The concentration of heavy metals Arsenic (As) and Chromium (Cr) in hepatopancreas, gills, muscle and whole body of crab, Barytelphusa guerini was carried out during different seasons summer, monsoon and winter in order to ascertain the pollution status of the river. The results showed varying levels of accumulation of Arsenic and Chromium in the crab. The level of As in muscle, gills, hepatopancreas and whole body in summer, monsoon and winter seasons was found that higher than the recommended maximum allowable standards in food. Where as Cr level in muscle and gills in summer seasons, hepatopancreas and whole body in monsoon and muscle and whole body in winter season were higher than the recommended maximum allowable standards in food. The level of Cr in muscle (monsoon), gills (monsoon and winter), hepatopancreas (summer and winter) and whole body (summer) were lower than the standards. The results suggest that the Godavari river system is contaminated with heavy metals.
Keywords |
| Heavy metals, Pollution, Bioaccumulation |
INTRODUCTION |
| Bio-concentration is the net accumulation of a substance from water into an
aquatic organism resulting from the simultaneous uptake and elimination of
the substance. Fish, crab, bivalve molluscs etc are used in bioaccumulation
tests because they are higher tropic level organisms and are usually eaten by
man. Tissues such as liver, kidney, muscle, viscera and whole organisms are
analysed to determine the concentration of the metals Dublin-Green (1994).
In an attempt to define and measure the effects of presence of pollutant on
aquatic system, biomarkers have attracted a great deal of interest. The principle
behind the biomarker approach is the analysis of organisms for their metal
contents in order to monitor the excess metals in their tissues. The various
aquatic organisms living in rivers, lakes and sea are potentially useful as biomarker
of metals pollution, they include fish, shellfish, oyster, crabs, mussels,
clams, aquatic animals and plants Khallaf et al. (1994), Magliette et al. (1995)
and Stewart et al. (1997). |
| Increase in metal concentration from different sources is a result of increasing
metal pollution in the rivers and its accumulation in aquatic organisms and
their edible tissues. Many workers demonstrate that metal concentrations in
aquatic organisms are higher than in water, which indicates the bioaccumulation.
They studied on the transfer of metals through the trophic food chain
Kalfakakon et al. (2000), Subrahmanyam et al. (2001) and Gary (2002). |
| Crabs is important food item and source of protein to man. Since there is no
formal control of effluent discharge from industries and homes into the river,
it is important to monitor the levels of metals in the reservoir in comparison.
The concentration of Arsenic and Chromium were measured in the gills,
muscle, hepatopancreas, and whole body of crabs in order to assess the food
consumption safety. It could also establish a baseline for future studies of
heavy metal pollution. |
Materials and Methods |
| Healthy uniform size adult crabs, Barytelphusa guerini were collected from
the Godavari river near Aurangabad. The crabs were collected every season
for a period of one year from February-2005 to January-2006.The crabs were
brought to the laboratory and placed in fresh river water for few hours to
remove mud. Hepatopancreas, Gills and Muscle were dissected out from these
crabs. These tissues separated from crabs were taken into petridishes and kept
in a hot air oven maintained at 600C for a period of 48 –72 hours. The heavy
metals concentrations were analyzed from these tissues and whole body.
