Paper Title: A Study of Marine Sediments at Mumbai High Offshore Oil Field, India

摘要

Heavy metals can be termed as conservative pollutants, introduce into the aquatic systems as a result of the weathering of soils and rocks, from under water volcanic eruption and other anthropogenic activities. Thereby it changes the natural concentration of metals in seawater resulting in a ten or even hundred fold increase near the source of an effluent discharge. While some metals like manganese (Mn), copper (Cu), iron (Fe) and zinc (Zn) are biologically important for marine life, others like lead (Pb), mercury (Hg), Barium (Ba), Nickel (Ni) and chromium (Cr) are non-essential and become toxic at higher concentrations. Associated to particulate matters, heavy metals tends to stay in solution for a very long time, but they will end up in the sediments, therefore concentrations in the sediments are often higher than those in solution. In the sediments, these particles may form an important secondary source of contamination, even after the primary source has disappeared. Similarly petroleum is one of the top priority pollutants in the ocean. In aquatic system, petroleum hydrocarbon may partly assimilate or partly absorbed on suspended solids whereby it can sink down to bottom. Water column being mobile in nature, analysis of sea sediments can become an important module for environment impact analysis. As oil exploration is having the potential to accumulate heavy metal and petroleum hydrocarbon in sea sediments, the paper focuses on analysing non-essential heavy metals like Chromium, Nickel, Barium and Lead along with petroleum hydrocarbon content in sea sediments around offshore oil field of Mumbai High. A trend analysis of the above metals and PHC has been made in sea sediments around the oil field from the period of 1994 to 2010. It is concluded that the oil field activity in the western offshore has not make any significant impacts on the marine sediments by these metals and petroleum hydrocarbon.