Abstract:
Heavy metals affect the ecosystems through bioaccumulation and bio-magnification
processes. Studies done elsewhere showed contamination of coastal sediments with heavy
metals. However, information available on this aspect in India is sparse. As such studies are
useful in assessing the pollution status of coastal areas, the present study was undertaken.
Sediment samples were collected onboard Sagar Sampada using Smith- McIntyre grab
along seven transects at the depths of 30 m, 50 m, 75 m, 100 m, 150 m and 200 m. The
pollution status was assessed using heavy metals such as cobalt, copper, iron, manganese,
nickel, lead, mercury and zinc employing the method of Walting. The mean concentration
of mercury recorded only in Cuddalore SIPCOT was 0.01 ± 0.01 ppm (30 m depth). The
contamination factor and the geo-accumulation index revealed the uncontaminated nature
of shelf except mercury which showed moderate contamination at Cuddalore – SIPCOT at
30 m depth (0.0365). This is attributed to industrial activities here. The study concluded that
the continental shelf of southeast coast of India except Cuddalore-SIPCOT is generally free
from heavy metal pollution. However the nearby coastal areas (< 30 m depth) needs constant
monitoring to avoid ecological disasters. A detailed study is needed over the entire coast
covering riverine and non-riverine areas to determine the role of rivers in determining the
heavy metal levels in the continental shelf area.
