on the data
harvester. So cross contamination could have occurred during
manipulation.
• It would have been desirable if all fish were of the same size.
• It would have been desirable if other statistical package used to
analyse data.
IMPROVEMENTS AND
RECOMMENDATIONS
• As there was no access to better equipment, it was not feasible to
investigate the possible influence of the copper ions on the physiology of
the fish. Neither has a standard been used when carrying test on the
samples.
• It would have been possible to collect a sufficient number of samples to
work with statistically if another approach had been used. To increase
validity, more powerful statistics should have been applied; such as
analysis of variance and student T test. Standard error of sample should
have been determined. Powerful statistical packages could have been
used, such as Data log pro.
• Due to limitation of sensors, accurate results could not have been
obtained. More sophisticated sensors which can be used in situ should
have been used. Other aquatic species should have been included but due
to ethical issues on organism right and protection of biodiversity this has
not been possible.
• Survey with more questions should have been given to
respondents; due to lack of time this was not possible.
Other method to collect data could have also been
used, such as interview. Larger sample size could have
been used.
•
• Information on the danger of heavy metals should be
made available to students in order to increase their
awareness on the topic. This could be done by using
poster, essay, elocutions and debate contest on heavy
metals. Science and other subjects should infuse topic
related to heavy metals in their lessons.
CONCLUSIONS
• The data obtained during this study demonstrated that at
concentration 0.2ppm copper ions were found to be lethal
to fish after 105min. The results provide also some
background information of copper with the aquatic
environment; copper ions have little effects on
temperature (28.2±1.3 oC) , pH (5.6 ±0.3) and oxygen
concentration (32.2 ±1.9%) of the aquatic system used.
Conductivity of water and breathing rate of fish were
however affected with increasing concentration of the
heavy metal and with time. There was a decrease of 76.6%
in breathing rate of fish and an increase of 368.3% in
conductivity of water system. The survey revealed that
students are not aware of heavy metals and their toxicology
on environment, organisms and human health.
ACKNOWLEDGEMENTS
• In the elaboration of this project, special
thanks must go to the following persons: Mr.
Ramen, Mr. Shadobaccus, Mr. Busgeeth, Mrs.
Ransurn, Miss. Shahabun, Students of Form
IIO, Upper six Science and form IVR.
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http://www.dnr.state.wi.us/org/water/dwg/copper.htm
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http://www.academicjournals.org/IJPS
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[accessed April 23, 2012] (www.excelwater.com/thp/filters/WaterPurification.htm)
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