MERCURY CONCENTRATION IN SOME SPECIES OF FRESH WATER FISH OF BANGLADESH

De
Publié par

Mercury concentration in some species of fresh water fish of Bangladesh has been determined by neutron activation

Publié le : jeudi 21 juillet 2011
Lecture(s) : 214
Nombre de pages : 9
Voir plus Voir moins
Journal of National Oceanographic, Atmospheric and Marine Institute
©
NOAMI
Vol.24, No.2, 2007
ISSN: 1027-2119
MERCURY CONCENTRATION IN SOME SPECIES OF FRESH WATER FISH OF
BANGLADESH
A.K.M.Sharif
Bangladesh Atomic Energy Commission, Dhaka-1000, Bangladesh
M.Alamgir, Stanly A.Bajue and Rashed Alam
Department of Physical, Environmental and Computer Sciences
Medgar Evers College, CUNY, NY, U.S.A.
_____________________________________________________________________________________
Abstract
: Mercury concentrations in edible portion of some popular fresh water
fish species, namely,
Tenualosa Ilisha
,
Pangasius pangasius, Septinna phasa, Neopropius atherinoides,Otolithoides pama ,
Puntius sarana
,
Ompok pabda, Sperata aor, Clarias batrachus, Heteropneustes fossil ,Labeo rohita,
and
Catla catla
were determined by radiochemical neutron activation analysis (RNAA). The results were
found to vary from 0.243 to 0.675 μg g
-1
on dry weight, where four species had mercury concentration,
0.243 -0.299 μg g
-1
, six, 0.303-0.384 μg g
-1
and the rest two, 0.536-0.675 μg g
-1
. The results were found
to agree well with other published data on river and marine fishes and within permissible levels accepted
internationally.
Key words
: Mercury, Fish, Radiochemical neutron activation analysis, Bangladesh.
_____________________________________________________________________________________
INTRODUCATION
Mercury is one of the most toxic elements to man and other animals. In the last two decades,
measurement and evaluation of mercury in environment has received much attention. The presence of
high concentration of mercury in river and marine organisms is well–documented (Lee and Hultberg,
1990: Bjorklund
et al
., 1981: Akielazek and Haines, 1981 and Bacci, 1989). Investigatiions of heavy
metals in aquatic ecosystems have been well documented in Europe, Australia and North America, but
few studies are available about the levels of contamination, particularly that of Hg in the fishes from
rivers, and of the Bay of Bengal. Sharif
et al
., (1991, 1993a, 1993b) reported level of few metals
including Hg in some rivers and marine fishes of the Bay of Bengal.
In the rivers and sea, mercury comes mainly from weathering, sewage disposal and industrial wastes.
From discharges of Chloro-alkali industries of Chittagong and Sylhet, through the rivers,the Karnaphuli
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
and the Surma, mercury comes to the Bay of Bengal. Nearly, one hundred and eighty tons of Hg is
introduced every year into the Indian environment alone (Chaudhury, 1980). Yearly 2.4 billion tons of
sediments (Holeman, 1968; Coleman, 1969 and Khan, 1978) are carried by the river system of
Bangladesh. Thus the high mercury level in the Bay of Bengal may be due to direct disposal of industrial
wastes or solid wastes dumped into the rivers of the subcontinent.
An
estimated value of Hg content in daily diet varies from 5 to 20 mg and may reach up to 100- 300 mg
in coastal areas (Sharif et al., 1993b). Fish can accumulate both organic and inorganic mercury in its
metabolic system and they are the natural sources of Hg to human being (Chovjka and Williams, 1980).
The total intake of Hg from other sources is negligible ( Clarkson, 1984; Turner
et al
., 1980).
People living to the coastal areas are directly or indirectly dependent on the resources of the sea. The
