MERCURY CONCENTRATIONS IN TWELVE COMMONLY CONSUMED FRESH WATER FISH OF BANGLADESH

De
Publié par

Mercury concentrations in 12 commonly consumed fresh water have been determined by neutron activation analysis.

Publié le : jeudi 21 juillet 2011
Lecture(s) : 158
Nombre de pages : 7
Voir plus Voir moins
Journal of National Oceanographic, Atmospheric and Marine Institute
©
NOAMI
Vol.25, No.1, 2008
ISSN: 1027-2119
MERCURY CONCENTRATIONS IN TWELVE
COMMONLY CONSUMED
FRESH WATER
FISH OF BANGLADESH
A.K.M.Sharif
Bangladesh Atomic Energy Commission, Dhaka-1000, Bangladesh
M.Alamgir, Stanley A.Bajue and Rashed Alam
Department of Physical, Environmental and Computer Sciences
Medgar Evers College, CUNY, NY, U.S.A.
Abstract
:
Mercury levels in edible portion of some commonly consumed fresh water fish (12 varieties),
namely,
Chitala chitala, Cirrhinus cirrhous, Ctenophryngodon idella, Colisa fasciata, Cyprinus carpio carpio,
Glossogobius giuris, Hypophthalmichthus michthys molitrix, Labeo boggut, Monopterus cuchia, Ailia coila, Labeo
calbasu
and
Channa punctala
were determined by radiochemical neutron activation analysis (RNAA). The
results were found to range from
(
0.250-0.438
) μg g
-1
on dry weight, where four species had mercury
concentration, ( 0.250 -0.293)
μg g
-1
, four, ( 0.335-0.393) μg g
-1
, two, ( 0.407-0.413)
μg g
-1
,and the rest
one,0.500 μg g
-1
based the average values of
12 species of
fish. The total average value of all fish
samples is 0.359±0.063 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
INTRODUCTION
Bangladesh is a country through which a large number of big rivers, the Meghna, the Bhramaputra, the
Surma, the Karnaphuli and the Padma flow. A good number of small rivers also flow through this
country. Basically, it is a country of big and small rivers. Besides these rivers, there are lots of “Bills”,
“Howors”, “Khals”, ponds, water reservoirs, lakes, and submerged lands where water exists throughout
the year in this country.
Fish is collected from these big and small rivers. Fish is also available in the “Bills and Howors”,”Khals”,
lakes and ponds. Besides these sources, fish is produced and nourished in big water reservoirs, ponds,
lakes and submerged watery land.
Another most important source of fish is the Bay of Bengal.
Bangladesh has a large coastal belt.
J.Nat.O.A.M.Institute Vol.25, No.1, 2008
The Bangladeshis depend on rice and fish. The rich people of Bangladesh can purchase large types of fish
like “Rohi”, “Katla”,”Hilsha” “Chital”,”Kalibasu”, etc. The poor people cannot afford to purchase them.
They generally purchase small types of fish, like, “Tangra”, “Taki”,”Bele”, etc. Sometimes and
occasionally, they purchase medium sized fish varieties, low in price. In order to evaluate the
concentration of mercury in small and medium size fish specimens, this work was undertaken.
Mercury is one of the most toxic elements detrimental to man and other animals. Due to adverse effects
on them, much attention has been focused on the measurement of mercury in environment. The presence
of high concentration of mercury in river and marine organisms is well–documented [1-4]. Investigations
on
heavy metals in aquatic
ecosystems have recently got much attention and interest
in Europe,
Australia and North America, but few studies are available about the level of contamination, particularly
that of Hg in different types of fish from rivers, and of the Bay of Bengal. The reports [5-7] gave good
information on level of few metals including Hg in some river and marine fishes of the Bay of Bengal.
In the rivers and sea, mercury originates mainly from coal burning, weathering, sewage disposal and
industrial wastes. From discharges of Chloro-alkali industries of Chittagong and Sylhet, through the
rivers, the Karnaphuli and the Surma, mercury discharges to the Bay of Bengal. Nearly, one hundred and
eighty tons of Hg is introduced every year into the Indian environment alone [8]. Every year nearly, 2.4
billion tons of sediments [9-11] 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
rivers of the subcontinent, which ultimately comes to the Bay of Bengal. .
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 [7]. Fish can accumulate both organic and inorganic mercury in its metabolic system.
