Distribution of Total and Methyl Mercury in a Creek Ecosystem Near Bombay
527
Table 2. Concentration of total mercury and methylmercury in sediment sal?ples collected at TTCA in
may 1995
Serial
Location
Concentration of mercury (ng/g d.w.)"
Methyl
number
mercury (0/0)
Total
Methyl
I.
Airoli
Top layer
1600
46.8
2.8
15 cm
811
n.d.
2.
Ghansoli
Top layer
2140
65.5
3.1
15 cm
21.5
n.d.
3.
Koperkhairane
Top layer
75
5.9
7.8
15 cm
64.7
n.d.
n.d: not detected.
"Percentage of moisture ranged from 58-62.
Table 2 gives concentrations of total mercury and methylmercury in sediment
samples collected from the TTC area during May 1995. The sediments from
Ghansoli and Airoli showed high concentrations of Hg in the topmost segment,
indicating the possibility of a mercury source in the nearby region. The level of
total mercury and methylmercury at Koparkhairane showed very low concentration. Percentage of methylmercury to total mercury ranged from 2.8% (Airoli)
to 7.8% (Koparkhairane) indicating more biological activity at Koparkhairane
Oha et al. 1996). The high values of total mercury in sediment samples may be
attributed to the presence of clay material (48-65%) with a mean grain size of 29 ~Lm, and the presence of montmorillonite with a minor amount of kaoliniteand illite-type minerals.
Several fish used for consumption by the local inhabitants were analyzed for
total and methylmercury. Table 3 summarizes the concentrations of total
Table 3. Concentrations of total mercury and methylmercury in various types of fish samples
collected May 1995 in the Trans Thane Creek area
Serial
Species
Biological name
Concentration of mercury
Methyl
number
(ng/g d.w.)"
mercury
(0/0)
Total
Methyl
I.
Boi
Mungil dusumieri
62.5
20.4
32.6
2.
Black fish
Tilapia mossambique
137.5
80.2
50.3
3.
Red prawn
Metapaenpios affinis
67.8
42.3
62.4
4.
Cat fish
Macrones vitattus
176.1
123.0
70.0
5.
Prawn
548.1
310.1
56.5
6.
Salpa
154.4
94.2
61.0
7.
Dhoma
Sciaena
84.1
60.5
72.0
8.
Mudskipper
Boleophthalmas
109.2
50.9
46.6
9.
Crab
352.4
344.4
97.0
"Percentage of moisture ranged from 60-70.
527
Table 2. Concentration of total mercury and methylmercury in sediment sal?ples collected at TTCA in
may 1995
Serial
Location
Concentration of mercury (ng/g d.w.)"
Methyl
number
mercury (0/0)
Total
Methyl
I.
Airoli
Top layer
1600
46.8
2.8
15 cm
811
n.d.
2.
Ghansoli
Top layer
2140
65.5
3.1
15 cm
21.5
n.d.
3.
Koperkhairane
Top layer
75
5.9
7.8
15 cm
64.7
n.d.
n.d: not detected.
"Percentage of moisture ranged from 58-62.
Table 2 gives concentrations of total mercury and methylmercury in sediment
samples collected from the TTC area during May 1995. The sediments from
Ghansoli and Airoli showed high concentrations of Hg in the topmost segment,
indicating the possibility of a mercury source in the nearby region. The level of
total mercury and methylmercury at Koparkhairane showed very low concentration. Percentage of methylmercury to total mercury ranged from 2.8% (Airoli)
to 7.8% (Koparkhairane) indicating more biological activity at Koparkhairane
Oha et al. 1996). The high values of total mercury in sediment samples may be
attributed to the presence of clay material (48-65%) with a mean grain size of 29 ~Lm, and the presence of montmorillonite with a minor amount of kaoliniteand illite-type minerals.
Several fish used for consumption by the local inhabitants were analyzed for
total and methylmercury. Table 3 summarizes the concentrations of total
Table 3. Concentrations of total mercury and methylmercury in various types of fish samples
collected May 1995 in the Trans Thane Creek area
Serial
Species
Biological name
Concentration of mercury
Methyl
number
(ng/g d.w.)"
mercury
(0/0)
Total
Methyl
I.
Boi
Mungil dusumieri
62.5
20.4
32.6
2.
Black fish
Tilapia mossambique
137.5
80.2
50.3
3.
Red prawn
Metapaenpios affinis
67.8
42.3
62.4
4.
Cat fish
Macrones vitattus
176.1
123.0
70.0
5.
Prawn
548.1
310.1
56.5
6.
Salpa
154.4
94.2
61.0
7.
Dhoma
Sciaena
84.1
60.5
72.0
8.
Mudskipper
Boleophthalmas
109.2
50.9
46.6
9.
Crab
352.4
344.4
97.0
"Percentage of moisture ranged from 60-70.