main objective of the present study is to know the level of mercury in the tropical fresh water fishes of
rivers, and from other water sources of Bangladesh, and to compare whether it is safer or not to health
.
MATERIALS AND METHODS
Samples of Collection
Fish samples -
Tenualosa Ilisha
,
Pangasius pangasius, Septinna phasa, Neopropius
atherinoides,Otolithoides pama , Puntius sarana
,
Ompok pabda, Sperata aor, Clarias batrachus,
Heteropneustes fossil ,Labeo rohita,
and
Catla catla
were collected from different fish markets of Dhaka,
Commilla,Chandpur,Chittagong,Sylhet,and
Khulna. Special precautions were taken during their
collection and preservation in containers so that these specimens were kept in good condition. Their
weights and sizes were recorded. The samples were cleaned and washed with demineralized water. Only
the flesh samples after removal internal organs, head, skin and tails, were taken out from the body. These
samples were sun-dried .The dried samples were then chopped into pieces with the help of a stainless
steel knife (steam cleaned). Only the edible muscle tissue samples were used for analysis.
The samples
pieces were dried at 105-110
o
C in an oven until a constant weight was obtained (dry weight) .The dried
samples were ground, sieved and thoroughly mixed in a stainless steel rotating drum for 100 hours to
produce homogeneous powders .These powder samples were finally preserved in clean and dry analysis
polythene bottles prior to analysis.
All the chemicals and reagents were of analytical grade.
2
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
Irradiation
Portions of the samples (200-300 mg each) were thermally sealed in polyethylene bags and
irradiated for
15 hours along with a known amount of MA-A-2™, the fish flesh homogenate standard of IAEA
(International Atomic Energy Agency)
in the TRIGA MARK II
reactor at AERE, Savar, Dhaka at a flux
of about (0.5 to 1.0) x10
12
n.cm
-2.
s
-1
.
Radiochemical Separation
The process for dissolution and chemical separation was the same as the process described
elsewhere (Sharif
et al
.1993b).
Counting
The samples and the standard were counted on a 125cm
3
HPGe detector connected to a 4096 pulse height
analyzer
PCA II MCA card. The energies (in keV) chosen for the evaluation of the peak areas were
[
197
Hg: t
1/2
(65 h)] Eγ = 69 and 77.3 keV. The minimum detection limit was one nanogram for mercury
for the total sample volume. The counting errors at the detection limits were around 7% .The blank
polyethylene bag did not show any measureable mercury content.
Accuracy and Precision
Experiments were initially carried out using a radioactive tracer and the corresponding carrier to evaluate
the recovery. The accuracy of the method was evaluated by analyzing the homogenate fish flesh (IAEA)
Standard Reference Material, MA-A-2 (TM). The mercury concentration was 0.45± 0.06-μg g
-1
and this
is in good agreement with the IAEA certified value (0.47±0.02 μg g
-1
).
RESULTS AND DISCUSSION
The concentration of mercury found in the samples of
fish has been shown in Table 1. Mercury
concentration was observed at the level 0.243
to 0.675 μg g
-1
in these samples. The highest concentration
(0.582-0.836±0.127 μ g g
-1
) is found in
Setipinna phasa
and the lowest (0.250-0.260±0.004 μg g
-1
)
Neopropius atherinoides
. It is observed that the level of Hg in fishes of fresh water origin is much lower
than that in other countries. A. comparison of mercury concentrations in some fresh water fishes available
in Bangladesh and West Bengal (India) (μg g
-1
dry weight basis
)
is shown in Table 2. A relationship
between the amount of mercury (μg g
-1