Various species of fish are the natural sources of Hg to man [12]. The total intake of Hg from other
sources is negligible [13-14].
Inhabitants near 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 mercury level in the commonly consumed fresh water
fish of rivers of Bangladesh, and to compare the results whether they are safe or not to health
.
MATERIALS AND METHODS
Samples of Collection
:
Fish samples-
Chitala chitala, Cirrhinus cirrhous, Ctenophryngodon idella, Colisa
fasciata, Cyprinus carpio carpio
,
Glossogobius giuris, Hypophthalmichthus michthys molitrix, Labeo boggut,
Monopterus cuchia, Ailia coila, Labeo calbasu
and
Channa punctala
were collected from different fish markets
of Dhaka, Commilla, Chandpur, Chittagong,Sylhet, Rajshahi 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 deionized 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).
2
J.Nat.O.A.M.Institute Vol.25, No.1, 2008
Only the edible muscle tissue samples were used for analysis.
The sample 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 a homogeneous
powder .These powder samples were finally preserved in clean and dry
polythene bottles prior to
analysis.
All the chemicals and reagents were of analytical grade.
Irradiation
Portions of the samples (200-300 mg each) were thermally sealed in polyethylene bags and
irradiated for
18 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 [7].
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
result is in good agreement with the IAEA certified value (0.47±0.02 μg g
-1
).
RESULTS AND DISCUSSION
In the
Table 1, Mercury concentrations in some commonly consumed fresh water fish of Bangladesh and
their comparison with those available in West Bengal (India) (μg g
-1
dry weight basis) are shown.
Average mercury concentration was observed in the level, 0.359± 0.063
μg g
-1
in these samples. The
highest concentration
(0.40-0.65)±0.108
μg g
-1
is found
in
Glossogobius giuris
and the lowest,
(0.22-
0.28)±0.026
μg g
-1
in
Cirrhinus cirrhous
. It is observed that the level of Hg in fishes of fresh water origin is
muc
h
lower than that in other countries. 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.25, No.1, 2008
Table 1.Mercury concentration in some commonly consumed fresh water fish of Bangladesh and their
comparison with those available in West Bengal (India) (μg g
-1
dry weight basis)
Sl.No.
Type
of fish(Local
Names
In Bangladesh)
Scientific names
Mercury
(Bangladesh)
Mean
Mercury
(West Bengal,
India)**
1
Clown knifefish
(Chital)
Chitala chitala
(0.35-0.40)
±0.0600
0.392
0.32-0.42
2
Mrigal
(Mrigal)
Cirrhinus cirrhous
(0.22-0.28)
±0.026
0.250
0.18-0.24
3
Grass carp
(Grass carp)
Ctenophryngodon
idella
(0.35-0.48)
±0.0562
0.407
0.32-0.47
4
Banded Bachcha
(Khailsha)
Colisa fasciata
(0.28-0.42)
±0.054
0.338
0.25-0.36
5
Common
crap(Common crap)
Cyprinus carpio
carpio
(0.22-0.35)
±0.056
0.283
0.25-0.32
6
Tank goby
(Bele)
Glossogobius
giuris
(0.40-0.65)
±0.108
0.500
0.48-0.69
7
Silver crap
(Silver crap)
Hypophthalmichth-
us michthys
molitrix
(0.22-0.38)
±0.072
0.293
0.19-0.32
8
Boggut labeo
(Ghonia)
Labeo boggut
(0.35-0.52)
±0.077
0.438
0.32-0.45
9
Cuchia
(Kuchia)
Monopterus cuchia
(0.32-0.42)
±0.044
0.365
0.28-0.35
10
Gangetic ailia
(Kajuli)
Ailia coila
(0.25-0.34)
±0.075
0.293
0.20-0.28
11
Organe-fin
(Kalibaus)
Labeo calbasu
(0.38-0.45)
±0.030
0.413
0.35-0.38
12
Spotted snakehead
(Taki)
Channa punctala
(0.22-0.46)
±0.101
0.335
0.17-0.41
Average:
0.359±0.063
Range: ( 0.22-0.65) μg g
-1
4
J.Nat.O.A.M.Institute Vol.25, No.1, 2008
**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 also
accumulated at higher level only in the muscle of fish [15] 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 water.
