Comparison between petroleum hydrocarbon concentrations and magnetic properties in Chennai coastal sediments, Bay of Bengal, INDIA

Petroleum hydrocarbon concentrations (PHC) of surface sediments along the Chennai coast, India, were measured by UV-Fluorescence (UVF) Spectroscopy and the results are expressed in terms of Chrysene equivalents. The concentration of PHC in sediment varies widely (from 1.88 ppm to 39.76 ppm) as compared to the baseline (1.88 ppm) with higher values obtained in the northern part of the study area. The highest magnetic susceptibility (96.8 × 10−8 m3kg−1) value was determined from the Chennai harbour area. The magnetic parameters show that the Chennai coastal sediments are dominated by ferrimagnetic minerals. The positive correlation (r2 = 0.86; p < 0.05) between petroleum hydrocarbon concentrations and magnetic susceptibility suggests that the magnetic minerals and petroleum hydrocarbons along the Chennai coast are derived from the same sources. Factor analysis shows that the magnetic concentration dependent parameters (χ, χARM and SIRM) covary with the petroleum hydrocarbon concentration, suggesting that large amounts of magnetic minerals originate from anthropogenic activities. It is evident that using magnetic measurements may be considered a simple, rapid, cheap and non-destructive method to determine petroleum hydrocarbon concentrations in coastal sediments. Furthermore, this technique may be applied to petroleum exploration studies. Magnetic susceptibility measurements in sediments have been proposed as complementary or alternative means of exploration and assessment of hydrocarbon reservoirs.