) and the number of fishes is shown in Figure 1.
3
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
Table.1. Mercury concentrations in different varieties of fresh water fishes of Bangladesh
(μg g-1 dry weight basis)
Type
of fish(Local
Names
In Bangladesh
Scientific names
Mercury
Mean
1.
Hilsa Shad
(Ilish)
Tenualosa ilisha
0.334-0.442±0.052
0.364
2.
Yellow tail catfish
(Pangas)
Pangasius pangasius
0.355-0.426±0.027
0.384
3.
Gangetic hairfish
Anchovy(Phasa)
Setipinna phasa
0.582-0.836±0.127
0.675
4.
Indian potasi
(Batashi)
Neopropius
atherinoides
0.250-0.260±0.004
0.253
5.
Pana croaker
(Poa)
Otolithoides pama
0.277-0.342±0.027
0.303
6.
Olive barb
(Shorputi)
Puntius sarana
0.22-0.44±0.11
0.35
7.
Pabo catfish
(Pabda)
Ompok pabda
0.230-0.264±0.015
0.243
8.
Long-whiskered
Catfish (Ayre)
Sperata aor
0.267-0.875±0.304
0.536
9.
Walking catfish
(Koi)
Clarias batrachus
0.246-0.344±0.042
0.295
10.
Air breathing fish
(Singh)
Heteropneustes fossil
0.288-0.320±0.016
0.299
11.
Ruhu
(Rui)
Labeo rohita
0.214-0.448±0.167
0.323
12.
Catla
(Katol)
Catla catla
0.250-0.340±0.045
0.303
Average:0.362 μg g
-1
Range: 0.243-0.675 μg g
-1
4
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
Table 2.Comparison of Mercury concentrations in some fresh water fishes available in Bangladesh and
West Bengal (India) (μg g
-1
dry weight basis
)
Type
of fish(Local
Names
In Bangladesh and India)
Scientific names
Mercury
(Bangladesh)
Mercury
(West Bengal,
India**
1.
Hilsa Shad
(Ilish)
Tenualosa ilisha
0.334-0.442±0.052
0.55-0.83
2.
Yellow tail catfish
(Pangas)
Pangasius pangasius
0.355-0.426±0.027
0.22-0.52
3.
Gangetic hairfish
Anchovy(Phasa)
Setipinna phasa
0.582-0.836±0.127
0.96-1.09
4.
Indian potasi
(Batashi)
Neopropius
atherinoides
0.250-0.260±0.004
0.25-0.42
5.
Pana croaker
(Poa)
Otolithoides pam
0.277-0.342±0.027
0.20-0.35
6.
Olive barb
(Shorputi)
Puntius sarana
0.22-0.44±0.11
0.48-0.60
7.
Pabo catfish
(Pabda)
Ompok pabda
0.230-0.264±0.015
0.20
8.
Long-whiskered
Catfish (Ayre)
Sperata aor
0.267-0.875±0.304
0.20-1.02
9.
Walking catfish
(Koi)
Clarias batrachus
0.246-0.344±0.042
0.28-0.40
10.
Air breathing fish
(Singh)
Heteropneustes fossil
0.288-0.320±0.016
0.20-0.47
11.
Ruhu
(Rui)
Labeo rohita
0.214-0.448±0.167
0.20-0.59
12.
Catla
(Katol)
Catla catla
0.250-0.340±0.045
0.20-0.59
5
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
________________________________________________________________________________
**Mercury in Fish : A Global Health Hazard, Mercury Policy Project, pp 1-51
ZeroMercury, February 2009 (Edward Groth III, PhD, Groth Consulting Services, Pelham, NY, USA)
_________________________________________________________________________________
Though the liver and kidney are usual organs for major concentrations of metals but mercury is
accumulated at higher level only in the muscle of fish (Peterson
et al
., 1973) and in its case
biomagnifications occurs through food chain.
The permissible limit varies a little bit from country to country. One proposed by FDA (Food and Drug
Administration) of the United States is 500 ppb. The mercury level in the present investigation is much
lower than this value. The trend of increasing concentration of Hg with increases in size of fish indicates
long time of its conservation in fish.
Estimation of Dietary Intake of Hg in Bangladesh
Average concentration of Hg found in the fish samples of various sources of fresh water, is 0.362 μg g
-1
.
Assuming Maximum average of fish consumption person
-1
day
-1
is 6-10 g dry fish for Chittagong and
6
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
1
2
3
4
5
6
7
8
9
10
11
12
Amt.OfHg(μgg^-1)
No. of fish
Figure 1
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