Estimation of Dietary Intake of Hg in Bangladesh
Average concentration of Hg found in the samples fish of fresh water origin is 0.359±
0.063
μg g
-1
.
Assuming maximum average of fish consumption person
-1
day
-1
is 6-10 g dry fish for various areas of
Bangladesh, the maximum Hg intake through fish is estimated to be (2.54-3.59) μg
person
-1
day
-1
. This
value is well below the maximum acceptable level for human being (0.5 μg g-
1
wet weight) [16 – 20]
Similarly,70 g dry fish per week would result in an intake of 25.13 μg of Hg which is also below the
tolerable limit (7.0 mg kg
-1
body wt.day
-1
) of an about 70 kg man as suggested by[20].
5
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
1
2
3
4
5
6
7
8
9
10
11
12
AmountofHg
Serial of Fish
Fig.1
J.Nat.O.A.M.Institute Vol.25, No.1, 2008
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 various types of fish are from pollution or
mercury contamination and come from clean environment. So there is no danger to have these fishes for a
Bangladeshi person.
Acknowledgement
The authors express thanks to Dr.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
[1] 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(1), pp. 201-208.
[2] Bacci,E.(1989) Mercury in the Mediterranean,
Mar. Pollute .Bull
. , 20(2), pp.59-63.
[3 ] Bjorklund, I., Borg, H. and Johanssson, K. (1984)
Mercury in Swedish lakes, its regional distribution and
causes,
Ambio.
, 13(2), pp 118-121
[4] Lee,Y.H. and Hultberg, H. (1990), Methylmercury in some Swedish surface waters,
Environmental Toxicology
and Chemistry,
Vol. 9, pp.833-841.
[5] Sharif, A.K.M., Mustafa, A.I., Amin.N.M. and Safiullah,S (1991),Trace metals in tropical marine fish
from the
Bay of Bengal,
Sci .Total Environ.,
107, pp. 135-142.
[6] Sharif, A.K.M., Mustafa,A.I., Mirza, A.H. and Safiullah,S.(1993a),Trace element concentrations in ten species
of freshwater fish of Bangladesh,
Sci. Total Environ.,
138, pp. 223-234.
[7] Sharif. A.K.M., Alamgir, M., Krishnamoorty, K.R. and Mustafa, A.I. (1993b), Determination of arsenic,
chromium, mercury, selenium and zinc in tropical marine fish,
Nucl.Chem.170
, pp.299-307.
[8] Chaudhury, N. (1980)
Increasing danger of mercury pollution,
Ind..Exp
., 48, p 9.
[9] Holeman, J.N. (1968), The sediment field of major rivers of the world,
Water Resources research
, Vol.4 (4), pp.
737-747.
[10] Coleman, J.M. (1969) , Bhrahmaputra Rivers: Channel Processes and sedimentation,
Sedimentary Geology
,
Vol. 3(2-3), pp. 129-238.
[11] Khan.H.R. (1978) A
Study of Water Resources Development Activities in Bangladesh
. A report for Ford
Foundation, Dhaka, p. 87.
[12] Chovjka, R. and Williams, R.J. (1980) Mercury levels in six species of Australian Commercial fish,
Aust. J.
Mar .Fresh water Res
., 31, pp. 469-473.
6
J.Nat.O.A.M.Institute Vol.25, No.1, 2008
[13] Clarkson, T.W .(1984), Mercury, In: J.O.Nriagu (ed.)
Changing Metals Cycles and Human Health
, Springer
Vertag, Berlin, pp. 258-309.
[14]
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.
[15 ] Peterson, C.L., Klawe,W.K. and Sharp G.D.(1973),Mercury in Tunas: A review,
Fish Bull
., 71. pp. 603-612.
[16] Hakanson, L., Nilsson, A. and Andersson, T.(1988), Mercury in fish in Swedish Laeks,
Environ Pollut
., 49, pp.
145-162.
[17] FAO/WHO (1972-1987),
Joint FAO/WHO Expert Committee on Food Additives, Reports
505, 631,683, 696
and 751. World Health Organization, Geneva.
[18] Nauen, C.E.(1983) , Complication of legal limits for hazardous substances in fish and fishery products,
FAO
Fish Cric
., 764.
[19] 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.
[20] WHO (1976) ,
Environmental Health Criteria, I-Mercury
, WHO, Geneva.
7
Soyez le premier à déposer un commentaire !

17/1000 caractères maximum.