Heavy metal like Arsenic and Chromium were estimated by using standard
methods as described by APHA (1998). |
Digestion of Crab Tissues |
| The samples were digested in open beakers on a hot plate. 0. 5 gm of each
organ was weighed out in an open beaker and allowed to digest by adding
nitric acid and perchloric acid in (4:1) ratio. Kept on hot plate and the temperature
gradually allowed to rise to 60o C continue adding both acids in (4:1) ratio till the sample become colourless. The digested sample were allowed
to cool and transferred to 25 ml volumetric flasks and made up to mark with
de-ionised water. The digests were kept in plastic bottles and later the heavy
metal concentrations was determined using an atomic absorption spectrophotometer
(AAS). The actual concentration of each metal was calculated
using the formula: |
 |
ResultS and Discussion |
| The estimation of heavy metal in different tissue like muscle, gills, hepatopancreas
and whole body of crab, Barytelphusa guerini was carried out different
seasons summer, monsoon and winter in a year. The samples were analysed and contents of heavy metals were detected in order to know the concentration
of these metals in crab tissues. The results are given in Table 1& 2 and
illustrated in Figure (1 and 2). |
| In the present investigation it was found that Arsenic (As) in muscle it
varied from 1.37 ppm in winter to 1.17 ppm in summer. In gills it varied from
1.38 ppm in winter to 1.12 ppm in summer. In hepatopancreas it varied from
1.37 ppm in winter to 1.31 ppm in monsoon. In whole body it varied from
1.28 ppm in monsoon to 1.26 ppm in winter. From all the tissue, maximum
concentration i.e. 1.38 ppm of arsenic was recorded in gills in winter. However
minimum concentration was observed i.e. 1.12 ppm in gills in summer. In all
the tissues arsenic content in crab sample from Godavari river exceeded from
Indian standard limit of 1.1 mg/kg in food Awashthi (2000). |
| Arsenic biogeochemical cycle occurs mostly in the aquatic environment and
its bioaccumulation is an important ecotoxicological aspects. Inorganic arsenic
produce acute, sub acute and chronic toxic effects, which may be either local
or system. Acute toxic effects include abdominal cramping, hypersthesia in
extremities, abdominal patellar reflexes and abdominal electrocardiograms.
Other effects of arsenic include peripheral vascular disturbances resulting in
gangrene and a disease termed Black foots disease Rajesh and Agrawal (2005).
In the present study it was found that Chromium (Cr) in muscle it varied
from 26.25 ppm in summer to 17.00 ppm in monsoon. In gills it varied from
28.75 ppm in summer to 10.62 ppm in winter. In hepatopancreas it varied
from 23.33 ppm in monsoon to 16.12 ppm in winter. In whole body it varied
from 24.20 ppm in winter to 16.50 ppm in summer. From all the tissue,
maximum concentration i.e. 28.75ppm of chromium was recorded in gills in
summer. However minimum concentration was observed i.e. 10.62 ppm in
gills in winter. |
| Chromium (Cr) level in muscle and gills in summer seasons, hepatopancreas
and whole body in monsoon and muscle and whole body in winter season were higher than the recommended maximum allowable standards
in food. The level of Cr in muscle (monsoon), gills (monsoon and winter),
hepatopancreas (summer and winter) and whole body (summer) were lower
than the Indian standard limit of 20.00 mg/kg. |
| Obasohan et al. (2006) studied the heavy metals concentrations in two
tropical fish species, Malapterurus electricus and Chrysichthus nigrodigitarus
from Ogba river in Benin city, Nigeria. It was found that the level chromium
in both fishes were higher than the world health origination (WHO) recommended
maximum allowable standards in food fish. |
| The harmful effects of chromium to human are mostly associated with its
hexavalent form. Chromium toxicity includes liver necrosis, nephrites and
gastrointestinal irritation Athar and vohora (1995). |
| Therefore, special attention should be given to the water quality and bioaccumulation
of metals (arsenic and chromium) in crab, Barytelphusa guerini.
In present investigation it was found that the level of arsenic and chromium
in some tissues crab, Barytelphusa guerini were higher than the recommended
maximum allowable standards in food. These results suggested that the Godavari
river system was contaminated with heavy metals and the consumption
of crab of the river could pose heath hazards to man. It is also suggested that
Barytelphusa guerini may be useful as a potential indicator of metal pollution,
but it should be remembered that there is no certainty that the metal concentration
in the environment will be accurately reflected in the tissue of the crab,
for there exists a degree of regulation and elimination of metal in the body of
Barytelphusa guerini. |
Tables at a glance |
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| Table 1 |
Table 2 |
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Figures at a glance |
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| Figure 1 |
Figure 2 |
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References |
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- Athar, M. and Vohora, S.B. 1995. Heavy metals and environment. In : Man and Environment Series (Ed. P.K.Ray) Wiley Easton Ltd. New Delhi, pp. 1-195.
- Awashthi, S.K. 2000. Prevention of Food Adulteration Act No. 37 of 1954 Central and State Rules as Amended for 1999, 3rd edition.Ashoka Law House, New Delhi.
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