Food and Environment Safety - Journal of Faculty of Food Engineering, tefan cel Mare University - Suceava
Volume XI, Issue 3 – 2012

68

FISH POLLUTION WITH HEAVY METALS

*Camelia POPA1, Petru BULAI2

1 tefan cel Mare University of Suceava, Faculty of Food Engineering,
 camelia.popa@ fia.usv.ro

2Stefan cel Mare University of Suceava, Faculty of Mechanical Engineering, Mechatronics and Management,
Department of Technology and Management, 13 Universitatii Street, 720229 Suceava, Romania

bulaipetru@yahoo.com
*Corresponding author

Received 15 July 2012, accepted 20 August 2012

Abstract: The aim of this work is to identify and to find the concentration of some heavy
metals (Cr, Ni, Fe, Hg, Pb) of  different assortment of fish that we buy from markets: herring,
sprat, hake, pangasius, trout, broad snout, and mackerel. Heavy metal concentrations were
measured using EDX and UV-VIS spectrometer techniques. Laboratory studies showed that
these fishes don’t contain Ni, Hg, Pb. They contain only Cr and Fe but the concentration
don’t’ exceed the maximum admissible limit from current legislation. Also, heavy metals
content in bone is higher than in meat. Hake species do not accumulate heavy metals in meat,
but they accumulate in the bone, completely.

Keywords: heavy metals, fish, contaminants

1. Introduction

In heavy metal group there are a range of
chemical elements that have a great
toxicity for living organisms. The toxic
effect is manifested to overcome a certain
threshold  below  which  some  (Co,  Cu,  Fe,
Ni, Zn) may even be essential components
of proteins involved in different metabolic
pathways. Hevy metals are normally found
in environment and may come from
different pollutants, like nutrients or
burning combustible waste gases [1].
Heavy metal content is monitored in
environment and in foods. Toxicity of
heavy metals is the rezult of their binding
to important enzymatic systems from
animal cell or their membrane
[2]. Heavy metals discharged into the
environment eventually reach the living
bodies which in return behave as a filter
for them, meaning that they accumulate
[3]. Thus, if the food would be totally free
of metal it would appear nutritional

deficiencies. Heavy metals are found in
various concentrations in soil, water, air,
vegetable or animal food, depending on
various factors that determine their
pollution.
The good reputation of fish as healthy food
has distant origins, ancient. We know that
fish is good food for humans. It has
beneficial properties to the development of
intellect, because its constituents rich in
phosphorus and lecithin which is derived
from fish oil. In fish culture we meet
growth hormones, antibiotics, pesticides.
But the biggest concern that exists is in
connection with these contaminants, which
accumulate along the food chain. Fishes
cannot escape from the effects of these
pollutants [4]. Contamination with a wide
range of pollutants and heavy metals in
particular has become a serious problem
that has threatened this important source of
food: fish [5]. Heavy metals enter in living
organisms by ingestion, breathing and skyn
contact and produces intoxications by

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Food and Environment Safety - Journal of Faculty of Food Engineering, tefan cel Mare University - Suceava
Volume XI, Issue 3 – 2012

69

cumulative effect. They deposite in
organisms in various organs, muscles and
bones. Depending on environmental
contamination, fish can contain small or
large quantities of heavy metals.
Accumulation depends on the species, fish
age, sex, weight and its position in the food
chain: an old fish will contain a larger
amount of heavy metals than the yanger
one grown in the same conditions. A
predator fish will be contaminated in
,,pyramid” [6,7]. The aim of this work is to
identify  and  to  find  the  concentration  of
some heavy metals (Cr, Ni, Fe, Hg, Pb) of
different assortment of fish that we buy
from markets: herring, sprat, hake,
pangasius, trout, broad snout, and
mackerel.

2. Materials and methods

Materials. Different fish species from
markets: herring, sprat, hake, pangasius,
trout, and broad snout. Were performed in
parallel three samples of meat and fish
bones from the same type of fish and made
the average of determinations.
Sampling. For determinations were
weighted  on  analytical  balance  about  5  g
of each meat sample and 2 g of each bones
samples. Samples were dried in porcelain
crucible previously dried to constant
weight at 1050C. Drying and calcination
was made gradually on temperature ramp,
3 hours at 6000C. After calcination
samples were cooled in desiccator. To
solve the metals from ash was used HNO3
5% at boiling. Residue was filtered on
watman filter, washed with distilled water
and completed to 25 ml (solution 1).
Determination of iron. Iron were
determined according to SR ISO 805:1995
by spectrophotometric method [8].

Principle method: Fe3+ ions was
reduced to Fe2+ with hydroxyl amine
chlorohydrin in sodium acetate made with
1,10 phenanthroline, a complex that may
be measured at 510 nm.

Reagents and instruments: HCl for
analysis, acetic acid-sodium acetate buffer
for 4,4 pH, 5 g/L hydroxyl amine
chlorohydrin solution, 2,5g/L 1,10
phenanthrolin solution, 10 mg/L Fe2+
standard solution, UV-VIS
spectrophotometer UVI 1700 Schimadzu
model, 1 cm quartz cells.

Calibration curve:  was  draw
calibration curve for 0,1-0,8 mg/L Fe2+
field using FeSO4 7H2O certified reference
material, Figure1.

y = 0,2001x + 0,0857
R2 = 0,9904

0

0,05

0,1

0,15

0,2

0,25

0,3

0 0,2 0,4 0,6 0,8 1
mg/L

E

Figure 1.  Fe2+ calibration curve

Handling: a well defined part of
solution 1 was transferred into 100ml
volumetric flask, add 25ml buffer solution,
5ml of hydroxyl amine chlorohydrin
solution and 5 ml 1,10 phenanthrolin
solution and distilled water to sign. Blank
sample  was  prepared  in  the  same  way
using the same volumes of reagents. The
red complex was measured at 510 nm.