a coastal area of Bangladesh, the maximum Hg intake through fish is estimated to be 2.172-3.62 μg
person
-1
day
-1
. This value is well below the maximum acceptable level for human being (0.5 μg g-
1
wet
weight) (WHO, 1976: FAO/WHO, 1972-1987: Nauen, 1983: Denton
et a
l. ,1996: Hakanson
et a
l.,1988.
Similarly, 70 g dry per week would result in an intake of 25.34 μg of Hg which is also below the tolerable
limit (7.0 μg
kg
-1
body wt.day
-1
) of an about 70 kg man as suggested by WHO (1976).
CONCLUSION
The level of mercury reported here may be taken as a convenient baseline for determining future pollution
trends. Low Hg content observed in this study indicates that water from different sources has pollution
free and clean environment. So there is no danger to have these fishes for a Bangladeshi person.
Acknowledgement
The authors express thanks to Mr.K.R.Krishnamorti,
Analytical Chemistry Division, Bhava Atomic
Research Center, Trombay, India, for using the method, the radiochemical separation of trace metals in
biological samples, used in that Laboratory.
REFERENCES
Akielazek.J.J. and Haines,T.A.(1981). Mercury in the muscle tissue of fish from three northern marine
lakes,
Bull Environ. Contom.Toxically
, 27, pp. 201-208
Bacci,E.(1989) Mercury in the Mediterranean,
Mar.Pollute.Bull
. , 20(20,pp.59-63
Bjorklund, I., Borg, H. and Johanssson, K. (1981), Mercury in Swedish lakes, its regional distribution and
causes,
Ambio.
, 3, pp 118-121.
Chaudhury, N. (1980)
, Ind..Exp
., 48, p 9.
Chovjka,R. and Williams, R.J. (1980)
Aust.J.Mar.Fresh water Res
., 31, pp. 469-473.
Clarkson, T.W .(1984), Mercury, In: J.O.Nriagu (ed.)
Changing Metals Cycles and Human Health
,
Springer Vertag, Berlin, pp. 258-309.
Coleman, J.M. (1969) , Bhrahmaputra Rivers: Channel Processes and sedimentation,
Sedimentary
Geology
, Vol. 3(2-3), pp. 129-238.
Denton, G.R.W. and Burdon-Jones, C (1996), Trace
metals in fish from Great Barrier Reef
. Marine
.
Pollute. Bull.
30(5), pp. 201-209.
7
J.Nat.O.A.M.Institute Vol.24, No.2, 2007
FAO/WHO (1972-1987),
Joint FAO/WHO Expert Committee on Food Additives, Reports
505, 631, 696
and 751. World Health Organization, Geneva.
Hakanson, L., Nilsson, A. and Andersson, T.(1988), Mercury in fish in Swedish Laeks,
Environ Pollut
.,
49, pp. 145-162.
Holeman, J.N. (1968), The sediment field of major rivers of the world,
Water Resources research
, Vol.4
(4) pp. 737-747.
Khan.H.R. (1978) A
Study of Water Resources Development Activities in Bangladesh
. A report for Ford
Foundation, Dhaka, p. 87.
Lee,Y.H. and Hultberg, H.(1990), Methylmercury in some Swedish surface waters,
Environmental
Toxicology and Chemistry,
Vol. 9, pp.833-841.
Nauen, C.E.(1983) , Complication of legal limits for hazardous substances in fish and fishery products,
FAO Fish Cric
., 764.
Peterson, C.L., Klawe,W.K. and Sharp G.D.(1973),
Fish Bull
., 71. pp. 603-612.
Sharif, A.K.M., Mustafa, A.I., Amin.N.M. and Safiullah,S (1991).
Sci .Total Environ.,
107, pp. 135-142.
Sharif, A.K.M.,Mustafa,A.I., Mirza, A.H. and Safiullah,S.(1993a),
Sci. Total Environ.,
138, pp. 223-234.
Sharif. A.K.M., Alamgir, M., Krishnamoorty, K.R. and Mustafa, A.I. (1993b),
Nucl.Chem.,
170, pp.299-
307.
Turner, M.D., March, D.O., Smith, J.C., Inglics, J.B., J.B., Clarkson, T.W., Rubio, C.E., Chirboga, J. and
Chiriboga, C.C.(1980), Methylmercury in population eating large quantities of marine fish,
Arch.Evviron
.
Health
., 35, pp. 367-370.
WHO (1976) ,
Environmental Health Criteria, I-Mercury
, WHO, Geneva.
8
Les commentaires (1)
Écrire un nouveau message

17/1000 caractères maximum.

malamgir46

It is a research paper useful to those who work in this field.

vendredi 30 juillet 2010 - 17:38