522
G.G. Pandit et aI.
chemical and pesticide formulations. In order to project long-term risks and
ecological impact associated with the distribution of mercury in the environment, a study to determine total and methylmercury has been carried out in a
creek ecosystem near Bombay. This chapter describes the spatial profile of total
and methylmercury in the creek ecosystem based on the samples collected during
premonsoon (May) and postmonsoon (October) periods.
2
Experimental
2.1
Study Area
The Trans Thane creek is a part of Bombay Harbour Bay, which is connected
with the Arabian Sea in the south and the Ulhas river through Thane creek in the
north. The bay is subjected to diurnal tides, the range of tidal rise observed being
4.8 and 0.8 m. The Thane Belapur stretch, which is about 20 km long and 2 km
wide, encompasses a total area of about 2560 ha. The volume of tidal water on an
average is 4.8 x 10 8 m 3 (Pillai et al. 1958). Along the east and west sides of the
Thane creek, many industrial units have been established. The Thane creek,
which is the ultimate recipient of all the liquid discharges from the industries,
was monitored three times for total and methylmercury once during the pre- and
postmonsoon periods of 1994 and once during the premonsoon period in 1995.
The major industries located in the TTC industrial area are shown in Fig. 1, where
the area has been divided into four sectors: (A) Airoli; (B) Ghansoli; (C)
Koparkhairane and (D) Sanpada. The creek sampling locations such as
confluence points of canals (A, B, C, D) with the creek upstream (AI, Bl, Cl,
Dl), downstream (A2, B2, C2, D2) and midway points of the creek (A3, B3, C3, D3)
are also presented in Fig. 1.
2.2
Sample Collection
The creek water samples were collected about 0.2 km from the Airoli coast (A) as
well as 0.2 km on the other side (AI and A2). In addition, samples were also
collected at the midpoint of the section (A3). Similarly, water samples were also
collected at different locations of the coast such as Ghansoli, Sanpada and
Koparkhairane. Water samples were filtered immediately with 0-45-~m membrane filter paper in acid-cleaned polythene bottles containing concentrated
nitric acid with concentration adjusted to 0.5% nitric medium. Prior to collection
of field samples, the acid-cleaned polythene bottles were tested for blank mercury
contents. The bottles were filled with 0.5% HN0 3 overnight and known aliquots
were used for blank evaluation. The 0.5% HN0 3 solutions showed no mercury
G.G. Pandit et aI.
chemical and pesticide formulations. In order to project long-term risks and
ecological impact associated with the distribution of mercury in the environment, a study to determine total and methylmercury has been carried out in a
creek ecosystem near Bombay. This chapter describes the spatial profile of total
and methylmercury in the creek ecosystem based on the samples collected during
premonsoon (May) and postmonsoon (October) periods.
2
Experimental
2.1
Study Area
The Trans Thane creek is a part of Bombay Harbour Bay, which is connected
with the Arabian Sea in the south and the Ulhas river through Thane creek in the
north. The bay is subjected to diurnal tides, the range of tidal rise observed being
4.8 and 0.8 m. The Thane Belapur stretch, which is about 20 km long and 2 km
wide, encompasses a total area of about 2560 ha. The volume of tidal water on an
average is 4.8 x 10 8 m 3 (Pillai et al. 1958). Along the east and west sides of the
Thane creek, many industrial units have been established. The Thane creek,
which is the ultimate recipient of all the liquid discharges from the industries,
was monitored three times for total and methylmercury once during the pre- and
postmonsoon periods of 1994 and once during the premonsoon period in 1995.
The major industries located in the TTC industrial area are shown in Fig. 1, where
the area has been divided into four sectors: (A) Airoli; (B) Ghansoli; (C)
Koparkhairane and (D) Sanpada. The creek sampling locations such as
confluence points of canals (A, B, C, D) with the creek upstream (AI, Bl, Cl,
Dl), downstream (A2, B2, C2, D2) and midway points of the creek (A3, B3, C3, D3)
are also presented in Fig. 1.
2.2
Sample Collection
The creek water samples were collected about 0.2 km from the Airoli coast (A) as
well as 0.2 km on the other side (AI and A2). In addition, samples were also
collected at the midpoint of the section (A3). Similarly, water samples were also
collected at different locations of the coast such as Ghansoli, Sanpada and
Koparkhairane. Water samples were filtered immediately with 0-45-~m membrane filter paper in acid-cleaned polythene bottles containing concentrated
nitric acid with concentration adjusted to 0.5% nitric medium. Prior to collection
of field samples, the acid-cleaned polythene bottles were tested for blank mercury
contents. The bottles were filled with 0.5% HN0 3 overnight and known aliquots
were used for blank evaluation. The 0.5% HN0 3 solutions showed no mercury