Results calculation:

100(%)

D
M
C

C
p

x
        (1)

were: Cx = Fe2+ concentration from
calibration curve; Mp = sample weight (g);
D = sample dilution. The report of the
components from sample was found using
EDX technique, normalization method.



Food and Environment Safety - Journal of Faculty of Food Engineering, tefan cel Mare University - Suceava
Volume XI, Issue 3 – 2012

70

3. Results and discussion

Among of different metals analysed are
classified as chemical hazards and
maximum residual levels have been
prescribed for human (EC 2001, FAO
1983). After EDX analysis of heavy metals
from fish for 5 chemical elements (Cr, Ni,
Fe,  Hg,  Pb    )  were  identified  and
measured the concentrations for two
elements  ,  Fe  and  Cr,   the  other  three
elements being in too small concentrations,
below the detection limit of the method.
Table  1  shows  the  results  obtained  for  Cr
and Fe. EDX technique shows the ratio of
the components in the sample. UV-VIS
technique shows the real percent of the
component in the sample. Knowing the
ratio of components in EDX analysis and
the real concentration of iron by
spectrophotometric technique was
calculated the real concentration of Cr.

)real(CrC
)real(FeC

)EDX(CrC
)EDX(FeC         (2)

The concentrations of heavy metals
detected in the samples are given in the
Table  2.  From  this  table  results  the
following conclusions: The types of fish
studied contain iron and chromium in
quantifiable concentrations. The high
content in heavy metals studied is
contained by broad snout meat and the
lowest, zero, it has meat hake. The high
chromium  content  is  found  in  broad  snout
and trout (meat). The high iron content
presents sprat and broad snout (meat).
Heavy metals content in bone is higher
than in meat. Hake species do not
accumulate heavy metals in meat, but they
accumulate in the bone, completely. The
concentrations of heavy metals studied
were lower than maximum admissible
levels [9,10]: Cr = 12 µg/g, Ni = 70 µg/g,
Pb = 0.3 µg/kg, Hg = 1 µg/kg.

Table 1.
Calculation of Fe and Cr concentrations

Species of fish Fe(µg/kg)
Cr

(µg/kg)

Mackerel 0.75 0.40

Sprat 1.02 0.40
Hake 0 0

Pangasius 0.37 0.19

Trout 0.93 0.63

Broad snout 1.21 0.64

Trout bone 1.06 0.56

Hake bone 2.86 1.71
Mackerel bone 0 0

0

0,2

0,4

0,6

0,8

1

1,2

1,4

Sprat Mackerel Hake Pangasius Trout Broad snout

Species

C
on

ce
n

tr
at

io
n 

of
 F

e 
an

d 
C

r,
 µ

g
/k

g

Fe
Cr

Figure 2. Fe and Cr meat content for the studied
types  of fishes

4. Conclusions

Water pollution is a major problem that
threatens an important source of food: fish
meat. From our studies we see that for the
studied species were identified only Cr and
Fe, the other elements being in
concentrations under the detection limit of
the analysis.
This  work  also  shows  that  heavy  metals
content for fish meat decreases in the order
broad snout, trout, sprat, herring, hake. The
high content of these heavy metals is for
broad snout meat and the lowest, zero, is



Food and Environment Safety - Journal of Faculty of Food Engineering, tefan cel Mare University - Suceava
Volume XI, Issue 3 – 2012

71

for meat hake. The high Cr content is
found in broad snout and trout (meat). The
high Fe content presents sprat and broad
snout (meat). Heavy metals content in
bone is higher than in meat and do not
exceed the quality rules to date: content in
Pb maximum 0.3µg/kg, Hg maximum
1µg/kg [10]

5. References

[1]. COJOCARU I., Sources, process and
pollution produscts,  Junimea Publishing,
Ia i, (1995)

[2]. POUILLY  M.,  PEREZ  T.,  REJAS  D.  et
al., Mercury bioaccumulation patterns in
fish from the Itenez river basin Bolivian
Amazon, Ecotoxicology and Environment
Safety, (83): 8-15, (2012)

[3]. WAKAR A., Levels of selected heavy
metals in Tuna fish, Arab J. Sci. Eng.,
(31): 89-92, (2004).

[4]. OLAIFA F.G., ONWUDE T.E., Lethal
and sublethal effects of copper to the
African Cat fish (Clarias gariepnuts), Afr.
J. Biomed. Res. (7): 65-70, (2004)

[5]. VELEZ D., MONTORO R., Arsenic
speciation in manufactured seafood
products, J. food. Protect. (9): 1240-1245,
(1998)

[6]. VINODHINI R., NARAYANAN M.,
Bioaccumulation of heavy metals in
organs of fresh water fish Cyprinus carpio,
J. Environ. Sci. Tech., (5), 179-182: (2008)

[7]. KENSOVA R., CELEKOCSKA O. et.al.,
Concentration of metals in tissues of fish
from the Zdenka Svobodova, Acta Vet.
Brno 79: 335-345, (2010)

[8].  SR ISO 805:1995, Iron content
determination. Spectrophotometric
methode with  1,10-phenantroline.

[9]. FAO, Compilation of legal limits for
hazardous substances in fish and fishery
products , FAO fishery circular 464: 5-
100, (1983)

[10].  FDA, Fish and Fisheries Products
Hazards and Controls Guidance, Centre
for Food Safety and Applied Nutrition, US
Food and Drug Administration, 3-edition,
(2001).